In layers, a direct relationship between dietary protein level and nitrogen excretion, as well as better utilization of protein, has been reported, when hens were fed diets with lower protein concentrations than the requirements [31]. However, a reduction in the dietary concentration of protein may result in imbalance of amino acid concentrations and may also change the optimal requirements of the limiting amino acids (lysine and methionine) at lower dietary protein levels. Taking steps to correct factors that may have triggered poor performance measured in terms of some parameters in layers may yield encouraging results. There are indications that the resultant lowering effect of nitrogen output in broilers fed low-protein diets appeared to be less effective as the quantum of reduction in dietary protein increased [30]. Therefore, to minimize performance losses of broilers fed low-CP diets while at the same time maintaining a significant reduction in environmental risks resulting from nitrogen excretions, there is a limit to which dietary protein could be reduced [32, 33].

**Table 8.** Effects of feeding low-CP diets on nitrogen output of chickens.

#### *5.1.2. Undesirable effects of feeding low-protein diets to watch out for in chicken production*

[26]. This helps to obtain a balance of dietary amino acids closer to the animal's requirements. Feeding low-protein diets may therefore enable a farmer to cut down on the cost of the diet depending on the constituents of the feed while at the same time reducing nitrogen loss and its attendant environmental challenges. Formulating complete diets for specific amino acids rather than crude protein content can reduce the oversupply of amino acids provided in most protein-rich feedstuffs, thereby reducing nitrogen excretion (**Table 8**). Reduced nitrogen excretion and anthropogenic propensity without compromising animal performance have

In layers, a direct relationship between dietary protein level and nitrogen excretion, as well as better utilization of protein, has been reported, when hens were fed diets with lower protein concentrations than the requirements [31]. However, a reduction in the dietary concentration of protein may result in imbalance of amino acid concentrations and may also change the optimal requirements of the limiting amino acids (lysine and methionine) at lower dietary protein levels. Taking steps to correct factors that may have triggered poor performance measured in terms of some parameters in layers may yield encouraging results. There are indications that the resultant lowering effect of nitrogen output in broilers fed low-protein diets appeared to be less effective as the quantum of reduction in dietary protein increased [30]. Therefore, to minimize performance losses of broilers fed low-CP diets while at the same time maintaining a significant reduction in environmental risks resulting from nitrogen excretions, there is a limit to which dietary protein could be

**Protein level N-related parameter Level of reduction in N-related**

Nitrogen output intensity

Nitrogen output intensity

Nitrogen output intensity

Nitrogen output intensity

Nitrogen output intensity

Broiler 16–20% Nitrogen output 49.2–65.6%

Broiler 20–22% with met. + Lys. Nitrogen output 16–38%

Broiler 20% + enzymes supplementation Nitrogen output 25.8–35.1%

Laying hens 11.5–17.5% Nitrogen output 26.6–36.3%

Laying hens 13.5% + enzymes supplementation Nitrogen output Similar

**Table 8.** Effects of feeding low-CP diets on nitrogen output of chickens.

**parameters**

12.50–45.83%

18.75–40.63%

37.5–43.8%

20.0–33.3%

12.5–43.7%

been demonstrated for this approach [27].

52 Animal Husbandry and Nutrition

reduced [32, 33].

*Sources*: Based on [28–30].

**Type of chicken**

Feed intake is one of the areas in which some marked differences in the response of birds to low dietary protein has been observed when compared with those on higher dietary protein regime. Effects of low dietary protein levels on feed intake of birds have some degree of variation which could range from no effects on consumption to higher or depressed feed intake. Reduced or increased feed intake in chickens fed low-protein diets is desirable if accompanied with similar or improved performance per unit input when compared with birds fed high protein diets. However, it calls for concern if it leads to poor performance in the birds. Suspected factors contributing to cases of lower feed intake in birds fed low-protein diets have been identified. These include increased methionine level, ambient temperatures, extent of reduction of CP contents, change in dietary net energy concentration and protein ratio, the class and age of birds, and the extent to which the intact protein sources are kept at constant ratios to minimize amino acid imbalance [34–36].

Feeding low-protein diets could result in a wide range of response on different production and economic performance parameters. These could range from lowering, neutral, and/or raising effect on some critical parameters such as growth, feeding intake, carcass yield, egg production, egg weight, and feed efficiency. A similar performance between birds fed lowprotein diets and those fed higher levels may be considered a desirable development particularly if it translates to lower cost of production and lower feed conversion ratio [28]. However, there is a limit to which dietary protein could be reduced without any adverse effects on the performance of the birds. This means that dietary protein should not be increased or lowered arbitrarily but care must be taken to ensure that the physiological and other requirements of the birds are met by the adopted feed regime to guide against negative impact on performance, profit, and the environment.

#### *5.1.3. Some issues of and corrective measures for undesirable effects of feeding low-protein diets in chicken production*

Some reasons alluded for poor performances of birds fed low-protein diets, which provides a level of insights for providing corrective measures for sustainability. This includes:

diets must match the requirements for the stage of growth of the birds in order to optimize the performance. In other words, reduction in crude protein must not be excessive but kept within reasonable limits that do not negate the performance of the birds while retaining the environmental benefits. Ref. [34] indicated that egg weight increased when dietary protein level was increased from 15 to 16.5% during the early laying phase. They reported that on the basis of egg weight, body weight, and feed efficiency data, 15% CP is adequate for layers during the entire laying cycle of 21–72 weeks of age.

**5.2. Manure management strategies for reducing nitrogen emissions in chicken**

One of the most important aims of manure management is possibly ensuring the loss of nutrients is prevented or kept at the minimum in the manure chain. The manure chain is the period from collection to storage, treatment, and application for feed production. Handling chicken manure in an environmentally sustainable way would help realize its value as a nutrient resource for crops and as a feedstock for renewable energy. Emissions at the various stages of manure management could be tackled in animal house, during storage, processing, and application/discharge. Thus, instead of losing nutrients into the environment, efforts should be directed at keeping them in the food and/or feed chain where they could enhance crop growths and contribute to significant reduction in the use of inorganic fertilizers. Sustainable manure management will contribute to household food security and income, improvement in agricultural production, reduction in public health risks, reduction in environmental pollution and greenhouse gases emissions, and decelerate global warming. Although several approaches and technologies are available to achieve this goal, unsustainable manure management practices are still very prevalent in some countries. Some of these unsustainable manure management practices include direct application and indiscriminate disposal of manure such discharge into water bodies, burning or open dumping and indiscriminate land application. Lack of relevant policies and/or regulations, as well as nonenforcement of some of the relevant available policies or regulations, are among the major contributor to unsustainable manure management practices. Ref. [5] provided some valuable information or tips that would contribute to handling and managing manure in such a way that keeps the nutrients intact as much as practicable. Some of these are highlighted

Nitrogen Emissions and Mitigation Strategies in Chicken Production

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55

*Collection point*: This could be in the barn or the house of the animal. The type of chicken management system affects the form in which the manure is handled. While manure is mostly in solid state in chickens raised on floor, it is in the wet form in layers raised in cages. It is critical to ensure that the animal housing allows for ease of manure collection and prevents losses. Consequently, the floor should be waterproof and covered against the rain to prevent losses

*Manure storage*: Manure storage could be indoor or outdoor, and it is essential to ensure the nutrients are intact from the period of collection to application. Manure could also be stored either in dry or liquid form. Liquid storage could be in lagoons which can be covered or open. More nitrogen losses occur in open than in covered lagoon. It is important to store manure properly to ensure optimal application. It is therefore advisable to provide cover for the manure in outdoor storage. Storage roofing will prevent losses into the soil and water through leaching, run-off. Providing a storage facility that is air-tight will also prevent losses through volatilization. There are some marked differences in the major gaseous losses depending on the state in which the manure is stored. Nitrogen volatilization from chicken manure occurs mainly in the form of ammonia, nitrous oxide, and nitrogen gas in dry storage. However, nitrogen could be lost to the environment through leaching when there is contact with water. Apart from nitrogen, other nutrients in the manure could also find their way

through nutrient volatilization, run-off, and leaching.

**production**

below:

#### *5.1.4. Cobenefits of feeding low-protein diets to chickens*

Some co-benefits have been observed when reductions in dietary protein are kept within the limits that do not adversely affect the performance of the chicken. One of the cobenefits of feeding low-CP diets to chicken is perhaps better utilization of protein.

Another cobenefit of feeding low dietary protein is reduced cost of production per unit of product (egg or meat) especially when reduction in offered protein level is kept within limits that will not adversely affect performance. Economic returns of chickens during the starter phase could be improved by increasing the amino acid density of the diets.

Significant reduction in excretion of nutrients other than nitrogen in chickens fed low dietary proteins could be of immense benefits to the environment and the producers [43]. Lowprotein diets are also a potential means of reducing mineral excretions, such as phosphorus, calcium, magnesium, potassium, sodium, manganese, zinc, and copper, and lead in poultry production [43, 44].

Lowered amount of excreted nitrogen (including NH3 ) contributes to reductions in potentially offensive odor and pollution from broiler production facility [45]. Quantitative reduction in nitrogen output with lower dietary protein could imply reduction in risk for the environment due to significant reduction in the amount of fecal nitrogen available for conversion to ammonia and nitrous oxide and eventual release into the atmosphere.

#### **5.2. Manure management strategies for reducing nitrogen emissions in chicken production**

diets must match the requirements for the stage of growth of the birds in order to optimize the performance. In other words, reduction in crude protein must not be excessive but kept within reasonable limits that do not negate the performance of the birds while retaining the environmental benefits. Ref. [34] indicated that egg weight increased when dietary protein level was increased from 15 to 16.5% during the early laying phase. They reported that on the basis of egg weight, body weight, and feed efficiency data, 15% CP is

**iii.** Altered ionic imbalance owing to lower potassium levels in the diets particularly when soybean meal is reduced in the diet [39]. Ref. [40] reported that FCR and egg production were significantly improved in the low-protein diet group with high electrolyte balance. This suggests that correcting some of the factors responsible for inferior performance of low-protein diets in hens could lead to additional benefits in form of improvement in

**iv.** Deficiencies or Inadequate intake of some amino acids has been implicated for poor performance in terms of egg weight and/or egg mass and body weight gain in chickens fed low-protein diets [41]. There are cases of recovery or better performance of the birds with

**v.** Use of low-quality feedstuffs and/or inadequate utilization of some components of the supplied diets. A wide range of enzymes have been used to correct some of the performance deficiencies and/or even lead to some superior performance in chicken supplied

Some co-benefits have been observed when reductions in dietary protein are kept within the limits that do not adversely affect the performance of the chicken. One of the cobenefits of

Another cobenefit of feeding low dietary protein is reduced cost of production per unit of product (egg or meat) especially when reduction in offered protein level is kept within limits that will not adversely affect performance. Economic returns of chickens during the starter

Significant reduction in excretion of nutrients other than nitrogen in chickens fed low dietary proteins could be of immense benefits to the environment and the producers [43]. Lowprotein diets are also a potential means of reducing mineral excretions, such as phosphorus, calcium, magnesium, potassium, sodium, manganese, zinc, and copper, and lead in poultry

offensive odor and pollution from broiler production facility [45]. Quantitative reduction in nitrogen output with lower dietary protein could imply reduction in risk for the environment due to significant reduction in the amount of fecal nitrogen available for conversion to ammo-

) contributes to reductions in potentially

adequate for layers during the entire laying cycle of 21–72 weeks of age.

the supplementation of the diets with the limiting amino acids [42, 43].

with low-protein diets compared with those on higher levels (**Table 8**).

feeding low-CP diets to chicken is perhaps better utilization of protein.

phase could be improved by increasing the amino acid density of the diets.

performance parameters.

54 Animal Husbandry and Nutrition

production [43, 44].

*5.1.4. Cobenefits of feeding low-protein diets to chickens*

Lowered amount of excreted nitrogen (including NH3

nia and nitrous oxide and eventual release into the atmosphere.

One of the most important aims of manure management is possibly ensuring the loss of nutrients is prevented or kept at the minimum in the manure chain. The manure chain is the period from collection to storage, treatment, and application for feed production. Handling chicken manure in an environmentally sustainable way would help realize its value as a nutrient resource for crops and as a feedstock for renewable energy. Emissions at the various stages of manure management could be tackled in animal house, during storage, processing, and application/discharge. Thus, instead of losing nutrients into the environment, efforts should be directed at keeping them in the food and/or feed chain where they could enhance crop growths and contribute to significant reduction in the use of inorganic fertilizers. Sustainable manure management will contribute to household food security and income, improvement in agricultural production, reduction in public health risks, reduction in environmental pollution and greenhouse gases emissions, and decelerate global warming. Although several approaches and technologies are available to achieve this goal, unsustainable manure management practices are still very prevalent in some countries. Some of these unsustainable manure management practices include direct application and indiscriminate disposal of manure such discharge into water bodies, burning or open dumping and indiscriminate land application. Lack of relevant policies and/or regulations, as well as nonenforcement of some of the relevant available policies or regulations, are among the major contributor to unsustainable manure management practices. Ref. [5] provided some valuable information or tips that would contribute to handling and managing manure in such a way that keeps the nutrients intact as much as practicable. Some of these are highlighted below:

*Collection point*: This could be in the barn or the house of the animal. The type of chicken management system affects the form in which the manure is handled. While manure is mostly in solid state in chickens raised on floor, it is in the wet form in layers raised in cages. It is critical to ensure that the animal housing allows for ease of manure collection and prevents losses. Consequently, the floor should be waterproof and covered against the rain to prevent losses through nutrient volatilization, run-off, and leaching.

*Manure storage*: Manure storage could be indoor or outdoor, and it is essential to ensure the nutrients are intact from the period of collection to application. Manure could also be stored either in dry or liquid form. Liquid storage could be in lagoons which can be covered or open. More nitrogen losses occur in open than in covered lagoon. It is important to store manure properly to ensure optimal application. It is therefore advisable to provide cover for the manure in outdoor storage. Storage roofing will prevent losses into the soil and water through leaching, run-off. Providing a storage facility that is air-tight will also prevent losses through volatilization. There are some marked differences in the major gaseous losses depending on the state in which the manure is stored. Nitrogen volatilization from chicken manure occurs mainly in the form of ammonia, nitrous oxide, and nitrogen gas in dry storage. However, nitrogen could be lost to the environment through leaching when there is contact with water. Apart from nitrogen, other nutrients in the manure could also find their way into the environment and cause some damages if excessive. In liquid storage, the main form of gaseous emission is methane, a greenhouse gas which is classified as a short-lived climate pollutant. To ensure proper capture of methane and prevent its losses to the atmosphere, anaerobic digesters could be used for storage. Anaerobic bio-digester technologies are relatively simple and adoptable at any level and scale, industrial, village, and farm level. The bio-digester must be recharged daily after biogas production commences. Manure used for biogas production is mixed with water in equal ratio (that is, 1 kg manure: 1 L of water) and fed into the bio-digester. The captured methane could be used as bio-energy, while the bioslurry could be used as fertilizer as the nutrients are still intact. This could be a direct or an indirect source of additional income to farmers. Although chicken manure can yield considerable amount of biogas (310 m3 /ton DM), comparable to other feedstock materials, a major challenge with the use of chicken manure for biogas production is that it is high in ammonium, which could inhibit the process of methanogenesis or biomethanation. Therefore, it is advisable to use chicken manure in small quantity. Biogas is composed of 50–70% methane, 30–45% carbon dioxide, 0–3% nitrogen, hydrogen, oxygen and hydrogen sulfide and therefore could be purified and used to power generators. When used for household cooking, caution must be exercised because of the highly inflammable characteristic of methane which is the main component of biogas.

Composting could be carried out using heap or pit method. Composting could be done in small and in large scale, and solid or liquid manure could be used. A major disadvantage of composting is that it could be labor intensive. Air drying could practically lead to the loss of manure nitrogen into the atmosphere. Air drying manure should only be done on waterproof

Nitrogen Emissions and Mitigation Strategies in Chicken Production

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57

*Manure application as organic fertilizer*: Manure could be used as a valuable fertilizer resource. It is however critical to carry out both soil and manure tests to establish the nutrient levels and needs to avoid nutrient overload. Manure applications as fertilizer must be strictly need-based. It is advised that manure be incorporated into the soil during

Environmental approach to chicken production is an increasingly important consideration all over the world. Major emissions in chicken production include ammonia, nitrous oxide, and other oxides of nitrogen and methane produced through the poultry supply chain. Uncontrolled emissions of deleterious gases into the environment could pose serious challenges and negatively impact the future use of resources. Sustainability approaches to chicken production hold immense benefits for the planet and the people while at the same time guaranteeing profitability. Several technologies are available for use in reducing the environmental footprint of chicken. To minimize the loss of nutrients, appropriate knowledge of various emissions/losses is required, and appropriate measures are taken across the entire chicken and manure management chain. Enactment and enforcement of relevant policies, laws, regulations, and creating enabling environments will considerably promote sustainable practices

\*, Stephen Abiodun Bolu2

1 Livestock Research Division, Coordination of Technical Research Programme,

2 Faculty of Agriculture, Animal Production Department, University of Ilorin,

3 Burreau of Gender and Youth in Agricultural Research, Office of the Executive

Secretary, Agricultural Research Council of Nigeria, Abuja, Nigeria

\*Address all correspondence to<EMAIL_ADDRESS>
Agricultural Research Council of Nigeria, Abuja, Nigeria

, Aliyu Shuaibu Madugu1

and

floor. Air dried manure are easy to handle as they be bulked.

application.

**6. Conclusions**

in chicken production.

Gabriel Adebayo Malomo1

Zainab Suleiman Usman3

**Author details**

Ilorin, Nigeria

*Manure treatment and processing*: There are several reasons for treating manure, namely; to reduce the volume, to improve handling as well as increase its value, applicability, reduce health related risks, and to prevent nutrient losses to safeguard the environment. There are several available methods of manure treatments, ranging from simple to highly complex one. These include air drying, anaerobic digestion, separation, adding solid materials to liquid manure, refining, composting, and amendment with alum or use of acidifying agents, and so on.

Manure treatment could begin from the animal house. For example, treatment of poultry litter with alum is a practice that is known to reduce manure nitrogen losses and commonly carried out during chicken production operations. Several types of alum used for water treatments could also be used effectively for chicken manure amendment. Ref. [46] compared poultry litters treated with salt solution, alum, and air exclusion and reported that alum treated feces had significantly higher percentage nitrogen retention and lower nitrogen depletion rate than salt and air-tight treatments. Ref. [46] also observed that maize seeds planted on alum treated and air excluded litter soils had an average germination percentage (GP) range of 65–75% and 54–75%, respectively, which were comparable to the average GP of 75% recorded for soil treated with the control manure. Sorghum plots also recorded a mean value of 99% GP on alum treated soil within 2 weeks of planting, surpassing airtight treated soil with mean value of 89% GP; however, seeds planted on salt treated litter soil recorded 0% germination. Ref. [30] suggested that ammonium alum was the least effective in preventing nitrogen losses in stored chicken manure compared with other forms of alum. Some of the benefits of using alum in chicken manure amendment include decreases in chicken house ammonia level, reduction in energy usage, improvement in birds' performance, precipitation of soluble phosphorus, reduction of phosphorus and heavy metals runoff, and imposition of drying effect that reduces litter moisture.

Composting could be carried out using heap or pit method. Composting could be done in small and in large scale, and solid or liquid manure could be used. A major disadvantage of composting is that it could be labor intensive. Air drying could practically lead to the loss of manure nitrogen into the atmosphere. Air drying manure should only be done on waterproof floor. Air dried manure are easy to handle as they be bulked.

*Manure application as organic fertilizer*: Manure could be used as a valuable fertilizer resource. It is however critical to carry out both soil and manure tests to establish the nutrient levels and needs to avoid nutrient overload. Manure applications as fertilizer must be strictly need-based. It is advised that manure be incorporated into the soil during application.

## **6. Conclusions**

into the environment and cause some damages if excessive. In liquid storage, the main form of gaseous emission is methane, a greenhouse gas which is classified as a short-lived climate pollutant. To ensure proper capture of methane and prevent its losses to the atmosphere, anaerobic digesters could be used for storage. Anaerobic bio-digester technologies are relatively simple and adoptable at any level and scale, industrial, village, and farm level. The bio-digester must be recharged daily after biogas production commences. Manure used for biogas production is mixed with water in equal ratio (that is, 1 kg manure: 1 L of water) and fed into the bio-digester. The captured methane could be used as bio-energy, while the bioslurry could be used as fertilizer as the nutrients are still intact. This could be a direct or an indirect source of additional income to farmers. Although chicken manure can yield consid-

challenge with the use of chicken manure for biogas production is that it is high in ammonium, which could inhibit the process of methanogenesis or biomethanation. Therefore, it is advisable to use chicken manure in small quantity. Biogas is composed of 50–70% methane, 30–45% carbon dioxide, 0–3% nitrogen, hydrogen, oxygen and hydrogen sulfide and therefore could be purified and used to power generators. When used for household cooking, caution must be exercised because of the highly inflammable characteristic of methane which is

*Manure treatment and processing*: There are several reasons for treating manure, namely; to reduce the volume, to improve handling as well as increase its value, applicability, reduce health related risks, and to prevent nutrient losses to safeguard the environment. There are several available methods of manure treatments, ranging from simple to highly complex one. These include air drying, anaerobic digestion, separation, adding solid materials to liquid manure, refining, composting, and amendment with alum or use of acidifying agents, and so on.

Manure treatment could begin from the animal house. For example, treatment of poultry litter with alum is a practice that is known to reduce manure nitrogen losses and commonly carried out during chicken production operations. Several types of alum used for water treatments could also be used effectively for chicken manure amendment. Ref. [46] compared poultry litters treated with salt solution, alum, and air exclusion and reported that alum treated feces had significantly higher percentage nitrogen retention and lower nitrogen depletion rate than salt and air-tight treatments. Ref. [46] also observed that maize seeds planted on alum treated and air excluded litter soils had an average germination percentage (GP) range of 65–75% and 54–75%, respectively, which were comparable to the average GP of 75% recorded for soil treated with the control manure. Sorghum plots also recorded a mean value of 99% GP on alum treated soil within 2 weeks of planting, surpassing airtight treated soil with mean value of 89% GP; however, seeds planted on salt treated litter soil recorded 0% germination. Ref. [30] suggested that ammonium alum was the least effective in preventing nitrogen losses in stored chicken manure compared with other forms of alum. Some of the benefits of using alum in chicken manure amendment include decreases in chicken house ammonia level, reduction in energy usage, improvement in birds' performance, precipitation of soluble phosphorus, reduction of phosphorus and heavy metals runoff, and imposition of drying

/ton DM), comparable to other feedstock materials, a major

erable amount of biogas (310 m3

56 Animal Husbandry and Nutrition

the main component of biogas.

effect that reduces litter moisture.

Environmental approach to chicken production is an increasingly important consideration all over the world. Major emissions in chicken production include ammonia, nitrous oxide, and other oxides of nitrogen and methane produced through the poultry supply chain. Uncontrolled emissions of deleterious gases into the environment could pose serious challenges and negatively impact the future use of resources. Sustainability approaches to chicken production hold immense benefits for the planet and the people while at the same time guaranteeing profitability. Several technologies are available for use in reducing the environmental footprint of chicken. To minimize the loss of nutrients, appropriate knowledge of various emissions/losses is required, and appropriate measures are taken across the entire chicken and manure management chain. Enactment and enforcement of relevant policies, laws, regulations, and creating enabling environments will considerably promote sustainable practices in chicken production.

## **Author details**

Gabriel Adebayo Malomo1 \*, Stephen Abiodun Bolu2 , Aliyu Shuaibu Madugu1 and Zainab Suleiman Usman3

\*Address all correspondence to<EMAIL_ADDRESS>
1 Livestock Research Division, Coordination of Technical Research Programme, Agricultural Research Council of Nigeria, Abuja, Nigeria

2 Faculty of Agriculture, Animal Production Department, University of Ilorin, Ilorin, Nigeria

3 Burreau of Gender and Youth in Agricultural Research, Office of the Executive Secretary, Agricultural Research Council of Nigeria, Abuja, Nigeria

## **References**

[1] Xin H, Gates RS, Green AR, Mitloehner FM, Moore Jr PA, Wathes CM. Environmental impacts and sustainability of egg production systems. Poultry Science. 2011;**90**:267-277. DOI: 10.3382/ps.2010-00877

[14] Tetra Tech, Inc. 2004. Technical Fundamentals of CAFOs for Permit Writers and Inspectors—

Nitrogen Emissions and Mitigation Strategies in Chicken Production

http://dx.doi.org/10.5772/intechopen.74966

59

[15] Malomo GA, Suleiman ZG, Bolu SA, Egberuare TA. Assessment of nutrient contents of finished broiler starter and finisher diets in Nigeria. Journal of Agricultural Research

[16] Rotz CA. Management to reduce nitrogen losses in animal production. Journal of Animal

[17] Bussink DW, Oenema O. Ammonia volatilization from dairy farming systems in tem-

[18] Hansen DJ. Manure as a nutrient source. In: Haering KC, Evanylo GK, editors. The Mid-Atlantic Nutrient Management Handbook. USA: Mid-Atlantic Regional Water Program;

[19] Millner PD.Bioaerosols associated with animal production systems. Bioresource Technology.

[20] Nicholson FA, Chambers BJ, Smith KA. Nutrient composition of poultry manures in

[21] Moreki JC, Chiripasi SC. Poultry waste management in Botswana: A review. Online

[22] Edwards DR, Daniel TC. Environmental impacts of on-farm poultry waste disposal—A

[23] Wood DJ, Van Heyst BJ. A review of ammonia and particulate matters control strategies for poultry housing. Transactions of the ASABE. 2016;**59**(1):329-344. DOI: 10.13031/

[24] Si J, Fritts CA, Burnham DJ, Waldroup PW. Extent to which crude proteins may be reduced in corn-soyabean meal broiler diets through amino acid supplementation.

[25] Buyse J, Decuypere E, Berghman L, Kuhn ER, Vandesande F. Effect of dietary protein content on episodic growth hormone secretion and on heat production of male broiler

[26] Bregendahl KJL, Sell JL, Zimmerman DR. Effect of low-protein diets on growth performance and body composition of broiler chicks. Poultry Science. 2002;**81**:1156-1167 [27] Bolu SA, Ojo V, Malomo GA, Oladele PO, Olonijolu TO. Dietary levels of protein and sustainable broiler production. Journal of Applied Agricultural Research. 2011;**3**:133-139

[28] Malomo GA, Bolu SA, Olutade SG. Effects of dietary crude protein on performance and nitrogen economy of broilers. Sustainable Agricultural Research. 2013b;**2**(3):52-57 [29] Malomo GA, Bolu SA, Olutade SG, Suleiman ZG. Effects of feeding low protein diets with methionine and lysine supplementation on the performance and nitrogen economy of broilers. Research Opinions in Animal and Veterinary Sciences. 2013;**3**(9):330-334

perate areas: A review. Nutrient Cycling Agroecosystems. 1998;**51**:19-33

England and Wales. Bioresource Technology. 1996;**58**:279-284

Journal of Animal and Food Research. 2011;**1**(6):285-292

International Journal of Poultry Science. 2004;**3**:46-50

chickens. British Poultry Science. 1992;**33**:1101-1109

review. Bioresource Technology. 1992;**41**:9-33

Student Text; Session 4 Tetra Tech, Pasadena, CA

and Development. 2013;**12**(1):75-78

Science. 2004;**82**(E. Suppl):E119-E137

2006. pp. 207-224

2009;**100**:5379-5385

trans.59.10836

[14] Tetra Tech, Inc. 2004. Technical Fundamentals of CAFOs for Permit Writers and Inspectors— Student Text; Session 4 Tetra Tech, Pasadena, CA

**References**

58 Animal Husbandry and Nutrition

DOI: 10.3382/ps.2010-00877

agee.2005.08.015

Life Cycle Assessment. Rome: FAO; 2013. 196 p

Cycling Agroecosystem. 2003;**65**:221-230

Agricultural Science. 1991;**117**:91-100

Research. 2008;**17**:421-431

International; 1992. pp. 345-357

[1] Xin H, Gates RS, Green AR, Mitloehner FM, Moore Jr PA, Wathes CM. Environmental impacts and sustainability of egg production systems. Poultry Science. 2011;**90**:267-277.

[2] MacLeod M, Gerber P, Mottet A, Tempio G, Falcucci A, Opio C, Vellinga T, Henderson B, Steinfeld H. Greenhouse Gas Emissions from Pig and Chicken Supply Chains—A Global

[3] Monteny GJ, Bannink A, Chadwick D. Greenhouse gas abatement strategies for animal husbandry. Agriculture, Ecosystems and Environment. 2006;**112**:163-170. DOI: 10.1016/j.

[4] Munir K, Maqsood S. A review on role of exogenous enzyme supplementation in poul-

[5] Teenstra E, De Buisonjé F, Ndambi A, Pelster D. 2015. Manure Management in the Sub-Tropics; Training Manual for Extension Workers. Netherlands: Wageningen,

[6] Mattila PK, Joki-Tokola E. Effect of treatment and application technique of cattle slurry on its utilization by ley: I. Slurry properties and ammonia volatilization. Nutrient

[7] Sommer SG, Olesen JE, Christensen BT. Effects of temperature, wind speed and air humidity and ammonia volatilization from surface applied cattle slurry. Journal of

[8] Patterson P. Using Dietary and Management Strategies to Reduce the Nutrient Excretion

[9] Fangmeier A, Hadwiger-Fangmeier A, Van der Eerden L, Jager HJ. Effects of atmospheric ammonia on vegetation—A review. Environmental Pollution. 1994;**86**:43-82 [10] Gerber PJ, Steinfeld H, Henderson B, Mottet A, Opio C, Dijkman J, Falcucci A, Tempio G. Tackling Climate Change through Livestock – A Global Assessment of Emissions and

[11] Li H, Xin H, Burns RT, Liang Y. Reduction of ammonia emission from stored poultry manure using additives: Zeolite, Al+Clear, Ferix-3 and PLT. Journal of Applied Poultry

[12] Tamminga S. Gaseous pollutants produced by farm animal enterprises. In: Philips C, Piggins D, editors. Farm Animals and the Environment. Vol. 2008. Tucson, AZ: CAB

[13] Koerkamp PWG. Review on ammonia emission from housing systems for laying hens in relation to sources, processes, building design and manure handling. Journal of

Wageningen UR (University & Research centre) Livestock Research; 2015. 56 p

try production. Emirate Journal of Food Agriculture. 2013;**25**(1):66-80

of Poultry. USA: The Pennsylvania State University; 2001. 32 p

Mitigation Opportunities. FAO: Rome; 2013. 139 p

Agricultural Engineering Research. 1994;**59**:73-87

[30] Malomo GA. Effects of protein manipulation, enzymes supplementation and feacal treatment on nitrogen emissions in chicken production [thesis]. Ilorin: University of Ilorin, Ilorin, Nigeria; 2016

[43] Malomo GA, Bolu SA, Olutade SG, Suleiman ZG. Effects of alum (aluminium sulphate) on feacal quality of broilers fed low protein diets. Research Opinions in Animal and

Nitrogen Emissions and Mitigation Strategies in Chicken Production

http://dx.doi.org/10.5772/intechopen.74966

61

[44] Hassan K, Ziaei N, Pilevar M. Effects of dietary crude protein fluctuation on performance, blood parameters and nutrient retention in broiler chicken during starter period.

[45] Ferguson NS, Gates RS, Taraba JL, Cantor AH, Pescatore AJ, Straw ML, Ford MJ, Burnham DJ. The effect of dietary protein and phosphorus on ammonia concentration

[46] Bolu SA, Aderibigbe SA, Olawale S.Effects of treated poultry litter on potential greenhouse gas emission and field application. Animal Research International. 2014;**11**(2):2027-2034

and litter composition in broilers. Poultry Science. 1998;**77**:1085-1093

Veterinary Sciences. 2014;**4**(3):133-137

Global Veterinária. 2011;**6**:162-167

[43] Malomo GA, Bolu SA, Olutade SG, Suleiman ZG. Effects of alum (aluminium sulphate) on feacal quality of broilers fed low protein diets. Research Opinions in Animal and Veterinary Sciences. 2014;**4**(3):133-137

[30] Malomo GA. Effects of protein manipulation, enzymes supplementation and feacal treatment on nitrogen emissions in chicken production [thesis]. Ilorin: University of

[31] Novak C, Yakout HM, Scheideler SE. The effect of dietary protein level and total sulfur amino acid:Lysine ratio on egg production parameters and egg yield in Hy-Line W-98

[32] Waldroup PW, Jiang Q, Fritts CA. Influence of ad libitum or control feeding on performance of broilers fed diets low in crude protein. International Journal of Poultry Science.

[33] Waldroup PW, Jiang A, Fritts CA. Effects of supplementing broiler diets low in crude protein with essential and nonessential amino acids. International Journal of Poultry

[34] Rama Rao SV, Ravindran V, Srilatha T, Panda AK, Raju MVLN. Effect of dietary concentrations of energy, crude protein, lysine, and methionine on the performance of White Leghorn layers in the tropics. Journal of Applied Poultry Research. 2011;**20**:528-541 [35] Sohail SS, Bryant MM, Roland Sr DA, Apajalahti JHA, Pierson EE. Influence of Avizyme-1500 on performance of commercial leghorns. Journal of Applied Poultry

[36] Dean DW, Bidner TD, Southern LL. Glycine supplementation to low protein, amino acidsupplemented diets supports optimal performance of broiler chicks. Poultry Science.

[37] National Research Council. Nutrient Requirements of Poultry. 9th ed. Washington, DC:

[38] Rezaei M, Moghaddam HN, Reza JP, Classen HL. Effects of different levels of crude protein and dietary electrolyte balance on the performance and body composition of broiler

[39] Waldroup PW. Do crude protein levels really matter? In: Proceeding 15th Annual ASAIM Southern Asian Food Technology and Nutrition Workshop; 27-30 May 2007; Conrad Bali

[40] Rohollah G, Torki M, Hossein AG. Effects of dietary crude protein and electrolyte balance on production parameters and blood biochemicals of laying hens under tropical

[41] Keshavarz K, Jackson ME. Performance of growing pullets and laying hens fed low pro-

[42] Keshavarz K, Austic RE. The use of low-protein, low-phosphorus, amino acid- and phytase-supplemented diets on laying hen performance and nitrogen and phosphorus

summer condition. Tropical Animal Health and Production. 2014;**46**(5):717-723

tein, amino-acids supplemented diets. Poultry Science. 1992;**71**(5):905-918

chicks. Agricultural sciences and Technology. 2004;**18**(2):69-78

Ilorin, Ilorin, Nigeria; 2016

Science. 2005b;**4**(6):425-431

Research. 2003;**12**:284-290

National Academy Press; 1994

Resort, Indonesia. 2007

excretion. Poultry Science. 2004;**83**:75-83

2006;**85**:288-296

2005;**4**:274-279

60 Animal Husbandry and Nutrition

hens. Poultry Science. 2006;**85**:2195-2206

**Chapter 4**

**Provisional chapter**

**Quality of Chicken Meat**

**Quality of Chicken Meat**

http://dx.doi.org/10.5772/intechopen.72865

Danica Hanžek

**Abstract**

health benefit

**1. Introduction**

Danica Hanžek

Gordana Kralik, Zlata Kralik, Manuela Grčević and

Gordana Kralik, Zlata Kralik, Manuela Grčević and

DOI: 10.5772/intechopen.72865

Chicken meat is considered as an easily available source of high-quality protein and other nutrients that are necessary for proper body functioning. In order to meet the consumers' growing demands for high-quality protein, the poultry industry focused on selection of fast-growing broilers, which reach a body mass of about 2.5 kg within 6-week-intensive fattening. Relatively low sales prices of chicken meat, in comparison to other types of meat, speak in favor of the increased chicken meat consumption. In addition, chicken meat is known by its nutritional quality, as it contains significant amount of high-quality and easily digestible protein and a low portion of saturated fat. Therefore, chicken meat is recommended for consumption by all age groups. The technological parameters of chicken meat quality are related to various factors (keeping conditions, feeding treatment, feed composition, transport, stress before slaughter, etc.). Composition of chicken meat can be influenced through modification of chicken feed composition (addition of different types of oils, vitamins, microelements and amino acids), to produce meat enriched with functional ingredients (n-3 PUFA, carnosine, selenium and vitamin E). By this way, chicken meat becomes a foodstuff with added value, which, in addition to high-quality nutritional composition, also contains ingredients that are beneficial to human health. **Keywords:** chicken meat, nutritive value, meat quality, n-3 PUFA, carnosine, selenium,

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Throughout the world, poultry meat consumption continues to grow, both in developed and in the developing countries. In 1999, global production of chickens reached 40 billion, and by 2020 this trend is expected to continue to grow, so that poultry meat will become the consumers' first choice [1]. Fresh chicken meat and chicken products are universally popular. This

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

## **Chapter 4**

**Provisional chapter**

## **Quality of Chicken Meat**

**Quality of Chicken Meat**

Gordana Kralik, Zlata Kralik, Manuela Grčević and Danica Hanžek Danica Hanžek Additional information is available at the end of the chapter

Gordana Kralik, Zlata Kralik, Manuela Grčević and

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72865

#### **Abstract**

Chicken meat is considered as an easily available source of high-quality protein and other nutrients that are necessary for proper body functioning. In order to meet the consumers' growing demands for high-quality protein, the poultry industry focused on selection of fast-growing broilers, which reach a body mass of about 2.5 kg within 6-week-intensive fattening. Relatively low sales prices of chicken meat, in comparison to other types of meat, speak in favor of the increased chicken meat consumption. In addition, chicken meat is known by its nutritional quality, as it contains significant amount of high-quality and easily digestible protein and a low portion of saturated fat. Therefore, chicken meat is recommended for consumption by all age groups. The technological parameters of chicken meat quality are related to various factors (keeping conditions, feeding treatment, feed composition, transport, stress before slaughter, etc.). Composition of chicken meat can be influenced through modification of chicken feed composition (addition of different types of oils, vitamins, microelements and amino acids), to produce meat enriched with functional ingredients (n-3 PUFA, carnosine, selenium and vitamin E). By this way, chicken meat becomes a foodstuff with added value, which, in addition to high-quality nutritional composition, also contains ingredients that are beneficial to human health.

DOI: 10.5772/intechopen.72865

**Keywords:** chicken meat, nutritive value, meat quality, n-3 PUFA, carnosine, selenium, health benefit

#### **1. Introduction**

Throughout the world, poultry meat consumption continues to grow, both in developed and in the developing countries. In 1999, global production of chickens reached 40 billion, and by 2020 this trend is expected to continue to grow, so that poultry meat will become the consumers' first choice [1]. Fresh chicken meat and chicken products are universally popular. This

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

occurrence can be explained by the fact that this meat is not a subject of culturally or religiously set limitations, and it is perceived as nutritionally valuable foodstuff with low content of fat, in which there are more desirable unsaturated fatty acids than in other types of meat [2, 3]. More importantly, quality poultry products are available at affordable prices, although their production costs may vary [4]. If referring to overall consumption of all types of meat, poultry meat consumption takes one of the leading places in all countries throughout the world [3]. Such good rating of poultry meat is influenced by many factors, such as short fattening duration, excellent space utilization, high reproductive ability of poultry, excellent feed conversion, satisfactory nutritional value of poultry meat and relatively low sales prices. The quality of broiler meat is affected by a number of factors, as follows: fattening system, duration of fattening, hybrid and sex, feeding treatment, handling before slaughter, freezing of carcasses, storage time, etc. [5–11]. It should be emphasized that nowadays poultry is fattened in an intensive way, so the stress is an inevitable factor, and the feed, with increased content of microalgae and vegetable and fish oils used to enrich poultry products with desirable fatty acids, is susceptible to oxidation [11–14]. The same as designed poultry feed mixtures with increased microalgae or oil content, poultry products (meat and eggs) enriched with omega-3 fatty acids are also subjected to oxidation. In order to reduce oxidation in poultry feed, it is necessary to supplement it with some antioxidants, such as selenium or vitamin E. Such chicken meat is considered as "functional food", as it has the increased content of bioactive substances, which positively influences consumers' health. The most common bioactive substances used to enrich chicken meat are conjugated linoleic acid (CLA), vitamins, microelements, amino acids, microalgae and oils rich in omega-3 PUFA (polyunsaturated fatty acids) [14–19].

The aim of this research was to present the nutritive value of chicken meat, as well as to assess the influence of different fattening system factors that determine the meat quality. Furthermore, the aim was to elaborate the possibility of enriching the meat with omega-3 fatty acids, carnosine and selenium, and to point out the benefits that consumption of enriched chicken meat has on human health.

to people suffering from heart and coronary diseases. When compared to cholesterol content, white chicken meat does not differ much from other types of meat, however, if considering other benefits (more protein, less total fat, less saturated fat and less calories), it has better nutritional quality and therefore, it is recommended for consumption to anyone who takes care of diet and health. High protein content makes chicken meat an ideal foodstuff for all consumers who need high-quality, easily degradable protein (athletes, children, the elderly). Average daily requirement (AR—average requirements) of adults for protein is 0.66 g/kg body weight (BW), while young children and athletes' needs are twice as high (1.12 g/kg body weight). Pregnant women's needs for protein are considerably higher and they depend on the pregnancy trimester, by increasing to an additional 23 g/day for the third pregnancy trimester [21]. Because of all stated above, chicken meat is recommended as a rich source of high-quality protein in human nutrition. Chicken meat contains low collagen levels, which is another positive characteristic. Collagen is a structural protein that reduces meat digestibility,

**Nutrient Chicken1 Pork2 Beef3 Lamb4** Energy/kcal 165 165 185 180 Water/g 65.26 65.75 64.83 64.92 Protein/g 31.02 28.86 27.23 28.17 Total fat/g 3.57 4.62 7.63 6.67 Saturated fatty acids 1.010 1.451 2.661 2.380 Monounsaturated fatty acids 1.240 1.878 3.214 2.920 Polyunsaturated fatty acids 0.770 1.066 0.285 0.440 Cholesterol (mg) 85 86 78 87

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Chicken meat is also a good source of some minerals and vitamins (**Table 2**). When compared to red meat (except for pork meat), it contains more calcium, magnesium, phosphorus and sodium. Content of iron is almost the same as in pork. Iron is necessary for creation of hemoglobin, for prevention of anemia, as well as for normal muscle activity. Calcium and phosphorus are important for healthy bones and teeth. Sodium is an electrolyte, and magnesium is important for normal synthesis of protein and proper muscle activity. Out of the total content of vitamin in chicken meat, niacin (vitamin B3) is contained in highest portion, and content of vitamins A and B6 is also higher than in other types of meat. Niacin is very important for proper metabolism of carbohydrates and for energy creation. It is also important for healthy skin, hair and eyes, as well as for nervous system. It plays a role in the synthesis

so chicken meat is easier to digest than other types of meat [22].

Chicken, broilers or fryers, breast, meat only, cooked, roasted.

Beef, round, bottom round, roast, separable lean only, trimmed to 0″ fat, choice, cooked, roasted.

Lamb, domestic, leg, shank half, separable lean only, trimmed to 1/4″ fat, choice, cooked, roasted.

Pork, fresh, leg (ham), rump half, separable lean only, cooked, roasted.

**Table 1.** Nutritive content of different types of meat (per 100 g).

Source: [20].1

2

3

4

## **2. Nutritional value of chicken meat**

Chicken meat is appropriate for quick and simple preparation, yet it offers a variety of combinations with different foodstuffs, thus making itself as a usual choice of consumers faced with modern lifestyle. When compared to other types of meat (**Table 1**), it is proved that chicken meat (breasts) contains more protein and less fat than red meat, thus making it a dietetic product.

It is important to mention that chicken with skin contains 2–3 times more fat than chicken without skin, so it should be eaten without skin to ensure the intake of high-quality protein without extra calories and fat.

**Table 1.** Nutritive content of different types of meat (per 100 g).

occurrence can be explained by the fact that this meat is not a subject of culturally or religiously set limitations, and it is perceived as nutritionally valuable foodstuff with low content of fat, in which there are more desirable unsaturated fatty acids than in other types of meat [2, 3]. More importantly, quality poultry products are available at affordable prices, although their production costs may vary [4]. If referring to overall consumption of all types of meat, poultry meat consumption takes one of the leading places in all countries throughout the world [3]. Such good rating of poultry meat is influenced by many factors, such as short fattening duration, excellent space utilization, high reproductive ability of poultry, excellent feed conversion, satisfactory nutritional value of poultry meat and relatively low sales prices. The quality of broiler meat is affected by a number of factors, as follows: fattening system, duration of fattening, hybrid and sex, feeding treatment, handling before slaughter, freezing of carcasses, storage time, etc. [5–11]. It should be emphasized that nowadays poultry is fattened in an intensive way, so the stress is an inevitable factor, and the feed, with increased content of microalgae and vegetable and fish oils used to enrich poultry products with desirable fatty acids, is susceptible to oxidation [11–14]. The same as designed poultry feed mixtures with increased microalgae or oil content, poultry products (meat and eggs) enriched with omega-3 fatty acids are also subjected to oxidation. In order to reduce oxidation in poultry feed, it is necessary to supplement it with some antioxidants, such as selenium or vitamin E. Such chicken meat is considered as "functional food", as it has the increased content of bioactive substances, which positively influences consumers' health. The most common bioactive substances used to enrich chicken meat are conjugated linoleic acid (CLA), vitamins, microelements, amino

acids, microalgae and oils rich in omega-3 PUFA (polyunsaturated fatty acids) [14–19].

chicken meat has on human health.

64 Animal Husbandry and Nutrition

product.

**2. Nutritional value of chicken meat**

The aim of this research was to present the nutritive value of chicken meat, as well as to assess the influence of different fattening system factors that determine the meat quality. Furthermore, the aim was to elaborate the possibility of enriching the meat with omega-3 fatty acids, carnosine and selenium, and to point out the benefits that consumption of enriched

Chicken meat is appropriate for quick and simple preparation, yet it offers a variety of combinations with different foodstuffs, thus making itself as a usual choice of consumers faced with modern lifestyle. When compared to other types of meat (**Table 1**), it is proved that chicken meat (breasts) contains more protein and less fat than red meat, thus making it a dietetic

It is important to mention that chicken with skin contains 2–3 times more fat than chicken without skin, so it should be eaten without skin to ensure the intake of high-quality protein without extra calories and fat. When compared to red meat, the main advantage of white chicken meat is in its low caloric value and a low portion of saturated fat, so consumption of white chicken meat is recommended to people who want to reduce the fat intake, as well as to people suffering from heart and coronary diseases. When compared to cholesterol content, white chicken meat does not differ much from other types of meat, however, if considering other benefits (more protein, less total fat, less saturated fat and less calories), it has better nutritional quality and therefore, it is recommended for consumption to anyone who takes care of diet and health. High protein content makes chicken meat an ideal foodstuff for all consumers who need high-quality, easily degradable protein (athletes, children, the elderly). Average daily requirement (AR—average requirements) of adults for protein is 0.66 g/kg body weight (BW), while young children and athletes' needs are twice as high (1.12 g/kg body weight). Pregnant women's needs for protein are considerably higher and they depend on the pregnancy trimester, by increasing to an additional 23 g/day for the third pregnancy trimester [21]. Because of all stated above, chicken meat is recommended as a rich source of high-quality protein in human nutrition. Chicken meat contains low collagen levels, which is another positive characteristic. Collagen is a structural protein that reduces meat digestibility, so chicken meat is easier to digest than other types of meat [22].

Chicken meat is also a good source of some minerals and vitamins (**Table 2**). When compared to red meat (except for pork meat), it contains more calcium, magnesium, phosphorus and sodium. Content of iron is almost the same as in pork. Iron is necessary for creation of hemoglobin, for prevention of anemia, as well as for normal muscle activity. Calcium and phosphorus are important for healthy bones and teeth. Sodium is an electrolyte, and magnesium is important for normal synthesis of protein and proper muscle activity. Out of the total content of vitamin in chicken meat, niacin (vitamin B3) is contained in highest portion, and content of vitamins A and B6 is also higher than in other types of meat. Niacin is very important for proper metabolism of carbohydrates and for energy creation. It is also important for healthy skin, hair and eyes, as well as for nervous system. It plays a role in the synthesis

By applying different feeding treatments, the nutritional profile of chicken meat, such as fat and cholesterol content and fatty acid profile, can be modified in order to produce a foodstuff of improved nutritional value. Furthermore, supplementation of various antioxidants (selenium and vitamin E) to chicken feed influences their deposition in chicken tissue, thus enabling production of enriched foodstuff. The possibilities of enriching chicken meat with

Quality of Chicken Meat

67

http://dx.doi.org/10.5772/intechopen.72865

In present times, emphasis is put on importance of chicken meat consumption for maintaining and reducing body weight. It is known that the intake of dietary protein is effective in reducing body weight, so the chicken meat is often a part of the diet aimed to reduce body weight, because of its high protein and low fat content. The studies have shown that weight loss was higher in people who consumed low calorie meals rich in protein in comparison with low calorie meals with low protein content. This is due to the fact that protein provides a greater sense of satiety, so that people consume less calories during the day, thus reducing the intake

Chicken meat is considered as desirable foodstuff in prevention of cardiovascular diseases. Saturated fat, cholesterol and heme iron, which is more contained in red than in white meat, are very important factors in development of atherosclerosis, cardiovascular diseases, hypertension and in increase of blood cholesterol [30]. According to the data of Bernstein et al., by replacing meals with red meat with white chicken meat, the risk of cardiovascular disease occurrence can be lowered by 19% [31]. The authors assumed that this was a consequence of less intake of heme iron and sodium, and of more polyunsaturated fatty acids in meals. Therefore, chicken meat, as a source of protein, could be a significant factor in reducing risks

There has been recently a lot of evidence on how the lifestyle has been influencing the increase or the decrease of disease risk occurrence, such as diabetes. Changes in our lifestyle and nutrition can significantly affect the decrease of that disease occurrence. The increased risk of developing diabetes is related to various factors, of which the intake of saturated animal fat is among the most significant ones [32]. The authors stated a positive correlation between the intake of saturated fat intake and the resistance to insulin. The research results of Pan et al. pointed out that consumption of red meat, especially of red meat products, was associated with increased risk of developing the type 2 diabetes [33]. Although the increased intake of protein of animal origin represents a risk of developing diabetes, consumption of chicken meat, as a part of balanced diet, is recommended for prevention of disease development and its control [34]. Healthy lifestyle, which includes consumption of chicken meat, fruit, legumes, nuts, whole grains and vegetable oils, is associated with reduced risk of death in patients suffering from diabetes [35]. The results of these studies encourage the change of lifestyle and dietary habits, within which white chicken meat with low content of saturated fat serves as a healthier alternative to animal

protein intake in daily meals, so it is recommended as a part of a healthy diet.

As stated above, excessive intake of proteins of animal origin is associated with the risk of developing diabetes. Still, some studies have also confirmed that excessive intake of meat, especially

favorable omega-3 fatty acids and antioxidants are explored in the following text.

**2.1. Health benefit of chicken meat**

of carbohydrates [28, 29].

of cardiovascular disease development.

Source: [20].1 Chicken, broilers or fryers, breast, meat only, cooked, roasted.

2 Pork, fresh, leg (ham), rump half, separable lean only, cooked, roasted.

3 Beef, round, bottom round, roast, separable lean only, trimmed to 0″ fat, choice, cooked, roasted.

4 Lamb, domestic, leg, shank half, separable lean only, trimmed to 1/4″ fat, choice, cooked, roasted.

**Table 2.** Content of minerals and vitamins in different types of meat (per 100 g).

of sex hormones and in improving circulation and reducing cholesterol level. Niacin is often used as an additional therapy in patients that take drugs for lowering of blood lipids. In this case, it is scientifically proven that niacin affects the increase of high density lipoprotein (HDL) cholesterol level, but it does not affect the improvement of cardiovascular disease state [23, 24]. When niacin is taken as an independent therapy, it reduces the development of cardiovascular diseases, and lowers the mortality associated with cardiac or cardiovascular diseases [25, 26]. The chronic lack of niacin in the organism causes pelagic disease, which is characterized by uneven skin pigmentation (skin redness), gastrointestinal disorders (diarrhea) and brain function disorder (dementia), [27]. In light of the abovementioned, chicken meat is considered as convenient, affordable and acceptable source of basic nutrients, vitamins and minerals necessary for proper body functioning.

By applying different feeding treatments, the nutritional profile of chicken meat, such as fat and cholesterol content and fatty acid profile, can be modified in order to produce a foodstuff of improved nutritional value. Furthermore, supplementation of various antioxidants (selenium and vitamin E) to chicken feed influences their deposition in chicken tissue, thus enabling production of enriched foodstuff. The possibilities of enriching chicken meat with favorable omega-3 fatty acids and antioxidants are explored in the following text.

#### **2.1. Health benefit of chicken meat**

of sex hormones and in improving circulation and reducing cholesterol level. Niacin is often used as an additional therapy in patients that take drugs for lowering of blood lipids. In this case, it is scientifically proven that niacin affects the increase of high density lipoprotein (HDL) cholesterol level, but it does not affect the improvement of cardiovascular disease state [23, 24]. When niacin is taken as an independent therapy, it reduces the development of cardiovascular diseases, and lowers the mortality associated with cardiac or cardiovascular diseases [25, 26]. The chronic lack of niacin in the organism causes pelagic disease, which is characterized by uneven skin pigmentation (skin redness), gastrointestinal disorders (diarrhea) and brain function disorder (dementia), [27]. In light of the abovementioned, chicken meat is considered as convenient, affordable and acceptable source of basic nutrients, vitamins and minerals neces-

Chicken, broilers or fryers, breast, meat only, cooked, roasted.

Beef, round, bottom round, roast, separable lean only, trimmed to 0″ fat, choice, cooked, roasted.

Lamb, domestic, leg, shank half, separable lean only, trimmed to 1/4″ fat, choice, cooked, roasted.

Pork, fresh, leg (ham), rump half, separable lean only, cooked, roasted.

**Table 2.** Content of minerals and vitamins in different types of meat (per 100 g).

**Chicken1 Pork2 Beef3 Lamb4**

Calcium (mg) 15 16 6 8 Iron (mg) 1.04 0.97 2.40 2.06 Magnesium (mg) 29 27 18 26 Phosphorus (mg) 228 273 172 208 Potassium (mg) 256 425 222 342 Sodium (mg) 74 80 36 66 Zinc (mg) 1.00 2.48 4.74 5.02

Vitamin C (mg) 0.0 0.0 0.0 0,0 Thiamin (mg) 0.070 0.523 0.057 0.110 Riboflavin (mg) 0.114 0,408 0.170 0,280 Niacin (mg) 13.712 7.940 5.232 6.390 Vitamin B6 (mg) 0.600 0.538 0.380 0.170 Folate (μg) 4 0 9 24 Vitamin B12 (μg) 0.34 0.67 1.61 2.71 Vitamin A (μg) 6 1 0 0 Vitamin E (mg) 0.27 0.26 0.37 0.18 Vitamin D (D2 + D3) (μg) 0.1 0.3 — — Vitamin K (μg) 0.3 0.0 1.3 —

sary for proper body functioning.

**Minerals**

66 Animal Husbandry and Nutrition

**Vitamins**

Source: [20].1

2

3

4

In present times, emphasis is put on importance of chicken meat consumption for maintaining and reducing body weight. It is known that the intake of dietary protein is effective in reducing body weight, so the chicken meat is often a part of the diet aimed to reduce body weight, because of its high protein and low fat content. The studies have shown that weight loss was higher in people who consumed low calorie meals rich in protein in comparison with low calorie meals with low protein content. This is due to the fact that protein provides a greater sense of satiety, so that people consume less calories during the day, thus reducing the intake of carbohydrates [28, 29].

Chicken meat is considered as desirable foodstuff in prevention of cardiovascular diseases. Saturated fat, cholesterol and heme iron, which is more contained in red than in white meat, are very important factors in development of atherosclerosis, cardiovascular diseases, hypertension and in increase of blood cholesterol [30]. According to the data of Bernstein et al., by replacing meals with red meat with white chicken meat, the risk of cardiovascular disease occurrence can be lowered by 19% [31]. The authors assumed that this was a consequence of less intake of heme iron and sodium, and of more polyunsaturated fatty acids in meals. Therefore, chicken meat, as a source of protein, could be a significant factor in reducing risks of cardiovascular disease development.

There has been recently a lot of evidence on how the lifestyle has been influencing the increase or the decrease of disease risk occurrence, such as diabetes. Changes in our lifestyle and nutrition can significantly affect the decrease of that disease occurrence. The increased risk of developing diabetes is related to various factors, of which the intake of saturated animal fat is among the most significant ones [32]. The authors stated a positive correlation between the intake of saturated fat intake and the resistance to insulin. The research results of Pan et al. pointed out that consumption of red meat, especially of red meat products, was associated with increased risk of developing the type 2 diabetes [33]. Although the increased intake of protein of animal origin represents a risk of developing diabetes, consumption of chicken meat, as a part of balanced diet, is recommended for prevention of disease development and its control [34]. Healthy lifestyle, which includes consumption of chicken meat, fruit, legumes, nuts, whole grains and vegetable oils, is associated with reduced risk of death in patients suffering from diabetes [35]. The results of these studies encourage the change of lifestyle and dietary habits, within which white chicken meat with low content of saturated fat serves as a healthier alternative to animal protein intake in daily meals, so it is recommended as a part of a healthy diet.

As stated above, excessive intake of proteins of animal origin is associated with the risk of developing diabetes. Still, some studies have also confirmed that excessive intake of meat, especially of red meat, is a potential risk factor for development of certain types of cancer. Red meat contains more potentially harmful ingredients than white meat. These potentially harmful ingredients are saturated fat, heme iron, sodium, N-nitroso compounds and aromatic amines produced by high temperature cooking, so the consumption of red meat represents a risk of developing cancers. Therefore, red meat is associated with a higher risk of cancers, while white meat shows neutral or moderately protective correlation to cancer occurrence [36, 37]. Cancers in digestive system are usually associated with consumption of animal products. This conclusion was confirmed by researches carried out among populations with significantly higher consumption of meat than recommended. It is assumed that myoglobin from red meat activates pre-cancerous damage by accelerating the heme iron influence on the formation of carcinogenic N-nitroso compounds and by developing cytotoxic and genotoxic aldehydes through the lipid peroxidation process [38].  Zhu et al. carried out a comprehensive review of literature on the occurrence of esophageal cancer, and concluded that there was a reverse correlation between the number of chicken meat meals a week and the risk of developing esophageal cancer [39]. The authors stated researches showed the decreasing risk of developing esophageal cancer by about 53% in Europe in cases of increased consumption of chicken meat. Of course, such research conclusions should be interpreted cautiously, because it cannot be stated with full certainty that red meat causes cancers and white meat does not, yet there is a lot of evidence that consumption of white meat is more favorable than consumption of red meat.

appearance. Consumers connect the color of meat with its freshness. The color of meat can be determined visually or using instruments (colorimeters). For the visual evaluation of the meat color, it is necessary to have trained panelists, who evaluate the appearance of meat by using the hedonic scale. The instrumental determination of meat color is more efficient and the methods of reflection or extraction are used to quantify the amount of pigment. The color of foods can be defined as the interaction of a light, an object, an observer and the surroundings of the food. Recently, the International Commission on Illumination described how background can influence the appreciation of color. Instruments used for evaluation of meat color by reflection method are colorimeters, for example, CR Minolta 300 or 400 that work on the principle of meat color comparison in regard to standard color values. The International Commission on Illumination lists three values: CIE L\*, a\* and b\*. CIE L\* indicates lightness, where values range from 0 (black) to 100 (white). The value of CIE a\* shows redness while CIE b\* indicates yellowness. Negative a\* and b\* values indicate the appearance of green and blue color of the meat.

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Kralik et al. reported that the chicken genotype did not influence the CIE L\* (lightness) and CIE b\* (yellowness) values referring to meat color [45]. As of the results, the CIE L\* 49.93 and CIE b\* 10.17 was reported for chicken meat of Cobb 500 genotype, and for the Hubbard Classic, the values were CIE L\* 51.11 and CIE b\* 10.50 (P > 0.05). Furthermore, the authors stated that there was a negative correlation between pH and CIE L\* value r = −0.285 for Cobb 500 and r = −0.438 for Hubbard Classic genotypes. In the research into the influence of chicken sex on the quality of fresh and cooked meat, Salakova et al. also determined the negative correlation between pH and CIE L\* value measured in fresh and cooked breast meat of the Ross 308 chicken genotype (r = −0.41, P < 0.001 and r = −0.31, P < 0.05), [46]. The authors stated that male chickens of the Ross 308 genotype had statistically significantly higher pH values than female chickens (P < 0.05), which was not depending on the portion of crude protein in the finisher mixture (A = 22.6%, B = 20.1% and C = 18.7%). The highest pH values were measured in breast meat of male and female chickens of the group A (pH = 6.08 and pH = 5.97, respectively), while in feeding treatments with lower portion of crude protein in feeding mixture the value of pH in breast meat of both sexes decreased (♂ B = 5.99 and C ♂ =5.77 and ♀ B = 5.85 and ♀ C = 5.66). Female chickens had statistically significantly brighter meat color than male chickens in the A treatment (CIE L\* 54.90 and CIE L\* 52.24, respectively; P < 0.01). The same trend referring to the meat color was noticed in other feeding treatments, however, the differences were not statistically significant (♀ B=CIE L\* 59.43 C=CIE L\* 58.11 and ♂ B=CIE L\* 58.36 C=CIE L\*55.17). The research of Živković et al. describes the influence of extruded linseed in chicken feed on the physico-chemical and sensory traits of meat [47].  The control group (C) consumed the commercial mixture and the experimental group (E) had mixture supplemented with 6% of extruded linseed. The authors concluded that feeding treatment influenced the protein content in meat of thighs of females only (C = 19.27% E = 17.76%; P < 0.05). The feeding treatment had effect on the breast meat color (P < 0.05). Experimental group of chickens had lighter breast meat color than the control. Male chickens had statistically significantly lighter breast meat than females (P < 0.05). The value of CIE a\* (redness) reduced significantly in *m. pectoralis profundus*, and CIE b\* increased in *m. pectoralis superficialis* in both chicken sexes (P < 0.001). In thigh muscles

**3.1. Influence of genotype, sex and feeding on the chicken meat quality**

## **3. Parameters of chicken meat quality**

When considering nutritional aspects, poultry meat is good for consumers because it is rich in protein and minerals, and contains a small amount of fat with high portion of unsaturated fatty acids and a low cholesterol level [2]. Changes in consumers' lifestyle in developed countries have influenced the meat market by changing the demand and supply of certain types of meat, which the food industry used as an advantage to market so called "fast food" and more recently also "functional food". In both food groups, chicken meat is highly represented [3]. This growing demand for poultry meat influenced the scientists to create chickens of fast-growing genotypes, which have good feed conversion, better carcass formation (higher portion of breast meat and less abdominal fat), lower mortality, etc. However, all of these positive changes in new chicken genotypes cause greater stress, and many researchers point out that this fast growth of chickens resulted in histological and biochemical modifications of muscle tissue [40, 41, 42]. The researches proved that selection of fast-growing chickens had negative effects on some meat quality parameters: reduced water holding capacity of meat, poor cohesiveness in cooked meat, appearance of pale, soft, exudative (PSE) meat, that is, of dark, firm, dry (DFD) meat [43, 44]. In addition to the mentioned factors, the available literature states that parameters of chicken meat quality are affected by the keeping system and duration of chicken fattening, feeding treatment and sex of chickens, pre-slaughter handling, transport to slaughterhouse, etc.

An important factor for consumers when deciding on the purchase of meat is its appearance, therefore, in this chapter are described some technological features such as color, pH value, drip loss, cooking loss and water holding capacity (WHC), that have a direct impact on meat appearance. Consumers connect the color of meat with its freshness. The color of meat can be determined visually or using instruments (colorimeters). For the visual evaluation of the meat color, it is necessary to have trained panelists, who evaluate the appearance of meat by using the hedonic scale. The instrumental determination of meat color is more efficient and the methods of reflection or extraction are used to quantify the amount of pigment. The color of foods can be defined as the interaction of a light, an object, an observer and the surroundings of the food. Recently, the International Commission on Illumination described how background can influence the appreciation of color. Instruments used for evaluation of meat color by reflection method are colorimeters, for example, CR Minolta 300 or 400 that work on the principle of meat color comparison in regard to standard color values. The International Commission on Illumination lists three values: CIE L\*, a\* and b\*. CIE L\* indicates lightness, where values range from 0 (black) to 100 (white). The value of CIE a\* shows redness while CIE b\* indicates yellowness. Negative a\* and b\* values indicate the appearance of green and blue color of the meat.

#### **3.1. Influence of genotype, sex and feeding on the chicken meat quality**

of red meat, is a potential risk factor for development of certain types of cancer. Red meat contains more potentially harmful ingredients than white meat. These potentially harmful ingredients are saturated fat, heme iron, sodium, N-nitroso compounds and aromatic amines produced by high temperature cooking, so the consumption of red meat represents a risk of developing cancers. Therefore, red meat is associated with a higher risk of cancers, while white meat shows neutral or moderately protective correlation to cancer occurrence [36, 37]. Cancers in digestive system are usually associated with consumption of animal products. This conclusion was confirmed by researches carried out among populations with significantly higher consumption of meat than recommended. It is assumed that myoglobin from red meat activates pre-cancerous damage by accelerating the heme iron influence on the formation of carcinogenic N-nitroso compounds and by developing cytotoxic and genotoxic aldehydes through the lipid peroxidation process [38].  Zhu et al. carried out a comprehensive review of literature on the occurrence of esophageal cancer, and concluded that there was a reverse correlation between the number of chicken meat meals a week and the risk of developing esophageal cancer [39]. The authors stated researches showed the decreasing risk of developing esophageal cancer by about 53% in Europe in cases of increased consumption of chicken meat. Of course, such research conclusions should be interpreted cautiously, because it cannot be stated with full certainty that red meat causes cancers and white meat does not, yet there is a lot of evidence that consumption of white meat is more

When considering nutritional aspects, poultry meat is good for consumers because it is rich in protein and minerals, and contains a small amount of fat with high portion of unsaturated fatty acids and a low cholesterol level [2]. Changes in consumers' lifestyle in developed countries have influenced the meat market by changing the demand and supply of certain types of meat, which the food industry used as an advantage to market so called "fast food" and more recently also "functional food". In both food groups, chicken meat is highly represented [3]. This growing demand for poultry meat influenced the scientists to create chickens of fast-growing genotypes, which have good feed conversion, better carcass formation (higher portion of breast meat and less abdominal fat), lower mortality, etc. However, all of these positive changes in new chicken genotypes cause greater stress, and many researchers point out that this fast growth of chickens resulted in histological and biochemical modifications of muscle tissue [40, 41, 42]. The researches proved that selection of fast-growing chickens had negative effects on some meat quality parameters: reduced water holding capacity of meat, poor cohesiveness in cooked meat, appearance of pale, soft, exudative (PSE) meat, that is, of dark, firm, dry (DFD) meat [43, 44]. In addition to the mentioned factors, the available literature states that parameters of chicken meat quality are affected by the keeping system and duration of chicken fattening, feeding treatment

and sex of chickens, pre-slaughter handling, transport to slaughterhouse, etc.

An important factor for consumers when deciding on the purchase of meat is its appearance, therefore, in this chapter are described some technological features such as color, pH value, drip loss, cooking loss and water holding capacity (WHC), that have a direct impact on meat

favorable than consumption of red meat.

68 Animal Husbandry and Nutrition

**3. Parameters of chicken meat quality**

Kralik et al. reported that the chicken genotype did not influence the CIE L\* (lightness) and CIE b\* (yellowness) values referring to meat color [45]. As of the results, the CIE L\* 49.93 and CIE b\* 10.17 was reported for chicken meat of Cobb 500 genotype, and for the Hubbard Classic, the values were CIE L\* 51.11 and CIE b\* 10.50 (P > 0.05). Furthermore, the authors stated that there was a negative correlation between pH and CIE L\* value r = −0.285 for Cobb 500 and r = −0.438 for Hubbard Classic genotypes. In the research into the influence of chicken sex on the quality of fresh and cooked meat, Salakova et al. also determined the negative correlation between pH and CIE L\* value measured in fresh and cooked breast meat of the Ross 308 chicken genotype (r = −0.41, P < 0.001 and r = −0.31, P < 0.05), [46]. The authors stated that male chickens of the Ross 308 genotype had statistically significantly higher pH values than female chickens (P < 0.05), which was not depending on the portion of crude protein in the finisher mixture (A = 22.6%, B = 20.1% and C = 18.7%). The highest pH values were measured in breast meat of male and female chickens of the group A (pH = 6.08 and pH = 5.97, respectively), while in feeding treatments with lower portion of crude protein in feeding mixture the value of pH in breast meat of both sexes decreased (♂ B = 5.99 and C ♂ =5.77 and ♀ B = 5.85 and ♀ C = 5.66). Female chickens had statistically significantly brighter meat color than male chickens in the A treatment (CIE L\* 54.90 and CIE L\* 52.24, respectively; P < 0.01). The same trend referring to the meat color was noticed in other feeding treatments, however, the differences were not statistically significant (♀ B=CIE L\* 59.43 C=CIE L\* 58.11 and ♂ B=CIE L\* 58.36 C=CIE L\*55.17). The research of Živković et al. describes the influence of extruded linseed in chicken feed on the physico-chemical and sensory traits of meat [47].  The control group (C) consumed the commercial mixture and the experimental group (E) had mixture supplemented with 6% of extruded linseed. The authors concluded that feeding treatment influenced the protein content in meat of thighs of females only (C = 19.27% E = 17.76%; P < 0.05). The feeding treatment had effect on the breast meat color (P < 0.05). Experimental group of chickens had lighter breast meat color than the control. Male chickens had statistically significantly lighter breast meat than females (P < 0.05). The value of CIE a\* (redness) reduced significantly in *m. pectoralis profundus*, and CIE b\* increased in *m. pectoralis superficialis* in both chicken sexes (P < 0.001). In thigh muscles (*m. biceps femoris*), the value of CIE a\* reduced significantly (P < 0.05) in meat of male chickens, while in female chickens the values of CIE b\* increased significantly (P < 0.05). The feeding treatment, sex and their interaction did not influence the results of chicken meat sensory analysis. In their research into the effects of genotype on some parameters of chicken meat quality, Kralik et al. reported that breast meat of the Hubbard Classic genotype was of better quality than the breast meat of Cobb 500 and Ross 308 genotypes [48]. Hubbard Classic chickens had better pH45min and CIE L\* values than other two genotypes (Cobb 500 and Ross 308). The highest pH45min was determined in Cobb 500 chickens, while the values for pH45min in Ross 308 and Hubbard Classic chicken were similar (6.05, 5.99 and 5.98, respectively; P > 0.05). Genotype had no effect on pH24h values (P > 0.05). Hubbard Classic chickens had the lowest CIE L\* value in breast muscle tissue (53.86), while Ross 308 and Cobb 500 chickens had slightly higher CIE L\* values (55.12 and 54.36, respectively; P > 0.05). Kralik et al. reported statistically significant influence of genotype on pH<sup>1</sup> (P = 0.004) and pH<sup>2</sup> (P < 0.001), drip loss (P = 0.015) and meat color (CIE L\* P = 0.015 and CIE a\* P < 0.001) in their research [49]. The values of pH were measured 45 minutes after slaughtering (pH1 ) and 24 h after slaughtering and cooling of chickens (pH2 ). The authors stated that chicken sex had statistically significant influence on meat color (P < 0.001). Female chickens had lower CIE L\* values than male chickens (Cobb ♀ = CIE L\* 49.24 and ♂ = CIE L\* 50.60, i.e. Hubbard ♀ = CIE L\* 49.97 and ♂ = CIE L\* 52.61).  In the research into the influence of pH values on the meat quality of different chicken genotypes, Ristić and Damme concluded that the chicken genotype and sex had statistically significant effect on the pH measured 15 minutes after slaughtering of chickens [50]. Male chickens had statistically significantly lower pH values than females. In the research into the influence of chicken genotype (Cobb, Ross and Hubbard) and the age (42 and 50 days) on the quality of meat, Glamoclija et al. stated that the pH values measured at different times after slaughtering (pH15min; pH24h and pH48h) were influenced by the chicken age at slaughter (P < 0.05), [51]. Older chickens had higher pH values of breast meat than younger ones. Interaction of chicken genotype and age had effect on the pH15min value, while the genotype did not affect the pH values (P > 0.05).

K56 days = 52.02% and K81 days = 55.26%, and O56 days = 51.82% and O81 days = 53.17% (P < 0.05), while the values in thighs were as follows: K56 days = 59.69% and K81 days = 60.15%, and O56 days = 56.21% and O81 days = 57.45% (P < 0.05). The values of pH in breast muscles of the treatments K56 days and K81 days were statistically significantly higher (P < 0.05) than in the treatments O56 days and O81 days (pH 5.96 and pH 5.98, and pH 5.75 and pH 5.80, respectively). Referring to all other meat quality parameters of both tested tissue (breasts and thighs), chicken meat from organic production had better values than the meat produced in conventional fattening system (cooking loss %, CIE

).

**3.3. Influence of transport and pre-slaughter handling on the chicken meat quality**

When animals are exposed to long-lasting stress (long-distance transport, lack of feed before transport and slaughter, overcrowded transport cages, high or low temperatures in the production facility or during transport, etc.), they will be exhausted and the glycogen stored in muscles will turn into lactic acid, which will then lead to a sudden lowering of pH value in muscles after slaughter, while the carcass is still warm. High temperature and low pH in chicken meat will stimulate protein denaturation, which will further influence lowering of the water holding capacity in meat. Low pH values stimulate the oxidation of myoglobin (pink color) and oxyhemoglobin (red color) to metamyoglobin (brown meat color). If animals are exposed to longer stress before slaughtering, they will have less stored glycogen in muscles because of exhaustion. Reduced glycogen reserve affects postmortem changes after slaughtering, meaning that the pH value remains high, which causes the occurrence of DFD meat. In this meat, protein denaturation and drip loss are slowed down [41]. In their study about influences of transport-caused stress on the meat quality parameters, Doktor and Połtowicz [55] stated that after 42 days of fattening of Hubbard Flex chickens, their treatment before and during transport to slaughter-

(%), shear force (N)). Bressan and Beraquet studied the influence of heat stress during fattening on the chicken meat quality and determined that chickens exposed to high daily temperatures (ambient temperature 30°C) had higher cooking loss measured in breast meat when compared to chickens kept at lower ambient temperatures (17°C), (28.7 and 27.2%, respectively), [56].

Since appearance and odor, as the parameters of meat quality, significantly affect the consumers' preferences at purchase, it is important to achieve "normal" meat color with the odor typical for fresh meat [57]. The stated authors assessed the consumers' opinions toward pale, soft and exudative chicken meat. In their research they used meat of lighter color (L\* = 59.26), that is, the meat color that was considered as normal for chicken filets (L\* = 49.24). The examinees made differences between PSE and meat of normal quality in stores, while panelists assessed sensory quality of cooked meat and showed preference toward control samples (meat of "normal" quality).  Furthermore, the authors defined the values for breast muscle color measured 24 hours post mortem, as of the following: dark L\* 45.68, normal L\* 51.32 and light L\* 55.95. Woelfel et al.

**3.4. Influence of some technological parameters on the chicken meat quality**

, while other meat quality parameters

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, meat color (L\*, a\*, b\*), drip loss (%), water holding capacity—WHC

L\*, CIE a\*, CIE b\* and shear value kg/cm<sup>2</sup>

house had statistically significant influence only on pH<sup>1</sup>

were not influenced (pH<sup>2</sup>

#### **3.2. Influence of keeping system and fattening duration on the chicken meat quality**

Bogosavljević-Bošković et al. determined that the fattening system (intensive or semi-intensive) had statistically significant influence on the portion of breasts and drumsticks with thighs (P < 0.05), [52]. The authors indicated that the portion of muscle tissue in chickens kept in semiintensive system was by 1.44% higher (P < 0.01), but the same chickens had the portion of bone and skin by 0.82 and 0.67% lower than chickens fattened in the intensive system (P < 0.05). Li et al. investigated the influence of chicken keeping systems (free range, cage and litter) on production parameters and meat quality and they reported that the keeping system had statistically significant influence on the final weight of chickens and feed consumption, as well as on the texture and portion of intramuscular fat in breast meat (P < 0.05), [53]. However, chicken keeping system had no effect on pH and drip loss in breast meat (P > 0.05). Castellini et al. [54] studied the influence of keeping systems (K = conventional and O = organic) and duration of fattening of chickens (56 and 81 days) on the quality of chicken meat, and they confirmed that breast and thigh meat of chickens kept in organic production had lower WHC values and pH24h than meat of chickens fattened conventionally. The breast meat had the following WHC values: K56 days = 52.02% and K81 days = 55.26%, and O56 days = 51.82% and O81 days = 53.17% (P < 0.05), while the values in thighs were as follows: K56 days = 59.69% and K81 days = 60.15%, and O56 days = 56.21% and O81 days = 57.45% (P < 0.05). The values of pH in breast muscles of the treatments K56 days and K81 days were statistically significantly higher (P < 0.05) than in the treatments O56 days and O81 days (pH 5.96 and pH 5.98, and pH 5.75 and pH 5.80, respectively). Referring to all other meat quality parameters of both tested tissue (breasts and thighs), chicken meat from organic production had better values than the meat produced in conventional fattening system (cooking loss %, CIE L\*, CIE a\*, CIE b\* and shear value kg/cm<sup>2</sup> ).

#### **3.3. Influence of transport and pre-slaughter handling on the chicken meat quality**

(*m. biceps femoris*), the value of CIE a\* reduced significantly (P < 0.05) in meat of male chickens, while in female chickens the values of CIE b\* increased significantly (P < 0.05). The feeding treatment, sex and their interaction did not influence the results of chicken meat sensory analysis. In their research into the effects of genotype on some parameters of chicken meat quality, Kralik et al. reported that breast meat of the Hubbard Classic genotype was of better quality than the breast meat of Cobb 500 and Ross 308 genotypes [48]. Hubbard Classic chickens had better pH45min and CIE L\* values than other two genotypes (Cobb 500 and Ross 308). The highest pH45min was determined in Cobb 500 chickens, while the values for pH45min in Ross 308 and Hubbard Classic chicken were similar (6.05, 5.99 and 5.98, respectively; P > 0.05). Genotype had no effect on pH24h values (P > 0.05). Hubbard Classic chickens had the lowest CIE L\* value in breast muscle tissue (53.86), while Ross 308 and Cobb 500 chickens had slightly higher CIE L\* values (55.12 and 54.36, respectively; P > 0.05). Kralik et al. reported statistically significant

(P = 0.004) and pH<sup>2</sup>

color (CIE L\* P = 0.015 and CIE a\* P < 0.001) in their research [49]. The values of pH were mea-

**3.2. Influence of keeping system and fattening duration on the chicken meat quality**

Bogosavljević-Bošković et al. determined that the fattening system (intensive or semi-intensive) had statistically significant influence on the portion of breasts and drumsticks with thighs (P < 0.05), [52]. The authors indicated that the portion of muscle tissue in chickens kept in semiintensive system was by 1.44% higher (P < 0.01), but the same chickens had the portion of bone and skin by 0.82 and 0.67% lower than chickens fattened in the intensive system (P < 0.05). Li et al. investigated the influence of chicken keeping systems (free range, cage and litter) on production parameters and meat quality and they reported that the keeping system had statistically significant influence on the final weight of chickens and feed consumption, as well as on the texture and portion of intramuscular fat in breast meat (P < 0.05), [53]. However, chicken keeping system had no effect on pH and drip loss in breast meat (P > 0.05). Castellini et al. [54] studied the influence of keeping systems (K = conventional and O = organic) and duration of fattening of chickens (56 and 81 days) on the quality of chicken meat, and they confirmed that breast and thigh meat of chickens kept in organic production had lower WHC values and pH24h than meat of chickens fattened conventionally. The breast meat had the following WHC values:

). The authors stated that chicken sex had statistically significant influence on meat color (P < 0.001). Female chickens had lower CIE L\* values than male chickens (Cobb ♀ = CIE L\* 49.24 and ♂ = CIE L\* 50.60, i.e. Hubbard ♀ = CIE L\* 49.97 and ♂ = CIE L\* 52.61).  In the research into the influence of pH values on the meat quality of different chicken genotypes, Ristić and Damme concluded that the chicken genotype and sex had statistically significant effect on the pH measured 15 minutes after slaughtering of chickens [50]. Male chickens had statistically significantly lower pH values than females. In the research into the influence of chicken genotype (Cobb, Ross and Hubbard) and the age (42 and 50 days) on the quality of meat, Glamoclija et al. stated that the pH values measured at different times after slaughtering (pH15min; pH24h and pH48h) were influenced by the chicken age at slaughter (P < 0.05), [51]. Older chickens had higher pH values of breast meat than younger ones. Interaction of chicken genotype and age had effect on the pH15min value, while the genotype did not affect the pH values (P > 0.05).

(P < 0.001), drip loss (P = 0.015) and meat

) and 24 h after slaughtering and cooling of chickens

influence of genotype on pH<sup>1</sup>

70 Animal Husbandry and Nutrition

(pH2

sured 45 minutes after slaughtering (pH1

When animals are exposed to long-lasting stress (long-distance transport, lack of feed before transport and slaughter, overcrowded transport cages, high or low temperatures in the production facility or during transport, etc.), they will be exhausted and the glycogen stored in muscles will turn into lactic acid, which will then lead to a sudden lowering of pH value in muscles after slaughter, while the carcass is still warm. High temperature and low pH in chicken meat will stimulate protein denaturation, which will further influence lowering of the water holding capacity in meat. Low pH values stimulate the oxidation of myoglobin (pink color) and oxyhemoglobin (red color) to metamyoglobin (brown meat color). If animals are exposed to longer stress before slaughtering, they will have less stored glycogen in muscles because of exhaustion. Reduced glycogen reserve affects postmortem changes after slaughtering, meaning that the pH value remains high, which causes the occurrence of DFD meat. In this meat, protein denaturation and drip loss are slowed down [41]. In their study about influences of transport-caused stress on the meat quality parameters, Doktor and Połtowicz [55] stated that after 42 days of fattening of Hubbard Flex chickens, their treatment before and during transport to slaughterhouse had statistically significant influence only on pH<sup>1</sup> , while other meat quality parameters were not influenced (pH<sup>2</sup> , meat color (L\*, a\*, b\*), drip loss (%), water holding capacity—WHC (%), shear force (N)). Bressan and Beraquet studied the influence of heat stress during fattening on the chicken meat quality and determined that chickens exposed to high daily temperatures (ambient temperature 30°C) had higher cooking loss measured in breast meat when compared to chickens kept at lower ambient temperatures (17°C), (28.7 and 27.2%, respectively), [56].

#### **3.4. Influence of some technological parameters on the chicken meat quality**

Since appearance and odor, as the parameters of meat quality, significantly affect the consumers' preferences at purchase, it is important to achieve "normal" meat color with the odor typical for fresh meat [57]. The stated authors assessed the consumers' opinions toward pale, soft and exudative chicken meat. In their research they used meat of lighter color (L\* = 59.26), that is, the meat color that was considered as normal for chicken filets (L\* = 49.24). The examinees made differences between PSE and meat of normal quality in stores, while panelists assessed sensory quality of cooked meat and showed preference toward control samples (meat of "normal" quality).  Furthermore, the authors defined the values for breast muscle color measured 24 hours post mortem, as of the following: dark L\* 45.68, normal L\* 51.32 and light L\* 55.95. Woelfel et al. determined the border values for "normal" chicken breasts L\* 52.15, drip loss 3.32% and cooking loss 21.02%, while for PSE meat these values were: L\* 59.81, drip loss 4.38% and cooking loss 26.39% [59]. Border values reported by Karunanayaka et al. are slightly higher than those determined by the abovementioned authors [60]. According to Karunanayaka et al., the values for normal meat are L\* 56.82 and WHC 77.95, while the PSE meat has the following values: L\* 61.83 and WHC 77.12 [60]. **Table 3** presents border values for PSE, normal and DFD chicken meat, as reported by various authors.

**4. Enrichment of chicken meat with functional ingredients**

Science on nutrition has developed over the years, and new analytical methods have enabled the determination of various functional food ingredients that have a beneficial effect on human health and that help to reduce the disease risks. Such ingredients, called nutricines, have an important biological activity in human cells [65]. The concept of functional food has been first mentioned in Japan in the 1980s. The project foods for specified health uses (FOSHU) was focused on food that was expected to have a specific health effect based on the content of some important and useful ingredients [66]. Ingredients in which consumers show interest are n-3 PUFA, Se, vitamin E, lutein and carnosine. Chicken meat can be enriched with n-3 PUFA if the content of FA (Fatty Acids) is changed in their feed [10, 67, 68, 69]. The optimal ratio of n-6 PUFA:n-3 PUFA is from 10:1 to 5:1 [70, 71]. The RDI (Recommended Daily Intake) for n-3 longchain PUFA is 350–400 mg. Vegetable and fish oils are predominant sources of omega-3 fatty acids. Vegetable oils are the main source of α-linolenic acid (C18:3n3, ALA), and fish oils are the main source of eicosapentaenoic acid (C20:5n3, EPA) and docosahexaenoic acid (C22:6n-3, DHA), [72]. Vegetable oils contain significant amounts of polyunsaturated omega-6 fatty acids, of which linoleic acid (C18:2n-6, LA) is the most significant. It is also present in sunflower and soybean oils [65]. Metabolic processes are initiated over arachidonic acid (C20:4n6, AA) and EPA in endoplasmic reticulum, and further carried out by the enzymes elongase Δ6 and desaturase ∆5. The mechanism of conversion into DHA is still not fully known, yet is believed that this

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**4.1. Polyunsaturated fatty acids (n-3 PUFA)**

**Figure 1.** Metabolism of n-3 and n-6 PUFA [76].

According to Zhang and Barbut, meat color typical to PSE meat is L\* > 53, the meat of normal quality has the values ranging between 46 < L\* < 53, and the DFD meat has the value L\* < 46 [63]. The same authors stated the cooking loss of meat classified as of color: 20.96% for PSE meat, 25.77% for normal meat and 21.32% for DFD meat. Referring to the values of meat color (L\*, a\* and b\*), Kissel et al. classified the chicken meat as normal, with measured values of L\* = 51.42, a\* = 7.26 and b\* = 6.74, and as PSE meat with measured values L\* = 57.63, a\* = 2.11 and b\* = 5.46 [62]. In their research into the PSE chicken meat in further processing (marinating and cooking), Barbut et al. [64] reported that fresh PSE meat was of lighter color (L\* = 57.7) and had lower pH (5.72), while DFD meat was of darker color L\* = 44.8 and higher pH (6.27). Carvalho et al. determined that PSE meat had L\* = 58.90; drip loss = 6.52%, cooking loss = 27.02% and WHC 79.84% [61]. The authors defined the meat to be of normal quality if exhibiting the following values: L\* = 56.86; drip loss = 4.04, cooking loss = 24.41% and WHC = 85.43%.

**Table 3.** Typical limits of pH values for PSE, normal and DFD chicken meat.

## **4. Enrichment of chicken meat with functional ingredients**

#### **4.1. Polyunsaturated fatty acids (n-3 PUFA)**

determined the border values for "normal" chicken breasts L\* 52.15, drip loss 3.32% and cooking loss 21.02%, while for PSE meat these values were: L\* 59.81, drip loss 4.38% and cooking loss 26.39% [59]. Border values reported by Karunanayaka et al. are slightly higher than those determined by the abovementioned authors [60]. According to Karunanayaka et al., the values for normal meat are L\* 56.82 and WHC 77.95, while the PSE meat has the following values: L\* 61.83 and WHC 77.12 [60]. **Table 3** presents border values for PSE, normal and DFD

According to Zhang and Barbut, meat color typical to PSE meat is L\* > 53, the meat of normal quality has the values ranging between 46 < L\* < 53, and the DFD meat has the value L\* < 46 [63]. The same authors stated the cooking loss of meat classified as of color: 20.96% for PSE meat, 25.77% for normal meat and 21.32% for DFD meat. Referring to the values of meat color (L\*, a\* and b\*), Kissel et al. classified the chicken meat as normal, with measured values of L\* = 51.42, a\* = 7.26 and b\* = 6.74, and as PSE meat with measured values L\* = 57.63, a\* = 2.11 and b\* = 5.46 [62]. In their research into the PSE chicken meat in further processing (marinating and cooking), Barbut et al. [64] reported that fresh PSE meat was of lighter color (L\* = 57.7) and had lower pH (5.72), while DFD meat was of darker color L\* = 44.8 and higher pH (6.27). Carvalho et al. determined that PSE meat had L\* = 58.90; drip loss = 6.52%, cooking loss = 27.02% and WHC 79.84% [61]. The authors defined the meat to be of normal quality if exhibiting the fol-

lowing values: L\* = 56.86; drip loss = 4.04, cooking loss = 24.41% and WHC = 85.43%.

pH 5.83 pH 5.61 pH ≤ 5.8 pH24h 5.77 pH < 5.7 pH 5.72 pH 5.76

pH 5.97 pH 5.96 pH 5.9–6.2 pH24h 5.93 pH < 6.1 pH 6.07

pH > 6.1 pH 6.27

**Condition pH Value of meat References**

[61] [60] [57] [50] [62] [63] [64] [59]

[61] [60] [57] [50] [62] [63] [59]

[50] [63] [64]

chicken meat, as reported by various authors.

72 Animal Husbandry and Nutrition

PSE pH24h 5.75

Normal pH24h 5.94

DFD pH ≥6.3

**Table 3.** Typical limits of pH values for PSE, normal and DFD chicken meat.

Science on nutrition has developed over the years, and new analytical methods have enabled the determination of various functional food ingredients that have a beneficial effect on human health and that help to reduce the disease risks. Such ingredients, called nutricines, have an important biological activity in human cells [65]. The concept of functional food has been first mentioned in Japan in the 1980s. The project foods for specified health uses (FOSHU) was focused on food that was expected to have a specific health effect based on the content of some important and useful ingredients [66]. Ingredients in which consumers show interest are n-3 PUFA, Se, vitamin E, lutein and carnosine. Chicken meat can be enriched with n-3 PUFA if the content of FA (Fatty Acids) is changed in their feed [10, 67, 68, 69]. The optimal ratio of n-6 PUFA:n-3 PUFA is from 10:1 to 5:1 [70, 71]. The RDI (Recommended Daily Intake) for n-3 longchain PUFA is 350–400 mg. Vegetable and fish oils are predominant sources of omega-3 fatty acids. Vegetable oils are the main source of α-linolenic acid (C18:3n3, ALA), and fish oils are the main source of eicosapentaenoic acid (C20:5n3, EPA) and docosahexaenoic acid (C22:6n-3, DHA), [72]. Vegetable oils contain significant amounts of polyunsaturated omega-6 fatty acids, of which linoleic acid (C18:2n-6, LA) is the most significant. It is also present in sunflower and soybean oils [65]. Metabolic processes are initiated over arachidonic acid (C20:4n6, AA) and EPA in endoplasmic reticulum, and further carried out by the enzymes elongase Δ6 and desaturase ∆5. The mechanism of conversion into DHA is still not fully known, yet is believed that this

**Figure 1.** Metabolism of n-3 and n-6 PUFA [76].

process is supported by the enzyme desaturase ∆4 [73]. Infante and Huszagh stated that DHA is synthesized in mitochondrial membranes, while EPA and AA are synthesized in the endoplasmic reticulum [74, 75]. **Figure 1** presents the metabolism of n-3 and n-6 PUFA.

to lower the risk of cardiovascular diseases development [82]. The second reason is that fats are replaced by polyunsaturated oils [83, 84, 85]. It is known that fish flour and oil are rich in essential n-3 PUFAs (EPA, DHA), however it is also proved that, if supplemented to chicken feed in higher amounts, they have negative effect on organoleptic properties of meat [86]. For that reason, as an alternative to fish oil, scientists use vegetable oils as supplements to chicken feed (soybean, rapeseed, sunflower and linseed oils), as well as combinations of those oils [11, 12, 77, 87]. In addition to oils, chicken feed can be supplemented also by extruded linseed or rapeseed [88], in order to change the FA profile. References about the use of various oils in chicken diets for the purpose of enriching broiler meat with n-3 PUFA are overviewed in **Tables 4** and **5**.

According to some researches, people have changed their dietary habits, so that over the past 150 years, once favorable and very narrow n-6 PUFA/n-3 PUFA ratio turned into unfavorable and wide ratio. There is also increased consumption of saturated fat originating from livestock fed grains, as well as increased consumption of trans-fatty acids originating from hydrogenated vegetable oils, along with significantly increased consumption of n-6 PUFA [91]. In developed countries, there is daily consumption of about 2.92 mg ALA, 48 mg EPA and 72 mg DHA [92], which is considered as insufficient. The studies have shown that human nutrition in Western European countries is lacking n-3 PUFA, and due to the significant amounts of n-6 PUFA in animal products, the n-6 PUFA/n-3 PUFA ratio is unfavorable, as it ranges from 15/1 to 16.7/1 [93, 94]. At present times, our diet is richer in calories than the food that man consumed in the Paleolithic. Nutrition in industrial societies is characterized by a surplus of calories, by increased consumption of SFA, n-6 PUFA and trans-fatty acids, and at

**Reference Diet ALA EPA DHA**

[89] Fish oil 6%

[80] Corn oil 15%

[10] Linseed oil 6%

[81]

\*

Fish oil 4% + 2% linseed oil

Canola oil 5% + corn oil 10% Canola oil 10% + corn oil 5%

Linseed oil 6% + 0.3% Se Linseed oil 6% + 0.5% Se

Soybean oil 6%

Canola oil 15%

[90] Sunflower oil 3% + linseed oil 3%

\* Rice bran oil S 1% + F 2%

Fish oil 2% + 2% linseed oil +2% sunflower oil

Sunflower oil 3% + linseed oil 3% + 0.5 mg Se/kg feed

Rice bran oil (S 0.7% + F 1.6%) + linseed oil (S 0.3% + F 0.4%) Rice bran oil (S 0.3% + F 1.0%) + linseed oil (S 0.7% + F 1.0%)

Rice bran oil and linseed oil supplemented to starter (S) and finisher (F) mixtures in the amounts as presented.

**Table 5.** Supplementation of oils to chicken diets and their effects on enrichment of thigh muscles with n-3 PUFA.

**% of total FA**

5.66 3.83 1.94 -

– – – 0.01

0.17 0.26 0.17

0.107 0.100

0.82 0.35 0.71 6.27 4.72 2.84 0.72

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0.09 0.08 0.14 0.03

0.17 0.18 0.19

0.107 0.127

1.20 0.48 1.23

1.01 1.80 2.27 3.37

1.97 2.13 3.55 3.67

6.75 11.90 8.28

4.755 5.692

0.41 0.07 0.20

There are two reasons for increasing the concentration of n-3 PUFA in chicken meat. The first reason is that nutritionists recommend the reduced consumption of saturated fatty acids (SFA)

S-starter diet.

F-finisher diet.\* Rice bran oil and linseed oil are supplemented to S and F diets in the amounts as presented. \*\*Oils of different origin are supplemented in the amount of 2% to S and 3% to F diets.

**Table 4.** Supplementation of oils in chicken feeding mixtures and their effect on enriching of breast muscles with n-3 PUFA.

to lower the risk of cardiovascular diseases development [82]. The second reason is that fats are replaced by polyunsaturated oils [83, 84, 85]. It is known that fish flour and oil are rich in essential n-3 PUFAs (EPA, DHA), however it is also proved that, if supplemented to chicken feed in higher amounts, they have negative effect on organoleptic properties of meat [86]. For that reason, as an alternative to fish oil, scientists use vegetable oils as supplements to chicken feed (soybean, rapeseed, sunflower and linseed oils), as well as combinations of those oils [11, 12, 77, 87]. In addition to oils, chicken feed can be supplemented also by extruded linseed or rapeseed [88], in order to change the FA profile. References about the use of various oils in chicken diets for the purpose of enriching broiler meat with n-3 PUFA are overviewed in **Tables 4** and **5**.

process is supported by the enzyme desaturase ∆4 [73]. Infante and Huszagh stated that DHA is synthesized in mitochondrial membranes, while EPA and AA are synthesized in the endoplas-

There are two reasons for increasing the concentration of n-3 PUFA in chicken meat. The first reason is that nutritionists recommend the reduced consumption of saturated fatty acids (SFA)

**Reference Diet ALA EPA DHA**

**% of total FA**

0.79 0.93 1.32 1.18

0.75 1.18 0.62

1.04 5.84 8.53 10.54

0.77 0.73 0.51

0.29 0.34 0.29

– – – –

0.15 0.50 0.98

0.17 0.25 0.63 1.74 2.72 5.62 6.44 8.95 5.66

0.87 2.03 0.75

0.15 0.66 2.39 3.80

0.90 0.93 0.84

0.39 0.59 0.50

0.07 0.05 0.13 0.07

0.43 0.88 1.77

0.23 0.63 1.47 3.51 5.76

3.16 2.37 2.36 6.25

0.72 0.37 0.61

1.59 0.70 2.17 2.14

7.09 8.51 6.78

5.14 6.29 4.39

2.21 2.01 3.41 3.52

0.33 0.86 0.98

0.23 0.92 3.23 5.02 4.60

mic reticulum [74, 75]. **Figure 1** presents the metabolism of n-3 and n-6 PUFA.

Rice bran oil and linseed oil are supplemented to S and F diets in the amounts as presented.

**Table 4.** Supplementation of oils in chicken feeding mixtures and their effect on enriching of breast muscles with n-3 PUFA.

 F-finisher diet.\* Soybean oil 2.5% + fish oil 2.5% Rapeseed oil 2.5% + fish oil 2.5% Linseed 2.5% + fish oil 2.5%

According to some researches, people have changed their dietary habits, so that over the past 150 years, once favorable and very narrow n-6 PUFA/n-3 PUFA ratio turned into unfavorable and wide ratio. There is also increased consumption of saturated fat originating from livestock fed grains, as well as increased consumption of trans-fatty acids originating from hydrogenated vegetable oils, along with significantly increased consumption of n-6 PUFA [91]. In developed countries, there is daily consumption of about 2.92 mg ALA, 48 mg EPA and 72 mg DHA [92], which is considered as insufficient. The studies have shown that human nutrition in Western European countries is lacking n-3 PUFA, and due to the significant amounts of n-6 PUFA in animal products, the n-6 PUFA/n-3 PUFA ratio is unfavorable, as it ranges from 15/1 to 16.7/1 [93, 94]. At present times, our diet is richer in calories than the food that man consumed in the Paleolithic. Nutrition in industrial societies is characterized by a surplus of calories, by increased consumption of SFA, n-6 PUFA and trans-fatty acids, and at

Rice bran oil and linseed oil supplemented to starter (S) and finisher (F) mixtures in the amounts as presented.

**Table 5.** Supplementation of oils to chicken diets and their effects on enrichment of thigh muscles with n-3 PUFA.

**Table 6.** Ratio of n-6 PUFA/n-3 PUFA in human nutrition.

the same time, by reduced consumption of n-3 PUFA, as well as of fruits, vegetables, protein, antioxidants and calcium. **Table 6** gives an overview of the n-6 PUFA/n-3 PUFA ratios in human nutrition according to different time periods and geographic locations [95].

ALA deposition was noticed in thighs than in breasts, and it was not depending on the feeding treatment. These results can be explained by the fact that thigh meat has higher content of fat than breast meat in all investigated groups. The content of fat in thighs was ranging from 8.97% (7.5% linseed) to 9.85% (combination 10% rapeseed + 10% linseed), and in breasts it was 6.79% (7.5% linseed). Combination of linseed and rapeseed as dietary supplement proved to be the most efficient in enriching of chicken meat (breasts and thighs) with the n-3 PUFA, however, the same group had statistically significantly higher concentration of MDA μg/kg thigh meat than meat of other investigated groups (P < 0.01). The authors explained the statistically significantly higher oxidation of fat in meat of the mentioned group by the weak stability of n-3 PUFA.

**Table 7.** Effects of fish oil in the diet and breed of chicken on the mean EPA and DHA concentration (mg/100 g meat) in

EPA 7.5 6.9 17.4 20.0 27.2 30.8 NS\* <0.001 DHA 39.6 38.6 54.9 64.3 118 126 NS <0.001

**Ross2 Cobb Ross Cobb Ross Cobb Breed Diet**

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**Fatty Acid Control1 Lofish Hifish P**

Diets contained fish oil at Control 0, Lofish 20 and Hifish 40 g/kg diet.

Breed of birds used, Ross 308 and Cobb 500.

Rymer and Givens [99], citation Givens [16], stated that there was a possibility of enriching

The authors concluded that the chicken genotype did not influence the incorporation of EPA and DHA in muscle tissue, however, the dosage of fish oil to feed is very significant (20 g/kg feed, i.e. 40 g/kg feed). The stated amounts enriched white chicken meat with n-3 PUFA for 171 and 573%, respectively. The authors recommended the supplementation of 200 mg/kg vitamin E to chicken feed in order to preserve oxidative stability and organoleptic traits. Yan and Kim reported the efficient usage of microalgae in enrichment of poultry products (meat

Carnosine is a dipeptide composed of ß-alanine and L-histidine, which is considered as a bioactive food component because of its physiological role in an organism. As a dipeptide precursor, L-histidine is important in the synthesis of carnosine (ß-alanine – L-histidine), homocarnosine (γ-glutamine – L-histidine) and anserine (ß-alanine – 3-methyl-L-histidine). Haug et al. supplemented histidine in the amount of 1 g/kg of feed and achieved the increase in carnosine concentration in chicken breast muscle for 64%, as well as the increase of anserine for 10% [100]. The authors concluded that higher amounts of histidine can cause the growth depression and the increase in feed conversion. Hu et al. did not determine the influence of carnosine supplementation (0.5% from 1st–21st day and from 22nd–42nd day of fattening) on the growth performances [101]. Experimental groups had higher weight of breast muscle and reduced thiobarbituric acid reactive substances (TBARS) values, while the meat color and pH values did not depend on the supplemented amount of carnosine to diets. Kopec et al.

white chicken meat by using fish oil (**Table 7**).

**4.3. The increase of carnosine in chicken meat**

and eggs) with DHA [14].

1

2

\*

NS: Not Significant.

white chicken meat.

#### **4.2.  Among the unsaturated fatty acids, the most present are oleic and linoleic acids, α-linolenic and arachidonic acids are represented in small amounts. Eicosapentaenoic and docosahexaenoic fatty acids are present only in traces or not present at all. In order to ensure the deposition of desirable fatty acids into poultry muscle tissue, chickens should be fed diet rich in polyunsaturated fatty acids. Vegetable oils, such as rapeseed and linseed oils, are rich in α-LNA, but they do not contain EPA and DHA. When supplementing fish oil to poultry feed, meat can obtain a "fishy" smell and taste that is undesirable for consumers [86]. Intensive researches into the effects of different diets on the content and profile of fatty acids in chicken meat are carried out, with the aim to produce meat with increased portion of n-3 PUFA and to retain organoleptic properties that are acceptable to consumers. Zelenka et al. concluded that broilers have limited capacity of desaturation and elongation of ALA into long-chain FA [96]. This conclusion was confirmed also by Lopez-Ferrer et al. [97]. Within the research into efficiency of enriching meat with EPA and DHA by using individual vegetable oils, such as sunflower, soybean, rapeseed and linseed oil in the amount of 5% as dietary supplements, it was proven that the most efficient was linseed oil as chicken feed supplement, as it achieved in muscle lipids the following results: 0.89% EPA and 1.85% DHA, which was, respectively, 7.41 and 1.92 times higher than the results achieved by the control fed sunflower oil [98].

Rahimi et al. fattened broilers with linseed and rapeseed as dietary supplements (7.5 and 15%, respectively), as well as with combination of both seeds (10 + 10%), and they determined that the combination of seeds influenced the increase of n-3 PUFA concentration in breast muscle when compared to the control group (0.004–0.25 mg/g meat), and the decrease of AA (0.08– 0.03 mg/g), as well as the decrease of n-6/n-3 PUFA ratio (from 47.78 to 8.14), [13]. The authors pointed out that the most favorable ratio of n-3/n-6 fatty acids in chicken thighs was determined in the group of chickens which consumed diets supplemented with 15% linseed (P < 0.05). Furthermore, the same group had the highest content of n-3 PUFA (1.15 mg/g), while the least content of those fatty acids was determined in the control group (0.26 mg/g). Better tendency of

1 Diets contained fish oil at Control 0, Lofish 20 and Hifish 40 g/kg diet.

2 Breed of birds used, Ross 308 and Cobb 500.

\* NS: Not Significant.

the same time, by reduced consumption of n-3 PUFA, as well as of fruits, vegetables, protein, antioxidants and calcium.  Among the unsaturated fatty acids, the most present are oleic and linoleic acids, α-linolenic and arachidonic acids are represented in small amounts. Eicosapentaenoic and docosahexaenoic fatty acids are present only in traces or not present at all. In order to ensure the deposition of desirable fatty acids into poultry muscle tissue, chickens should be fed diet rich in polyunsaturated fatty acids. Vegetable oils, such as rapeseed and linseed oils, are rich in α-LNA, but they do not contain EPA and DHA. When supplementing fish oil to poultry feed, meat can obtain a "fishy" smell and taste that is undesirable for consumers [86]. Intensive researches into the effects of different diets on the content and profile of fatty acids in chicken meat are carried out, with the aim to produce meat with increased portion of n-3 PUFA and to retain organoleptic properties that are acceptable to consumers. Zelenka et al. concluded that broilers have limited capacity of desaturation and elongation of ALA into long-chain FA [96]. This conclusion was confirmed also by Lopez-Ferrer et al. [97]. Within the research into efficiency of enriching meat with EPA and DHA by using individual vegetable oils, such as sunflower, soybean, rapeseed and linseed oil in the amount of 5% as dietary supplements, it was proven that the most efficient was linseed oil as chicken feed supplement, as it achieved in muscle lipids the following results: 0.89% EPA and 1.85% DHA, which was, respectively, 7.41 and 1.92 times higher than the results achieved by the control fed sunflower oil [98]. Rahimi et al. fattened broilers with linseed and rapeseed as dietary supplements (7.5 and 15%, respectively), as well as with combination of both seeds (10 + 10%), and they determined that the combination of seeds influenced the increase of n-3 PUFA concentration in breast muscle when compared to the control group (0.004–0.25 mg/g meat), and the decrease of AA (0.08– 0.03 mg/g), as well as the decrease of n-6/n-3 PUFA ratio (from 47.78 to 8.14), [13]. The authors pointed out that the most favorable ratio of n-3/n-6 fatty acids in chicken thighs was determined in the group of chickens which consumed diets supplemented with 15% linseed (P < 0.05). Furthermore, the same group had the highest content of n-3 PUFA (1.15 mg/g), while the least content of those fatty acids was determined in the control group (0.26 mg/g). Better tendency of

human nutrition according to different time periods and geographic locations [95].

**Period – area n-6/n-3**

**4.2. The increase of PUFA in chicken meat**

**Table 6.** Ratio of n-6 PUFA/n-3 PUFA in human nutrition.

Paleolithic

Current US

Greece prior to 1960 Current Japan Current India, rural

76 Animal Husbandry and Nutrition

Current India, urban

Current UK and Northern Europe

**Table 7.** Effects of fish oil in the diet and breed of chicken on the mean EPA and DHA concentration (mg/100 g meat) in white chicken meat.

ALA deposition was noticed in thighs than in breasts, and it was not depending on the feeding treatment. These results can be explained by the fact that thigh meat has higher content of fat than breast meat in all investigated groups. The content of fat in thighs was ranging from 8.97% (7.5% linseed) to 9.85% (combination 10% rapeseed + 10% linseed), and in breasts it was 6.79% (7.5% linseed). Combination of linseed and rapeseed as dietary supplement proved to be the most efficient in enriching of chicken meat (breasts and thighs) with the n-3 PUFA, however, the same group had statistically significantly higher concentration of MDA μg/kg thigh meat than meat of other investigated groups (P < 0.01). The authors explained the statistically significantly higher oxidation of fat in meat of the mentioned group by the weak stability of n-3 PUFA.

Rymer and Givens [99], citation Givens [16], stated that there was a possibility of enriching white chicken meat by using fish oil (**Table 7**).

The authors concluded that the chicken genotype did not influence the incorporation of EPA and DHA in muscle tissue, however, the dosage of fish oil to feed is very significant (20 g/kg feed, i.e. 40 g/kg feed). The stated amounts enriched white chicken meat with n-3 PUFA for 171 and 573%, respectively. The authors recommended the supplementation of 200 mg/kg vitamin E to chicken feed in order to preserve oxidative stability and organoleptic traits. Yan and Kim reported the efficient usage of microalgae in enrichment of poultry products (meat and eggs) with DHA [14].

#### **4.3. The increase of carnosine in chicken meat**