soybean meal is an ingredient of choice to supply energy and proteins to layers and broilers . because of that
, costs and availability of soybean meal are strongly correlated with the price of agricultural commodities on the world market [ 1 , 2 ] .
the trypsin inhibitors of soybean grain are well characterized and are an important determinant of nutritive value [ 3 , 4 ] .
toasting is suggested within other heat processing procedures to reduce trypsin inhibitors in soybean grains or meals [ 6 , 7 ] . in benin , only jupiter variety of soybean is produced ; and the toasting method is adopted for processing grains and meal .
on other side , laying performance of hens is lower when they are too fat . thus , soybean grains even toasted are used at lower rate in pullets and layers diets than broilers diets .
farmers reject the utilization of toasted soybean grains in layers diet in benin ; but   included efficiently up to 22% of toasted soybean grains in broiler diet . in tropical climate ,
important increase of dietary energy may be result a decrease of feed intake by poultry .
toasted soybean grains have a high content of energy and protein , it is important to evaluate their optimal rate in diets of pullets and layer hens in hot and humid climate , mainly for birds from heavy lines often used in africa .
the study was conducted in a poultry house ( 20  m  15  m ) .
the house was divided into twelve ( 12 ) partitions of 25  m each .
each partition had three feeders ( 1.5  m of length ) and two automatic drinkers .
a total of 1000 harco ( rhode island red  plymouth rock ) day - old chicks were imported from nigeria .
they were vaccinated against newcastle disease , gumboro , infectious bronchitis , and avian pox .
chicks were also treated regularly against helminthes and coccidiosis . at three - week - old ( starting of the experiment ) , the average weight of chicks was 206.5  2.69  g. chicks were divided into 12 groups of 81 chicks each .
thus , at pullet and laying phases , there were 3.2  chicks / m .
diets were formulated by phases . at starter ( 4 to 8 weeks - old ) , pullet ( 9 to 18 ) and laying ( 19 to 26 ) phases , respectively , four diets were formulated ( tables 1 , 2 , and 3 ) . in diets , soybean grains
were included at 0% ( r0 , control ) , 5% ( r5 ) , 10% ( r10 ) , and 15% ( r15 ) .
soybean grains were toasted before the processing of diets to reduce trypsin inhibitors effect . at each phase , the same quantity of feed was provided to each replicate and the birds consumed all the available feed .
they are used to compare the efficiency of diets . the general linear model ( glm )
a significant effect of diets is stated when p value ( p ) is less than 0.05 .
the effects of replication and of the interaction between diets and replications were not significant ( p > 0.05 ) .
hence , the statistical model was 
 ( 1)yi=+gi+i , 
 where yi is the observation for dependent variables ;  is the general mean ; gi is the fixed effect of soybean grains ; i is the residual error .
the results are presented in two phases : the growth phase ( starting and pullet phases ) and the laying phase .
performances during the five weeks of starting phase are shown in table 4 and figure 1 .
no significant difference ( p > 0.05 ) was recorded on , daily weight gain , mortality and feed conversion ratio in spite of difference in feed composition between diets .
the inclusion of toasted soybean grains at different rates in the diet did not affect significantly the growth and survivability of chicks .
these results suggest a similar efficacy of diets at starter phase .   also , during the pullet phase the growth performance was not significantly affected by the diet ( table 5 and figure 1 ) .
however , the feed conversion ratio and the mortality rate increased at pullet compared to the starter phase . at starter and pullet phases , the prices of the formulated feeds decreased when the soybean grains rate increased in the diet ( table 6 ) .
thus , at pullet phase , the feeding cost per kg of live body weight gain decreased in soybean - based diets compared to the control diet ( table 7 ) .
however , at starter phase , due to the light decrease of live body weight gain in the soybean grains - based diets , the feeding cost increased ( table 6 ) .
the soybean grains based diets are therefore more efficient at pullet phase than at starter phase .
the feed efficiency evaluated at the end of pullet phase , demonstrated that for each unit of money invested in feed , the revenue from the selling of the live weight gain varied between 2.15 and 2.48 times ( table 7 ) .
the efficiency of the diet increased significantly ( p < 0.05 ) with an increase of the toasted soybean grains rate .  
the laying phase was recorded until the peak of lay between 25 and 26 week - old ( figure 2 ) .
while feed intake was equal between treatments , the results demonstrated an improvement of laying rate in layers fed r15 diet compared to the control diet . in the second month , the average laying rate in r15 was 67.8% versus 64.7% in control diet , without any significant difference between treatments .
at the peak ( 26-week - old ) , laying rates were 73.9% , 68.3% , 67.1% , and 82.5% in r0 , r5 , r10 , and r15 diets , respectively .
furthermore , the egg weight of layers fed r15 diet increased significantly ( p < 0.05 ) in the second month of laying ( table 8) .
thus , during the two first months of laying the feed conversion of layers fed r15 was the lowest , and there was no significant effect of diet on mortality rate of hens ( p > 0.05 ) .
thus , the feeding cost per egg decreased significantly during the first month of laying , but not later ( table 9 ) . respectively , in first and second months , the feeding cost in r15 diet represented about 32% and 86% of that in control diet , indicating a better efficiency of r15 diet compared to the control diet and the two other soybean grains - based diets .
the similarity on growth performance of pullets up to 18-week - old demonstrates the efficiency of toasted soybean grains based diets in general and r15 diet in particular .
the live body weight gain of pullets was higher than reported , and they grew regularly .
thus , the final weights of pullets ( 1366 to 1456  g ) are in the range of 1341 to 1594  g recorded at 20-week - old in shika - brown pullets .
the live weight of pullets at the starting of the laying period is one of more important criteria focused by farmers . in this study , at 18-week - old the live weight of pullets was very similar in r0 and r15 diets ( 1454  g versus 1456  g ) . during pullet phase
the feed conversion ratios were lower than the 5.73 to 6.62 found between 8 and 20 weeks in hy - line pullets .
furthermore , the light increase of mortality rate in soybean based diets compared to control diet was not significant .
these results confirmed the efficacy of all the diets . up to 15% of toasted soybean grain
up to peak , the laying rate in r15 diet was the highest , with a significant difference from 24 to 26 weeks of age .
thus , efficiency of toasted soybean grains based diets was also effective during the first eight laying weeks .
the average laying rate was higher than 63.868.4% , 64.0% , and 61.4%   recorded respectively with harco and hy - line layers up to 28-week - old . at laying phase , the feed conversion ratio was also lower in r15 diet compared to the control diet .
however , the feed conversion ratios were higher than 2.814.07  g feed / g egg .
no significant diet effect was found on hens ' mortality . in the second month , the egg weights were significantly higher in r15 diet , but lower than the 60  g reported by other [ 1517 ] . in first month , the egg weights were in the range of 41.047.4  g .
energy requirement of hens is lower in hot and humid climate than in temperate climate .
soybean grains being very energetic , during the latest laying weeks , hens could get fat . that might reduce their laying performance .
an evaluation of the laying performance during the whole laying period is therefore relevant for heavy layers breeds fed with whole toasted soybean grains in hot and humid climate .
the incorporation of toasted soybean grains in diets reduces feed prices . at growth and laying phases ,
thus , feeding cost and feed efficiency improved significantly in soybean - based diets during the growth phase of pullets .
the feeding of harco pullets with toasted soybean grains diets can be therefore recommended in hot and humid regions .
the significant decrease of feeding cost from first to second laying months was due to the increase of laying rate until the peak .
this study shows the efficiency of toasted soybean - based diets in harco pullets and hens feeding in hot and humid climate .
the toasting processing used in benin to improved soybean grain efficacy in poultry diet is therefore suitable .
however , the price of toasted soybean grains should be kept at a level where the energy and protein costs from these grains should be lower than those from other main energy and protein sources like soybean and fish meals .
 the aim of this paper was to evaluate the effects of toasted soybean grains on bioeconomic performance of pullets and layer hens in hot and humid environment . 
 a total of 972 three - week - old harco chicks were divided into 12 groups . at starter , 
 pullet and laying phases , birds were fed four diets containing 0% ( r0 ) , 5% ( r5 ) , 10% ( r10 ) , and 15% ( r15 ) of soybean grains . 
 results showed similar feed intake , body weight gain , laying rate , feed conversion ratio , and mortality rate between dietary treatments at each phase . 
 the egg weight increased significantly in diet r15 ( p < 0.05 ) . 
 the use of soybean grains reduced the feed prices . 
 feeding cost decreased significantly ( p < 0.05 ) during growth and laying phases in soybean grains added diets . feeds efficiency increased significantly ( p < 0.05 ) with the increase of dietary soybean grains rate . properly toasted soybean grains can be therefore included up to 15% in heavy line layer hens ' diet in tropical conditions . 
1. Introduction
2. Materials and Methods
3. Results
4. Discussion
5. Conclusion