Simple SummaryAs a result of the increasing intensification and globalization of poultry production, the number of poultry breeds/varieties is consistently declining. The elimination of populations well adapted to local conditions risks losing desirable traits such as high survival rates, resistance to diseases and adverse environmental conditions, and high reproductive capacities. Production based on local breeds can be useful for use in agriculturally poor regions, contributing to the effective management of these areas and to the production of eggs and meat with a unique nutrition and taste. An analysis of the performance and egg quality of three hen strains included in a conservation program in Poland was carried out. It was shown that the random mating system used in the reproduction of flocks effectively protects populations from an increase in the degree of inbreeding. Hens kept in small, closed populations, in which selection aimed at improving performance traits was not carried out, retained their genetic distinctness, manifesting, among other things, in significant differences in performance traits and egg quality.AbstractThe aim of the study was to evaluate the effect of genotype on the productivity and egg quality of three hen strains included in the genetic resource protection program in Poland. The study encompassed populations of laying hens, i.e., Rhode Island Red/RIR (R-11 and K-22) and Rhode Island White (A-33). The analysis over five generations included the basic production traits, i.e., the weight of the birds at 20 weeks (g), egg weights at 33 and 53 weeks, sexual maturity, the number of eggs laid up to 56 weeks of age, and hatchability parameters. In addition, the effective population size (Ne) and flock homozygosity coefficient (Fx) were calculated for each breed. Population health during the rearing and production periods was also recorded. The study also determined egg content and shell quality traits in relation to the age of the hens. The birds were kept on litter at a stocking rate of 5 hens/m2and fed ad libitum with a standard feed mixture for hens. Based on the results, it was concluded that the evaluated hen populations (R-11, K-22, and A-33) are valuable strains, representing a reservoir of unique phenotypic and egg quality traits. It was shown that the random mating system used in the reproduction of flocks effectively protects the populations from an increase in the degree of inbreeding. An influence of hens’ origin (genotype) and age on the performance results, as well as egg quality traits, was found. Over five generations, the evaluated hen strains were characterized by high survival rates (above 98%). The study also found a large variation between the R-11 and K-22 strains and the A-33 strain in terms of the evaluated performance traits, especially in the body and egg weights, sexual maturity age, and laying performance of hens. The earliest to start laying were hens from the K-22 strains, which also showed significantly (p≤ 0.05) higher laying performances compared to R-11 hens. The results also indicate that the quality of eggs from hens of the compared strains varied. This was particularly true for such traits as shell color; egg, shell, and yolk weight; and shell quality. It was also shown that many egg and shell quality traits change with the age of the hens. The analysis of the obtained data indicates that the adopted methods of conservative breeding for these populations have influenced the success of the conservation program.