Influence of genotype on carcass composition, metric traits of the digestive system and leg bones of laying hens after the egg-production season

Context The genotype of laying hens is one of the most important factors influencing their carcass composition and anatomical features. Aims The aim of the present study was to compare two genotypes of laying hens, Lohmann Brown and Lohmann White, after the laying period. Methods The experimental material consisted of 26 carcasses obtained after slaughtering spent laying hens at the age of 83 weeks. Key results The genotype of the birds had a significant (P < 0.05) effect on carcass weight, and the proportion (%) of the breast muscle, leg muscle and gizzard weight. Significant correlations were also found between bodyweight and the weight of the stomach, proventriculus, liver and spleen. The origin of the laying hens also had a significant impact on the length of the sections on intestinal segments, namely, jejunum, ileum and colon. Significant differences in the correlations between bodyweight and length of duodenum, jejunum and rectum were also found. The compared hybrids of laying hens differed significantly in the dimensions of the femur and tibia. Lohmann Brown (LB) hens were characterized by higher greatest length, medial length, smallest breadth of the corpus, and greatest breadth of the distal end of the femur compared with Lohmann White (LW) hens. Dimensions of the tibia greatest length, axial length, smallest breadth of the corpus, greatest breadth of the distal end and greatest depth of the distal end in LB hens were also significantly (P < 0.05) higher than those in LW hens. Conclusions The results showed that the genotype of laying hens tested after the laying period influenced carcass weight and muscle percentage, as well as differentiated the birds in terms of dimensions of individual segments of the digestive tract, femur, and tibia bones. Implications The results of this research may be useful for consumers of laying hen carcasses and people interested in poultry anatomy.