Effect of genotype and sex on carcass composition, physicochemical properties, texture and microstructure of meat from parent stock laying hens after the reproductive period.

1. The aim of this study was a detailed evaluation of the influence of genotype and sex on carcass traits and meat quality (chemical composition, physicochemical properties, texture and structure) of spent hens (parent stock of laying hens after the reproductive period).2. After slaughter (83 weeks of age), the eviscerated carcass weight and the proportion of carcass components were determined. Analyses were performed for 24 h post-mortem pH (pH24), electrical conductivity (EC24), cooking loss, colour parameters (L*, a* and b*) and composition of breast and leg muscles. Texture and microstructure analysis of the pectoralis major muscle was conducted.3. Genotype significantly influenced carcass weight (Hy-Line Brown 1.775 kg vs. Isa Brown 1.564 kg), breast muscle, abdominal fat, skin with subcutaneous fat, wings and carcass remainders. Genotype affected the water and fat content in both breast and leg muscles and protein in breast muscles. Differences between the genotypes were seen for pH and cooking loss in leg muscles and in the electrical conductivity in breast muscles (Hy-Line Brown 9.68 mS/cm vs. Isa Brown 7.12 mS/cm) and leg muscles. Breed influenced lightness (L*) of both muscles and redness (a*) in breast muscles. Shear force of pectoralis major was significantly different as was the thickness of the perimysium and endomysium, depending on genotype.4. Sex influenced carcass weight, the proportion of breast muscles and leg muscles, abdominal fat, skin with subcutaneous fat and neck weight. It affected water, protein, fat and collagen content in both breast and leg muscles, as well as the pH of breast muscles and EC of both breast and leg muscles. Sex also affected the redness (a*) of the breast and leg muscles. Analysis of the pectoralis major muscle texture and structure revealed sex-related differences in most evaluated traits, except for vertical fibre diameter (V).5. Meat from spent breeder hens can be successfully used in meat processing, especially where mechanical or thermal treatment helps minimise quality differences due to age. Higher protein and relatively low fat content in the muscles of older hens may even be technologically advantageous. For consumers, this offers a cheaper alternative to more expensive broiler meat, provided it is properly prepared.