Effect of Genotype and Sex on Chemical Composition, Physicochemical Properties, Texture and Microstructure of Spent Broiler Breeder Meat

The aim of this research is to compare the carcass composition and meat quality characteristics of spent Cobb 500 and Ross 308 broiler breeders. A total of 28 carcasses were evaluated—7 female and 7 male carcasses from each genotype. Dissection was performed, and the percentages of neck, wings, skin with subcutaneous fat, abdominal fat, residual components, breast and leg muscles were calculated relative to the eviscerated carcass weight. The breast and leg muscles were evaluated for their chemical composition, color attributes (Lab), acidity (pH 24 ), and electrical conductivity (EC 24 ). Analysis of the structure and texture of the pectoralis major muscle was performed. The genotype of the birds had an impact on the eviscerated carcass weight, percentage of skin with subcutaneous fat, leg muscles, wings, and neck. Broiler breeder genotypes differed in terms of the chemical composition of the breast and leg muscles, except for the water content in the breast muscle and the collagen content in both the breast and leg muscles. The breast muscles of Cobb 500 exhibited lower cooking loss, pH 24 , redness, and yellowness, while the leg muscles of Ross 308 had lower EC 24 but higher cooking loss and lightness values. The pectoralis major muscle of Cobb 500 was firmer and more tender, with a smaller cross-sectional area of the muscle fiber and a smaller vertical (V) diameter of the muscle fiber. Males were characterized by a greater carcass weight and a higher percentage of leg muscles, neck, and carcass remains. On the other hand, females had a higher percentage of breast muscles, skin with subcutaneous fat, and abdominal fat. The sex of the birds affected the chemical composition of the breast and leg muscles, with the exception of the water content in the breast muscles and collagen content in the breast and leg muscles. The breast muscles of females were characterized by higher values of yellowness, although they also exhibited lower pH and cooking loss. In terms of texture analysis of the pectoralis major muscle, the meat of females was characterized by higher tenderness and firmness. However, the analysis of the structure showed that males had a thicker perimysium and endomysium. Regardless of broiler origin and sex, significant differences were found between the breast and leg muscles in terms of the assessed physicochemical features (pH 24 , EC 24 , cooking loss), color attributes (Lab) and chemical composition (protein, intramuscular fat, and collagen contents). Genotype and sex interactions were significant for the chemical composition of the breast muscles (protein, fat, collagen) and leg muscles (fat), as well as for the yellow color saturation of the breast muscles and springiness of the pectoralis major muscle. The study produced results that showed the meat and carcasses of spent hens and roosters to be suitable for processing due to their favorable chemical composition, high nutritional value and good technological properties, as assessed based on the results of meat texture and structure.