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

Abstract

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 (pH24), and electrical conductivity (EC24). 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, pH24, redness, and yellowness, while the leg muscles of Ross 308 had lower EC24 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 (pH24, EC24, 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.

Influence of Genotype on Meat Quality in Laying Hens after the Egg Production Season

“…LB and LW leg muscles after laying were characterized by significantly (p < 0.05) lower lightness (L*) and higher levels of yellowness (b*) and redness (a*) compared to pectoral muscles. Our results were confirmed in previous studies [11,22,26]. In our study, the genotype of birds did not significantly affect the pH 24 value of pectoral and leg muscles.…”

“…The EC 24 value of leg muscles was higher in LB by 1.1 (mS/cm) compared to LW. The reported EC 24 results of the pectoral muscle in our study were similar to those in other works [26,30]. In contrast, in the study conducted by Biegniewska et al [30], the EC 24 of leg muscles (6.3-6.8 mS/cm) in Ross 308 at 64 weeks of age was significantly lower than the results obtained in our study (9.7-10.8 mS/cm).…”

“…In our study, the genotype of the birds did not significantly affect the texture characteristics of the pectoralis major muscle. The shear force value (LB-70.0 N) was significantly higher than in our earlier study of Ross 308 (60.2 N) and Cobb 500 (48.1 N) broiler breeders [26]. The higher shear force values in laying hens obtained in our study compared to the parent flocks of meat hens are most likely due to the chemical composition, in particular, the amount of intramuscular fat, which is more abundant in the pectoral muscle in the parent flocks of meat hens.…”

“…Many authors have shown that the textural characteristics of the pectoral muscle are influenced by genotype, age of the birds, sex, nutrition and handling of carcasses after slaughter [11,26,38,39]. In our study, the genotype of the birds did not significantly affect the texture characteristics of the pectoralis major muscle.…”

“…The obtained results of pH 24 of pectoral muscles in the above studies are lower than in our study (LB, BM-5.99). Regardless, the obtained results of the acidity of the pectoral muscles and leg muscles are within the limits (5.90-6.20) of meat suitable for technological processes [26]. An important characteristic for assessing meat quality is EC 24 .…”