Vliv genotypu a věku na kvalitu jatečně opracovaného těla u brojlerů a nosných kohoutků

Abstract

In the study the carcass quality of fast growing broilers (F) and slow growing layer males (S) was compared. The effect of age on the carcass quality of S (S1, S2) was also evaluated. The weights of the carcasses were as follows: F 1110 g, S at 90 days of age 1116 g (S1) and S at the age of 132 days 1878 g (S2). Despite similar carcass weight in F and S1, the weight of the breast, and it’s proportion to the total body weight was significantly higher (P < 0.001) in F (265 g and 23.9% vs. S1 174 g and 15.6%). Continued fattening of the layer males resulted in increased breast weight (S2 276 g, P < 0.001) but not in breast proportion (S2 14.7%).The weight of the legs was significantly higher (P < 0.001) in S1 in comparison with F, but it was due to the heavier weight of the leg bones in S1 (P < 0.001). There was no difference neither in the weight of the leg muscles, nor of the leg proportions between F and S1. The proportion of the leg muscles increased significantly (P < 0.05) in S2 (25.6%) in comparison with S1 (24.1%). The content of abdominal fat, fat in the breast and fat in the leg muscles was significantly lower (P < 0.01, P < 0.01, P < 0.05, respectively) in the layer males S1 in comparison with the F broilers. The proportion of abdominal fat was 1.79% in F, and 0.54% in S1. The content of the breast fat was 1.24% in F and 0.56% in S1. The proportion of fat in the leg muscles was 8.45% in F and 2.78% in S1. As the birds became older, the content of the fat increased: the abdominal fat in S2 – 1.38% (P < 0.01), the breast fat in S2 – 0.96% (P < 0.01) and the leg muscles fat in S2 – 3.94% (P < 0.05). There was significantly lower (P < 0.001) content of dry matter in S1 than in F both in the breast and in the leg muscles.At the same carcass weight as the broilers, the layer males had a lower proportion of breast meat and also a lower content of abdominal fat, fat in the breast and fat in the leg muscles. The proportion of the leg muscles was comparable between the two groups. Concerning meat production, the quality of the carcasses of the layer males improved with age. Comparing the F carcasses with weight at 1110 g with the S2 carcass with weight of 1878 g, the weigh of the breast was almost the same, the weight of the leg muscles was higher in S2, and mainly the content of the fat in leg muscles was lower. The content of the abdominal fat and the breast fat was similar in both groups.