The effect of age and sex of broiler chickens on slaughter value, feed conversion and production costs

Age-related changes in the distribution of lean, fat with skin and bones in duck carcases

The experimental birds were Pekin ducks (352 males and 352 females) reared to the age of 13 weeks. They were fed standard diets ad libitum. Starting from the second week, 21 males and 21 females were slaughtered every 7 d. Their carcases were divided into the following elements: neck, wings, legs, breast and back, which were then dissected into lean, skin with fat and bones. The body weights of one-day-old ducklings were similar (circa 62 g), but at 5 weeks of age the males were heavier than the females, and at 13 weeks of age their body weights were 3537 g and 2994 g, respectively. In 2-week-old ducks 55.77% of lean was located in the legs, 15.91% in the back part, 2.78% in the wings, 12.47% in the neck and only 13.12% in the breast. Considerable changes in the distribution of lean were noted in the ducks aged 7 weeks. Its percentage decreased in the legs (to 29.34%) and increased in the breast and wings (to 36.86% and 10.96%, respectively). Age-related changes in the distribution of skin with fat were smaller. Its percentage increased in the wings, legs and back, and decreased in the neck and breast. Until the age of 7 weeks the percentage of bones was decreasing quickly in the legs and increasing in the neck and breast, compared with their total weight in the carcase.

Age-Related Changes in the Distribution of Lean Fat with Skin and Bones in Goose Carcasses

The experimental materials comprised White Italian geese (128 males and 128 females) reared to 14 wk of age. The birds were fed standard diets ad libitum. Starting from 2 wk of age, 14 males and 14 females were killed at 2-wk intervals. The carcasses were divided into neck, wings, legs, breast, and back, which were then dissected into muscle, skin with fat, and bones. Before slaughter, the BW of males and females were 6,814 and 5,736 g, respectively. At 2 wk of age, more than half of total muscle content was in the legs (60.98%), and the rest was in the back (17.84%), neck (9.43%), breast (8.78%), and wings (2.97%). To 10 wk of age, the rate of muscle deposition was relatively slow in the legs (a decrease to 31.29%) and fast in the breast and wings (an increase to 34.12 and 12.90%, respectively). Age-related changes in the distribution of skin with fat in the carcass were smaller, compared with changes in muscle distribution. A rising tendency was observed in the muscle content of wings and breast and in the content of skin with fat in the wings and neck, whereas a falling tendency was observed in the other carcass parts. Over the first 8 wk, the proportion of bones decreased in the legs, back, and neck and increased in the wings and breast, as compared with the total bone weight in the carcass.