Effect of Growth Rate on Body Composition of Broiler Chickens at Eight Weeks of Age

The influence of growth rate on body composition and of cut up chicken parts relative to eviscerated carcass weight was determined. 380 male and 390 female chickens (Lohmann) were divided into three groups for each sex by body weight (large, medium, and small) and by shank length (long, middle, and short), and slaughtered at 59-d of age. Average body weights of three weight groups were 2,826, 2,584, and 2,387 for females, and 3,399, 3,078, and 2,638 g for males. Average body weights of three groups by shank length were 2,708, 2,526, and 2,577 for females, and 3,308, 3,096, and 2,789 g for males. Correlation between shank length and body weight for females was 0.44 and for males was 0.84. Proportions of body components by weight were not significantly different for females and males. Proportions of blood (3.51%, females, 3.95%, males), of head and shank (5.54%, females, 6.15%, males) and of abdominal fat (3.68%, females, 2.81%, males) differed by sex (P<0.05). Proportions of blood, feathers, head and shank, inedible viscera and edible viscera by shank length were not significantly different between sexes but proportion of eviscerated carcass weight was lower in the short shank length group (P<0.05). Percentages of cut up parts to eviscerated carcass weight for females and males were 35.8 and 36.4 for thigh-drumstick, 28.5 and 28.5 for breast, 11.7 and 11.7 for wing, and 7.9 and 7.7 for neck, respectively. Percentages of thigh-drumstick were different between sex (P<0.05). Percentages of cut up parts to eviscerated carcass weight did not differ among body weight groups in females. Percentage for necks was higher in large (7.91%) than in small weight group (7.17%). Percentage for wings was higher in small (12.15%) than in large weight group (11.43%) in males. Percentages of eviscerated carcass weight for wings in males and for thigh-drumsticks in females were significantly different among shank length groups (P<0.05).