Growth pattern and carcase development in male ducks selected for growth rate

1. Growth patterns of the whole body, eviscerated carcases, breast muscle, leg and thigh muscles and abdominal fat pads were compared in 4 lines (Line s A, B, C, and D) of male ducks selected for market weight (n=1305) using g rowth curve analysis, allometric growth analysis and repeated measure analy sis. At 49 d of age, Line A was heaviest, followed by Line B, Line C and Li ne D. 2. Ducks were fed ad libitum under 24-h lighting and 12 or 24 ducks were ki lled to determine body carcass, breast-muscle, leg and thigh-muscle, and ab dominal fat weights at time points from hatching until 53 d of age. 3. The Weibull function was chosen for growth curve analysis. The asymptote and inflection point from the Weibull growth curves identified 3 lines (Li nes B, C, and D) with discrete body and carcase growth patterns but did not distinguish Line A from Line B. In all 4 lines the asymptote ranged from 4 437 g to 3008 g for body weight and from 3334 g to 2098 g for carcase weigh t; the inflection point ranged from 22.5 d to 25.3 d for body weight and fr om 25.4 d to 29.6 d for carcase weight. 4. The allometric growth coefficient, relative to whole-body growth, was hi gher than 1.00 for breast muscle and lower than 1.00 for leg and thigh musc les during from 4 d to 53 d of age. 5. Body fat accumulation was estimated by abdominal fat. Line D accumulated more abdominal fat than other lines. The pattern of fat accumulation in Li ne D was different from Lines A, B and C and there were no differences betw een Lines A, B and C.