EFFECTS OF DIETARY-PROTEIN AND STRAIN ON THE GROWTH OF BROILER BREEDER PULLETS FROM ZERO TO 5 WEEKS OF AGE

In a series of four experiments, the effects of differences in dietary protein intake on BW, skeletal growth and the weight of the Pectorali s major muscle was studied in Hubbard Standard and Hubbard Hi-Y broile r breeder pullets. In Experiment 1, pullets were fed diets with either 15, 17, or 19% CP from 1 to 21 d. There was a linear increase in BW g ain and feed consumption with each increase in CP and Hubbard Standard pullets consumed significantly more feed than Hubbard Hi-Y pullets. F rom 21 to 34 d, pullets were subjected to feed restriction every day ( ED) or every-other-day (EOD). On Day 35, pullets were given ad libitum access to feed and ED-restricted pullets consumed significantly more feed than EOD-restricted pullets through 3.5 h postfeeding. In Experim ent (Exp.) 2, pullets were fed the 19% CP diet for approximately 14 d (300 g) or 20 d (600 g) before being switched to the 15% CP diet. In E xperiment 3, the 19% CP diet was fed for exactly 7 or 21 d before swit ching to the 15% CP diet. Ln all experiments, Hubbard Standard pullets weighed significantly more than Hubbard Hi-Y pullets and had increase d overall skeletal growth. When the pullets from both strains were res tricted to only 380 g BW at 28 d, (Exp. 3) the longer period of protei n intake significantly enhanced breast muscle weight but there were no significant strain differences. When BW at 28 d was increased to 480 g, (Exp. 2), dietary protein and strain differences were observed.