Broiler breeder performance in response to diet protein and energy

Two hundred and forty Hubbard X Hubbard broiler breeders at 19 weeks of age were weight-sorted and transferred to individual laying cages where one of six experimental diets was provided to 41 weeks of age. Each diet was represented by 10 replicate groups of 4 individually caged and fed birds. Feed allocation was gradually increased to 150 g/bird per day, which provided 19 or 25 g crude protein and either 325, 385, or 450 kcal metabolizable energy (ME)/bird per day. Hens were inseminated every 7 days with .05 ml pooled semen from Hubbard males. Hen-day production was 1.6% lower with the high vs. low protein intake. Peak egg production occurred at 31 weeks and was 77.3, 87.9, and 84.1% for the low (L), medium (M), and high energy (H) intakes, respectively (P less than or equal to .01). Egg weight increased as the protein or energy intake increased; yolk content increased as energy intake increased or as broiler breeders aged (P less than or equal to .01). Carcass fat, protein, and moisture content of defeathered 41-week-old breeders were L: 45.5, 44.4, 56.6; M: 49.0, 40.4, 54.8; and H: 58.4, 32.5, 50.4, respectively (P less than or equal to .01). There were no dietary effects on hatchability, embryonic mortality, or fertility. From 32 to 35 weeks of age the higher protein intake increased egg weight by 1.2 g (P less than or equal to .05) and chick weight by .6 g; whereas hatched live chick weight was 39.6, 39.7, and 41.0, for L, M, and H diets, respectively (P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)