Effects of Rearing Feeding Programs, Phosphorous, and Phytase on Female Broiler Reproduction Performance and the Effect of Phytase on Progeny Live Performance

Previous research compared sigmoid and linear feeding programs for Ross 308 broiler breeder females to 21 wk of age. The linear treatment, where the feed allocation at 6 wk of age was 43 versus 50 g/pullet/d for the sigmoid program, exhibited increased fertility. Ross 308 and 708 were bred for different purposes. The Ross 308 had been selected to produce a high number of eggs combined with good hatchability, while the Ross 708 had been developed to produce higher breast meat yielding broilers. Therefore, the present experiments in Manuscript I and II investigated the effect of feeding programs for Ross 708 broiler breeder females that were the primary flock type in North Carolina. In Manuscript I, the cumulative fertility and hatchability of the treatment with lower feed intake during early rearing was significantly increased as compared to the other two treatments. There was no difference in fertile hatchability or egg production. Feeding Ross broiler breeder pullets lower feed intake early in rearing as compared to higher feed intake produced an improved persistency of fertility. Manuscript II compared four rearing feeding programs with Ross 708 broiler breeders. The 4 female breeder feeding programs were termed high-high (HH), high-low (HL), low-high (LH), and low-low (LL) with feed/pullet/d at 6, 15, and 21 wk of age being (HH) 52-70-94, (HL) 52-64-94, (LH) 47.5-70-94, and (LL) 47.5-64-94, respectively. The LH feeding program exhibited the best fertility and hatchability, while the HH feeding program produced the poorest results.;Manuscripts III and IV investigated the effects of dietary available phosphorus (AvP) and phytase in broiler breeders and their broiler progeny. Manuscript III studied two levels of AvP (A-POS and B-NEG) in grower and layer diets and two levels of phytase (C-NEG+250 FTU or D-NEG+500 FTU) "on top" of the low AvP treatment. The A-POS treatment and D-NEG+ 500 had the best overall fertility and total egg hatchability from 25 to 64 wk of age relative to B-NEG and C-NEG+250. Total egg weight was decreased by reduced dietary AvP and addition of phytase recovered the lost egg weight. Egg component results complemented the hatchability and fertility results, where the A-POS eggs had the greatest yolk:albumen ratio and thinnest egg shell and exhibited the best hatchability from 25 to 34 wk of age. Manuscript IV studied the live performance of the broiler progeny chicks that originated from the broiler breeder study in Manuscript III. These broilers were provided one of three diets, two levels of AvP and 1000 IU phytase "on top" of the lower AvP diet (CON, NC, and NC+1000) in a 4 breeder diet X 3 broiler diet design. No interactions of breeder and broiler dietary treatments were observed. The BW at hatching as affected by breeder diet was greater in the A-POS, and D-NEG+500, followed by C-NEG+250 breeder treatment relative to the B-NEG diet, which was expected due to a heavier initial egg weight as the recovery of egg weight due to phytase was reflected in chick weight.