EFFECT OF FEED ALLOWANCE DURING REARING AND BREEDING ON FEMALE BROILER BREEDERS .1. GROWTH AND CARCASS CHARACTERISTICS

The influence of feed allowance on growth and carcass characteristics was investigated with female Indian River broiler breeders. Four feeding programs were imposed: FF, provided ad libitum access to feed throughout; FR, provided ad libitum access to feed from 0 to 18 wk of age and restricted thereafter; RF, provided ad libitum access to feed from 0 to 4 wk, restricted from 4 to 18 wk, and consumed feed ad libitum thereafter; RR, provided ad libitum access to feed from 0 to 4 wk of age and restricted thereafter. All birds received a starter diet (2,739 kcal ME/kg, 19.1% CP) from 0 to 3 wk of age, a grower diet (2,729 kcal ME/kg, 15.5% CP) from 3 to 22 wk of age, and a layer diet (2,889 kcal ME/kg, 14.6% CP) from 22 to 62 wk of age. Restricted feeding (limited amount, fed daily) was based on commercial BW guidelines. Feed restriction (37.2% of ad libitum intake) during rearing (4 to 18 wk) slowed growth. At 18 wk of age, restricted birds (RF, RR) had an average BW of 1.9 kg and a shank length of 9.2 cm compared with ad libitum-fed birds (FF, FR), which had an average BW of 4.2 kg and a shank length of 10.8 cm. Despite the large difference in BW, percentage carcass protein did not differ significantly between the two rearing treatments; however, percentage carcass fat was almost four times greater in ad libitum-fed than in feed-restricted birds. The growth deficit remained significant to 62 wk of age in RF birds compared with FF birds. During the prebreeding period (18 to 23 wk), feed intake of RF birds was 209% that of RR birds and 133% that of FF birds. At sexual maturity, the BW of RF birds was 3.6 kg, compared with 4.6,4.5, and 2.6 kg for FF, FR, and RR birds, respectively. Stepwise regression indicated that BW was the most important (R2 = .363, P = .0001) among 11 variables in determining the number of large (> 10 mm) follicles in the ovaries of breeders at sexual maturity.