EFFECT OF REARING AND ADULT FEED RESTRICTION AND PHOTOPERIOD REGIMENS ON THE PERFORMANCE OF FOUR MEAT PARENT CHICKEN GENOTYPES

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Abstract
Two experiments were conducted each involving 2600 birds consisting of four commercial, chicken broiler, parent genotypes. The first experiment was designed to compare full feeding with two rearing feed restriction systems and two photoperiod treatments (1) a constant 14-h daylength and (2) a "17–9–14-h daylength." In experiment 2, adult full feeding was compared with two levels of feed intake restriction and the 17–9–14-h daylength used in experiment 1 was compared with a "simulated natural daylength." The rearing period skip-a-day feeding systems resulted in reduced body weight, delayed sexual maturity, heavier initial egg weight, increased number of hatching eggs, higher fertility, higher hatchability of total eggs set and more broiler chicks compared with full-fed birds. Controlled skip-a-day feeding resulted in reduced body weights, increased egg production, higher egg fertility, higher hatchability and more broiler chickens compared with ad libitum skip-a-day feeding. Body weights were lower with adult feed restriction than with full feeding. The more severe level of feed restriction resulted in fewer eggs produced and reduced egg weights. Restricted-fed birds produced more broiler chicks. There was some evidence that not all genotypes responded to these feeding systems in the same manner. Performance of the 17–9–14-h photoperiod birds was equal or superior to that of birds under either the constant 14-h daylength or the photoperiod with an increasing daylength during the rearing period.