Growth and laying performance of light‐hybrid pullets subjected to quantitative food restriction

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Abstract
1. Three degrees of quantitative food restriction producing body weights 88, 76 or 64% of controls at 20 weeks and three times of starting restriction 3, 6 or 9 weeks of age were compared with ad libitum‐fed pullets in a factorial experiment with 1800 light‐hybrid hens. Restrictions were applied such that the target weights were produced irrespective of time of starting. 2. Food intake was least when restrictions were started at 3 weeks. 3. Sexual maturity was delayed in proportion to the severity of restriction and resulted in lower percentages of small eggs. 4. Egg numbers decreased as restriction increased. 5. Mortality in restricted groups during rearing and laying was higher. 6. Optimal restriction was apparently intermediate between treatments producing 88 or 76% of ad libitum‐fed body weight. Body weight was so excessively affected by the most severe restriction that total production was adversely affected. 7. Restriction from 3 weeks was more profitable than restriction from 6 or 9 weeks, resulting in lower food cost during rearing and higher total egg production.