Abstract
Collaborative experiments at 6 Prefectural Poultry Experiment Station with 1, 444 White Plymouth Rock pullets were carried out to study the effect of regulation of body weight by restricting the daily supply of feed. Feed supply was so restricted that body weight of pullets at 24 weeks of age was either 80, 70 or 60% of that of control pullets fed ad libitum in each Experiment Station. After 24 weeks of age, all the pullets were fed the layer diet full.
1. Pullets kept their body weight at 80% level started to lay almost simultaneously and with similar egg weight to the control pullets. In average, they produced hatching egg at the rate of 5.6% higher with 1.5yen/egg less feed cost than those of the control did.
2. Pullets kept their body weight at 70% level delayed in sexual maturity by 5 days and layed a significantly heavier first egg. The production of hatching egg was 9.7% higher and feed cost per hatching egg was 2.0 yen lower then those of the control, the difference being significant at 1 and 5% levels, respectively.
3. Pullets kept their body weight at 60% level delayed in sexual maturity by 16 days and layed a significantly heavier first egg. The production of hatching egg was 7.3% higher and feed cost per hatching egg was 3.8 yen lower than those of the control, the difference being significant at 5 and 1% levels, respectively.
4. Summarizing all of the data, it was suggested that body weight at 24 weeks of age should be kept at the level less than 70% of the control to get better performance in laying period.
Little effect on mortality of the pullet was observed among the different feeding programs.
