Effects of nutrition in the growing period on the subsequent performance of crossbred layers

Abstract

Crossbred White Leghorn-Australorp pullets were reared from 5 weeks of age to point of lay on 8 nutritional treatments. These included : a. an ad libitum fed positive control, b. 2 physically restricted treatments in which energy intake was reduced by 25 and 40 per cent, c. 3 low lysine treatments (0.36 per cent dietary lysine) in which the arginine-lysine ratios were 1.4, 1.8 and 2.2 : 1, d. 2 diets which contained excessive levels of methionine and lysine respectively. In the laying phase 4 ad libitum nutrient treatments were applied factorially with the rearing treatments. All experimental rearing treatments improved overall conversion of feed into eggs by 3.6-6.6 per cent compared with the positive control rearing treatment. This improvement was despite the fact that both the physical restriction and the low lysine treatments delayed sexual maturity by 9.5-26.2 days. The 40 per cent physical restriction and the low lysine treatments resulted in smaller sized pullets at point of lay, which laid significantly heavier eggs. There were no differences in subsequent performance between pullets reared on the three low lysine diets of differing arginine content. The data indicated that smaller sized pullets resulting from controlled energy intake during rearing may respond more to elevated nutrient intakes during the laying phase compared with ad libitum reared pullets.