Effect of protein and energy levels on laying performance of strains of different bodyweights

Abstract

Three laying strains of different bodyweights were fed two dietary levels of both protein and energy in a factorial experiment. The level of methionine in the diets was equalized. The laying performance of the lightweight strain was inferior to that of the medium and heavy-weight crossbred strains. The medium weight strain was the most efficient in converting feed, protein and calories to egg product. Birds fed 15 per cent crude protein diets gained less bodyweight and produced eggs with higher yolk colou scores than those fed the 17 per cent crude protein diets. The performance of birds fed diets with 2840 kcal ME kg-1 was better than those fed diets containing 266 kcal ME kg.-1 The high level of energy resulted in greater pigmentation of egg yolks and better conversion feed to egg product. There were significant interactions between dietary protein and energy levels on egg weight, and on inta of feed, calories and protein. Mortality was higher among birds fed the medium-energy diets than in those fed the high-energy diets a a high proportion of deaths was due to lymphoid leucosis.