Egg production of light and medium hybrids given diets varying in protein level during the rearing and laying stages

Abstract

Synopsis From 6 to 16 weeks of age Sterling White Links and Sterling Ranger II's were given one of four diets containing 0 or 5.1 per cent meat‐and‐bone meal and 5.1 or 10.2 per cent soyabean meal. During the laying stage they were given one of two diets containing 14 per cent protein (meeting the Agricultural Research Council's (1963) estimated amino acid requirements as closely as possible) or 16.0 per cent protein. Reducing the level of protein in the rearing diet led to a significant (P < 0.001) reduction in live‐weight at 16 weeks and to a significant decrease in mean egg weight (P < 0.05), but age at onset of lay and egg number and total weight of eggs were not significantly influenced. Increasing the level of protein in the laying diet did not significantly influence the number of eggs laid but led to a significant (P < 0.001) increase in mean egg weight. At all stages the medium hybrids were heavier than the light hybrids; in addition they laid fewer but larger eggs and their food conversion effic...