Effect of genetic strain, cage space and dietetic tryptophan level on the laying hens performance

Abstract

The aim of this study was to evaluate the effect of lineage, battery cage space allowance and tryptophan level in diet on commercial laying hens performance. A total of 720 hens from two different lineages and 31-47 weeks of age were used in a 2x3x4 factorial experimental design (lineages A and B; space allowances of 563, 450 and 375 cm²/animal and tryptophan levels of 0,175%; 0,195%; 0,392% e 0,591%), with twenty-four treatments and three replications each. The different space allowances were obtained according with the number of laying hens in the cage. The results showed effects of lineage on egg production, egg weight and animal mortality. When space allowance was reduced from 563 to 375 cm²/laying hen, the feed intake and egg weight decreased and animal mortality increased independent of hens' lineage. In conclusion, the diets containing different levels of tryptophan were not efficient to control negative effects of overcrowding on laying hens performance.