Growth and Body Composition of Laying Hens under Different Feeding Programs up to 72 Weeks

This study aimed at comparing growth and changes in body composition of laying hens under different feeding programs from hatch to 72 week old. Hens from W36 or Brown lineages were fed 95% (P1 ), 100% (P2 ) or 105% (P3 ) of their nutritional requirements. Six pens (replicates) with 46 hens each were used for each combination of lineage and feeding program. Growth curves were fitted using Gompertz's model. The highest body growth rate was observed for Brown-hens fed P2 at 8 week old, when the maximum growth rate and maturity rate were achieved. The same lineage of hens fed P3 presented the greatest estimated body weight at maturity. W36 hens had higher deposition of fat and protein throughout the 6th week at maximum growth rate compared to Brown hens. This resulted in W36 hens that reached body weights at maturity faster than Brown hens. Fat deposition occurred at a later age than protein deposition in both lineages and all feeding programs. The present data support the usage of 105% of the declared nutritional requirement for the best growth performance.