Reevaluation of lysine requirement based on performance responses in broiler breeder hens

This experiment was conducted to study lysine requirement in broiler breeder hens. The treatments consist of 6 levels of lysine (0.50, 0.57, 0.64, 0.71, 0.78 and 0.85%) in a completely randomized design with 4 replicates and 8 hens in each pen, from 52 to 62 weeks of rearing period. The strain of hens was Arian. The first 3 weeks were considered as a period of depletion. The hens selected were of nearly the same body weight (3600±15 g) for maximum uniformity in treatments groups. Each pen was equipped with a four-hole nest, a tube feeder, and an automatic waterier. Amino acid profile and composition of feed ingredients were analyzed and results of them were used for diet formulation. The results showed that different levels of lysine had significant effects on egg production (%), egg mass (g/h/d), egg content (g) and settable egg (%) (P < 0.05). There were no significant differences in double yolk eggs, small eggs, hatch of fertile eggs and chicks weight (P > 0.05). The broken-line model was used for determination of requirement. Broken-line regression analysis indicated that lysine requirement for egg production (%), egg mass (g/h/d), egg content (g) and settable egg (%) were 0.64 , 0.67 , 0.67 and 0.63%, respectively. Finally, the results indicated that lysine requirements for egg mass and content and also R2 were higher than determination of lysine requirements based on egg production and settable egg.