Effects of differences in the initial body weight of groups on laying performance and egg quality parameters of Lohmann laying hens

This study was carried out to investigate the effect of different body weight groups (light (L) = 1 400–1 500; medium (M) = 1 500–1 600 and heavy (H) = 1 600 < g) on performance and egg quality traits of Lohmann hens, 24 weeks of age, in different laying periods. A total of 288 Lohmann White layers were allocated randomly to three groups with respect to live weight, each consisting of 24 replicated cages as subgroups, comprising four hens. The study period lasting for 60 weeks was investigated as four different age periods (first period = 24–40 weeks; second period = 40–54 weeks; third period = 54–68 weeks; fourth period = 68–84 weeks). Differences in the initial live weight at the beginning of experiment among the groups continued to the end of experimental period. Considering the egg production, differences among the groups were not significant (P > 0.05) during the experimental period. Egg weight was determined to be lower in the group with low body weight (64.58 g) than in medium (64.97 g) and heavy hen groups (66.30 g). Differences in feed intake and feed conversion ratio among the groups were found significant, and the mean values were 123.93, 127.48 and 130.67 for feed consumption (g/day); 2.23, 2.28 and 2.27 for feed conversion ratio. Except for the feed conversion ratio, the effect of weight groups by age period interaction on performance parameters was significant (P < 0.01). The effects of body weight on shell strength, shell thickness and yolk index were not significant during the experimental period. However, different body weight groups significantly affected shape index, yolk colour, albumen index and Haugh unit parameters. Shell strength, yolk colour and yolk index values were affected by weight groups by age period interaction. In conclusion, Lohmann White hens in the light group in a uniform flock had higher egg production and lower feed conversion ratio values than those of other weight groups.