Interrelationships among egg weight, hatchability, chick weight, post-hatch performance and rearing method in broiler breeders

Hatching eggs, from 2 broiler lines, categorised into 4 groups. viz, up to 60g (A), 60.1-65g(B), 65.1-70g (C) and above 70g (D), were incubated after being stored for 0-9 days at 10-15 degrees C. The hatchlings of each group were reared either separately or in mixed group together with those of other groups to assess their performance till 6 weeks of age. While fertility and per cent hatch weight remained unaffected by egg size, hatchability decreased with increasing egg weight. Correlation coefficient between egg weight and body weight at all ages of measurement was positive. Day-old chick weight increased significantly (P < 0.01) with increase in egg weight. Body weight at 6 weeks was significantly (P < 0.01) lower in group A and was highest in groups C and D. Feed efficiency was comparable for all the groups. Mortality was highest in group A. Rearing of chicks according to body size yielded higher body weight with low mortality and reduced variation in chick performance among the groups. Length of storage had no effect on the traits. studied.