Heritability of Body Weight at Three Ages in Cross-bred Broiler Chickens Resulting from Two Systems of Breeding

BODY WEIGHT at broiler age frequently is considered the most important character in a breeding program directed toward improvement of meat-type chickens. Heritability of body weight at different ages up to broiler age has been estimated by a number of workers. The magnitude of an estimate may be influenced, however, by the absolute amount of genetic variation present, the extent to which environmental variation has been controlled during the experiment, the experimental design and by the method of statistical analysis. Studies investigating the influence of age on the efficiency of genetic selection for early growth are limited and findings from them are not consistent. El-Ibiary and Shaffner (1951) in a population of New Hampshires found sire component estimates of heritability in general smallest at 2 weeks, slightly higher at 10 weeks, and consistently higher in females than in males. Martin et al. (1953) with Rhode Island Reds calculated heritability estimates …