INSIGHT INTO EGG WEIGHT AND ITS IMPACT ON CHICK HATCH-WEIGHT, HATCHABILITY AND SUBSEQUENT GROWTH INDICES IN CHICKENS- A REVIEW

This paper reviews the influence of egg weight on chick–hatch weight, hatchability potentials and subsequent growth indices in chickens. Though the spectrum of factors that affect chick-hatch-weight, hatchability potentials and subsequent growth indices in chickens is broad, however, increased interest in this concept is attributed to conflicting evidence in the literature indicating that performance in chickens in terms of chick-hatch weight, hatchability and subsequent growth indices in chickens may be closely related to the weight of the eggs and not by the hatcheries ability to effectively hatch eggs per se. This conflicting evidence in effect, creates a questionable atmosphere for chicken farmers as they are not appropriately guided on the influence of egg weight on chick-hatch weight, hatchability and subsequent growth indices in chicken. Often, the negative effect of this lack of proper guidance manifests itself in the farmer’s inability to maintain a uniform chick-hatch weight and hatchability values in their poultry farms especially in rural farming communities. This becomes an important factor creating variability at slaughter age. However, based on re-evaluation of numerous research data, it is concluded that hatchability, post-hatch performance in terms of chick-hatch weight and growth parameters in chickens is influenced by egg weight when all other non-genetic factors are kept under control. This influence is breed or strain specific because chick-hatch weight and hatchability are interrelated heritable traits that vary among breeds, variety or individuals in a breed or variety. Thus, because of the important implications of these differences, sorting of eggs by weight prior to incubation might be advantageous in optimizing productivity of any chicken breed and in particular, help to minimize the variability at slaughtering age often observed in many poultry farms.