Influence of Energy Restriction and Pre-Incubation Holding Period of Eggs on Fertility and Hatchability in Aged Broiler Breeders (Report‪)‬

INTRODUCTION Broiler breeders are sensitive to free allowances of feed. Excess feeding of breeders negatively affected egg production, shell quality, fertility and hatchability (Mc Daniel et al., 1981). Broiler breeders with access to ad libitum feeding consume energy (643 kcal/d), which is almost twice the quantity of actual requirement (370 kcal/d) for maintenance and egg production (Lopez and Leeson, 1994). Therefore, feed restriction during rearing and laying periods was effective in considerably reducing erratic oviposition and improving the number of settable eggs, even during later period (62 wk of age) of production (Yu et al., 1992). Further, feed restriction improved the duration of fertility (12.7 d) compared to full feeding (10 d) (Goerzen et al., 1996). The fertile eggs collected from broiler breeders are often stored under controlled temperature and humidity for variable lengths of time depending upon the operational requirements of the hatchery. Storage of eggs decreased the hatchability and the extent of decline is related to the length of storage period (Meijerhof, 1992) and it was observed that fertile eggs stored beyond 7 days reduced hatchability by 0.5% per day (Tandron et al., 1983). However, irrespective of storage conditions, both hatchability and chick weight varied with hen's age. The decline in hatchability in aged breeders was related to poor quality of cuticle, thin egg shells and shell membranes causing late embryonic death of germs (Ruiz and Lunam, 2002). The magnitude of decline in fertility and hatchability is influenced by the breeder nutrition, pre-incubation holding period, quality of eggs and more importantly the age of breeders. However, in aged breeders the hatch losses can be minimized by regulating body weight during production period and egg holding period prior to incubation. In the current study, an attempt was made to improve egg production in breeders up to 64 weeks of age through measured energy feeding, and optimize egg holding period to minimize hatch losses.