Published data concerning the effect of reverse protein rearing diets on fertility and hatchability are lacking. However, single stage low protein rearing diets seem to have no adverse effect upon fertility and hatchability as reported by Sunde and Bird and Lillie and Denton who fed 15 and 12% CP diets for the entire rearing period,respectively.
Age of the hen appears to have influence upon fertility and hatchability. Insko et al. reported the general tendency for fertility and hatchability to decline with age. Hays and Taimadge and Tomhave concluded that hens are likely to show a decline in hatchability as they grow older.
Sunde and Bird reported that eggs laid by hen which has just reached sexual maturity did not hatch as well as later eggs. Tomhave also noticed greater variation in percentage offertile eggs early in production cycle than later. According to Garwood and lowe, hatchability increased with chronological age and reached a maximum in the 6th week after maturity. Standard breeds were used in the previous works but no similar studies were carried out on Saudi Arabian Baladi chickens. The objective of the present study was to investigate the effect of reverse and single stage low protein rearing diets and age of the hen on fertility, hatchability and embryonic mortality at 1-7,8-18 and 19-21 days of the incubation period.
