Effects of age of breeding hens and size of hatching eggs on the growth rate of broilers.
Charalambous K. | Antoniou T. | Mavrogenis A.
A population of Hubbart meat type hens (hybrids) was stratified into three age groups (young = 30 wks, normal = 38 wks and old = 67 wks of age). Two egg sizes (small and medium, medium and large and large and extra large) within the three age classes above were selected. An equal number of eggs from each subclass (168 eggs) was set for hatching. Fifty day-old chicks (15 males and 25 females) were randomly selected from each hen-age egg-size combination and were fattened in adjacent pens to 9 weeks of age. A representative sample from both sexes was slaughtered at the end of the study for carcass evaluation. Egg hatchability, growth rate and carcass yield were all affected by both egg-size and age of hen, but the latter was a major factor affecting hatchability of eggs and chick growth rate. These effects were attributed not only to age and egg-size, but also to the improved "vitality" of the hatching egg. The lower hatchability of eggs from old hens and the higher cost of producing them (low feed efficiency) should be seriously considered, before allowing hens to breed after a certain age.Show more [+] Less [-]