Effect of Ages at the Onset of Light Restriction on Growth and Laying Performance in the Native Chicken

Abstract

An experiment was conducted to study the effect of ages at the onset of light restriction during growing period on growth and laying performance in the native chicken. Four groups of the native chickens were subjected to normal day length (NDL) and to restricted 8 hours/days lighting: started from the age of 10 weeks (LR10), or 12 weeks (LR12), and or 14 weeks (LR14), respectively; before being exposed to the same photoperiod of 15 hours/day from the age of 20 weeks. The results showed no significant difference (P>0.05) in the growth characteristics studied. The NDL, LR10, LR12 and LR14 groups had average body weights at 20 weeks of age of 1.38, 1.37, 1.34 and 1.36 kg; cumulative feed conversion ratios of 6.4, 6.6, 6.4, and 7.0; prelaying mortality rates of 2.5, 1.7, 1.1, and 1.0%, respectively. Age at the onset of light restriction affected sexual maturity of the native chicken. Ages at the onset of lay of the LR14 and LR12 pullets were 159.3 and 161.5 days, respectively, which were earlier than (P<0.05) 164.0 days of the LR10 pullet and 167.3 days of the NDL pullet. Body weights and egg weights at the onset of lay of the four groups were, however, not significantly different (P>0.05). In term of laying performance, the LR12 and LR14 groups showed a trend of having higher hen-day egg production and lower feed conversion ratios (for eggs) than the LR10 and NDL groups. A significant difference (P<0.05) was, however, observed only at some stages of production. Cumulative egg production of the LR12 and LR14 hens were 73.9 and 71.4 eggs/hen/28 weeks, respectively, which were higher than (P<0.05) 65.4 eggs/hen/28 weeks of the LR10 hen, and 64.2 eggs/hen/28 weeks of the NDL hen. Cumulative feed conversion ratios of the LR12 and LR14 groups were 4.9 and 4.8, respectively, which were lower than (P<0.05) 5.4 of the LR10 group and 5.5 of the NDL group. Subsequent laying mortality rate as well as egg weight and egg component were unaffected by light restriction during the growth phase.