The effects of photoperiodism on energy metabolism in broiler chickens

The effects of sex, light treatment (16L:8D versus constant light), and dietary energy and their interactions on growth performance of broiler chickens were evaluated. The diets used were isonitrogenous (23% CP); the dietary energy concentration was either 3300 kcal ME/kg diet or 2475 kcal ME/kg diet. The results indicated that light treatment had significant effects on weight gain, feed consumption, and gain/feed ratio. Constant light depressed growth after the third week of age in each trial. Birds reared under a 16L:8D photoperiod and fed a high energy diet performed best. Within light treatment, males gained more, consumed more feed, and had a higher feed efficiency than females. The light treatment x dietary energy concentration interaction was found to be significant for feed consumption and gain/feed ratio. It was concluded that combining a photoperiod of 16L:8D with high dietary energy under either an ad-libitum or restricted feeding regime resulted in a substantial and significant improvement in overall performance of broiler chickens.