The effects of photoperiod, light intensity and their interaction on growth performance and carcass characteristics of broilers were investigated in two trials by USDA Agricultural Research Service scientists at the Poultry Research Unit in Mississippi State.

In International Journal of Poultry Science, H.A. Olanrewaju and colleagues report their experiment, which consisted of a factorial arrangement of treatments in a randomised complete block design. In each trial, all treatment groups were provided 23L:1D with 20 lux of intensity from placement to seven days and then subjected to the treatments.

The nine treatments comprised three photoperiods - long/continuous (23L:1D) from days 8 to 56; regular/intermittent (2L:2D) and short/non-intermittent (8L:16D) from days 8 to 48 and 23L:1D from days 49 to 56, respectively - and exposure to three light intensities (10, 5.0 and 0.5 lux) from days 8 to 56 at 50 per cent relative humidity.

Birds were provided a four-phase feeding programme and water was provided ad libitum. Birds and feed were weighed on days 0, 14, 28, 42 and 56 age for growth performance evaluation. At 56 days of age, 20 (10 males and 10 females) birds from each room were randomly selected, slaughtered and processed to determine weights and yields.

Broilers subjected to a short/non-intermittent photoperiod showed the significantly (P<0.05) lowest bodyweight, bodyweight gain, feed intake, carcass weight and pectoralis major and minor weights as compared with broilers reared under long/continuous and regular/intermittent photoperiods.

Feed conversion and mortality were not affected by treatments.

There was no effect of light-intensity or photoperiod × light intensity interactions on any of the examined variables.

Corticosterone concentrations were not affected by treatments, suggesting an absence of physiological stress.

The Mississippi researchers concluded their results indicate that long/continuous and regular/intermittent photoperiods equally improved broiler performance as compared with a short/non-intermittent photoperiod with no significant effect due to light intensity treatments.

Reference

Olanrewaju H.A., J.L. Purswell, S.D. Collier and S.L. Branton. 2012. Influence of photoperiod, light intensity and their interaction on growth performance and carcass characteristics of broilers grown to heavy weights. International Journal of Poultry Science 11(12):739-746.

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February 2013