|Buhr, Richard - Jeff|
Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 5/1/2008
Publication Date: 7/20/2008
Citation: Brown, A., Webster, A.B., Fairchild, B.D., Buhr, R.J. 2008. Photoperiod effects on performance. Poultry Science Association Meeting Abstract. 87:(Supp. 1)MP332, p 105. Interpretive Summary:
Technical Abstract: Photoperiod is known to affect growth rate, BW, feed consumption, incidence of metabolic disease, and immune response of broilers. Previous studies have reported significantly lower BW in broilers receiving 18h photoperiod throughout grow-out compared to broilers receiving >20h. This study evaluated the effects of 3 photoperiod regimens on broiler performance. The 3 photoperiod treatments were 20h (20L:4D) or 18h (18L:6D) applied from 7-36d, or step-down/step-up program (stepped down to 12h by 13d in 3h increments and increased to 18h in 1h increments between 22-27d). The 20 and 18h treatments were increased to 23h at 37d and the step-down/step-up program was increased to 23h in 1h increments between 37-41d. Light intensity was maintained at 20 lux. From 1-7d all birds received 23h photoperiods. Two trials were conducted and each light treatment was applied to 2 rooms with 6 pens in each room. Broiler management protocols followed the breeder company recommended guidelines with a stocking density equated to 0.7 ft2/bird. Water and a standard series of broiler diets were provided ad libitum. At 21d BW, BW gain, and feed consumption were significantly lower for the step-down/step-up program compared to the 20 and 18h and treatments. There were no significant differences for these variables at 41d. Mortality was 3.7, 4.2, and 4.4% for the step-down/step-up program, 18, and 20h treatments respectively. In this modern broiler stock, compensatory gain overcame early photoperiod restrictions on feed consumption and BW.