Abstract
The objective of the present study was to evaluate carcass and parts' yield, abdominal fat deposition and breast and foot pad blisters of broilers reared under two lighting programs (nearly continuous or intermittent) in broilers houses with yellow and blue curtains. The experiment was conducted between June, 2004 and May, 2005. Six flocks were sequentially housed in four 12 × 10 m broiler houses divided into 4 pens with 200 birds each. The litter was reused six times or until flock 6. A completely randomized design in a 6 × 2 × 2 factorial arrangement (flocks, lighting programs, curtains) with four replicates per treatment was applied. A total of 288 birds were evaluated for carcass yield. Curtain color did not affect carcass or parts' yield. The effect of lighting program and curtain color on carcass yield may depend on other factors related to flock. Intermittent lighting program promoted the highest drumstick and thigh yields. Lighting programs and curtain colors did not affect abdominal fat deposition or the presence of breast and foot pad blisters.
Highlights
Understanding the influence of photoperiod on broiler production allows producers to select the best lighting program and make decisions to optimize the combination of production characteristics that bring higher profits
Broilers submitted to intermittent lighting program show higher productivity and fewer leg problems when compared to those reared under continuous lighting programs (Classen, 1996)
Moraes (2006), when studying the effect of lighting programs on parts yields, did not find any influence on the carcass yield of broilers slaughtered at 45 days of age, but those submitted to 23 daily hours of light presented higher breast yield, as reported by Renden et al (1992), Renden et al (1993) and Renden et al (1994), who observed higher breast yield in 49-day-old broilers submitted to a program of 23 hours of light relative to a program of 16 hours of light
Summary
Understanding the influence of photoperiod on broiler production allows producers to select the best lighting program and make decisions to optimize the combination of production characteristics that bring higher profits. Long duration lighting programs (24 hours of light) may have beneficial effects on breast yield, but increase leg problems in broilers. Intermittent lighting programs (23 hours of light and 1 hour of darkness or 16 hours of light and 8 of darkness) are characterized by repeated light and dark periods within 24 hours. Broilers submitted to intermittent lighting program show higher productivity and fewer leg problems when compared to those reared under continuous lighting programs (Classen, 1996). According to Renden et al (1991), despite the large number of studies on lighting programs, there is still little information on their effect on carcass yield or quality. In other studies, Renden et al (1991) and Renden et al (1996) did not find any influence of lighting programs
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