Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2006
Publication Date: 1/25/2007
Citation: Dozier III, W.A., Purswell, J.L., Kidd, M., Corzo, A., Branton, S.L. 2007. Apparent metabolizable energy needs of broilers from 2.0 to 4.0 kg as influenced by ambient temperature. Journal of Applied Poultry Research. 16:206-218. Interpretive Summary: Feed cost represents 65% of the total live production cost for broiler chickens that supports an industry that produces 8 billion birds annually. Large percentage of the cost of the diet is energy ingredients. Growing broilers to heavier weights is a trend in the United States. These heavy broilers (>3.4 kg) respond to lower temperatures than smaller broilers and dietary energy needs may be affected by ambient temperature. Research is sparse on the interactive effects of dietary energy and temperature on performance and meat yield of broilers. This study examined responses of broilers fed diets varying in energy subjected to two temperature regimens on performance and meat yield from 36 to 60 days of age. Results indicated that decreasing dietary energy did adversely affect growth and feed conversion when broilers were exposed to an ambient temperature of 21 C. In contrast dietary energy did not influence performance with broilers subjected to temperature decreasing from 21 to 13 C, which was reduced as the birds advanced with age. Furthermore, broilers exposed to the lower temperature regimen reached 3.82 kg BW 4.75 faster than the constant 21 C regimen based on prediction equations.
Technical Abstract: During winter production, the optimum temperature set points for heavy broilers (>3.4 kg) approaching market weight are subject to debate in commercial practice. Apparent metabolizable energy concentration needed to optimize nutrient utilization may be influenced by ambient temperature. This experiment examined potential interactive effects of AME × ambient temperature from 36 to 60 d of age. A 4 × 2 factorial arrangement of treatment was used. Dietary treatments were AME concentrations of 3,175, 3,220, 3,265, and 3,310 kcal/kg. Two temperature regimens were provided consisting of variable temperature regimen (VTR) or constant temperature regimen (CTR) set points. The VRT was 21.1 C from 36 to 38 d, 20.2 C from 39 to 42 d, 18.9 C from 43 to 46 d, 17.8 C from 47 to 50 d, 15.6 C from 51 to 54 d, and 12.8 C from 55 to 60 d. The CTR was 21.1 C from 36 to 60 d. Significant AME × temperature interactions were observed for cumulative BW, BW gain, feed consumption, feed conversion, and mortality. In the CTR, increasing AME led to increased BW gain but not in the VTR. As dietary AME increased, the improvement in feed conversion was more pronounced in the CTR than the VTR. With the VTR, decreasing AME resulted in greater rate of feed consumption. The experimental treatments did not influence abdominal fat percentage or total breast meat yield. These data provide evidence that broilers exposed to CTR respond to increased AME concentrations.