Faculty of Animal Husbandry, University of Jambi, Indonesia.
Poult Sci. 2012 Mar;91(3):537-49. doi: 10.3382/ps.2011-01559.
Self-selection assumes that at high ambient temperature, birds are able to select a diet from different sources to minimize the heat load associated with the ingested nutrient metabolism. The objective was to test the hypothesis that young chickens are able to compose an adequate ration by adjusting dietary nutrient intake from 3 different diets that vary in energy and in protein contents from a cafeteria system at high temperature (HT; 31-32°C) and at normal temperature (NT; 31-21°C). Night temperature was set at 25°C at HT and at 18°C at NT and 12 h dark:12 h light. Control birds were fed a standard control diet (CP: 215 g/kg; ME: 2,895 kcal/kg) for broiler chickens. The choice-fed birds could choose between the control diet, a high-protein diet (CP: 299 g/kg; ME: 2,780 kcal/kg), and a high-energy diet (CP: 150.7 g/kg; ME: 3,241 kcal/kg). The diets had similar pellet size and color. Birds had access to each diet in a separate feeding trough from 1 to 42 d of age. Results showed that broilers spent 3.3% more time eating at NT than at HT and showed 42% more panting behavior at HT than at NT. High temperature decreased feed intake, protein intake, energy intake, and BW gain. Choice-fed birds had similar feed intake and BW gain, 14% lower protein intake, and 6.4% higher energy intake than control-fed birds. Body temperature and heterophil/lymphocyte ratio were higher at HT than at NT. Water intake was 8% higher in control-fed birds than in choice-fed birds but similar at both temperature regimens. It can be concluded that broilers can compose a diet by selecting less protein but higher energy density from different diets compared with the control. Choice-fed birds had similar feed efficiency as control-fed birds at HT, indicating similar body composition for both groups. Extra energy intake of choice-fed birds at HT was used for panting activity.
自选择假设在环境温度较高时，鸟类能够从不同来源选择饮食，以最大程度地减少与摄入营养代谢相关的热负荷。本研究旨在检验以下假设：在高温（31-32°C）和常温（31-21°C）下的自助餐系统中，小鸡能够通过调整三种不同饲料的饮食营养摄入来组成适当的日粮。高温时的夜间温度设定为 25°C，常温时为 18°C，光照时间为 12 小时，黑暗时间为 12 小时。对照组小鸡饲喂标准肉鸡日粮（CP：215 g/kg；ME：2895 千卡/kg）。自由选择组小鸡可以选择对照组日粮、高蛋白日粮（CP：299 g/kg；ME：2780 千卡/kg）和高能量日粮（CP：150.7 g/kg；ME：3241 千卡/kg）。这些日粮的颗粒大小和颜色相似。1-42 日龄时，小鸡可通过单独的料槽接触到每种日粮。结果表明，与在常温相比，小鸡在高温下的进食时间多 3.3%，喘气行为多 42%。高温降低了采食量、蛋白质摄入量、能量摄入量和体重增加。与对照组相比，自由选择组的小鸡的采食量和体重增加相似，蛋白质摄入量低 14%，能量摄入量高 6.4%。高温时，体温和异嗜性/淋巴细胞比值高于常温。与对照组相比，选择组的小鸡的饮水量高 8%，但在两种温度条件下的饮水量相似。由此可见，与对照组相比，小鸡可以通过从不同日粮中选择低蛋白但高能量密度的日粮来组成日粮。高温时，自由选择组的小鸡与对照组的小鸡的饲料效率相似，表明两组的身体成分相似。高温时，自由选择组小鸡额外的能量摄入量用于喘气活动。
