Muhamad Y B, Hoffman M P, Self H L
J Anim Sci. 1983 Apr;56(4):747-54. doi: 10.2527/jas1983.564747x.
Observations on the effects of season, housing and diet were made on 916 steers in three winter and two summer trials. Diets consisted of corn grain and corn silage, in balanced rations, fed ad libitum with energy ratios of 25:75 (Diet 1), 55:45 (Diet 2) and 85:15 (Diet 3). There were three types of housing systems: outside lots without access to overhead shelter (NS), outside lots with access to overhead shelter (OS) and an open-front confinement building (C). Average ambient temperatures and precipitation for winter and summer trials were -1.0 and 15.3 C and 4.67 and 10.81 cm/mo, respectively. Steers gained more (P less than .05) in summer than in winter. Within housing system, OS and NS steers gained faster and consumed more dry matter (DM) and energy (P less than .05) than C steers; C-fed steers were less (P less than .05) efficient (kg feed DM/kg gain) than OS steers. Steers fed Diet 1 had lower (P less than .05) average daily gain (ADG) than those fed Diets 2 and 3. Steers on Diet 3 consumed less DM (P less than .05) than those on Diets 1 and 2. Estimated metabolizable energy intake (MEI) was significantly less for cattle fed Diet 1 than those fed Diets 2 or 3. Diet 3 was more (P less than .05) efficient than Diet 1. Season x diet (P less than .10) and season x housing (P less than .10) interactions were found for daily DM intake and MEI. This resulted in greater cattle growth rate responses to higher grain diets in summer than in winter and more pronounced adverse effects of confinement rearing in summer than in winter. No evidence was found of other two-way or three-way interactions for any of the performance characteristics studied. These results indicate that in addition to important singular effects of season, housing and diet, important interactions of these factors also exist.
在三项冬季试验和两项夏季试验中，对916头阉牛的季节、饲养环境和饮食的影响进行了观察。日粮由玉米谷物和玉米青贮饲料组成，按平衡日粮自由采食，能量比分别为25:75（日粮1）、55:45（日粮2）和85:15（日粮3）。有三种饲养系统类型：无顶部遮蔽的露天场地（NS）、有顶部遮蔽的露天场地（OS）和开放式圈舍（C）。冬季和夏季试验的平均环境温度及降水量分别为-1.0℃和15.3℃，以及4.67厘米/月和10.81厘米/月。阉牛夏季增重比冬季更多（P<0.05）。在饲养系统中，OS和NS组的阉牛增重更快，干物质（DM）和能量摄入量更多（P<0.05），高于C组阉牛；C组饲养的阉牛效率（千克饲料DM/千克增重）低于OS组阉牛（P<0.05）。采食日粮1的阉牛平均日增重（ADG）低于采食日粮2和3的阉牛（P<0.05）。采食日粮3的阉牛DM摄入量低于采食日粮1和2的阉牛（P<0.05）。采食日粮1的牛的估计可代谢能量摄入量（MEI）显著低于采食日粮2或3的牛。日粮3比日粮1更高效（P<0.05）。发现日DM摄入量和MEI存在季节×日粮（P<0.10）和季节×饲养环境（P<0.10）的交互作用。这导致夏季阉牛对高谷物日粮的生长速率反应大于冬季，且夏季圈养饲养的不利影响比冬季更明显。在所研究的任何性能特征中，均未发现其他双向或三向交互作用的证据。这些结果表明，除了季节、饲养环境和饮食的重要单一影响外，这些因素之间也存在重要的交互作用。
