1Instituto de Producción Animal,Universidad Austral de Chile,Valdivia 5090000,Chile.
3Escuela de Agronomía,Facultad de Recursos Naturales,Universidad Católica de Temuco,Temuco 4781312,Chile.
Animal. 2019 Jan;13(1):221-230. doi: 10.1017/S1751731118001131. Epub 2018 May 22.
Climate change is producing an increase on extreme weather events around the world such as flooding, drought and extreme ambient temperatures impacting animal production and animal welfare. At present, there is a lack of studies addressing the effects of climatic conditions associated with energy intake in finishing cattle in South American feed yards. Therefore, two experiments were conducted to assess the effects of environmental variables and level of metabolizable energy intake above maintenance requirements (MEI) on performance and carcass quality of steers. In each experiment (winter and summer), steers were fed with 1.85 or 2.72 times of their requirements of metabolizable energy of maintenance. A total of 24 crossbred steers per experiment were used and located in four pens (26.25 m2/head) equipped with a Calan Broadbent Feeding System. Animals were fed with the same diet within each season, varying the amount offered to adjust the MEI treatments. Mud depth, mud scores, tympanic temperature (TT), environmental variables, average daily gain, respiration rates and carcass characteristics plus three thermal comfort indices were collected. Data analysis considered a factorial arrangement (Season and MEI). In addition, a repeated measures analysis was performed for TT and respiration rate. Mean values of ambient temperature, solar radiation and comfort thermal indices were greater in the summer experiment as expected (P<0.005). The mean values of TT were higher in steers fed with higher MEI and also in the summer season. The average daily gain was greater during summer v. winter (1.10±0.11 v. 0.36±0.06) kg/day, also when steers were fed 2.72 v. 1.85 MEI level (0.89±0.12 v. 0.57±0.10) kg/day. In summer, respiration rate increased in 41.2% in the afternoon. In winter, muddy conditions increased with time of feeding, whereas wind speed and rainfall had significant effects on TT and average daily gain. We conclude that MEI and environmental variables have direct effects on the physiology and performance of steers, including TT and average daily gain, particularly during the winter. In addition, carcass characteristics were affected by season but not by the level of MEI. Finally, due to the high variability of data as well as the small number of animals assessed in these experiments, more studies on carcass characteristics under similar conditions are required.
气候变化导致世界各地极端天气事件（如洪水、干旱和极端环境温度）的发生频次增加，对动物生产和动物福利产生影响。目前，缺乏研究评估与南美饲料场育肥牛能量摄入相关的气候条件对其性能和胴体质量的影响。因此，进行了两项实验来评估环境变量和维持需要以上的可代谢能摄入量（MEI）水平对育肥牛性能和胴体质量的影响。在每个实验（冬季和夏季）中，牛都饲喂 1.85 或 2.72 倍其维持需要的 MEI。每个实验使用 24 头杂交公牛，安置在四个围栏（26.25 m2/头）中，配备 Calan Broadbent 饲养系统。在每个季节内，动物都饲喂相同的日粮，通过调整提供量来调整 MEI 处理。收集了泥浆深度、泥浆评分、鼓膜温度（TT）、环境变量、平均日增重、呼吸率和胴体特性以及三个热舒适指数。数据分析考虑了季节和 MEI 的因子排列。此外，还对 TT 和呼吸率进行了重复测量分析。如预期的那样，夏季实验中环境温度、太阳辐射和舒适热指数的平均值更高（P<0.005）。饲喂更高 MEI 的牛和夏季 TT 平均值更高。夏季平均日增重更高（1.10±0.11 比 0.36±0.06）kg/d，当牛饲喂 2.72 比 1.85 MEI 水平时更高（0.89±0.12 比 0.57±0.10）kg/d。在夏季，下午呼吸率增加了 41.2%。在冬季，随着喂料时间的增加，泥泞条件增加，而风速和降雨量对 TT 和平均日增重有显著影响。我们得出结论，MEI 和环境变量对牛的生理和性能有直接影响，包括 TT 和平均日增重，特别是在冬季。此外，胴体特性受季节影响，但不受 MEI 水平影响。最后，由于这些实验中数据的高度可变性以及评估的动物数量较少，需要在类似条件下进行更多关于胴体特性的研究。
