沙漠环境下 2 种奶牛降温系统对奶牛的影响比较。

Department of Animal Sciences and Industry, Kansas State University, Manhattan 66502, USA.

J Dairy Sci. 2010 Oct;93(10):4955-60. doi: 10.3168/jds.2010-3127.

An experiment was conducted to investigate the effects of operation time and size of Korral Kool (KK; Korral Kool Inc., Mesa, AZ) systems on core body temperature (CBT) of dairy cows. Two KK systems were compared: a system with 1.29-m-diameter, 3-hp fans spaced 6 m apart (referred to as small) and a system with 1.52-m-diameter, 5-hp fans spaced 8 m apart (referred to as big). Forty-eight multiparous Holstein cows were assigned randomly to 8 pens (4 big, 4 small), and pens were assigned randomly to a sequence of treatments (KK operated for 21 or 24 h/d) in a switchback design. A complementary calorimetric analysis was developed to investigate the cooling area under the KK units of the big and small systems. Twenty-five sensors distributed equally under the KK units measured ambient temperature at 5-min intervals for 2 h. Average ambient temperature was 35.0±0.6°C and relative humidity was 45±8%. There were significant treatment effects on mean CBT: cows on the small 24-h treatment had a lower mean CBT than cows on the small 21-h treatment (39.22 vs. 39.36±0.14°C), and cows on the big 24-h treatment had a lower mean CBT than cows on the big 21-h treatment (38.95 vs. 39.09±0.13°C). A significant treatment by time interaction was observed. The greatest difference between systems occurred at 0100 h; treatment means at this time were 39.05, 39.01, 39.72, and 39.89±0.16°C for the big 24-h, big 21-h, small 24-h, and small 21-h treatments, respectively. At certain times of day, the big system reduced CBT more than the small system. These results show that CBT of multiparous cows decreased when KK system operational time was increased from 21 to 24 h regardless of the size of the KK cooling system used. The calorimetric analysis showed that even though the big system resulted in lower mean ambient temperatures than the small system, the distance between units in the big system should be decreased to reduce the variation in temperature under the big units.

一项实验旨在研究科拉尔酷尔（Korral Kool）系统的运行时间和大小对奶牛核心体温（CBT）的影响。比较了两种科拉尔酷尔系统：一种是直径为 1.29 米、每 6 米安装一个 3 马力的风机（简称小系统），另一种是直径为 1.52 米、每 8 米安装一个 5 马力的风机（简称大系统）。48 头经产荷斯坦奶牛被随机分配到 8 个畜栏（4 个大系统，4 个小系统），畜栏被随机分配到一个反转设计的处理序列中（KK 系统每天运行 21 或 24 小时）。开发了一种补充的量热分析来研究大、小系统的 KK 装置下的冷却面积。25 个传感器均匀分布在 KK 装置下，每隔 5 分钟测量环境温度 2 小时。平均环境温度为 35.0±0.6°C，相对湿度为 45±8%。处理对平均 CBT 有显著影响：小系统 24 小时处理的奶牛 CBT 平均值低于小系统 21 小时处理的奶牛（39.22 比 39.36±0.14°C），大系统 24 小时处理的奶牛 CBT 平均值低于大系统 21 小时处理的奶牛（38.95 比 39.09±0.13°C）。观察到处理与时间的显著交互作用。系统之间的最大差异出现在 0100 小时；此时大系统 24 小时、大系统 21 小时、小系统 24 小时和小系统 21 小时处理的 CBT 平均值分别为 39.05、39.01、39.72 和 39.89±0.16°C。在一天中的某些时间，大系统比小系统更能降低 CBT。这些结果表明，无论使用的科拉尔酷尔冷却系统的大小如何，将系统运行时间从 21 小时增加到 24 小时，多胎奶牛的 CBT 都会降低。量热分析表明，尽管大系统的平均环境温度低于小系统，但应减小大系统单元之间的距离，以减少大单元下的温度变化。