Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, BC, Canada, V6T 1Z4.
Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, BC, Canada, V6T 1Z4.
J Dairy Sci. 2022 Mar;105(3):2521-2530. doi: 10.3168/jds.2021-21064. Epub 2021 Dec 23.
Adult dairy cattle show a preference for outdoor spaces during summer nights, but little is known about such preferences for dairy calves. Our aim was to determine the preferences of dairy calves for outdoor access during their first 11 wk of age in summer conditions. Calves were paired (n = 10) at 7 d of age and placed in one of 10 pens (7.32 × 2.44 m, deep bedded with bark mulch), each with equally sized outdoor and indoor areas. All feed was provided indoors; calves had ad libitum access to water, hay and concentrate. During the preweaning period, from 5 to 29 d of age, calves were offered 12 L/d of milk divided into 2 feedings. Calves were weaned stepwise, with milk gradually reduced by 1 L/d from d 30 to 35 of age. Calves were fed 6 L/d from 35 to 51 d of age, then milk was again reduced by 1 L/d so that calves were completely weaned by 56 d of age. Calves remained in the trial until, on average (± SD), 72 ± 2 d of age. Pens were continuously video recorded, and behaviors were scored 3 d/wk using 5-min scan samples. Four observers scored whether calves were inside, outside, lying, standing, in the sun or shade (interobserver reliability = 0.97). Sun and shade could not always be detected, so a proportion was calculated as the amount of time in the sun or shade divided by the total time sun or shade was visible. Calves spent approximately one-third of their time outside throughout the experiment, and time spent outside was affected by several factors. Pairs of calves spent less time outside as the amount of rain increased. During the first 6 wk of age, time spent outside increased, but time spent outside decreased between wk 6 and 7, and remained around 200 min/d from wk 7 to 11. Calves with the highest average daily gain and calves that were approximately 50% white appeared to spend more time outdoors. When outside, calves spent similar amounts of time in the sun and shade during the first 8 wk, but after weaning they appeared to spend more time in the shade. When calves were outside they appeared to spend a greater proportion of their time standing than when they were indoors during the first 4 wk. These results indicate that, when given the option in the summer, calves make use of an outdoor space, but this appears to vary with weather, calf age, average daily gain, and coat color.
成年奶牛在夏季夜晚更喜欢户外活动，但对于奶牛犊牛是否也有这种偏好却知之甚少。本研究旨在确定夏季条件下，奶牛犊牛在 11 周龄前对户外环境的偏好。犊牛在 7 日龄时进行配对（n=10），并放置在 10 个围栏中（7.32×2.44m，铺有树皮覆盖物的深床），每个围栏的户外和室内面积相同。所有饲料都在室内提供；犊牛可以自由饮水、干草和浓缩饲料。在哺乳期，从 5 日龄到 29 日龄，犊牛每天提供 12L 牛奶，分为 2 次喂养。犊牛逐渐断奶，从 30 日龄到 35 日龄，每天减少 1L 牛奶。从 35 日龄到 51 日龄，犊牛每天喂 6L 牛奶，然后再减少 1L 牛奶，使犊牛在 56 日龄时完全断奶。犊牛在试验中一直待到平均（±SD）72±2 日龄。围栏连续进行视频记录，每周 3 天使用 5 分钟扫描样本进行行为评分。四名观察者记录犊牛是否在室内、室外、躺着、站立、在阳光下或阴凉处（观察者间可靠性=0.97）。阳光和阴凉处并不总是能被检测到，因此计算了一个比例，即阳光下或阴凉处的时间除以可见的阳光或阴凉处的总时间。在整个实验过程中，犊牛大约有三分之一的时间在户外，而在户外的时间受到几个因素的影响。随着降雨量的增加，成对的犊牛在户外的时间减少。在 6 周龄之前，犊牛在户外的时间增加，但在 6 周龄和 7 周龄之间，在户外的时间减少，从 7 周龄到 11 周龄，在户外的时间保持在 200 分钟/天左右。平均日增重最高的犊牛和大约 50%白色的犊牛似乎在户外的时间更多。当在户外时，犊牛在前 8 周内，在阳光和阴凉处的时间大致相同，但断奶后，它们似乎更多地在阴凉处度过时间。当犊牛在户外时，它们似乎比在室内时更多地站立，这在前 4 周尤其明显。这些结果表明，在夏季，如果有选择的话，犊牛会利用户外活动空间，但这似乎会随着天气、犊牛年龄、平均日增重和毛色的变化而变化。
