Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Department of Animal Sciences, University of Florida, Gainesville 32611.
J Dairy Sci. 2018 Sep;101(9):8123-8134. doi: 10.3168/jds.2018-14465. Epub 2018 Jun 28.
We investigated the effect of social housing on the behavioral, intake, and physiological changes that occur at weaning for dairy calves fed milk ad libitum. These changes were evaluated during the weaning (d 40 to 48 of age) and postweaning (d 49 to 56 of age) stages. Twenty male Holstein calves were fed milk replacer ad libitum and weaned gradually by dilution over 9 d starting at d 40 of age. Calves were housed in pairs (10 calves) or individually (10 calves) from birth until the beginning of the postweaning phase, when all calves were paired. Feed and water intake were monitored daily. Feeding time was video-recorded, and blood β-hydroxybutyrate concentration was measured on alternate days beginning on d 40 and ending on d 56 of age. Electronic accelerometers continuously recorded standing and lying behavior for the 17-d study. Solid feed consumption increased by more than 5-fold over the weaning phase in all calves; during this phase pair-housed calves consumed more than twice (0.96 vs. 0.50 kg/d on d 48) that of the individually housed calves. Postweaning all calves rapidly increased their solid feed intake, and to a greater extent for previously individually housed calves, such that intake was similar between treatments by d 56. Free water intake was stable during weaning; however, a decrease (of 6.6 L) occurred in the constituent milk replacer water intake across this phase. As result, total water intake (free water + milk replacer water content) decreased (by 6.0 L) over the weaning phase between d 40 (14.9 L/d) and d 48 (8.9 L/d). On the first day postweaning (d 49), total water intake for all calves increased sharply (to 19.0 L/d) and then returned to a lower baseline (13.2 L/d) the next day (d 50), and slowly increased over the following week. During the weaning phase, feeding time and feeding rate increased with time for all calves, whereas pair-housed calves had greater feeding rates than individually housed calves (13.4 vs. 6.6 g of DM/min). After weaning, calves previously housed individually spent more time feeding in the early hours of the day than calves housed in pairs. Lying time and lying bout frequency decreased with calf age during the weaning period across treatments, and pair-housed calves tended to spend less time lying than individually housed calves (1,015 vs. 1,039 min/d) during this time period. Blood β-hydroxybutyrate increased across treatments over the weaning period, with the largest increase occurring between d 48 (0.05 mmol/L) and d 50 (0.2 mmol/L). These results show that calves alter their behavioral patterns during weaning and that housing calves in pairs may ease the transition from milk to solid feed.
我们研究了社会住房对自由采食牛奶的奶牛断奶时行为、采食量和生理变化的影响。这些变化在断奶（40 至 48 日龄）和断奶后（49 至 56 日龄）阶段进行评估。20 头雄性荷斯坦奶牛自由采食代乳料，并从 40 日龄开始通过稀释逐渐断奶，持续 9 天。从出生到断奶后阶段开始，小牛一直被成对（10 头）或单独（10 头）饲养，然后所有小牛都被配对。每天监测饲料和水的摄入量。从第 40 天开始，每隔一天记录一次血β-羟丁酸浓度，直到第 56 天断奶结束。电子加速度计连续记录了 17 天的站立和躺卧行为。在所有小牛中，固体饲料的消耗量在断奶阶段增加了 5 倍以上；在这个阶段，群养的小牛比单独饲养的小牛多消耗了两倍多（48 日龄时分别为 0.96 和 0.50 公斤/天）。断奶后，所有小牛迅速增加了固体饲料的摄入量，以前单独饲养的小牛增加得更多，因此到第 56 天，处理之间的摄入量相似。断奶期间自由水的摄入量保持稳定；然而，在此期间，代乳料中的水摄入量减少了 6.6 升。因此，在 40 日龄（14.9 升/天）至 48 日龄（8.9 升/天）的断奶阶段，总水摄入量（自由水+代乳料水分含量）减少了 6.0 升。断奶后第一天（49 日龄），所有小牛的总水摄入量急剧增加（19.0 升/天），然后第二天（50 日龄）又回到较低的基线（13.2 升/天），并在接下来的一周内缓慢增加。在断奶阶段，所有小牛的进食时间和进食率随着时间的推移而增加，而群养的小牛的进食率高于单独饲养的小牛（13.4 比 6.6 克 DM/分钟）。断奶后，以前单独饲养的小牛在一天的早些时候花更多的时间进食，而群养的小牛则较少。在断奶期间，处理之间小牛的躺卧时间和躺卧频率随着年龄的增长而减少，群养的小牛在这段时间内的躺卧时间比单独饲养的小牛少（1015 比 1039 分钟/天）。在断奶期间，血液β-羟丁酸的含量在所有处理组中都有所增加，最大的增加发生在 48 日龄（0.05mmol/L）和 50 日龄（0.2mmol/L）之间。这些结果表明，小牛在断奶期间改变了它们的行为模式，并且将小牛成对饲养可能有助于它们从牛奶到固体饲料的过渡。
