Department of Animal Science, University of Tennessee, Knoxville 37996.
William H. Miner Agricultural Research Institute, Chazy, NY 12921.
J Dairy Sci. 2020 Jun;103(6):5455-5465. doi: 10.3168/jds.2019-17218. Epub 2020 Apr 8.
The objectives of this study were to (1) describe the calving location of dairy cattle given access to a pasture and barn; (2) identify factors associated with calving location; and (3) compare the lying and exploratory behavior of cows in the 24 h before calving and a previous day. Seventy-two Holstein dairy heifers and cows (n = 36 nulliparous and n = 36 primiparous and multiparous combined) were housed in a covered bedded-pack barn (167.4 m) with free access to 2.1 ha of pasture. The composition of the group was dynamic, because cows were moved in weekly at 19 ± 6 d [mean ± standard deviation (SD)] before their calving date, and were removed immediately after calving. To facilitate data collection, we divided the environment into 9 sections, including the barn (section 1; 167.4 m), 7 sections of open pasture (sections 2 to 8; 2,402 ± 60 m), and 1 section of pasture surrounded by natural forage cover (section 9; 3,593 m). We then collapsed these 9 sections into 3 distinct areas for further analysis: the barn, open pasture, and natural forage cover. Animals were fitted with accelerometers to measure lying time, lying bout duration, lying bouts, and steps for the 24 h before calving (calving day) and a similar 24 h period 4 to 11 d (median = 7) before calving (baseline day). We included parity (nulliparous vs. primiparous and multiparous) and heat stress [no heat stress = temperature-humidity index (THI) ≤68 vs. heat stress = THI >68 and ≤79] in all analyses; we included time of day and group composition as additional factors that may have affected calving location. We determined exploratory behavior using 10 min instantaneous scan sampling collected from video. At each scan, we recorded the section (1 to 9) the cow or heifer was located in, and then calculated the minimum number of sections that could be crossed between successive scans. Of the total sample, 39% calved in the barn, 26% calved in the open pasture, and 35% calved in the area with natural forage cover. Nulliparous heifers and those calving when heat stress was low (THI ≤68) selected the area with natural forage cover more frequently than the barn. On the calving day, cows spent more time lying down with more short bouts of lying, and crossed more sections compared with the baseline day. Steps were affected by an interactive effect of day, parity, and heat stress; nulliparous heifers took more steps on the calving day during conditions of heat stress compared with no heat stress. Results indicate that cows and heifers had different preferences for their environment at calving, and when provided access to pasture, both changed their lying and exploratory behavior on the day of calving compared with a previous day.
(1)描述在牧场和畜舍中饲养的奶牛的分娩位置；(2)确定与分娩位置相关的因素；(3)比较牛在分娩前 24 小时和前一天的卧息和探索行为。72 头荷斯坦奶牛后备牛和奶牛（n = 36 头初产牛和 n = 36 头经产牛）被安置在一个有覆盖物的卧床畜舍（167.4 m）中，可自由进入 2.1 公顷的牧场。该群体的组成是动态的，因为奶牛在预产期前 19 ± 6 天（平均值 ± 标准差（SD））每周被转移一次，并且在分娩后立即被转移。为了便于数据收集，我们将环境分为 9 个部分，包括畜舍（第 1 部分；167.4 m）、7 个开放牧场部分（第 2 至 8 部分；2,402 ± 60 m）和 1 个被天然草料覆盖的牧场部分（第 9 部分；3,593 m）。然后，我们将这 9 个部分合并为 3 个不同的区域进行进一步分析：畜舍、开放牧场和天然草料覆盖区。动物被佩戴加速度计，以测量分娩前 24 小时（分娩日）和分娩前 4 至 11 天（中位数= 7）的类似 24 小时期间的卧息时间、卧息持续时间、卧息次数和步数。我们在所有分析中都包括了胎次（初产牛与经产牛）和热应激[无热应激=温度-湿度指数（THI）≤68 与热应激=THI >68 和≤79]；我们还包括了时间和群体组成，因为它们可能影响了分娩位置。我们使用从视频中收集的 10 分钟即时扫描采样来确定探索行为。在每次扫描中，我们记录了奶牛所在的部分（1 到 9），然后计算了连续扫描之间可以穿过的最小部分数。在总样本中，39%的奶牛在畜舍中分娩，26%的奶牛在开放牧场中分娩，35%的奶牛在有天然草料覆盖的区域中分娩。初产牛和在低热应激（THI ≤68）下分娩的牛比畜舍更频繁地选择有天然草料覆盖的区域。在分娩当天，与基线日相比，奶牛的卧息时间更长，卧息次数更多，穿过的区域更多。步数受日、胎次和热应激的交互作用的影响；在热应激条件下，初产牛在分娩日的步数比无热应激时更多。结果表明，奶牛和后备牛在分娩时对环境有不同的偏好，当被允许进入牧场时，与前一天相比，它们在分娩当天的卧息和探索行为都发生了变化。
