Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
J Dairy Sci. 2013 Aug;96(8):5064-71. doi: 10.3168/jds.2012-6501. Epub 2013 Jun 13.
The effects of gradual versus abrupt cessation of milking at dry-off in dairy cows are not well understood, but gradually reducing milk production in human mothers is known to reduce discomfort and milk leakage. This study compared the effects of abrupt versus gradual cessation of milking on milk leakage and dairy cow behavior. Holstein dairy cows were housed in groups of 6 and randomly assigned to either abrupt milk cessation (i.e., dry-off on d 0) or gradual milk cessation (i.e., skipped milkings beginning on d 0; dry-off on d 5). Four replicates were performed over time, for a total of 24 cows (mean ± SD; parity=2.3±1.2; milk production the day before d 0=24±5 kg/d). Intramammary antibiotic, internal teat sealer, and external teat sealant were administered at dry-off. Measurements were taken from d -3 to 8 relative to dry-off. Three periods were identified for behavior data: baseline (d -3 to 1), period 1 (abrupt cows dry, gradual cows milking; d 0-4), and period 2 (all cows dry; d 5-8). Lying time was recorded with data loggers. Video scan samples (5-min intervals) were used to measure feeding time and motivation to be milked (i.e., standing at the pen's exit gate). Milk leakage was monitored every 20 min during the 2-h period following the milking times of 0500 and 1500 h after complete cessation of milking (period 1 for abrupt vs. period 2 for gradual). Composite milk samples were taken before dry-off (d -1, 0, and 5) and at the start of the next lactation (colostrum, 24h and 7-10 d postcalving) to determine somatic cell score (SCS) and conduct bacteriological examinations in clinical mastitis cases. Regardless of treatment, dry-off resulted in reduced lying time [14.1 vs. 13.2h/d; standard error of the difference (SED)=0.2], reduced lying bouts (10.7 vs. 8.3 bouts/d; SED=0.2), increased lying bout duration (1.4 vs. 1.7h/bout; SED=0.03) and increased feeding time (5.0 vs. 5.9h/d; SED=0.2). Compared with baseline, the odds of standing at the gate increased for abrupt cows (period 1: odds ratio=6.2; 95% CI: 2.7-14.4; and period 2: odds ratio=5.2; 95% CI: 1.8-14.6). No increase in time spent standing at the gate was noted in gradual cows. Frequency of leakage was greater in abrupt versus gradual cows (75 vs. 27%). Although the gradual treatment showed an increase in SCS over the 5 d of reduced milking frequency, both treatments showed an increase in SCS at calving and both returned to pre-experiment levels within 7 to 10 d after calving. This work demonstrates that gradually reducing milking frequency in high-producing cows results in reduced time spent anticipating milking and reduced milk leakage after dry-off.
奶牛干奶时逐渐停止挤奶与突然停止挤奶的效果尚不清楚，但众所周知，逐渐减少人类母亲的乳汁产量可减少不适和乳汁漏出。本研究比较了突然停止挤奶与逐渐停止挤奶对乳汁漏出和奶牛行为的影响。荷斯坦奶牛以 6 头为一组饲养，并随机分为突然停止挤奶组（即 d0 干奶）或逐渐停止挤奶组（即 d0 开始跳过挤奶；d5 干奶）。随着时间的推移进行了 4 次重复，共 24 头奶牛（平均值±SD；胎次=2.3±1.2；d0 前 1 天的产奶量=24±5kg/d）。干奶时给予乳房内抗生素、内乳头密封剂和外乳头密封剂。从干奶前 3 天至 8 天进行测量。行为数据分为三个时期：基线期（d-3 至 1）、时期 1（突然干奶的奶牛，逐渐干奶的奶牛；d0-4）和时期 2（所有奶牛均干奶；d5-8）。使用数据记录器记录卧息时间。视频扫描样本（5 分钟间隔）用于测量采食时间和挤奶动机（即站在畜栏出口门）。在完全停止挤奶后的 0500 和 1500h 挤奶时间后的 2 小时期间，每隔 20 分钟监测乳汁漏出情况（时期 1 为突然组，时期 2 为逐渐组）。在干奶前（d-1、0 和 5）和下一泌乳期开始时（初乳，产后 24h 和 7-10d）采集综合乳样，以确定体细胞评分（SCS），并在临床乳腺炎病例中进行细菌学检查。无论处理方式如何，干奶都会导致卧息时间减少[14.1 比 13.2h/d；差异的标准误差（SED）=0.2]、卧息次数减少（10.7 比 8.3 次/d；SED=0.2）、卧息时间延长（1.4 比 1.7h/次；SED=0.03）和采食时间增加（5.0 比 5.9h/d；SED=0.2）。与基线相比，突然组站立门的几率增加（时期 1：比值比=6.2；95%置信区间：2.7-14.4；时期 2：比值比=5.2；95%置信区间：1.8-14.6）。逐渐组站立门的时间没有增加。突然组的漏奶频率高于逐渐组（75%比 27%）。尽管逐渐处理组在减少挤奶频率的 5 天内 SCS 升高，但两种处理组在分娩时 SCS 均升高，并且在分娩后 7 至 10d 内均恢复到实验前水平。这项工作表明，在高产奶牛中逐渐减少挤奶频率可减少对挤奶的预期时间，并减少干奶后的乳汁漏出。
