Fustini M, Galeati G, Gabai G, Mammi L E, Bucci D, Baratta M, Accorsi P A, Formigoni A
Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, 40062 Ozzano dell'Emilia (BO), Italy.
Department of Veterinary Medical Sciences (DIMEVET), University of Bologna, 40062 Ozzano dell'Emilia (BO), Italy.
J Dairy Sci. 2017 Jan;100(1):620-628. doi: 10.3168/jds.2016-11293. Epub 2016 Nov 9.
Stressful situations trigger several changes such as the secretion of cortisol and dehydroepiandrosterone (DHEA) from the adrenal cortex, in response to ACTH. The aim of this study was to verify whether overstocking during the dry period (from 21±3 d to the expected calving until calving) affects DHEA and cortisol secretion and behavior in Holstein Friesian cows. Twenty-eight cows were randomly divided into 2 groups (14 animals each), balanced for the number of lactations, body condition score, and expected date of calving. Cows in the far-off phase of the dry period (from 60 to 21 d before the expected calving date) were housed together in a bedded pack. Then, animals from 21±3 d before the expected calving until calving were housed in pens with the same size but under different crowding conditions due to the introduction of heifers (interference animals) into the pen. The control condition (CTR) had 2 animals per pen with 12.0m each, whereas the overstocked condition (OS) had 3 interference animals in the same pen with 4.8m for each animal. On d -30±3, -21±3, -15±3, -10±3, and -5±3 before and 10, 20, and 30 after calving, blood samples were collected from each cow for the determination of plasma DHEA and cortisol concentrations by RIA. Rumination time (min/d), activity (steps/h), lying time (min/d), and lying bouts (bouts/d) were individually recorded daily. In both groups, DHEA increased before calving and the concentration declined rapidly after parturition. Overstocking significantly increased DHEA concentration compared with the CTR group at d -10 (1.79±0.09 vs. 1.24±0.14 pmol/mL), whereas an increase of cortisol was observed at d -15 (3.64±0.52 vs. 1.64±0.46ng/mL). The OS group showed significantly higher activity (steps/h) compared with the CTR group. Daily lying bouts tended to be higher for the OS group compared with CTR group in the first week of treatment. The overall results of this study documented that overstocking during the dry period was associated with a short-term changes in DHEA and cortisol but these hormonal modifications did not influence cow behavior.
应激情况会引发多种变化，例如肾上腺皮质在促肾上腺皮质激素（ACTH）的作用下分泌皮质醇和脱氢表雄酮（DHEA）。本研究的目的是验证干奶期（从预计产犊前21±3天至产犊）期间过度饲养是否会影响荷斯坦奶牛的DHEA和皮质醇分泌以及行为。28头奶牛被随机分为2组（每组14头），根据泌乳次数、体况评分和预计产犊日期进行平衡。处于干奶期远干奶期（预计产犊日期前60至21天）的奶牛被集中饲养在一个有垫料的牛舍中。然后，从预计产犊前21±3天到产犊期间，由于将小母牛（干扰动物）引入围栏，动物被饲养在大小相同但拥挤程度不同的围栏中。对照条件（CTR）每组有2头动物，每头动物的空间为12.0平方米，而过度饲养条件（OS）在同一围栏中有3头干扰动物，每头动物的空间为4.8平方米。在产犊前30±3、21±3、15±3、10±3和5±3天以及产犊后10、20和30天，从每头奶牛采集血样，通过放射免疫分析法（RIA）测定血浆DHEA和皮质醇浓度。每天单独记录反刍时间（分钟/天）、活动量（步数/小时）、躺卧时间（分钟/天）和躺卧次数（次数/天）。在两组中，DHEA在产犊前升高，分娩后浓度迅速下降。与CTR组相比，在第 -10天过度饲养显著提高了DHEA浓度（1.79±0.09对1.24±0.14 pmol/mL），而在第 -15天观察到皮质醇升高（3.64±0.52对1.64±0.46 ng/mL）。与CTR组相比，OS组的活动量（步数/小时）显著更高。在治疗的第一周，OS组的每日躺卧次数与CTR组相比有增加的趋势。本研究的总体结果表明，干奶期过度饲养与DHEA和皮质醇的短期变化有关，但这些激素变化并未影响奶牛的行为。
