Department of Animal Sciences, Faculty of Agriculture, Food and Environment, the Hebrew University, Rehovot 76100, Israel.
J Dairy Sci. 2012 Jun;95(6):3092-9. doi: 10.3168/jds.2011-5017.
Reduced fertility of dairy cows during periods of elevated temperature, humidity, or both might be associated with low plasma progesterone concentration. Alleviation of thermal stress by efficient cooling is a prerequisite for improving fertility by hormonal treatment. We examined whether insertion of a controlled intravaginal drug-releasing (CIDR) insert containing progesterone following artificial insemination (AI) would improve summer conception rate. Control (n = 195) and treated (CIDR; n=165) cows, yielding on average 42.3 kg milk/d, were inseminated following estrus detection during the summer (July to October) in 2 commercial dairy herds in Israel. Mean maximal air temperature and relative humidity during the study were 30.2°C and 86%, respectively. All experimental cows were efficiently cooled throughout the study, as confirmed by measuring the body temperature of random cows. Treated cows received a CIDR insert on d 5 ± 1 post-AI for 13 d and pregnancy was confirmed by palpation 45 d post-AI. Plasma progesterone concentration in treated cows was elevated by approximately 1.5 ng/mL. Multiple logistic regressions were used to analyze conception rate. Treatment did not alter the overall conception rate; however, probability of conception increased in CIDR-treated cows with low body condition score (BCS) compared with their control counterparts (53 vs. 27%, respectively). A pronounced increase in probability of conception was recorded in CIDR-treated cows exhibiting both low BCS and postpartum reproductive disorders, compared with their control counterparts (58 vs. 14%, respectively). Exogenous progesterone supplementation on d 5 post-AI for 13 d improves summer fertility of subpopulations of cows exhibiting low BCS and postpartum reproductive disorders. Reproductive management based on specific hormonal treatment of designated subgroups of cows known to derive beneficial effects from it might improve treatment efficiency and reduce expenses.
在高温、高湿度或两者同时存在的情况下，奶牛的繁殖力可能会降低，这可能与血浆孕酮浓度低有关。通过有效的冷却来缓解热应激是通过激素治疗提高繁殖力的前提。我们研究了在人工授精（AI）后插入含有孕酮的阴道内控释（CIDR）装置是否会提高夏季受孕率。在以色列的 2 个商业奶牛场，在夏季（7 月至 10 月）发情期间进行人工授精，对平均产奶量为 42.3 kg/d 的对照组（n=195）和处理组（CIDR；n=165）奶牛进行了研究。研究期间的平均最高空气温度和相对湿度分别为 30.2°C 和 86%。所有实验奶牛在整个研究过程中都得到了有效的冷却，这可以通过测量随机奶牛的体温来证实。处理组奶牛在 AI 后第 5 天±1 天接受 CIDR 植入物，持续 13 天，在 AI 后第 45 天通过触诊确认怀孕。处理组奶牛的孕酮浓度升高约 1.5ng/ml。采用多因素逻辑回归分析受孕率。处理并没有改变整体受孕率；然而，与对照组相比，低体况评分（BCS）的 CIDR 处理奶牛的受孕概率增加（分别为 53%和 27%）。与对照组相比，在低 BCS 和产后生殖障碍的 CIDR 处理奶牛中，受孕概率显著增加（分别为 58%和 14%）。在 AI 后第 5 天，外源孕酮补充 13 天可提高低 BCS 和产后生殖障碍奶牛的夏季繁殖力。基于特定激素治疗指定亚群的生殖管理，这些亚群已知可以从中受益，可能会提高治疗效率并降低成本。
