Browning R, Schrick F N, Thompson F N, Wakefield T
School of Agriculture and Home Economics, Tennessee State University, Nashville 37209, USA.
J Anim Sci. 1998 May;76(5):1448-54. doi: 10.2527/1998.7651448x.
We conducted research to evaluate whether ergot alkaloids associated with endophyte-infected tall fescue could alter plasma concentrations of hormones important to reproductive function in cows. Six primiparous, estrous-cycling Holstein cows nursing calves received single i.v. injections of ergotamine tartrate, ergonovine maleate, or saline vehicle in a simple cross-over design. Each cow received one compound per estrous cycle, d 15 or 16 after estrus, and all compounds over three estrous cycles. Blood samples were collected at 20-min intervals for 40 min before and 240 min after treatments to assess plasma concentrations of prolactin, LH, FSH, and the response by PGF2alpha metabolite 13,14-dihydro-15-keto-prostaglandin F2alpha (PGFM). Ambient temperature and respiratory rates were measured hourly. Ambient temperature averaged 26 degrees C during data collection. Treatment x time was a significant source of variation for respiration rate and plasma concentrations of every hormone evaluated except FSH. Ergotamine elevated (P < .01) respiration rates 2 to 4 h after treatment. Ergotamine and ergonovine reduced (P < .001) plasma concentrations of prolactin for 2 to 4 h after treatment compared to concentrations before treatment. Plasma concentrations of LH were lowered (P < .01) by ergonovine during the 3rd h after treatment and by ergotamine during the 4th h after treatment. Most cows exhibited secretory PGFM responses after ergotamine and ergonovine treatments compared with an absence of a PGFM response in all cows after saline (P < or = .01). Results indicated that ergot alkaloids implicated as causative agents for fescue toxicosis can alter plasma concentrations of reproductive hormones during the late luteal phase of the estrous cycle in cows.
我们开展了一项研究，以评估与感染内生真菌的高羊茅相关的麦角生物碱是否会改变对奶牛生殖功能至关重要的激素的血浆浓度。六头初产、处于发情周期的荷斯坦奶牛在哺乳犊牛，采用简单交叉设计，通过静脉单次注射酒石酸麦角胺、马来酸麦角新碱或生理盐水载体。每头奶牛在每个发情周期（发情后第15或16天）接受一种化合物，并在三个发情周期内接受所有化合物。在处理前40分钟和处理后240分钟，每隔20分钟采集血样，以评估催乳素、促黄体生成素（LH）、促卵泡生成素（FSH）的血浆浓度，以及前列腺素F2α代谢物13,14-二氢-15-酮-前列腺素F2α（PGFM）的反应。每小时测量环境温度和呼吸频率。数据收集期间环境温度平均为26摄氏度。处理×时间是呼吸频率和除FSH外所评估的每种激素的血浆浓度变化的一个显著来源。处理后2至4小时，酒石酸麦角胺使呼吸频率升高（P < 0.01）。与处理前的浓度相比，处理后2至4小时，酒石酸麦角胺和马来酸麦角新碱使催乳素的血浆浓度降低（P < 0.001）。处理后第3小时，马来酸麦角新碱使LH的血浆浓度降低（P < 0.01），处理后第4小时，酒石酸麦角胺使LH的血浆浓度降低（P < 0.01）。与生理盐水处理后所有奶牛均无PGFM反应相比，大多数奶牛在酒石酸麦角胺和马来酸麦角新碱处理后出现了分泌性PGFM反应（P ≤ 0.01）。结果表明，被认为是牛茅草中毒病原体的麦角生物碱可在奶牛发情周期的黄体后期改变生殖激素的血浆浓度。
