Colazo Marcos German, Martínez Marcelo Fabian, Kastelic John Patrick, Mapletoft Reuben John
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Sask., Canada S7N 5B4.
Anim Reprod Sci. 2002 Jul 15;72(1-2):47-62. doi: 10.1016/s0378-4320(02)00087-8.
Four experiments were conducted (with crossbred beef heifers) to determine the effects of dose and route of administration of cloprostenol on luteolysis, estrus and ovulation. In Experiment 1, 19 heifers with a CL > or = 17 mm in diameter were randomly allocated to receive cloprostenol as follows: 100 microg s.c., 250 microg s.c., or 500 microg i.m. Heifers given 100 microg s.c. had a longer (P<0.03) interval (120.0 h+/-10.7 h; mean+/-S.E.M.) from treatment to ovulation than those given either 250 microg s.c. or 500 microg i.m. (92.0 h+/-7.4 h and 84.0 h+/-8.2 h, respectively). In Experiment 2, 28 heifers were given porcine LH (pLH), followed in 7 days by cloprostenol (same doses and routes as in Experiment 1), and a second dose of pLH 48 h after cloprostenol. Luteolysis occurred in all heifers, and no difference was detected among treatment groups in the interval from cloprostenol treatment to ovulation (mean, 101 h; P<0.9). In Experiment 3, 38 heifers at random stages of the estrous cycle (but with plasma progesterone concentrations > or =1.0 ng/ml) received 500 or 125 microg cloprostenol by either i.m. or s.c. injection (2/2 factorial design). There was no difference (P<0.4) among groups in the proportions of heifers that were detected in estrus or that ovulated. However, the interval from cloprostenol treatment to estrus was shorter (P<0.02) in the group that received 500 microg i.m. (58.5h) than in the other three groups (500 microg s.c., 75.0 h; 125 microg i.m., 78.0 h; and 125 microg s.c., 82.3h). In Experiment 4, 36 heifers were treated (as in Experiment 3) on Day 7 after ovulation. The proportions of heifers detected in estrus and ovulating after 125 microg s.c. (33 and 44%, respectively) or 125 microg i.m. (55 and 55%) were lower (P<0.05) than in those that received 500 microg s.c. (100 and 100%), but not different from those receiving 500 microg i.m. (78 and 89%, respectively). Overall, ovulation was detected in 9/18 heifers given 125 microg and 17/18 heifers given 500 microg of cloprostenol, on Day 7 (P<0.01) and was detected in 17/20 heifers given 125 microg and 18/18 heifers given 500 microg of cloprostenol, at random stages of the estrous cycle (P>0.05). Although there was no significant difference in luteolytic efficacy between i.m. and s.c. injections of the recommended dose (500 microg) of cloprostenol, variability in responsiveness to a reduced dose depended upon CL sensitivity, therefore, reduced doses cannot be recommended for routine use.
进行了四项试验（以杂交肉牛小母牛为对象），以确定氯前列醇的给药剂量和途径对黄体溶解、发情和排卵的影响。在试验1中，将19头直径≥17mm的黄体（CL）的小母牛随机分组，按以下方式接受氯前列醇：100μg皮下注射、250μg皮下注射或500μg肌肉注射。皮下注射100μg氯前列醇的小母牛从给药到排卵的间隔时间（120.0小时±10.7小时；平均值±标准误）比皮下注射250μg或肌肉注射500μg的小母牛更长（P<0.03）（分别为92.0小时±7.4小时和84.0小时±8.2小时）。在试验2中，给28头小母牛注射猪促黄体素（pLH），7天后注射氯前列醇（剂量和途径与试验1相同），并在注射氯前列醇48小时后注射第二剂pLH。所有小母牛均发生黄体溶解，各治疗组从氯前列醇治疗到排卵的间隔时间无差异（平均值为101小时；P<0.9）。在试验3中，将38头处于发情周期随机阶段（但血浆孕酮浓度≥1.0ng/ml）的小母牛通过肌肉注射或皮下注射接受500或125μg氯前列醇（2×2析因设计）。在发情或排卵的小母牛比例上，各处理组间无差异（P<0.4）。然而，肌肉注射500μg氯前列醇的组从氯前列醇治疗到发情的间隔时间（58.5小时）比其他三组短（P<0.02）（皮下注射500μg，75.0小时；肌肉注射125μg，78.0小时；皮下注射125μg，82.3小时）。在试验4中，在排卵后第7天对36头小母牛进行处理（与试验3相同）。皮下注射125μg（分别为33%和44%）或肌肉注射125μg（分别为55%和55%）后发情和排卵的小母牛比例低于皮下注射500μg的小母牛（分别为100%和100%）（P<0.05），但与肌肉注射500μg的小母牛无差异（分别为78%和89%）。总体而言，在第7天，18头接受125μg氯前列醇的小母牛中有9头发情，18头接受500μg氯前列醇的小母牛中有17头发情（P<0.01）；在发情周期随机阶段，20头接受125μg氯前列醇的小母牛中有17头发情，18头接受500μg氯前列醇的小母牛中有18头发情（P>0.）。虽然肌肉注射和皮下注射推荐剂量（500μg）氯前列醇的溶黄体效力无显著差异，但对降低剂量的反应变异性取决于黄体敏感性，因此，不推荐将降低剂量用于常规使用。
