Kastelic J P, Olson W O, Martinez M, Cook R B, Mapletoft R J
Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta.
Can Vet J. 1999 Mar;40(3):173-8.
Fifty-six cows received a norgestomet implant and an injection of norgestomet and estradiol valerate; half (n = 28) received 500 IU equine chorionic gonadotrophin (eCG) at implant removal, 9 d later. A third group (n = 25) received 2 doses of cloprostenol (500 micrograms) 11 d apart. Estrous rate was higher (P < 0.05) for cows given norgestomet and estradiol plus 500 IU eCG (75.0%) than for those receiving cloprostenol (44.0%); for those receiving norgestomet and estradiol alone, it was intermediate (67.8%). Pregnancy rates to artificial insemination (after estrus or timed) were higher (P < 0.05) for cows given norgestomet and estradiol than for those given cloprostenol (23 of 28, 82.1% vs 13 of 25, 52.0%), and intermediate (67.8%) for those given norgestomet and estradiol plus eCG. In a second experiment, for heifers treated with norgestomet and estradiol plus eCG (n = 15) or with 2 doses of cloprostenol (n = 16), estrous rates were 66.7% vs 56.2% (P > 0.5), ovulation rates were 100.0% vs 81.2% (P = 0.08), intervals from implant removal or cloprostenol treatment to estrus were 48.0 +/- 4.4 hours vs 61.3 +/- 7.0 hours (P = 0.12) and to ovulation were 70.4 +/- 4.4 hours vs 93.2 +/- 7.5 hours (P < 0.01), respectively; pregnancy rates were 41.7 and 35.7%, respectively (P > 0.5). Norgestomet and estradiol were as good as (heifers) or superior to (cows) a 2-dose cloprostenol regimen. In cows given norgestomet and estradiol, injecting eCG at implant removal did not significantly improve estrous or pregnancy rates.
56头母牛接受了诺孕美特植入剂以及诺孕美特和戊酸雌二醇的注射；其中一半（n = 28）在植入剂移除后9天接受500国际单位的马绒毛膜促性腺激素（eCG）。第三组（n = 25）每隔11天接受2剂氯前列醇（500微克）。接受诺孕美特和戊酸雌二醇加500国际单位eCG的母牛发情率（75.0%）高于接受氯前列醇的母牛（44.0%）（P < 0.05）；对于仅接受诺孕美特和戊酸雌二醇的母牛，发情率处于中间水平（67.8%）。接受诺孕美特和戊酸雌二醇的母牛人工授精（发情后或定时授精）后的妊娠率高于接受氯前列醇的母牛（28头中的23头，82.1%对25头中的13头，52.0%）（P < 0.05），接受诺孕美特和戊酸雌二醇加eCG的母牛妊娠率处于中间水平（67.8%）。在第二项实验中，对于接受诺孕美特和戊酸雌二醇加eCG（n = 15）或2剂氯前列醇（n = 16）治疗的小母牛，发情率分别为66.7%和56.2%（P > 0.5），排卵率分别为100.0%和81.2%（P = 0.08），从植入剂移除或氯前列醇治疗到发情的间隔时间分别为48.0±4.4小时和61.3±7.0小时（P = 0.12），到排卵的间隔时间分别为70.4±4.4小时和93.2±7.5小时（P < 0.01）；妊娠率分别为41.7%和35.7%（P > 0.5）。诺孕美特和戊酸雌二醇在小母牛中效果与2剂氯前列醇方案相当，在母牛中优于该方案。对于接受诺孕美特和戊酸雌二醇的母牛，在植入剂移除时注射eCG并未显著提高发情率或妊娠率。
