生殖激素诱导母牛双胎效果及机理研究

Effects and Mechanism of Inducing Double-Calving of Cow With Reproductive Hormone

用生殖激素（PMSG和纯化的FSH）诱导母牛双胎进行了试验研究。PMSG处理组：选产后50d以上12头参试母牛，按其发情顺序随机分成3个组，每组4头牛，3组牛在发情周期的第10d分别各肌注PMSG2000IU，1650IU，1350IU，间隔48h再肌注氯前列烯醇2支（4mL），发情后按常规进行人工授精，同时再肌注与PMSG等量的抗PMSG，间隔12h再输精1次。上述3组牛每组随机选2头牛在输第一次精的同时肌注LRH－A_3200μg，以比较其对双胎率有无影响。纯化FSH处理组：选产后50d以上的6头参试母牛按发情顺序随机分成2组，一组FSH总剂量为6mg，另一组为5mg。其处理方法是在发情周期的第10，11，123d每天早、晚各1次给参试牛肌注FSH，在第一次肌注FSH48h后肌注氯前列烯醇2支（4mL），发情后正常输精，间隔12h再输精1次。上述6头参试牛中随机选3头牛于输第1次精的同时肌注LRH－A_3200μg。每头参试牛于不同生理时期，包括肌注生殖激素的当天，24h，48h；肌注氯前列烯醇后24h，48h；发情后48h，排卵时，妊娠后第5d，20d，60d。从颈静脉各采血1次，共采10次，每次10mL，离心后分离血清，用放免法测定上述各生理时期血清中P_4，LH，E_2水平，分析与单、双胎的关系。结果表明（1）适量的PMSG（1350～2000IU）和纯化FSH（5mg）均能诱导母牛?

Cow is monotocous. In order to improve the reproductivity of cow, inducing dou-ble-calving of cow with reproductive hormone (PMSG and purified FSH) was studied.PMSG treatment: 12 cows, postpartum 50 d and above, were divided into 3 groups at ran-dom each four according to estrus order. On the 10th day of the estrus cycle, all cows were given intramuscular injection with PMSG 2000 IU, 1650 IU and 1350 IU respectively, and with cloprostenol 4 ml after 48 h interval. After estrus, cows were inseminated artificially and given anti-PMSG with the same acount to PMSG, inseminated again after 12h interval.2 cows of each group were selected randomly and given intromuscular injection with LRH-A_3 200ug at the first insemination to study the influence of LRH-A_3 on the twinning rate.Purified FSH treatment: 6 cows, pospartum over 50 d, were divided into 2 groups, in-tramuscular injection with FSH 6 mg and with FSH 5 mg. On ds 10, 11 and 12 of estrous cy-cle, cows were treated with intromuscular injection with FSH2 times daily (in morning and evenning respectively). After 48h of the first intramuscular injection with FSH, cows were given intramuscular injection with cloprostenol 4 ml. Cow in estrus was inseminated artifi-cially and inseminated again after 12h interval. 3 of 6 cows were selected randomly and given intramuscular injection with LRH-A_3 200ug at the first insemination.Blood was collected from jugliar vein on d 10 of the setrus cycle, at 24 and 48h after in-tramuscular injcetion with reproductive hormone, at 24 and 48h after intramuscular injection with cloprostenol, at 48h after estrus, On d 5, 10, 20 and 60 after ovulation or pregnancy.The concentration of P_4, LH, and E_2 in serum of cow at each physiological period was de-termined by RIA.The Results were as follows: (1) Intramuscular injection with PMSG (1350~2000IU)and with purified FSH (5mg) could induce double-calving of cows, twinning rate was 42. 9% (3/7) and 33. 3% (1/3) respectively. (2) Twinning rate of intramuscular injection with LRH-A,was 5o. o% (3/6), 25. O percentage unite higher than that of control group (25.0% ). This indicated that cows given intramuscular injection with LRH-A,at insemination in-creased twinning rate. (3) Serum P' concentration of biparous and single pregnancy cows treated with PMSG on the d 5, 1o, 2O and 6O of pregnancy were 4. 21 ±4. 01, 11. 42±11.79, 12. 63±1. 91, 16. 96±10. 42ng/mL,and 4. 16±2. 30, 8. 68±2. 82, 9. 44±1. 14, 14. 19±2. 71ng/mL,respectively. (4) Serum P concentration of biparous and single pregnancy cows treated with FSH on the d 5, 10, 20 and 60 of pregnancy were 8. 70, 10. 80, 11. 30,11. 80ng/mL and 2. 01, 3. 13, 5. 52, 5. 46ng/mL, respectively. This observation suggested that serum P concentration of biparous cow at early pregnancy was higher than that of single pregnancy cow.