Gifford C A, Duffey J L, Knight R L, Hallford D M
Department of Animal and Range Sciences, New Mexico State University, Las Cruces, NM 88003-8003, USA.
Anim Reprod Sci. 2007 Jul;100(1-2):32-43. doi: 10.1016/j.anireprosci.2006.06.016. Epub 2006 Aug 8.
Two experiments were conducted during mid-gestation to examine effects in ewes of propylthiouracil (PTU) treatment alone or with melatonin on serum thyroid hormones, postpartum reproduction, and lamb performance. In the first experiment, beginning on day 0 (first day of treatment when all animals were 72.2+/-0.9 days of gestation), ewes received daily treatments (gavage) consisting of either 0mg (n=6) or 40 mg (n=6) PTU/kg body weight/day for 15 days. After 15 days, the 40 mg dosage was decreased to 20mg/kg body weight for an additional 20 days (35 days of PTU). Serum thyroxine (T4) did not differ (P>0.10) between groups through day 4; but on day 5, control females had a serum value of 67 ng/ml compared with 46 (+/-5)ng/ml for PTU-treated ewes (P=0.02). On the last day that 40 mg of PTU was administered, serum T4 averaged 67 and 7 (+/-5)ng/ml (P<0.001) in the two respective groups. Serum T4 remained low and was 80 and 1 ng/ml (P<0.001) in control and treated ewes on day 34. Serum T4 rose gradually after PTU but remained different from that observed in control ewes through day 48. Lambs from control and treated ewes had similar (P=0.46) T4 values at birth but lambs from PTU-treated ewes had lower (P=0.03) birth weights than did those from control ewes. Serum progesterone (P4) after parturition indicated a lack of cyclicity in all ewes. In the second experiment, beginning on day 0 (76.8+/-4.7 days of gestation), ewes received PTU as in Experiment 1. In addition, after 15 days of PTU, melatonin was given (i.m. injections at 5mg/day) for 30 days. Propylthiouracil decreased (P<or=0.05) serum T4 on days 25 through 41 of the treatment period. Serum T3 was lower (P<0.05) in PTU-treated ewes from day 8 through the end of PTU administration. Postpartum P4 was below 1 ng/ml on all days indicating acyclicity. Lamb body weight and serum IGF-I were similar (P>0.60) for lambs born to control and treated ewes. Female offspring of PTU+melatonin-treated dams reached puberty, became anestrus, and returned to cyclicity at similar (P>0.10) times to contemporary ewe lambs. Results indicate that 40/20mg PTU alone or with melatonin does not induce cyclicity after lambing in spring lambing ewes and has little effect on offspring performance.
在妊娠中期进行了两项实验，以研究丙硫氧嘧啶（PTU）单独治疗或与褪黑素联合治疗对母羊血清甲状腺激素、产后繁殖性能和羔羊生长性能的影响。在第一个实验中，从第0天（所有动物妊娠72.2±0.9天的第一天开始治疗）开始，母羊每天接受（灌胃）治疗，治疗组为0mg（n = 6）或40mg（n = 6）PTU/千克体重/天，持续15天。15天后，40mg剂量减至20mg/千克体重，再持续20天（PTU治疗35天）。在第4天之前，两组之间的血清甲状腺素（T4）没有差异（P>0.10）；但在第5天，对照母羊的血清值为67ng/ml，而PTU治疗的母羊为46（±5）ng/ml（P = 0.02）。在给予40mg PTU的最后一天，两组的血清T4平均分别为67和7（±5）ng/ml（P<0.001）。在第34天，对照和治疗母羊的血清T4仍然较低，分别为80和1ng/ml（P<0.001）。PTU治疗后血清T4逐渐升高，但直到第48天仍与对照母羊的不同。对照和治疗母羊的羔羊出生时T4值相似（P = 0.46），但PTU治疗母羊的羔羊出生体重低于对照母羊（P = 0.03）。产后血清孕酮（P4）表明所有母羊均无周期性。在第二个实验中，从第0天（妊娠76.8±4.7天）开始，母羊接受与实验1相同的PTU治疗。此外，在PTU治疗15天后，给予褪黑素（肌肉注射，5mg/天），持续30天。在治疗期的第25天至41天，丙硫氧嘧啶降低了（P≤0.05）血清T4。从第8天到PTU给药结束，PTU治疗的母羊血清T3较低（P<0.05）。产后所有天数的P4均低于1ng/ml，表明无周期性。对照和治疗母羊所生羔羊的体重和血清IGF-I相似（P>0.60）。PTU + 褪黑素治疗的母羊所生雌性后代达到青春期、进入乏情期并恢复周期性的时间与同期母羊羔羊相似（P>0.10）。结果表明，单独使用40/20mg PTU或与褪黑素联合使用，不会使春季产羔母羊产羔后出现周期性，对后代性能影响较小。
