Davies Morel Mina C G, Newcombe John R
University of Wales, Institute of Rural Sciences, Aberystwyth, Ceredigion, UK.
Anim Reprod Sci. 2008 Dec;109(1-4):189-99. doi: 10.1016/j.anireprosci.2007.10.005. Epub 2007 Oct 23.
Despite the widespread use of hCG to advance ovulation in the mare there is little information on efficacy of dose rates and any contraindications of its use. This study aims to investigate the effect of dose of hCG on ovulation within 48h and the effect of hCG on: ovulation, multiple ovulation (MO), pregnancy, multiple pregnancy (MP) rates and synchrony of MO; additionally whether any seasonal effect is evident. Sequential ultrasonic scanning was used to monitor the occurrence of ovulation, within 48h of treatment, in 1291 Thoroughbred mares treated with either 750iu hCG or 1500iu hCG s.c. Ovulation rate, type (single ovulations (SO), MO, synchronous, asynchronous) and subsequent pregnancy were then monitored in 1239 Thoroughbred mares on a commercial stud over 3 years, 536 of which were treated with 750iu hCG at mating, all mares were also allocated into groups according to month of mating. No significant difference existed between the two dose levels of hCG and no significant difference existed between treated and untreated mares in overall ovulations (1.32 and 1.28 respectively), MO (31.7% and 27.7%), pregnancy (65.1% and 65.6%) or MP rates (10.8% and 11.8%). There was no significant association between month of year and pregnancy or MP rates for either treated or control mares, nor for MO for untreated mares. A significant (p<0.05) association was evident between month and MO in treated mares, MO being lowest in April (22.3%). 95.9% of treated mares multiple ovulated within 48h compared with 90.7% controls, a near significant difference. In conclusion this study demonstrates that: (i) hCG dose of 750iu s.c. is just as effective in inducing ovulation within 48h as 1500iu, (ii) 750iu hCG has no significant effect on ovulation, MO, pregnancy or MP rates; (iii) a significant (p<0.05) association exists between season and MO in hCG treated mares; (iv) a tighter synchrony (ovulation within 48h) of MO is evident in hCG treated compared with control mares (p=0.052).
尽管人绒毛膜促性腺激素（hCG）在母马中广泛用于促进排卵，但关于剂量率的有效性及其使用的任何禁忌症的信息却很少。本研究旨在调查hCG剂量对48小时内排卵的影响以及hCG对排卵、多排卵（MO）、妊娠、多胎妊娠（MP）率和MO同步性的影响；此外，是否有明显的季节效应。采用连续超声扫描监测1291匹经皮下注射750iu hCG或1500iu hCG治疗的纯种母马在治疗后48小时内的排卵情况。然后在一个商业种马场对1239匹纯种母马进行了3年的监测，观察其排卵率、类型（单排卵（SO）、MO、同步、不同步）和随后的妊娠情况，其中536匹在配种时接受了750iu hCG治疗，所有母马也根据配种月份进行分组。hCG的两种剂量水平之间没有显著差异，治疗组和未治疗组母马在总体排卵（分别为1.32和1.28）、MO（31.7%和27.7%）、妊娠（65.1%和65.6%）或MP率（10.8%和11.8%）方面也没有显著差异。对于治疗组或对照组母马，一年中的月份与妊娠或MP率之间没有显著关联，对于未治疗组母马的MO也没有显著关联。在治疗组母马中，月份与MO之间存在显著（p<0.05）关联，4月份的MO最低（22.3%）。95.9%的治疗组母马在48小时内出现多排卵，而对照组为90.7%，差异接近显著。总之，本研究表明：（i）皮下注射750iu hCG在诱导48小时内排卵方面与1500iu同样有效；（ii）750iu hCG对排卵、MO、妊娠或MP率没有显著影响；（iii）在接受hCG治疗的母马中，季节与MO之间存在显著（p<0.05）关联；（iv）与对照组母马相比，接受hCG治疗的母马MO的同步性更高（48小时内排卵）（p=0.052）。
