Bracken C J, Radcliff R P, McCormack B L, Keisler D H, Lucy M C
Department of Animal Sciences, University of Missouri, Columbia 65211, United States.
Anim Reprod Sci. 2007 Nov;102(1-2):158-64. doi: 10.1016/j.anireprosci.2007.02.021. Epub 2007 Mar 2.
Intervals to estrus and ovulation in weaned sows depend partially on the diameter of ovarian follicles at weaning. The objective was to determine if follicular diameter in sows could be increased by a 48h period of GnRH infusion before weaning and whether this pre-weaning growth would advance follicular development after weaning. The posterior vena cava was cannulated in eight sows at 10+/-1 day after farrowing. Sows were randomly assigned to receive intravenous treatment with either 2mL of GnRH (1microg/mL; n=4) or 2mL of saline (n=4) every 0.5h for 48h beginning 94h before weaning. The average follicular diameter and the number of follicles within diameter classes were determined daily by ultrasonography. Serum LH concentrations increased on the first infusion day but serum LH was equal to control on the last infusion day (P<0.077). The GnRH infusion increased the average diameter of ovarian follicles (P<0.001). Serum estradiol increased (P<0.001) and serum FSH decreased (P<0.016) coincident with GnRH-induced follicular development but these changes were reversed within 24h after the end of the infusion period. Follicles that grew in response to GnRH regressed and were replaced by a new population of follicles within 4 days after weaning. Within the experimental model for the present study, a GnRH infusion increased follicular growth in lactating sows but follicles could not be sustained beyond the end of GnRH infusion.
断奶母猪发情和排卵的间隔时间部分取决于断奶时卵巢卵泡的直径。本研究的目的是确定在断奶前连续48小时输注促性腺激素释放激素（GnRH）是否能增加母猪的卵泡直径，以及断奶前卵泡的这种生长是否会促进断奶后卵泡的发育。在分娩后10±1天，对8头母猪的后腔静脉进行插管。从断奶前94小时开始，每隔0.5小时给母猪静脉注射2毫升GnRH（1微克/毫升；n = 4）或2毫升生理盐水（n = 4），持续48小时。通过超声检查每天测定卵泡的平均直径和不同直径等级卵泡的数量。在首次输注日，血清促黄体生成素（LH）浓度升高，但在最后输注日，血清LH浓度与对照组相当（P<0.077）。GnRH输注增加了卵巢卵泡的平均直径（P<0.001）。随着GnRH诱导的卵泡发育，血清雌二醇升高（P<0.001），血清促卵泡生成素（FSH）降低（P<0.016），但在输注期结束后24小时内，这些变化发生了逆转。对GnRH有反应而生长的卵泡在断奶后4天内退化，并被新的卵泡群体取代。在本研究的实验模型中，GnRH输注增加了泌乳母猪的卵泡生长，但在GnRH输注结束后，卵泡无法维持生长。
