Wise T, Klindt J, Howard H J, Conley A J, Ford J J
USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933-0166, USA.
J Anim Sci. 2001 Jan;79(1):176-87. doi: 10.2527/2001.791176x.
Endocrine differences between European crossbred and Chinese Meishan females have been somewhat modest. Indwelling jugular cannulas were placed in Meishan (n = 7) and White composite (n = 6) multiparous sows before weaning, and blood was sampled from 4 h before to 240 h after removal of litters. Temporal changes in FSH, triiodothyronine (T3), and tetraiodothyronine (T4) after weaning differed between Meishan and White composite sows. Plasma cortisol concentrations were higher in Meishan sows than in White composite sows (P < 0.01), but there were no temporal differences between breeds after weaning. Other hormones monitored (prolactin, GH, IGF-I, and inhibin) were not different between breeds. In the second experiment, Meishan gilts (n = 7) and sows (n = 7) and White composite sows (n = 9) were cannulated during the luteal phase of the estrous cycle and sampled after treatments consisting of GnRH (15 and 150 ng/kg BW), ovariectomy, estradiol cypionate challenge after ovariectomy (10 microg/kg BW), and GnRH antagonist. In response to GnRH challenge, White composite sows had elevated (P < 0.05) concentrations of gonadotropins compared with Meishan. Cortisol concentrations were elevated in Meishan as compared with White composite females (P < 0.01) but unaffected by GnRH treatment. After ovariectomy, LH concentrations increased 3 h sooner in White composite than in Meishan females. After GnRH antagonist, declines in gonadotropins were comparable in both breeds, but LH increased in Meishan females by 20 h but not until after 54 h in White composite females. White composite females demonstrated only a short decline in FSH in response to the GnRH antagonist, but Meishan females had a prolonged decline in FSH concentrations. Consistently elevated cortisol concentrations in Meishan females may positively impact ovarian function; thus, the assumption that high plasma cortisol concentration as an index of stress that impairs reproductive function should be reevaluated in swine. There were few endocrine differences that would relate to or explain increased ovulation rates found in the Meishan breed; thus, other mechanisms must exist to explain the increase in ovarian function in the Meishan breed.
欧洲杂交母猪与中国梅山母猪之间的内分泌差异相对较小。在断奶前，给梅山母猪（n = 7）和白色杂交母猪（n = 6）植入颈静脉插管，从仔猪断奶前4小时至断奶后240小时采集血液样本。梅山母猪和白色杂交母猪断奶后促卵泡激素（FSH）、三碘甲状腺原氨酸（T3）和四碘甲状腺原氨酸（T4）的时间变化存在差异。梅山母猪的血浆皮质醇浓度高于白色杂交母猪（P < 0.01），但断奶后不同品种之间没有时间差异。所监测的其他激素（催乳素、生长激素、胰岛素样生长因子-I和抑制素）在不同品种之间没有差异。在第二个实验中，在发情周期的黄体期给梅山后备母猪（n = 7）、经产母猪（n = 7）和白色杂交经产母猪（n = 9）植入插管，并在给予促性腺激素释放激素（GnRH，15和150 ng/kg体重）、卵巢切除、卵巢切除后给予环丙孕酮挑战（10 μg/kg体重）和GnRH拮抗剂处理后进行采样。与梅山母猪相比，白色杂交母猪对GnRH挑战的反应是促性腺激素浓度升高（P < 0.05）。与白色杂交母猪相比，梅山母猪的皮质醇浓度升高（P < 0.01），但不受GnRH处理的影响。卵巢切除后，白色杂交母猪的促黄体生成素（LH）浓度比梅山母猪提前3小时升高。给予GnRH拮抗剂后，两个品种的促性腺激素下降情况相当，但梅山母猪的LH在20小时时升高，而白色杂交母猪直到54小时后才升高。白色杂交母猪对GnRH拮抗剂的反应仅表现为FSH短暂下降，而梅山母猪的FSH浓度下降时间延长。梅山母猪中持续升高的皮质醇浓度可能对卵巢功能有积极影响；因此，关于高血浆皮质醇浓度作为应激指标会损害生殖功能的假设，在猪身上应该重新评估。几乎没有内分泌差异能够关联或解释梅山猪品种中发现的排卵率增加；因此，必然存在其他机制来解释梅山猪品种中卵巢功能的增强。
