对选择用于双羔生产的青春期前母羊羔进行释放激素激发试验后血清促黄体生成素、生长激素和胰岛素样生长因子-I的情况
Serum luteinizing hormone, growth hormone and insulin-like growth factor-I after releasing hormone challenge in prepubertal ewe lambs selected for twinning.
作者信息
Shirley K L, Hernandez J A, Hallford D M, Thomas M G
机构信息
Department of Animal and Range Sciences, New Mexico State University, Las Cruces 88003, USA.
出版信息
Theriogenology. 2001 Sep 15;56(5):867-77. doi: 10.1016/s0093-691x(01)00614-8.
Two studies evaluated hormonal markers as indicators of the onset of puberty in Debouillet sheep selected for twinning. In Trial 1, 29 ewe lambs (50 +/- 0.5 kg, 159 to 187 d of age) were given 10 microg GnRH (i.v.) on September 15 and blood was collected at 30 min intervals after the injection for 2 h. Additional samples were taken twice weekly and progesterone (P4) was measured. The day that serum P4 was greater than 1 ng/mL for 2 consecutive sampling days was classified as the day of puberty. Average day of puberty was October 12 (average age at puberty was 199 d) and ewes with values less or greater than the average were classified as early or late, respectively. Average weight at GnRH challenge was 50 kg and ewes weighing less or more were classified as light or heavy, respectively. Early ewes weighed more (P = 0.01) and reached puberty sooner (P = 0.01) than late ewes. Heavy lambs reached puberty earlier, weighed more at GnRH challenge, and had more LH area under the curve (AUC, P < 0.05) than light ewes. In Trial 2, we gave 27 ewe lambs (54 +/- 0.9 kg, 173 to 189 d of age) a single i.v. injection of 10 microg GnRH and 10 microg GHRH on September 17. Average day of puberty was October 13, average weight was 54 kg, and average age at puberty was 208 d. Categories were designated as described for Trial 1. Early lambs reached puberty sooner (P = 0.01) and weighed more (P = 0.01) than late lambs, but the puberty groups had similar LH AUC (P = 0.64) and GH AUC (P = 0.75), whereas IGF-I was greater (P = 0.01) in early puberty ewes than in late puberty ewes. Heavy lambs reached puberty earlier (P = 0.06), weighed more (P = 0.01), and tended (P = 0.11) to have more GH AUC than light ewes. No difference was observed in LH AUC or IGF-I between weight groups (P > 0.15). Results suggest that serum LH after GnRH is not a reliable indicator of the onset of puberty in ewe lambs selected for twinning, but heavier ewes tended to produce more GH after a GHRH challenge and reach puberty earlier than lighter ewe lambs.
两项研究评估了激素指标作为选择用于双羔生产的德布伊耶特绵羊青春期开始的指标。在试验1中，于9月15日给29只母羊羔羊（体重50±0.5千克，年龄159至187天）静脉注射10微克促性腺激素释放激素（GnRH），注射后每隔30分钟采集血液，持续2小时。另外每周采集两次样本并测定孕酮（P4）。血清P4连续两天采样均大于1纳克/毫升的那天被归类为青春期日。青春期平均日为10月12日（青春期平均年龄为199天），P4值低于或高于平均值的母羊分别被归类为早熟或晚熟。GnRH激发时的平均体重为50千克，体重低于或高于该值的母羊分别被归类为轻体重或重体重。早熟母羊比晚熟母羊体重更重（P = 0.01）且青春期来得更早（P = 0.01）。重羔羊比轻母羊青春期来得更早（P < 0.05），GnRH激发时体重更重，且促黄体生成素（LH）曲线下面积更大（AUC）。在试验2中，于9月17日给27只母羊羔羊（体重54±0.9千克，年龄173至189天）静脉注射10微克GnRH和10微克生长激素释放激素（GHRH）。青春期平均日为10月13日，平均体重为54千克，青春期平均年龄为208天。分类如试验1所述。早熟羔羊比晚熟羔羊青春期来得更早（P = 0.01）且体重更重（P = 0.01），但青春期各分组的LH AUC（P = 0.64）和生长激素（GH）AUC（P = 0.75）相似，而早熟青春期母羊的胰岛素样生长因子-I（IGF-I）高于晚熟青春期母羊（P = 0.01）。重羔羊比轻母羊青春期来得更早（P = 0.06），体重更重（P = 0.01），且GH AUC有更高的趋势（P = 0.11）。体重分组之间在LH AUC或IGF-I上未观察到差异（P > 0.15）。结果表明，GnRH刺激后的血清LH不是选择用于双羔生产的母羊羔羊青春期开始的可靠指标，但较重的母羊在GHRH激发后往往产生更多的GH，且比轻体重母羊羔羊青春期来得更早。
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