Ambrose J D, Pires M F, Moreira F, Diaz T, Binelli M, Thatcher W W
Department of Dairy and Poultry Sciences, University of Florida, Gainesville 32611, USA.
Theriogenology. 1998 Nov;50(7):1157-70. doi: 10.1016/s0093-691x(98)00216-7.
The objectives of this study were to investigate the effect of a synthetic GnRH-agonist (Deslorelin) implant on CL function and follicle dynamics when administered 48 h after PGF2 alpha, in a timed-insemination protocol, and to determine if the incorporation of a Deslorelin implant into a timed-insemination protocol to synchronize ovulation would be beneficial to the establishment of pregnancy. In Experiment 1, 15 non lactating cyclic Holstein cows received Buserelin (8 micrograms, i.m.) on Day-9, Lutalyse (25 mg, i.m.) on Day-2, and then on Day 0 received either a Deslorelin implant (700 micrograms, s.c.; n = 5), Buserelin (8 micrograms, i.m.; n = 5), or no treatment (control; n = 5). Blood samples were collected on Days-9, -2, 0 and thereafter daily until the next ovulation. Ovaries were scanned by ultrasound on Days-9, -2, 0, 1 (day of ovulation) and 3 times a week thereafter until a subsequent ovulation. From Days 0 to 15, the rate of increase of plasma progesterone (P4) was greater (P < 0.01) for Deslorelin than for control and Buserelin. Establishment of the first-wave dominant follicle (FWDF) as a Class 3 (> 9 mm) follicle was delayed (P < 0.01) with Deslorelin (14.2 +/- 1.3 d) compared with the control (4.6 +/- 1.3 d) and Buserelin (5.0 +/- 1.5 d) treatments. The FWDF resumed growth after Day 13 in all 5 Deslorelin-treated cows, and 2 cows ovulated spontaneously. In 1 Deslorelin-treated cow, the FWDF regressed, and a second-wave dominant follicle ovulated, while 2 other Deslorelin cows failed to ovulate until after Day 36. The cumulative numbers of Class 2 and 3 follicles was lowest in the Deslorelin group (P < 0.01), while the cumulative number of Class 1 follicles was highest (Deslorelin > Buserelin > Control; P < 0.01). The number of days to CL-regression and days to subsequent estrus did not differ (P > 0.05) among treatments. In Experiment II, 16 lactating potentially subfertile (body condition score 2.25) cows received Cystorelin (100 micrograms, i.m.; Day-9), Lutalyse (25 mg, i.m.; Day-2), and either a Cystorelin injection (100 micrograms, i.m.; n = 8) or Deslorelin implant (700 micrograms, s.c.; n = 8) on Day 0 and inseminated 16 h later. Deslorelin-treated cows had a higher plasma P4 concentration between Days 0 and 16 (P < 0.05) than the 2 other groups, and 5 of the 8 cows in this group were pregnant (Day 45, palpation) compared with 1 of 8 cows in the Cystorelin group (P < 0.05). Incorporation of a Deslorelin implant into a timed-insemination protocol enhanced the pregnancy rate in cows of poor body condition. The results support the hypothesis that enhanced CL function and delayed establishment of the first-wave dominant follicle may enhance embryo survival.
本研究的目的是在定时输精方案中，研究在前列腺素F2α给药48小时后植入合成促性腺激素释放激素激动剂（地洛瑞林）对黄体功能和卵泡动态的影响，并确定将地洛瑞林植入物纳入定时输精方案以同步排卵是否有利于妊娠的建立。在实验1中，15头非泌乳周期性荷斯坦奶牛在第-9天接受布舍瑞林（8微克，肌肉注射），在第-2天接受氯前列烯醇（25毫克，肌肉注射），然后在第0天接受地洛瑞林植入物（700微克，皮下注射；n = 5）、布舍瑞林（8微克，肌肉注射；n = 5）或不进行处理（对照组；n = 5）。在第-9天、-2天、0天采集血样，此后每天采集直至下次排卵。在第-9天、-2天、0天、1天（排卵日）用超声扫描卵巢，此后每周扫描3次直至随后排卵。从第0天到第15天，地洛瑞林组血浆孕酮（P4）的升高速率高于对照组和布舍瑞林组（P < 0.）。与对照组（4.6±1.3天）和布舍瑞林组（5.0±1.5天）相比，地洛瑞林组（14.2±1.3天）作为3级（>9毫米）卵泡的第一波优势卵泡（FWDF）的建立延迟（P < 0.01）。在所有5头接受地洛瑞林治疗的奶牛中，FWDF在第13天后恢复生长，2头奶牛自发排卵。在1头接受地洛瑞林治疗的奶牛中，FWDF退化，第二波优势卵泡排卵，而另外2头接受地洛瑞林治疗的奶牛直到第36天后才排卵。地洛瑞林组2级和3级卵泡的累积数量最低（P < 0.01），而1级卵泡的累积数量最高（地洛瑞林>布舍瑞林>对照组；P < 0.01）。各处理间黄体退化天数和随后发情天数无差异（P > 0.05）。在实验II中，16头泌乳期潜在繁殖力低下（体况评分2.25）的奶牛在第-9天接受促卵泡素（100微克，肌肉注射），在第-2天接受氯前列烯醇（25毫克，肌肉注射），并在第0天接受促卵泡素注射（100微克，肌肉注射；n = 8）或地洛瑞林植入物（700微克，皮下注射；n = 8），16小时后输精。与其他两组相比，地洛瑞林治疗的奶牛在第0天至第16天之间血浆P4浓度更高（P < 0.05），该组8头奶牛中有5头怀孕（第45天，触诊），而促卵泡素组8头奶牛中有1头怀孕（P < 0.05）。将地洛瑞林植入物纳入定时输精方案可提高体况较差奶牛的妊娠率。结果支持以下假设：增强的黄体功能和延迟的第一波优势卵泡的建立可能会提高胚胎存活率。
