Brito L F C, Satrapa R, Marson E P, Kastelic J P
Faculty of Veterinary Medicine, Federal University of Uberlandia, Uberlandia MG, Brazil.
Anim Reprod Sci. 2002 Sep 16;73(1-2):23-35. doi: 10.1016/s0378-4320(02)00124-0.
This study was conducted to identify factors affecting PGF(2alpha) efficacy to synchronize estrus in water buffalo cows. After detection of a corpus luteum (CL) by rectal palpation, cows were treated (im) with dinoprost (12.5, 25 or 50mg) or D(+) cloprostenol (75, 150 or 300 microg) in a total of 66 treatments. Blood samples were collected 0, 24 and 48 h after treatment and ultrasound examinations and observations for estrus were performed daily to the day of ovulation or to 6 days after treatment. No PGF(2alpha) dose-response pattern was observed and overall rates of luteal regression (progesterone <1.0 ng/ml at 48 h), estrus, no detected behavioral estrus with ovulation occurring, and ovulation were 71.2, 36.4, 19.7 and 54.5%, respectively. To analyze plasma progesterone concentrations and ovarian dynamics, cows were divided in three groups according to their response to treatment. Cows that failed to have ovulations from a follicle after treatment (Group A, n = 30) had (P < 0.05) a lower plasma progesterone concentration (2.98 ng/ml) and smaller CL area (CLA; 187.3 mm(2)) before treatment as compared with cows that had an ovulation from a follicle (4.43 ng/ml and 223.7 mm(2), respectively; Groups B and C, n = 36). In cows that failed to ovulate, plasma progesterone concentration decreased in the first 24 h, but did not decline further and was >1.0 ng/ml 48 h after treatment. Moreover, no significant change in CLA after treatment was detected, indicating that treatment induced only partial luteolysis. In cows that ovulated, plasma progesterone concentration and CLA decreased continuously from treatment to ovulation (consistent with complete luteolysis). Threshold values of 2.8 ng/ml for plasma progesterone concentration and 189 mm(2) for CLA were identified as the best predictors of ovulation before treatment (83.3 and 80.6% sensitivity and 58.6 and 65.5% specificity, respectively, with positive and negative predictive values around 71%). When the origin of the ovulatory follicle was investigated, the interval from treatment to ovulation was shorter (91.9 versus 113.3 h; P < 0.05), and the ovulatory follicle had a slower growth rate (1.02 versus 1.55 mm per day; P < 0.005), a lesser increase in diameter from treatment to ovulation (4.7 versus 8.0 mm; P < 0.001), and a greater maximum diameter (13.2 versus 12.1 mm; P < 0.05) in cows that ovulated from the largest follicle present in the ovary before treatment (Group B, n = 27) compared with cows that ovulated from the second largest follicle present in the ovary before treatment (Group C, n = 9). In summary, the efficacy of PGF(2alpha) for causing luteolysis and synchronizing estrus and ovulation in buffalo cows was dependent upon plasma progesterone concentration, CL size and ovarian follicular status before treatment.
本研究旨在确定影响前列腺素F2α（PGF2α）对水牛母牛发情同步化效果的因素。通过直肠触诊检测到黄体（CL）后，对母牛进行了总共66次处理，分别肌肉注射（im）地诺前列素（12.5、25或50mg）或D（+）氯前列醇（75、150或300μg）。在处理后0、24和48小时采集血样，并每天进行超声检查和发情观察，直至排卵日或处理后6天。未观察到PGF2α的剂量反应模式，黄体退化（48小时时孕酮<1.0ng/ml）、发情、未检测到行为发情但发生排卵以及排卵的总体发生率分别为71.2%、36.4%、19.7%和54.5%。为了分析血浆孕酮浓度和卵巢动态，根据母牛对处理的反应将其分为三组。处理后未能从卵泡排卵的母牛（A组，n = 30）与从卵泡排卵的母牛相比，处理前血浆孕酮浓度较低（2.98ng/ml），黄体面积较小（CLA；187.3mm²）（分别为4.43ng/ml和223.7mm²；B组和C组，n = 36）（P<0.05）。在未排卵的母牛中，血浆孕酮浓度在最初24小时内下降，但未进一步下降，处理后48小时>1.0ng/ml。此外，处理后未检测到CLA有显著变化，表明处理仅诱导了部分黄体溶解。在排卵的母牛中，从处理到排卵血浆孕酮浓度和CLA持续下降（与完全黄体溶解一致）。确定处理前血浆孕酮浓度2.8ng/ml和CLA 189mm²的阈值为排卵的最佳预测指标（敏感性分别为83.3%和80.6%，特异性分别为58.6%和65.5%，阳性和阴性预测值约为71%）。当研究排卵卵泡的来源时，与从处理前卵巢中第二大卵泡排卵的母牛相比，从处理前卵巢中最大卵泡排卵的母牛（B组，n = 27）从处理到排卵的间隔更短（91.9对113.3小时；P<0.05），排卵卵泡生长速度较慢（每天1.02对1.55mm；P<0.005），从处理到排卵直径增加较小（4.7对8.0mm；P<0.001），最大直径更大（13.2对12.1mm；P<0.05）（C组，n = 9）。总之，PGF2α在水牛母牛中引起黄体溶解、同步发情和排卵的效果取决于处理前的血浆孕酮浓度、黄体大小和卵巢卵泡状态。
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