Our objectives were to test the efficacy of intravaginal (IVG) administration of PGF2α to induce corpus luteum (CL) regression, compare circulating progesterone (P4) profiles in cows receiving IVG versus intramuscular (IM) treatment with PGF2α, and evaluate reproductive outcomes. Lactating Holstein cows were synchronized using a Double-Ovsynch protocol [GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later GnRH, 7 d later PGF2α, 1 d later PGF2α, 32 h later GnRH, 16 to 20 h timed artificial insemination (TAI)] to receive TAI at 67 ± 3 d in milk. Seven days after the first GnRH treatment (time 0), cows with at least 1 visible CL ≥15 mm were blocked by parity and randomly assigned to a treatment that consisted of IM injection (IM-PGF; n = 201) or IVG instillation (IVG-PGF; n = 201) of PGF2α. Cows in IM-PGF received a single 25-mg dose of PGF2α (dinoprost tromethamine) intramuscularly. Cows in IVG-PGF received two 25-mg doses of PGF2α 12 h apart delivered through a catheter in the cranial portion of the vagina. Blood samples were collected at 0, 12, 48, and 72 h after treatment. Ovulation to the first GnRH of Double-Ovsynch was determined through transrectal ultrasonography. Only cows with P4 ≥1 ng/mL (functional CL) at time 0 (IM-PGF = 169; IVG-PGF = 179) were included in the analyses. Binary and quantitative data were analyzed by logistic regression and ANOVA with repeated measures, respectively. Results are presented as least squares means. Concentrations of P4 and the proportion of cows with a new CL at time 0 did not differ. Overall, the proportion of cows with CL regression using 1 ng of P4/mL (IM-PGF = 89.0%; IVG-PGF = 86.7%) or 0.5 ng of P4/mL (IM-PGF = 82.2%; IVG-PGF = 82.1%) as the cutoff did not differ. Concentrations of P4 were affected by treatment, time, and treatment × time interaction. Cows in IVG-PGF had greater mean P4 at 12 h than cows in IM-PGF. Mean P4 did not differ at 48 or 72 h after treatment. The proportion of cows with estrus recorded within 3 d of treatment (IM-PGF = 45.4%; IVG-PGF = 48.9%), ovulation risk after treatment (IM-PGF = 88.5%; IVG-PGF = 85.1%), and pregnancies per artificial insemination after TAI (IM-PGF = 51.5%; IVG-PGF = 57.8%) did not differ. We concluded that 2 IVG doses of 25 mg of PGF2α 12 h apart were as effective as a single 25-mg IM dose of PGF2α for inducing luteal regression in lactating dairy cattle.

中文翻译：

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阴道内注射前列腺素F2α与肌肉注射在诱导泌乳奶牛黄体退化方面一样有效。

我们的目标是测试阴道内（IVG）施用PGF2α诱导黄体（CL）消退的功效，比较接受IVG与经PGF2α肌肉内（IM）治疗的奶牛的循环孕酮（P4）概况以及评估生殖结局。使用Double-Ovsynch协议同步泌乳的荷斯坦奶牛[GnRH，PGF2α后7天，GnRH后3天，GnRH后7天，PGF2α后7天，PGF2α后1天，GnRH后32小时，人工定时16至20小时授精（TAI）]，以在牛奶中67±3 d接受TAI。首次GnRH治疗后第7天（时间0），至少有1个可见CL≥15 mm的母牛被胎次封堵，并被随机分配为IM注射（IM-PGF； n = 201）或IVG滴注（ IVG-PGF； n = 201）。IM-PGF中的母牛肌肉内接受25 mg单剂量的PGF2α（迪诺前列素氨丁三醇）。IVG-PGF中的母牛接受了两个25 mg剂量的PGF2α，间隔12小时通过阴道颅部的导管输送。治疗后0、12、48和72小时收集血样。通过经直肠超声检查确定双卵形卵泡的第一个GnRH排卵。分析中仅包括时间0时P4≥1ng / mL（功能性CL）（IM-PGF = 169； IVG-PGF = 179）的母牛。二元和定量数据分别通过逻辑回归和重复测量的方差分析进行分析。结果以最小二乘均值表示。在时间0时，P4的浓度和具有新CL的母牛的比例没有差异。总体而言，使用1 ng P4 / mL进行CL消退的母牛比例（IM-PGF = 89.0％; IVG-PGF = 86。7％）或0.5 ng P4 / mL（IM-PGF = 82.2％; IVG-PGF = 82.1％），因为临界值没有差异。P4的浓度受治疗，时间和治疗×时间相互作用的影响。IVG-PGF中的母牛在12 h时的平均P4高于IM-PGF中的母牛。治疗后48小时或72小时，平均P4无差异。治疗后3天内记录的发情母牛比例（IM-PGF = 45.4％; IVG-PGF = 48.9％），治疗后排卵风险（IM-PGF = 88.5％; IVG-PGF = 85.1％）和怀孕TAI后的每次人工授精（IM-PGF = 51.5％； IVG-PGF = 57.8％）没有差异。我们得出的结论是，间隔12 h的2个IVG剂量的25 mgPGF2α可以与单独的25 mg IM剂量的PGF2α诱导泌乳奶牛黄体退化一样有效。P4的浓度受治疗，时间和治疗×时间相互作用的影响。IVG-PGF中的母牛在12 h时的平均P4高于IM-PGF中的母牛。治疗后48小时或72小时，平均P4无差异。治疗后3天内记录的发情母牛比例（IM-PGF = 45.4％; IVG-PGF = 48.9％），治疗后排卵风险（IM-PGF = 88.5％; IVG-PGF = 85.1％）和怀孕TAI后的每次人工授精（IM-PGF = 51.5％； IVG-PGF = 57.8％）没有差异。我们得出的结论是，间隔12 h的2个IVG剂量的25 mgPGF2α可以与单独的25 mg IM剂量的PGF2α诱导泌乳奶牛黄体退化一样有效。P4的浓度受治疗，时间和治疗×时间相互作用的影响。IVG-PGF中的母牛在12 h时的平均P4高于IM-PGF中的母牛。治疗后48小时或72小时，平均P4无差异。治疗后3天内记录的发情母牛比例（IM-PGF = 45.4％; IVG-PGF = 48.9％），治疗后排卵风险（IM-PGF = 88.5％; IVG-PGF = 85.1％）和怀孕TAI后的每次人工授精（IM-PGF = 51.5％； IVG-PGF = 57.8％）没有差异。我们得出的结论是，间隔12 h的2个IVG剂量的25 mgPGF2α可以与单独的25 mg IM剂量的PGF2α诱导泌乳奶牛黄体退化一样有效。治疗后3天内记录的发情母牛比例（IM-PGF = 45.4％; IVG-PGF = 48.9％），治疗后排卵风险（IM-PGF = 88.5％; IVG-PGF = 85.1％）和怀孕TAI后的每次人工授精（IM-PGF = 51.5％； IVG-PGF = 57.8％）没有差异。我们得出的结论是，间隔12 h的2个IVG剂量的25 mgPGF2α可以与单独的25 mg IM剂量的PGF2α诱导泌乳奶牛黄体退化一样有效。治疗后3天内记录的发情母牛比例（IM-PGF = 45.4％; IVG-PGF = 48.9％），治疗后排卵风险（IM-PGF = 88.5％; IVG-PGF = 85.1％）和怀孕TAI后的每次人工授精（IM-PGF = 51.5％； IVG-PGF = 57.8％）没有差异。我们得出的结论是，间隔12 h的2个IVG剂量的25 mgPGF2α可以与单独的25 mg IM剂量的PGF2α诱导泌乳奶牛黄体退化一样有效。