We examined the effects of human chorionic gonadotropin (hCG) treatment on Day 5 (Day 0 = day of artificial insemination: AI) and intravaginal progesterone device (IVPD) treatment from Day 5 to 19 on the conception and detection rates of return to estrus (re-estrus) in lactating dairy cows. A total of 306 cows from a commercial dairy farm were divided into the following three groups on Day 5: non-treatment group (n = 128), untreated; hCG group (n = 71), 3,000 IU hCG was administered (intramuscularly); IVPD group (n = 107), IVPD was inserted into the vagina from Day 5 to 19. Re-estrus detection was performed up to Day 25. Pregnancy was diagnosed by rectal palpation between Day 50 and 60. There was an interaction between treatment and AI number (P < 0.01) on the conception rate of first-AI. For cows with more than three AIs, the IVPD treatment (66.7%) was more effective than the non-treatment (23.1%) (P < 0.05). The re-estrus detection rate was significantly (P < 0.05) higher in the IVPD group (60.7%) than that in the non-treatment group (41.4%) and tended (P < 0.1) to be higher than that in the hCG group (37.8%). Our results suggested that the conception rate can be improved by IVPD treatment, especially in cows with more than three AIs. In addition, IVPD treatment can induce higher estrus expression up to 25 days after AI in non-pregnant cows.

中文翻译：

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人工授精后人绒毛膜促性腺激素和阴道内孕激素装置处理对正常和重复种泌乳奶牛繁殖性能的影响

我们检查了第 5 天（第 0 天 = 人工授精日：AI）的人绒毛膜促性腺激素 (hCG) 治疗和第 5 天至第 19 天的阴道内孕激素装置 (IVPD) 治疗对受孕和恢复发情检出率的影响。重新发情）在泌乳奶牛中。来自商业奶牛场的总共 306 头奶牛在第 5 天被分为以下三组：未处理组（n = 128）、未处理组；hCG 组（n = 71），给予 3,000 IU hCG（肌肉注射）；IVPD组（n = 107），IVPD从第5天到第19天插入阴道。直到第25天进行再发情检测。在第50天和第60天之间通过直肠触诊诊断怀孕。治疗和治疗之间存在相互作用AI数(P < 0.01)对首次AI受孕率的影响。对于具有三个以上 AI 的奶牛，IVPD 治疗 (66.7%) 比未治疗 (23.1%) 更有效 (P < 0.05)。IVPD组的再发情检出率（60.7%）显着（P<0.05）高于非治疗组（41.4%），且趋于（P<0.1）高于hCG组(37.8%)。我们的结果表明，IVPD 治疗可以提高受孕率，尤其是在具有三个以上 AI 的奶牛中。此外，IVPD 治疗可在非妊娠奶牛 AI 后长达 25 天诱导更高的发情表达。我们的结果表明，IVPD 治疗可以提高受孕率，尤其是在具有三个以上 AI 的奶牛中。此外，IVPD 治疗可在非妊娠奶牛 AI 后长达 25 天诱导更高的发情表达。我们的结果表明，IVPD 治疗可以提高受孕率，尤其是在具有三个以上 AI 的奶牛中。此外，IVPD 治疗可在非妊娠奶牛 AI 后长达 25 天诱导更高的发情表达。