摘要
An experiment was performed to compare the effects of 3 short-term treatments with progesterone and estradiol benzoate (EB) on follicular growth, synchrony of estrus and pregnancy rate after fixed-time insemination in lactating postpartum beef cows. In Treatment 1 (n = 46), each cow received a progesterone-containing intravaginal insert for 7 d with injection of EB (2 mg, im) at the time of device insertion. In Treatment 2 (n = 46), the insert was used for only 5 d with injection of EB (2 mg, im) at the time of insertion. Cows in Treatment 3 (n = 47) received an insert for 5 d with no EB at the time of insertion. Each cow in the 3 groups received PGF2α (25 mg, im) at the time of insert removal, followed by EB (1 mg, im) 30 h later. The cows were then inseminated 28 to 30 h after treatment with EB (58 to 60 h after insert removal). Treatment with 2 mg EB terminated the growth of the largest ovarian follicle (>5 mm in diameter) at device insertion in 16716 and 14/15 cows in Treatments 1 and 2, respectively. Estrus was detected within an 8-h target period (48 to 56 h after insert removal) in 93, 87 and 81% of cows in Treatments 1, 2 and 3, respectively (P > 0.05). Pregnancy rates at 39 d post insemination were 60, 50 and 51% for Treatments 1, 2 and 3, respectively (P > 0.05). The pregnancy rates did not differ between cows that were anovulatory or those that had ovulated before the initiation of treatments (54%), or among cows that were 28 to 40, 41 to 60 or >60 days post partum at insemination (43, 59 and 54%, respectively). Treatment with progesterone inserts for 5 or 7 d, PGF2α at the time of insert removal and 1 mg EB 30 h later induced the high degree of synchrony of estrus and ovulation necessary for fixed-time insemination.
摘要译文
通过实验比较3种孕酮和苯甲酸雌二醇（EB）短期处理对卵泡发育的影响，泌乳期产后牛的定期授精后发情同期妊娠率在治疗1（n \x3d 46）中，每只母牛在装置插入时接受含孕酮的阴道内插入物7天，注射EB（2mg，im）。在治疗2（n \x3d 46）中，在插入时插入物仅用5天，注射EB（2mg，im）。处理3（n \x3d 47）的母牛接受插入5天，插入时没有EB。在3个组中的每只母牛在插入去除时接受PGF2α（25mg，im），然后在30小时后接受EB（1mg，im）。然后在用EB处理后28至30小时将母牛授精（插入去除后58至60小时）。用2mg EB处理终止最大的卵巢滤泡（直径 5mm）的生长，分别在处理1和处理2中的16716和14/15头牛中插入装置。在处理1,2和3中，在93,87和81％的奶牛中，在8小时目标期（插入物去除后48至56小时）内检测到发情（P 0.05）。人工授精后第39天的妊娠率分别为60％，50％和51％（P 0.05）。在无排卵的母牛或开始治疗前排卵的母牛（54％）或母牛的排卵率在28-40之间，分娩后41-60天或 60天（分别为43,59和54％）。用孕酮插入物处理5或7天，在插入物去除时的PGF2α和在30小时后的1mg EB诱导了固定时间授精所必需的高度同步发情和排卵。
P.J.Bridges;P.E.Lewis;W.R.Wagner;E.K.Inskeep;. Licular growth, estrus and pregnancy after fixed-time insemination in beef cows treated with intravaginal progesterone inserts and estradiol benzoate[J]. Theriogenology, 1999,52(4): 573-583