Burns P D, Spitzer J C, Burns G L, Plyler B B
Department of Animal, Dairy and Veterinary Sciences Clemson University Clemson, SC 29634-0631 USA.
Theriogenology. 1993 Apr;39(4):863-73. doi: 10.1016/0093-691x(93)90424-4.
Forty-five nonpregnant, nonlactating, Angus and Brangus cows were utilized to determine how long a Norgestomet ear implant would inhibit estrus when administered at various stages of an estrous cycle. All cows completed a nontreated estrous cycle to ensure normal cyclicity. At the second observed estrus (estrus = Day 1), cows were randomly allotted to be treated at metestrus (Day 3 or Day 4, n = 15); at diestrus (Day 9 or Day 10, n = 14); or at proestrus (Day 15 or Day 16, n = 16). All cows received a 2-ml intramuscular injection of 3 mg of Norgestomet accompanied by a 6-mg Norgestomet ear implant, which remained in situ for 21 days, or until individual cows were observed in estrus. Estrus was inhibited for a mean (+/- SEM) of 18.7 +/- 0.7, 19.9 +/- 0.8, and 17.0 +/- 0.8 days, respectively, when cows were treated at metestrus, diestrus, and proestrus (metestrus and diestrus vs proestrus; P < 0.05). Estrus was inhibited for an entire 21-day implantation period in 27, 50, and 38% of cows treated at metestrus, diestrus, and proestrus, respectively (P > 0.10). Norgestomet inhibited estrus in all cows for 11, 17, and 11 days after implantation when treatment was initiated at metestrus, diestrus, and proestrus, respectively (P > 0.10). These data indicate that a 6-mg Norgestomet ear implant effectively inhibits estrus in all cows for a maximum of 11 days, with some cows exhibiting estrus by Day 12 with the Norgestomet implant in situ.
选用45头未怀孕、未泌乳的安格斯牛和婆罗格斯牛，以确定在发情周期的不同阶段给予诺孕美特耳埋植剂时，其抑制发情的时长。所有母牛均经历一个未处理的发情周期，以确保正常的发情周期。在第二次观察到的发情期（发情期 = 第1天），母牛被随机分配在发情后期（第3天或第4天，n = 15）、间情期（第9天或第10天，n = 14）或发情前期（第15天或第16天，n = 16）接受处理。所有母牛均接受一次2毫升肌肉注射3毫克诺孕美特，并同时植入一枚6毫克的诺孕美特耳埋植剂，该埋植剂原位留存21天，或直至观察到个别母牛发情。当母牛在发情后期、间情期和发情前期接受处理时，发情抑制的平均时长（±标准误）分别为18.7 ± 0.7天、19.9 ± 0.8天和17.0 ± 0.8天（发情后期和间情期与发情前期相比；P < 0.05）。在发情后期、间情期和发情前期接受处理的母牛中，分别有27%、50%和38%的母牛在整个21天的埋植期内发情受到抑制（P > 0.10）。当在发情后期、间情期和发情前期开始处理时，诺孕美特在植入后分别在所有母牛中抑制发情11天、17天和11天（P > 0.10）。这些数据表明，一枚6毫克的诺孕美特耳埋植剂可有效抑制所有母牛发情，最长可达11天，一些母牛在诺孕美特埋植剂仍原位留存的第12天就表现出发情。
