Spitzer J C
Department of Animal Science, Texas A&M University College Station, Texas 77843 USA.
Theriogenology. 1982 Apr;17(4):373-81. doi: 10.1016/0093-691x(82)90017-6.
A study was conducted to evaluate the effectiveness of treatment with Syncro-Mate-B (SMB) and gonadotropin releasing-hormone (GnRH) on inducing a fertile estrus and/or ovulation in peripuberal beef heifers. Two hundred and twenty-three, 13 to 15 month peripuberal beef heifers, primarily of Angus or Simmental breeding, were alternately allotted by weight and age within breed to a non-treated control group (C) and three groups which received the SMB treatment regime. Treated groups differed in that one group was inseminated approximately 12 hr after detected in estrus (T) while two other groups were inseminated at a fixed time after implant removal (T-G-I42, T-I48). Heifers in group T-G-I42 received 125 mug GnRH at 30 hr, and were inseminated 42 hr after implant removal. The remaining group of SMB-treated heifers received no additional hormone therapy but were inseminated 48 hr after implant removal (T-I48). Age had no significant effect on estrous response or pregnancy rate nor were there significant age by weight interactions on these parameters. Weight was a significant source of variation on interval from start of breeding to pregnancy (P<.01) and the effect on interval to estrus approached statistical significance (P<.0.9). In control heifers, increased weight had a positive effect on estrous response during the first 21 days of breeding (P<.05). Conversely, weight had no effect on estrous response during the 5-day synchronized period in heifers treated with SMB and observed for estrus (group T). Cumulative estrous response in control heifers was 10, 47, 48 and 55% in 5, 21, 27 and 45 days of breeding, respectively. Cumulative estrous response in SMB-treated heifers obsrved for estrus (group T) was 88, 91, 91 and 91% in 5, 21, 27 and 45 days of breeding, respectively. Pregnancy rate after 5 days of breeding was 9, 27, 18 and 30% for heifers in groups C, T, T-G-I42 and T-I48, respectively. Pregnancy rate after 21 days of breeding for heirfers in groups C, T, T-G-I42 and T-I48, respectively, was 33, 38, 21 and 41%; after 27 days of breeding was 36, 43, 40 and 48%; after 45 days of breeding was 48, 61, 51 and 69% and after the total 88-day breeding season was 59, 68, 71 and 72%. While a large percentage of peripuberal beef heifers with adequate age but insufficient weight were induced into estrus with the SMB treatment, pregnancy rates were low. Timed insemination programs with or without GnRH do not appear to be effective in improving pregnancy response in non-cyclic beef heifers.
开展了一项研究，以评估同步伴侣 - B（SMB）和促性腺激素释放激素（GnRH）治疗对诱导青春期前后肉用小母牛出现可育发情和/或排卵的有效性。223头13至15月龄的青春期前后肉用小母牛，主要为安格斯或西门塔尔品种，按体重和年龄在品种内交替分配到一个未治疗的对照组（C）和三个接受SMB治疗方案的组。治疗组的不同之处在于，一组在检测到发情后约12小时进行授精（T），而另外两组在取出植入物后的固定时间进行授精（T - G - I42，T - I48）。T - G - I42组的小母牛在30小时时接受125微克GnRH，并在取出植入物后42小时进行授精。其余接受SMB治疗的小母牛组未接受额外的激素治疗，但在取出植入物后48小时进行授精（T - I48）。年龄对发情反应或妊娠率没有显著影响，在这些参数上也没有显著的年龄与体重交互作用。体重是从开始配种到怀孕间隔时间变化的一个重要来源（P<0.01），对发情间隔时间的影响接近统计学显著性（P<0.09）。在对照小母牛中，体重增加对配种前21天的发情反应有积极影响（P<0.05）。相反，在接受SMB治疗并观察发情的小母牛（T组）的5天同步期内，体重对发情反应没有影响。对照小母牛在配种的5、21、27和45天的累积发情反应分别为10%、47%、48%和55%。接受SMB治疗并观察发情的小母牛（T组）在配种的5、21、27和45天的累积发情反应分别为88%、91%、91%和91%。配种5天后，C组、T组、T - G - I42组和T - I48组小母牛的妊娠率分别为9%、27%、18%和30%。配种21天后，C组、T组、T - G - I42组和T - I48组小母牛的妊娠率分别为33%、38%、21%和41%；配种27天后分别为36%、43%、40%和48%；配种45天后分别为48%、61%、51%和69%；在整个88天的配种季节后分别为59%、68%、71%和72%。虽然很大一部分年龄合适但体重不足的青春期前后肉用小母牛通过SMB治疗诱导发情，但妊娠率较低。无论有无GnRH的定时授精方案似乎都不能有效提高非发情周期肉用小母牛的妊娠反应。
