Cavalieri J, Fitzpatrick L A
Department of Biomedical and Tropical Veterinary Sciences, James Cook University, Townsville, Queensland.
Aust Vet J. 1995 Dec;72(12):441-7. doi: 10.1111/j.1751-0813.1995.tb03485.x.
Effects of body weight, condition score, ovarian cyclic status and insemination regimen on pregnancy rates were investigated in 164 Bos indicus heifers synchronised with norgestomet-oestradiol and pregnant mare serum gonadotrophin (PMSG). Oestrus detection techniques were also compared. Heifers were inseminated at either a fixed time (group 1, n = 83) of 48.0 +/- 0.2 h (mean +/- SEM) after implant removal or at 8.9 +/- 0.5 h after oestrus was detected (group 2, n = 81). Group 2 heifers that were not detected in oestrus by 72 h after implant removal were inseminated at that time. Oestrus was detected for the purpose of insemination using heatmount detectors. Tail-paint and oestrogen treated, chin-ball harnessed steers were used to compare the efficiency of oestrus detection. The probability of ovarian cyclicity increased with increasing body weight and condition score (P < 0.001). A higher proportion of heifers that were acyclic at the commencement of treatment, compared with cyclic heifers, were detected in oestrus at the time of insemination in the fixed-time inseminated group (P < 0.01). Analysis of covariance revealed that intervals from implant removal to oestrus were influenced by ovarian cyclic status (P < 0.01) and insemination group (P < 0.05). A higher pregnancy rate (% +/- SEM) was obtained in acyclic compared with cyclic heifers in the group 1 heifers (50.0 +/- 10 vs 28.1 +/- 6; P = 0.055) but not among the group 2 heifers (45.8 +/- 10 vs 49.1 +/- 7; P = 0.787). The probability of pregnancy was found to be associated negatively with body weight (P = 0.01) while a higher pregnancy rate was obtained in the group 2 compared with group 1 heifers (48.2% vs 34.9%; P = 0.093). The efficiency of oestrus detection was highest using heatmount detectors compared with tail-paint and chin-ball harnessed steers (90.7% vs 37.0% and 23.5%, respectively; P < 0.0001). We conclude that pregnancy rates can be increased in extensive environments when insemination follows oestrus detection using heatmount detectors compared with a fixed-time insemination. The fertility of heifers inseminated at a fixed time is influenced by ovarian cyclic status due to its influence on oestrus-to-insemination intervals.
在164头与诺孕美特 - 雌二醇和孕马血清促性腺激素（PMSG）同步发情的婆罗门小母牛中，研究了体重、体况评分、卵巢周期状态和授精方案对妊娠率的影响。还比较了发情检测技术。小母牛在取出植入物后48.0±0.2小时（平均值±标准误）的固定时间（第1组，n = 83）或检测到发情后8.9±0.5小时进行授精（第2组，n = 81）。第2组中在取出植入物后72小时未检测到发情的小母牛在此时进行授精。使用发情监测器检测发情以进行授精。使用尾涂颜料和雌激素处理、系有下巴球的公牛来比较发情检测的效率。卵巢周期性的概率随着体重和体况评分的增加而增加（P < 0.001）。与周期性发情的小母牛相比，在固定时间授精组中，在治疗开始时无发情周期的小母牛在授精时发情被检测到的比例更高（P < 0.01）。协方差分析显示，从取出植入物到发情的间隔受卵巢周期状态（P < 0.01）和授精组（P < 0.05）的影响。在第1组小母牛中，无发情周期的小母牛与有发情周期的小母牛相比，妊娠率更高（50.0±10对28.1±6；P = 0.055），但在第2组小母牛中并非如此（45.8±10对49.1±7；P = 0.787）。发现妊娠概率与体重呈负相关（P = 0.01），而第2组小母牛的妊娠率高于第1组小母牛（48.2%对34.9%；P = 0.093）。与尾涂颜料和系有下巴球的公牛相比，使用发情监测器检测发情的效率最高（分别为90.7%对37.0%和23.5%；P < 0.0001）。我们得出结论，在粗放环境中，与固定时间授精相比，使用发情监测器在检测到发情后进行授精可提高妊娠率。在固定时间授精的小母牛的生育力受卵巢周期状态的影响，因为它会影响从发情到授精的间隔。
