Kinsel M L, Etherington W G
Department of Animal and Veterinary Science, University of Idaho, Caldwell 83605, USA.
Theriogenology. 1998 Dec;50(8):1221-38. doi: 10.1016/s0093-691x(98)00222-2.
Data were collected on reproductive, health and production events in 45 dairy herds in southwestern and eastern Ontario, Canada, from July 1990 to July 1993. Mean and median days in milk at first estrus, at first service, and at conception were 85.1 and 83.9, 94.0 and 88.9, and 126.3 and 115.5 d, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. The most commonly used used therapeutic agents were GnRH (11.5% lactational incidence risk) and PG (13.1% lactational incidence risk). Estrus management accounted for the largest portion of PG use in the herds studied (69.4%). Results of a two sample t-test indicated no significant difference in reproductive performance among herds housed in free-stall compared with those housed in tie-stall barns. Multivariate linear regression models of 3 reproductive performance measures indicated that cows with ovarian cysts and/or increased peak milk production had significantly longer calving-to-first estrus and calving-to-conception intervals as well as lower conception rates than average producing cows without cysts. Cows with metritis were found to have significantly shorter calving-to-conception intervals but no detectable difference in conception rate or calving-to-first estrus interval than their herdmates. As lactation number increased reproductive performance improved. Cows that were observed in estrus earlier conceived earlier. Animals receiving uterine infusions had significantly longer calving-to-conception intervals and lower conception rates than their herdmates. There was no detectable difference in reproductive performance for cows treated with GnRH or PG compared with the nontreated cows. An increased estrus detection rate was associated with shorter calving-to-conception intervals and lower conception rates. Based on the range of performance in the study herds, the factors with the greatest potential influence on calving-to-conception interval in the average herd were the estrus detection rate and conception rate.
1990年7月至1993年7月期间，收集了加拿大安大略省西南部和东部45个奶牛场的繁殖、健康和生产事件数据。首次发情、首次配种和受孕时的平均泌乳天数和中位数泌乳天数分别为85.1天和83.9天、94.0天和88.9天、126.3天和115.5天。平均发情检出率为48.3%，最低为28.4%，最高为64.2%。平均总体受孕率为46.7%，最低为29.8%，最高为70.7%。最常用的治疗药物是促性腺激素释放激素（GnRH）（泌乳期发病风险为11.5%）和前列腺素（PG）（泌乳期发病风险为13.1%）。在研究的牛群中，发情管理占PG使用量的最大部分（69.4%）。两样本t检验结果表明，与栓系式牛舍饲养的牛群相比，自由站立式牛舍饲养的牛群在繁殖性能上没有显著差异。对3种繁殖性能指标的多变量线性回归模型表明，患有卵巢囊肿和/或产奶高峰期产量增加的奶牛，其产犊至首次发情和产犊至受孕的间隔时间明显长于没有囊肿的平均产奶奶牛，受孕率也更低。发现患有子宫炎的奶牛产犊至受孕的间隔时间明显缩短，但与同群奶牛相比，受孕率或产犊至首次发情间隔时间没有可检测到的差异。随着泌乳次数的增加，繁殖性能得到改善。较早观察到发情的奶牛受孕也较早。接受子宫灌注的动物产犊至受孕的间隔时间明显长于同群动物，受孕率也更低。与未治疗的奶牛相比，用GnRH或PG治疗的奶牛在繁殖性能上没有可检测到的差异。发情检出率的提高与产犊至受孕间隔时间的缩短和受孕率的降低有关。基于研究牛群的性能范围，对平均牛群中产犊至受孕间隔影响最大的因素是发情检出率和受孕率。
