Review: Semen handling, time of insemination and insemination technique in cattle
Review: Semen handling, time of insemination and insemination technique in cattle
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DOI：
10.1017/s1751731118000952
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发表时间：
2018-06-01
期刊：
影响因子：
3.6
通讯作者：
Diskin, M. G.
中科院分区：
文献类型：
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作者：
Diskin, M. G.
在牛中，人工授精不仅在成功建立妊娠中起着至关重要的作用，这是随后泌乳开始的先决条件，而且在加速遗传改良和促进遗传精英父系精液的分配方面也起着至关重要的作用。成功冷冻保存精液的能力极大地促进了后者。授精的目的是确保在排卵时，在输卵管峡部的尾部区域（奶牛的主要精子储存器）有足够的有能力、获能、活动的精子储存器，以确保受精。精液的处理，特别是0.25毫升的吸管，是至关重要的。解冻后的精液需要保护免受冷热冲击，并在解冻后6至8分钟内授精。子宫角授精对受孕率有一定的改善，特别是在子宫体授精后受孕率较低的情况下。大多数评估异精授精的研究仅在新鲜精液上进行，并且许多缺乏足够的重复性。因此，很难推断使用异精精子是否有真实的益处。虽然母牛和小母牛从发情开始到排卵时间的间隔似乎相似，约为28 h，但在此平均值附近存在巨大差异（标准差为5 - 6 h）。虽然当母牛在发情中期至发情开始后几小时进行授精时可获得最佳受胎率，但在实践中很难实现。有新的证据表明，如果授精技术良好且使用的精液具有高生育力，则在同一天对牛群中所有需要授精的奶牛进行授精时，具有一个授精时间不会影响生育力。
In cattle artificial insemination plays not only a vital role in the successful establishment of pregnancy, which is a prerequisite for initiation of the subsequent lactation, but also in accelerating genetic improvement and facilitating the distribution of semen from genetically elite sires. The latter has been greatly facilitated by the ability to successfully cryopreserve semen. The objective of an insemination is to ensure that there is an adequate reservoir of competent, capacitated, motile sperm in the caudal region of the oviductal isthmus, the site of the main sperm reservoir in the cow, at the time of ovulation to ensure fertilisation. Handling of semen, particularly the 0.25 ml straw, is critically important. Thawed semen needs to be protected from cold and heat shocks and inseminated within 6 to 8 min of thawing. Uterine horn insemination give a modest improvement in conceptions rates particularly in situations where conception rates are low following uterine body inseminations. Most of the studies that evaluated heterospermic insemination were conducted on fresh semen only, and many lacked adequate replication. Consequently, it is difficult to deduce if there are real benefits from using heterospermic semen. While the interval from oestrous onset to time of ovulation would appear to be similar for cows and heifers at about 28 h there is huge variation (standard deviations of 5 to 6 h) around this average. While best conception rates are achieved when cows are inseminated from mid oestrus to a few hours after the onset of oestrus, this is difficult to achieve in practice. There is emerging evidence that having one insemination time, when all cows requiring insemination in the herd on that day are inseminated, does not compromise fertility provided insemination technique is good and the semen used is of high fertility.