Seidel G E
Animal Reproduction and Biotechnology Laboratory, Foothills Campus, Colorado State University, ARBL Building, Fort Collins, CO 80523, USA.
Theriogenology. 2003 Jan 15;59(2):585-98. doi: 10.1016/s0093-691x(02)01242-6.
Over 20,000 calves have resulted from artificial insemination (AI) of cattle with sexed, frozen/thawed sperm in the course of experimentation in several countries, and from commercial sales in the United Kingdom. This technology likely will become commercially available in many countries within a few years. Accuracy of the process is about 90% for either sex, and resulting calves appear to be no different from non-sexed controls in birthweight, mortality, rate of gain, and incidence of abnormalities. The main determinants of the extent of use of sexed sperm will be pregnancy rate and cost. Fertility of low doses (1.5 x 10(6)-2 x 10(6)) of sexed, frozen sperm for AI of heifers usually has been in the range of 70-80% of unsexed sperm at normal doses (10 x 10(6)-20 x 10(6) sperm) in well managed herds; it has been lower in poorly managed herds, and likely will be lower with lactating dairy cows. It is expected that fertility of sexed sperm will increase significantly due to very recent improvements in the hydrodynamics of the sexing process and potential improvements in cryopreservation procedures. It is unclear how sexed sperm will be priced; the cost of sexed sperm for cattle will likely be more than double the cost of unsexed sperm in most markets. The economic benefit of using sexed sperm also will depend on the baseline fertility of the herd since at lower fertility, it takes more doses of semen per calf produced. It is noted that for a small percentage of elite cattle, the economics of using sexed sperm do not depend primarily on increased production or efficiency of producing meat or milk, but rather on factors such as scarcity, tradition, cattle show winnings, and biosecurity during herd expansion. Until sorting efficiencies improve and costs decline, sales likely will be limited primarily to these niche markets. With near normal fertility and a premium for sexing in the range of US$ 10 per insemination dose, sexed sperm likely would become economically and environmentally beneficial for many, if not most populations of cattle being bred by AI.
在几个国家的实验过程中，以及在英国的商业销售中，已有超过20000头小牛是通过用经性别分选、冷冻/解冻的精子对母牛进行人工授精而诞生的。这项技术可能会在几年内在许多国家实现商业化应用。该过程对两种性别的准确率约为90%，所产小牛在出生体重、死亡率、生长速度和畸形发生率方面似乎与未经性别分选的对照小牛没有差异。使用性别分选精子的程度的主要决定因素将是妊娠率和成本。在管理良好的牛群中，用于小母牛人工授精的低剂量（1.5×10⁶ - 2×10⁶）性别分选冷冻精子的受胎率通常为正常剂量（10×10⁶ - 20×10⁶精子）未分选精子的70 - 80%；在管理不善的牛群中受胎率较低，而对于泌乳奶牛可能更低。由于性别分选过程的流体动力学最近有了显著改进，以及冷冻保存程序可能得到改进，预计性别分选精子的受胎率将大幅提高。目前尚不清楚性别分选精子的定价方式；在大多数市场，牛用性别分选精子的成本可能是未分选精子成本的两倍多。使用性别分选精子的经济效益还将取决于牛群的基线受胎率，因为在受胎率较低时，每生产一头小牛需要更多剂量的精液。需要注意的是，对于一小部分精英牛来说，使用性别分选精子的经济效益并不主要取决于肉类或牛奶产量的增加或生产效率的提高，而是取决于稀缺性、传统、牛展获奖情况以及牛群扩群期间的生物安全等因素。在分选效率提高和成本下降之前，销售可能主要限于这些小众市场。如果人工授精的受胎率接近正常水平，且每次授精剂量的性别分选溢价为10美元左右，那么对于许多（如果不是大多数）通过人工授精繁育的牛群来说，性别分选精子在经济和环境方面可能是有益的。
