奶牛性控冻精人工授精影响因素研究

Factors of affecting pregnancy following AI of dairy cattle with frozen-thawed sexed semen

用分离X和Y精子的性控精液进行人工授精是控制家畜性别之最简单可行的方法。然而,低密度性控精液输精效果还不如常规人工授精,许多技术环节都有待改进。以常规冻精和稀释常规冻精为对照,研究解冻方法、输精时间和部位、不同精液来源和输精员以及育成和经产牛等因素对性控冻精人工授精妊娠率的影响。结果显示,精液解冻水浴温度和持续时间对人工授精效果有显著影响,性控精液对解冻水浴温度更敏感;性控冻精和稀释常规冻精比常规冻精对输精时间要求更严格;3种精液输精到排卵卵泡同侧子宫角基部受胎率都显著高于输精于子宫体和同侧子宫角前端;3种精液育成牛受胎率(80%)都显著高于经产牛(50%);于输精同时注射促排卵素3号明显提高性控冻精受胎率;经严格挑选、能够从事胚胎移植操作的技术熟练输精员之间性控冻精受胎率差异不显著;在所设计的不同条件下,性控冻精与稀释同样倍数的常规冻精行为相似,说明精子分离过程没有对精子造成特殊损伤。研究结果说明,精确控制人工授精各个技术环节可以实现消除性控与非性控、低密度与高密度精液之间的差别,获得高妊娠率。

Controlling the sex of domestic mammalian offspring is important for an efficient animal husbandry.The technique separating living X-and Y-chromosome-bearing sperm and inseminating with semen of desired sex has been proved the most feasible and simple method for sex control.However,pregnancy rates of insemination with low does of sexed sperm have been low compared to conventional AI,and therefore,procedures involved in AI using sexed sperm remain to be optimized.Factors of affecting pregnancy following AI of dairy cattle with frozen-thawed sexed semen,such as thawing protocols,time and site for semen deposition,different technicians and heifers or cows,were observed with conventional and diluted conventional cryopreserved semen as controls.The results obtained are as follows.（1） Both bathing temperature and duration during thawing had marked effect on pregnancy rates,and the sexed sperm were more sensitive to bating temperature.（2） The time window for insemination with high pregnancy rates was narrower for sexed semen and diluted conventional semen than for undiluted semen.（3） Higher pregnancy rates were obtained with all the three kinds of sperm when inseminates were deposited in the basal uterine horn ipsilateral to the ovulatory follicle than when semen was inseminated into either the uterine horn near the utero-tubal junction or the uterine body.（4） Pregnancy rates in heifers（80%） were significantly higher than in cows（50%） with all the three types of semen.（5） Injection of heifers with LHRH-A3 following insemination increased pregnancy rates significantly with all the three types of semen.（6） No significant difference was observed among the five technicians proven skillful for embryo transfer techniques in pregnancy rates following inseminations.（7） Under different conditions examined,sexed sperm behaved similar to diluted conventional sperm,indicating procedures for sperm sorting caused no special damage to sexed sperm.It is concluded that pregnancy rates as high as conventional AI can be achieved with sexed semen as long as management（nutrition,disease control,estrus detection,semen handling and insemination techniques） is excellent.