Use of frozen semen in equine reproduction

The recent field trials indicate that acceptable fertility with frozen semen may not differ significantly from the fertility of commerval fresh-Chilled semen. The success rate of insemination is considered to be result of the interaction of three major factors: (i) the quality of frozen-thawed semen, this cannot be influenced - except the thawing process - by the users, because the insemination doses are mainly imported from foreign stud farms; (ii) the reproductive performance of the mares: we can't adopt completely the experiences of the foreign artificial inseminations in many cases because the number of our local inseminations are low and individual; (iii) the good insemination management of the mare: this is the only factor which could be considerably influenced by the users. The aim of this study was to summarize the different factors which might affect the outcome of a mare's insemination management. A general goal for mares inseminated with frozen semen is to inseminate within 12 hours prior to or within 6 hours after ovulation. This period ensures the fertilization: fertilizable egg with viable sperm in the oviduct at the same time. The authors especially focused on the different technical steps, advantages and disadvantages of the different insemination methods which could lead to an acceptable pregnancy rate. If the insemination is done - without ovulation induction when one dose is available - it could lead to pregnancy but this needs a very intensive (every 12 or 6 hours, round-the-clock) ovarian control. Fixed time insemination protocols with ovulation induction using one or more doses are able to provide the most time, cost effective and successful methods. One fixed time artificial insemination (36th hour after ovulation induction) almost covers the whole fertilisable period (30-48th hour) of the egg. Two fixed time inseminations (24th and 40th hour after ovulation induction) cover completely the whole fertilisable period (18-52nd hour) of the egg.