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Have you ever wondered what happens to all those sperm the stallion produces every day (5 billion or more)? If he is not bred or collected then where do the sperm go? We know that sperm are produced in the testicle and move from the testicle into the efferent ducts and then into the head of the epididymis. It takes about 7-10 days for sperm to travel from the head of the epididymis to the cauda epididymis (tail; figure middle right). This time frame is not altered by how often the stallion ejaculates. The old wives tale that you can get immature sperm if the stallion is bred too often is just not true. In this article, Dr. Ed Squires and Dr. Pat McCue review the causes, diagnosis and treatment for stallions which accumulate sperm.

The sudden death of a stallion is a devastating event, not just emotionally, but potentially financially as well. In addition to any competitive goals the stallion was working towards, his untimely death may mean the loss of future breedings, particularly if a stock of frozen semen was not banked up whilst he was alive. In this situation it may be possible to harvest and freeze epididymal sperm by castrating the stallion immediately after death or euthanasia. Alternatively, collection and freezing of epididymal sperm may be an elective procedure performed at the time of castration. This offers an advantage to young stallions, i.e. some semen can be frozen without taking time out from a busy training schedule, or without exposing a young stallion to the breeding environment. For the mature stallion it represents an additional opportunity to collect semen for freezing. Here we review the process of epididymal sperm harvesting for freezing, and its subsequent application for breeding purposes.

The advantages and disadvantages of utilizing equine frozen semen are debated by stallion and mare owners alike. Will I continue to show my stallion or retire him to the breeding shed? Is there an international market for my stallion? What if my stallion is injured in an accident or suddenly dies? Is my mare a suitable candidate for breeding with frozen semen? Is it true conception rates with frozen semen are lower than those when using cooled semen? These are just a few questions to ask when considering whether to utilize equine frozen semen.

The advent of transported cooled semen significantly altered the logistics of the equine breeding industry. Shipping semen to mares rather than mares to stallions is incredibly more convenient; however it has resulted in the need for increased proficiency in semen processing techniques on the part of the stallion manager and expertise in reproductive technology and artificial insemination on the part of the field practitioner managing the mare. From the perspective of the stallion manager there are a number of factors that can influence the success of cooled transported semen such as stallion collection management, semen handling, extender composition, dilution rate, cooling rate, calculation of insemination dose and transport device. Our blog article this month will address the basic techniques for proper collection, evaluation and processing of stallion semen for cooled transport.

How many sperm does it take to get a mare pregnant?
1 billion?...500 million?... One? Actually, any one of those answers could be correct under certain conditions. The only way to really answer that question is... "it depends". Fertilization is a complex process requiring that both the sperm and egg possess a myriad of functional attributes expressed at the right time and in the right place. A motile sperm is not necessarily a fertile sperm. So, how many sperm must be deposited in the mare for "acceptable" fertility? It would seem that this would be the logical basis for determining sperm numbers in an insemination dose for commercially distributed semen. To achieve the goals of both the mare and stallion owner it is necessary for each dose of semen to contain sufficient numbers of functionally competent sperm to maximize the probability of conception. The relationship between sperm number and fertility is expressed as a typical dose response curve (see figure1). However, the slope of the curve and the maximum level of fertility are different for individual stallions.

There are a number of misconceptions about frozen semen that are pervasive in the horse breeding community and one of them relates to the relative costs of frozen vs. cooled semen. We have heard horror stories of mare owners spending thousands of dollars purchasing and then trying to get mares in foal with frozen semen only to end the season with an open mare. Then there are also stories of stallion owners investing large sums of money freezing semen that is of poor quality or doesn’t result in pregnancies. Many of these nightmares are the result of lack of quality control on the semen that is put on the commercial market and/or proficiency of the lab or technician that is freezing the semen. Poor quality semen, whether fresh, cooled or frozen will result in wasted money, empty mares and unhappy breeders. This article will present objective information on the true costs of using frozen semen so that stallion and mare owners can make informed decisions.

Last month we discussed the importance of tracking measures of reproductive efficiency, as promised this month we review some of the reported literature on reproductive success in various commercial programs. This is not intended as an exhaustive review of all the available literature on the subject. Rather, we have used specific references to illustrate various concepts related to reports of equine fertility.

Keeping good breeding records is one of the cornerstone principles of sound reproductive management. For many of you the breeding season is now coming to a close, whether you are a stallion owner reviewing the conception rates for the mares that were bred to your stallion, or a breeder reviewing the reproductive performance of your mare herd, now is a great time to start compiling the data. Best to do it now whilst your experiences are still fresh in your mind and you can readily lay your hands on the paperwork. Plus as a stallion owner it may take some time to get the feedback you need from your mare owners. In this blog article we discuss the importance of keeping detailed accurate breeding records and what parameters you should calculate and follow.