I have always been fascinated by the exquisite design of biological systems. The more we humans understand about biology, the more we realize we don’t know. The process of mammalian fertilization is one of these complex biological systems that in nature requires the proper coordination of so many factors ranging from the behavior of male and female to biochemical changes at the cellular and molecular level. Defined as: “A process in sexual reproduction that involves the union of male (sperm) and female (ovum) gametes (each with a single, haploid set of chromosomes) to produce a diploid zygote”, fertilization requires that functionally viable sperm, at the right stage of maturity, are present in the oviduct of the mare during a brief window of time when a functionally viable oocyte is present.Read More
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Tags: Frozen Semen
To understand why seminal plasma is beneficial in some situations and potentially harmful in others we must first review what it is, where it comes from and what we think are its roles in reproduction. The term seminal plasma refers to the fluid portion of ejaculated semen in which the spermatozoa are suspended. This fluid consists of secretions from the accessory sex glands in the stallion’s reproductive tract. These include the ampullae, the vesicular glands (seminal vesicles), the prostate gland and the bulbourethral glands (figure 1).Read More
There are many reasons and techniques for collecting a fractionated ejaculate from a stallion. In this article we will discuss some reasons why and demonstrate the technique we have used in our laboratory to manage a stallion with excessive gel fraction that contaminates ejaculates collected using standard in-line filter equipment.Read More
Tags: Stallion Management
For veterinarians and technicians accustomed to inseminating fresh or cooled semen in large (20-60 ml) volumes, the idea of inseminating 0.5 to 4 ml of thawed frozen semen can be intimidating. During processing, frozen semen is concentrated by centrifugation and is typically packaged in small 0.5 ml straws at a sperm concentration that is often as much as 5 to 10 times greater than cooled semen. Therefore, a full insemination dose of frozen semen may be contained in just a few milliliters of volume whereas the same number of sperm extended for cooling may require 30-40 ml of volume.Read More
During those dog days of late summer and the end of the breeding season, most of us who work in equine reproduction are ready for a break. You are left with those difficult mares that didn’t settle earlier in the season and stallions that may be growing tired of breeding. Mares may not cycle as predictably or conceive as readily and stallions may be tougher to collect or exhibit a decrease in semen quality. One of the factors that can contribute to these problems is heat stress. As ambient temperatures rise, stallions and mares may experience disruptions to normal reproductive function as a result. This article will briefly describe some of the effects of heat stress on mare and stallion reproductive function.
The most commonly used measure of semen quality is sperm motility, specifically “progressive motility”. But what exactly does that mean and how is it determined? The minimum post-thaw “progressive motility” generally recommended for commercial distribution of frozen semen is 30% to 35%. This article will address some of the factors that can affect the assessment of sperm motility as well as the various problems associated with techniques used for determining “progressive motility”.
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.
Tags: Stallion Management
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.
In the United States there are very few regulations concerning the collection, processing, distribution and insemination of stallion semen. Any owner who can manage to extract semen from his or her stallion can without any prior training, experience, certification or license, sell semen from that stallion without restriction of any kind. There are only a few individual states that require certain testing for diseases potentially transmitted in semen but in most cases there is no requirement for such screening within the breeding population in the U.S. The USDA has regulations concerning the importation of semen and breeding animals into the U.S. from other countries but there is no USDA oversight to regulate the horse breeding industry within the borders of the country. This is also true in many other countries as well.