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One of the advantages of embryo transfer is the ability to biopsy the embryos in an attempt to diagnose different genetic traits or determine gender. The ability to do so has existed for several years and the amount of genetic information that can be realized is ever expanding as geneticists learn more and tests become available to identify particular alleles.

Oxytocin is one of the most utilized hormones in broodmare practice. With so many possible clinical applications, a review of the use of oxytocin in the mare highlights the benefits of oxytocin, as well as necessary precautions with its use. Oxytocin is a nine-amino acid neuropeptide that is produced in the hypothalamus and released by hypothalamic neurons that terminate in the posterior pituitary. It is released in a natural pulsatile manner and exerts its effects by coupling with oxytocin receptors on various tissues such as the endometrium, myometrium, heart, kidney, pancreas, and fat tissue. There are also local effects of oxytocin and receptor binding, notably in the utero-placental tissues that help to increase the effect and intensity of pituitary derived oxytocin pulses. Clinically, oxytocin is available as a sterile injection, 20 IU (international units) per milliter. It can be administered intravenously or intramuscularly.

Horse breeders are always interested in the well being of their broodmares as well as the well being of the fetus they are carrying. Advances in reproductive techniques have made it possible to gain insight into how the fetus is progressing as well as the ability to determine its gender. Knowing whether a mare is carrying a colt or a filly can help owners make important decisions concerning their herds and the industry in general. For example, fetal sex determination is used on a regular basis among thoroughbred breeders prior to stock auctions. In this article, we discuss the sorting of equine sperm for sex as well as fetal sex determination via transrectal and transabdominal ultrasound.

Once young colts and fillies reach the age of puberty their behavior may become an issue in the show ring or on the race track. Castrating a colt which you intend to use for breeding purposes may not be an option and mares are not typically permanently sterilized. Their sexual behavior may also cause problems with housing, trail riding, etc. In this article, Dr. Ed Squires discusses some of the common ways stallion and mare owners suppress the behavior of their horses.

Color is among some of the earliest traits we selected in newly domesticated species (1). Today, color can be critical for registration and therefore, the value of our horses. For example, in breeds like the Friesian (which requires true black) and the exotic Mangalarga Marchador (which does not allow cremellos or perlinos) color is more than an aesthetic preference, it is a breed requirement. Indeed, on average, presence of a spotting pattern doubles the value of an APHA foal. For example, in 2006, the average price of an American Paint Horse Association (APHA) registered yearling without a spotting pattern was $1540, while a yearling APHA registered horse with the tobiano pattern averaged $2803 (2).

The tests have been done and the frozen semen is ready for export…Now what? In our article, Exporting Frozen Semen from the United States, we covered topics ranging from determining if there is a foreign market for your stallion, to how to export the semen once it’s been frozen. Stallion owners/agents also need to consider how they are going to offer the frozen semen to a foreign market in the form of their breeding contract. In this article, we will discuss ways to sell the semen (by the dose or with a live foal guarantee), responsibility of shipping fees, what is to be done with leftover doses as well as who covers the costs of health testing and freezing, plus more.

For most facilities, using a phantom is the preferred method of collecting semen from a stallion, as it is an efficient, organized and generally a safe process that mimics the natural position during live breeding. Ground semen collection (see video below) is an alternative option to the typical collection of a stallion on a phantom or mount mare.  This article describes ground semen collection, primarily summarizing previously published clinical and research reports of Sue McDonnell and colleagues at the University of Pennsylvania and Jim Crump of Roanoke AI.

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.

The majority of equine embryos are collected from the donor mare and transferred immediately as fresh embryos or shipped cooled to a recipient station for transfer within 24 hr. You can learn more about the basics of embryo transfer (ET) in our article, Embryo Transfer and Frequently Asked Questions. Very few equine embryos are frozen despite the numerous advantages of embryo cryopreservation. We discuss the process of freezing embryos in our article, Cryopreservation of Equine Embryos. However here is a quick review of some of the advantages of freezing embryos:

Juvenile and older males entering a new career as a breeding stallion don't have the luxury of a changing cascade of hormones or an event like parturition to jumpstart their innate nature to show them how to be a stallion. There is likely only a change in routine, location, or in their training schedule that cues them into their new roles as breeding animals. Many stallions make the transition seamlessly. Simply acting on the behavior they have been trying to use for years, allowing their behavior to mimic their springtime rise in testosterone. When exposed to a female, they have little doubt about the job at hand and will readily take to live cover or phantom training. Additional information for training the young stallion for collection can be found in our article, Collecting Semen from the Young Stallion. However, for some, the transition proves far more difficult and oftentimes frustrating for the stallion and for the staff at the shed.