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Breeding Soundness Exams in Small Ruminants

Updated: Apr 11, 2022

by Jessy Shanks – Small Ruminant & Youth Programs Extension Specialist

University of Tennessee


A breeding soundness exam (BSE) is a comprehensive evaluation of a male’s ability to settle a group of females during a breeding season. It is performed in several different species utilizing different criteria for each, but a BSE evaluates the male’s physical ability to breed females as well as his reproductive organs and sperm. In this blog post we will discuss when you should do a BSE on your males, why it is important, how they are performed, what each classification means, and what a BSE does not do.


When should I have my veterinarian do a BSE on my buck or ram?

It is important for a producer to have this done on their bucks/rams well in advance of breeding season to make sure their male is up to the task of settling all the females in the herd or flock. It takes about 60 days to make a sperm cell, so if a BSE detects a problem in your male’s sperm you want plenty of time to obtain a replacement male or give the problem time to correct itself (if possible). It is recommended to do a BSE 6-8 weeks before the start of breeding season just to make sure the male is in the best possible position to impregnate all the females he needs to.


Why is a BSE important?

A BSE is an valuable tool for several different reasons. By performing a BSE at the appropriate time you can be sure that your male has the physical ability to breed females during breeding season, and his sperm are normal and motile enough to help support him in this endeavor. A BSE is both a physical exam, as well as an exam of the male’s sperm morphology (shape and size of sperm) and motility (sperm movement). Without normally shaped, motile sperm, the buck or ram you have might have difficulty settling the females in your flock/herd. So the information a BSE provides producers is especially important and can help avoid the dreaded situation of having a non-existent or late lambing/kidding season. So yes, he might breed females, but can he do so at the rate your lambing/kidding season requires? Not if his sperm aren’t capable!


How will my veterinarian do a breeding soundness evaluation?

A BSE usually starts with a physical examination of the buck or ram. The veterinarian will look at the male’s body condition score (BCS) and determine where he stands on the 1-5 BCS scale. A score of 1 is emaciated and 5 is obese. Rams and bucks should enter the breeding season at a healthy score of 3.0-3.5 (not too fat, but not too skinny either). Structural soundness is also important because the male needs to be physically able to breed females. His feet should be trimmed and free from foot rot, teeth should be good (not worn down or missing), and he should be free of other impairments that might limit his ability to breed females (blindness, pink eye, abscesses, parasites etc.). This portion also includes an examination of the male’s testicles and measurement of the scrotal circumference. The testicles should be firm (not too hard but not too soft either), and they should be closely related in size (not identical but close). Ram scrotal circumference minimum values are summarized in the table below*. Rams 8-14 months old need to be greater than 36 cm to be considered exceptional, and if they are less than 30 cm at this age then they are considered questionable. Bucks should be greater than 25 cm when they are 14 months of age and older.














Source: Purdue Extension “Breeding Soundness Examinations of Rams and Bucks,” AS-599-W

Your veterinarian will also specifically palpate the epididymis (located on each testicle) to make sure there are no areas of inflammation or hard tissue, which can be cause for concern. Brucella ovis could be a culprit but is not the only cause of epididymitis (infection of the epididymis). No matter the cause this condition will cause a decrease in sperm quality. Next your veterinarian will collect a sperm sample either using an artificial vagina or electroejaculator. Either way is an acceptable method for collecting a sample. The main goal is to assess sperm morphology and motility to make sure his semen is high quality. Morphology must be >70% normal for the male to pass a BSE. Gross motility and progressive motility are typically both measured, but progressive forward motility must be >30%, for the animal to pass. Higher is better in this case because the sperm have a long way to travel up the female’s reproductive tract! If they don’t have progressive motility then they likely won’t make it to their destination.


BSE Classification and What it Means

Once the physical exam and assessment of semen quality are complete your male is ready to receive a classification of excellent, satisfactory, questionable, or unsatisfactory as a potential breeder. Each category of the exam has minimum acceptable standards that must be reached. The tables below are an effective way to summarize this information.

Source: Purdue Extension “Breeding Soundness Examinations of Rams and Bucks,” AS-599-W

Any ram or buck with one unsatisfactory rating in any of the above categories (SC, motility, morphology) is classified as unsatisfactory. Excellent and satisfactory are what we hope our males fall into, but if they receive a questionable or unsatisfactory classification all hope is not lost necessarily. It just depends on the reason for being in one of those categories. Some conditions might improve over time (morphology for example in a young buck or ram) and can be re-checked at a later date. If the male falls into the questionable or unsatisfactory category after the second BSE then it might be time to replace that male.


What a BSE Does Not Do

It is important to note that just because a male passes a breeding soundness exam does not mean that he will effectively breed females 100% of the time. It is not a guarantee that you will have pregnant females and then offspring during lambing/kidding time. A BSE means on the day the test was performed that male had no physical limitations to breeding females, his sperm was of sufficient motility and morphology, and his scrotal circumference was adequate.


Summary

This system is not perfect by any means and injury or insult to the testicles can happen between testing time and the start of breeding season which will in turn affect sperm quality prior to and during breeding season. Situations like this can occur, but by utilizing a BSE you have done everything possible to control the unknowns going into breeding season.

 

Jessy Shanks is the Small Ruminant & Youth Programs Extension Specialist for the University of Tennessee. Jessy raises Southdown and Dorper sheep with her husband and daughter in Lenoir City, TN. Jessy teaches producers in TN about small ruminant production and management, but she also teaches Sheep and Goat Production in the Animal Science Department to undergraduate students as well. She received her BS and MS in Animal Science from the University of Tennessee and has a specific interest in reproductive physiology and advanced reproductive techniques in small and large ruminants.










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