As spring rolls through, it’s time for birthing and breeding on some hobby farms. Breeding soundness examinations are objective assessments of male livestock fertility. They can be useful in evaluating an animal’s breeding value and therefore help you make breeding decisions. Let’s take a closer look at breeding soundness exams and how to utilize them.
Male breeding soundness exams (BSEs) are made up of four main components, regardless of what livestock species is being evaluated.
1. Physical Examination
Any male animal should be in decent physical overall health. One large factor for breeding is the structural soundness of the animal.
A minor lameness or conformation issue that may precede lameness can become a huge problem toward the end of the breeding season. If the bull, ram or boar is uncomfortable or physically has trouble mounting females, he’s less than adequate for a breeding operation.
Other parts of this examination may include diagnostic testing for transmittable diseases, depending on the age and source of the animal.
2. Scrotal Circumference
The size of the testicles is correlated to fertility in livestock species. It is an indication of the animal’s sperm-producing capacity.
A specialized tape measure is used to measure the circumference of the scrotum in centimeters. This measurement is then compared to species-specific charts. The animal should meet its minimum measurements based on age. For example, a bull should have a minimum circumference of 34 cm at the age of two years. A ram should measure over 30 cm if he is between six and eight months of age.
So far, the BSE has evaluated whether a male is physically capable of breeding. The second part of the exam evaluates whether the sperm he produces is of good quality. At this point, a semen sample is collected. First it is evaluated for volume, color and contamination (such as blood, pus or other debris)—clearly a negative sign.
After this, the sample is placed on a slide under a microscope and the following are evaluated.
3. Sperm Motility
Normal, healthy sperm cells are not just motile, but forwardly motile. The first thing that is evaluated is how well the sperm in the sample move. This is initially evaluated on low magnification.
The sample should appear to move in a wave-like manner under the microscope. Then, under higher magnification, individual sperm cells are observed for forward motility. For a sample to be deemed satisfactory, out of one hundred sperm cells, 30 (or 30 percent) should be motile.
In any sample, some cells will be immobile, twitch or move in circles.
Lastly, the shape of individual sperm cells is evaluated. Once again, one hundred cells are counted and classified as normal or abnormal. There are several types of sperm cell abnormalities, such as double or twisted tails, missing heads and cytoplasmic droplets, to name a few.
All of these aspects are then put together in a scoring sheet for a complete overview of the animal’s reproductive fitness. Results are usually placed into one of three categories: satisfactory, questionable or unsatisfactory.