by: Dr. Brett Kroeze
Breeding Soundness Exams (BSE’S) are a very useful tool in today’s sheep industry. It allows you to differentiate between the fertile rams and the sterile rams before you put them out with the ewes. There is nothing more devastating that having a ram mark ewes and then finding them all re-cycling back later. BSE’s are even more useful when trying to push the breeding season up. Rams, depending on the breed, will have seasonal infertility during the summer months where their sperm production is extremely low or nonexistent. There can also be heat induced infertility where there is sperm present but they are all dead. BSE’s allow you to determine if the ram will be capable of settling ewes. BSE’s do not give you an indication of his libido and physical ability to mate. This is something that the client must observe in the first part of the breeding season.
When doing a BSE, we first look at the ram and ensure he is in good body condition and good physical health through a thorough physical exam. We make sure that he is going to have enough body reserves to be able to make it through a breeding season. We look at the feet and legs to ensure that they are sound, free of signs of foot rot or foot scald, and well trimmed. We also look to make sure there are no injuries present. The next step is to palpate both testicles to make sure there size and shape is symmetrical and normal. We make sure there are no soft spots, hard spots, or enlargements on either testicle. A measurement is taken of the testicles to ensure that their size is up to par.
The next part of the BSE is to get a semen sample. We do this first by putting the ram on his rear end. This makes it easier to exteriorize the penis. We look for any active lesions or old scars in the prepuce and penis. One of the most common abnormalities would be pizzle rot. Next, we wrap the end of the penis with a gauze cloth to keep the penis exteriorized. We place the ram on its side and then use an electro-ejaculator to get a semen sample.
Finally we look at the sample under a microscope. We place a drop of semen on a glass slide and look under low power to determine the swirling effect of the sperm. This gives us an indication of the motility and concentration. Then we zoom in to a higher power to get a look at the individual sperm cells to make sure that the morphology is normal. We also look for white blood cells which is an indication of inflammation and or infection. If everything checks out, we classify him as excellent, very good, good, or satisfactory. If there are abnormalities on palpation or in the microscope evaluation of the sperm, we classify him as unsatisfactory. If there is inflammation or infection we will treat with an anti-inflammatory and antibiotic and suggest retesting in 30-60 days. If there is a low sperm concentration or poor motility we suggest retesting in 30-60 days. Re-testing in 30-60 days is based on the time it takes for the sperm cell to develop through the entire process. This allows time for healing or full development if it is early in the season. At the re-check, we will look for improvement. If there is no improvement, it could be that the ram is sterile.
A good sound mature ram can be breed between 50-100 ewes in a 60 day breeding season. A good ram lamb can breed up to 25 ewes in a breeding season. It is important that you measure the scrotal circumference, as this is an indication of the ram’s capacity. A ram lamb 8 to 14 months should be greater than 28 cm and ram older than 14 months should be greater that 32 cm.
In summary, the BSE is an exam to determine if the ram is a good potential breeder. It is something you want to do prior to breeding season but not immediately before. This will allow time to re-test the ram or find a different ram. It is a good idea to use a marking system to ensure that the ram is capable of physically breeding ewes. The BSE does not guarantee you will get lambs on the ground, but it is a useful management tool in selecting which rams to use.
8 TO 14 Months Older than 14 Months
SIZE RATING SIZE RATING
Smaller than 28 cm Questionable Smaller than 32cm Questionable
28 to 36 cm Satisfactory 32 to 40 cm Satisfactory
Larger than 36 cm Exceptional Larger than 40 cm Exceptional
**Testicles may be 2 to 3 cm smaller in the off season
Excellent Very Good Good Satisfactory Unsatisfactory
Gross Motility Rapid Swirl Fast Swirl Slow Swirl Generalized Poor Oscillation
Motility >70% >60% >40% >30% Less than 30%
Morphology >90% >80% >60% >50% Less than 50%