Dr. Colin Palmer is the Associate Director of the University of Saskatchewan, Livestock and Forage Centre of Excellence in Saskatoon, Saskatchewan. He and his family also own and operate their own herd of Red Angus cattle near Dundurn, Saskatchewan. Dr. Palmer is a theriogenologist (specialist in animal reproduction) practicing in western Canada for many years, but also has strong roots in eastern Canada.

“No producer wants to buy a fat bull but just try to sell him a skinny one.”

Fat deposits in the neck (top) of the scrotum can negatively impact sperm production. Photo credit Dr. Colin Palmer.

The investment in a herd sire is often a large purchase for any cow-calf operation. To ensure this investment will remain in the herd, breeding bulls must be properly maintained during and between breeding seasons.

Whether you are a commercial cattle producer looking to purchase a new herd sire or are a purebred operator who is developing bulls for sale, over-feeding is one of the biggest issues when it comes to young bull management, says Dr. Colin Palmer.

Pushing young bulls for large daily gains can lead to issues such as joint effusion (swelling), laminitis, acidosis, inflammation of the seminal vesicles, and over conditioning or simply becoming too fat.

Scrotal circumference measured during the breeding soundness evaluation. Photo credit Dr. Colin Palmer.

Overly conditioning bulls can have a direct impact on their performance as a herd sire. Fat deposits in the neck of the scrotum (top photo) can harm the cooling mechanism of the testes which can impair temperature regulation (both warm and cool). Dr. Palmer says this can lead to a reduction in testosterone and potential loss of sperm production in the testes.

Palmer says poor performance can also be a result of underfeeding bulls, particularly in mature bulls. “A balanced diet including salt and minerals is important for preparing mature bulls for the next breeding season. Feed testing is vital to ensure the proper nutrition is being met.” Palmer also suggests considering the use of feed additives such as Rumensin.

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Breeding Soundness Evaluation

Bulls that fail a breeding soundness evaluation may be re-tested a few to several weeks later.

Dr. Palmer says any bull that is not fertile at the beginning of the breeding season, regardless of the cause, is a liability for the cow-calf producer. Dr. Palmer also notes that although a bull may fail a Breeding Soundess Evaluation (BSE), this does not necessarily mean the bull will never pass the test in the future.

Stressors such as lameness, sudden temperature changes, and illness can negatively impact a bull’s ability to pass the BSE. He suggests testing bulls that failed the BSE initially to re-test a few to several week later depending upon the types of sperm defects present.

Bulls that are believed to be capable of passing the BSE in the near future may be given a “decision deferred” or “questionable” classifications. Decision deferred is preferred for young bulls that are intended for a bull sale but just need more time to mature.

Some causes of poor fertility may be genetic or due to a severe injury to the reproductive organs. Unfortunately, in many cases these occurrences may result in very long lasting or permanent poor fertility and these bulls are classified as unsatisfactory. Poor semen quality of course is only part of the picture – a satisfactory bull must also be able to mount and complete service. Dr. Palmer says producers may want to consider buying the ‘full meal deal’ when it comes to purchasing bull insurance, which includes the full fertility coverage.

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Bull Housing, Health and Biosecurity

Dr. Palmer advocates treating bulls with the same herd health program as the cow herd. Photo credit Dr. Colin Palmer.

Bull housing and effective shelter are also important. Dr. Palmer says adequate bedding is necessary to prevent frostbite on the testes which can negatively impact a BSE. He also suggests that easing bulls together into a new environment at the same time is helpful when establishing social dominance. Moving all the bulls to a new space ensures the surroundings are new to each of the bulls and you are not introducing a new guy to an already established group.

Dr. Palmer advocates treating bulls with the same herd health program as the cow herd. Bulls can often be overlooked when it comes to vaccinations, but it is critical that their vaccines for Clostridial diseases (Blackleg), bovine viral diarrhea virus (BVDV) and other bovine respiratory viruses are up to date. Bulls persistently infected (PI) with BVDV not only can spread disease within the herd, but it can negatively impact their fertility as well. Purchasing bulls from herds with sound vaccination programs is critical.

Sharing bulls with neighbouring herds or even in a community pasture system can create a biosecurity concern. Discuss with your veterinarian about herd health risks and consider taking additional precautions, including vaccinating your herd for reproductive diseases, requiring any external bulls be tested for trichomoniasis, ensuring parasite control protocols are in place, and a mitigation plan is in place for diseases such as Johne’s Disease.

There are a lot of factors that go into purchasing herd bulls. Careful selection, feed and nutrition, protection from the elements, and mitigating biosecurity risks are just a few things to remember when sourcing and maintaining bulls. Proper management of herd sires is key to ensuring longevity and a producer being able to use a bull for multiple breeding seasons, maximizing the return on their initial investment of the bull purchase.

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