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Bull Breeding Soundness Exam

October 2017

Many producers in the Carolinas will be in the thick of fall calving this month and looking toward breeding season starting in early winter. Even though Thanksgiving and Christmas may seem far away, now is the time to secure your bull power for a successful 2018 calving season. Identifying the best genetics available and ensuring adequate fertility is best accomplished 30 to 45 days before breeding starts. Otherwise, you may have to settle for lesser stock if preventative bull management is delayed.

There is a lot of down time for the bull’s reproductive system given the relative brevity of a breeding season and with that comes the potential for dysfunction. 20% of bulls I test initially fail to meet minimum standards considered indicative of acceptable fertility. Within the group I defer, about 15% will pass a retest in 30-60 days. That means approximately 17% of bulls in the population I test are deemed unsatisfactory for breeding. These bulls, in theory, would get fewer cows pregnant, leading to fewer calves being born, and ultimately less income generated by the cowherd annually. Last year, I tested around 300 bulls for potential breeding ability. Given my average statistics, I failed around 51 bulls and recommended they not be used for breeding. While these 51 bulls represented a liability to their owners in replacement costs or lost revenue from breeding stock sales, that group of bulls could have cost dramatically more if they had failed to breed a group of cows. If one average-fertility bull is expected to breed 25 cows, let’s assume a sub-fertile bull could only breed half that many in the same time period. That means 12 cows came up open in this breeding group of 25, and the producer had 10 fewer 500 pound calves to sell at weaning. At just $100 per hundredweight of calf, the one sub-fertile bull cost the producer $5000 (or the price of a higher end replacement bull!). Expand that hypothetical number out over the 51 bulls I failed last year, and the number gets much larger. Veterinarians in high cow-density areas test hundreds more bulls than I do a year. I feel safe saying they are making a huge impact on the economic efficiency of the beef industry through this value-added service. National average cost of a BSE is around $75 – you do the math as to whether that pencils out in black on the balance sheet.

For producers using retained herd bulls, a breeding soundness exam is recommended prior to the start of breeding season every year, even if the bull was a successful breeder in the previous season. Not all individuals get better with age, and bulls are no exception. A breeding soundness exam is a point-in-time measurement, and conditions can change year to year, if not week to week. If a producer is looking to purchase a bull, I would highly recommend sale being contingent upon passing a breeding soundness exam. Even when breeders guarantee to “make it right” if the bull fails to breed cows, the purchaser of the “dud” is still left with a group of open cows – a costly situation in a cow-year. Regardless of bull status, records of the breeding soundness exam should be available and retained for the duration of the bull’s time on the farm or ranch. These valuable documents contain much needed information for the veterinarian and owner should a problem arise, and can help interpret findings at the next breeding soundness exam.

Of particular importance to note: a passed BSE or “Satisfactory Potential Breeder” status does not mean that the bull will get all cows pregnant that he is exposed to. How I interpret the diagnosis is this: to the best of our ability, we deem the bull’s anatomy and semen of sufficient quality to impregnate an appropriate number of healthy fertile cows in a reasonable period of time (63-84 days). That is a dense sentence to digest, but it essentially means there are many factors involved in determining true fertility, many that are out of the purview of the breeding soundness exam. The BSE is a point-in-time evaluation, and the veterinarian is making their “best guess” diagnosis off the information present at that time. There is experience involved in that diagnosis, as well as some assumption about how the bull will be managed. Bottom line is: while there are a lot of unknowns, it is a very important exam to perform and represents the only insurance you can take out on a breeding season.

Some of these unknown factors include the bull’s sex drive, bull’s hierarchy in multi-sire pastures, cow fertility, cow nutrition, environmental conditions during the breeding season, and reproductive disease status of the herd. Also, the bull’s condition can change over the course of a breeding season. This past year, I tested a clean-up bull 4 days before the producer’s desired turn-out day. The bull had exceptional semen quality and passed his physical exam. I came back and pregnancy tested the cows using a rectal ultrasound 45 days after bull was removed from pasture (cows had been exposed for 45 days or two cycles following their synchronized AI). The only cows identified pregnant had been AIed 2 weeks prior to the bull’s turnout. On retest BSE, the bull’s semen was still exceptional. However, we identified old healing gash in the heelbulb of the right rear foot, and the owner confessed that as the bull stepped off the trailer after his trip to Raleigh for BSE testing, he had cut his foot on the trailer door lip, but that the bull walked off fine and was never noticed to be lame. Manure happens, so they say. The point of that story is to highlight how fertility assessment is important, but inherently flawed. We had record that the bull had the appropriate tools to get cows pregnant, and verified after a problem was identified. However, that record was obviously not a guarantee of fertility. I would like to make the inference that his foot injury made him reluctant/unwilling to breed, but the true problem could be that he had no interest in breeding cows anyway. There is quite a bit of risk involved in keeping the bull and giving him another chance. Those costs will have to be carried over for another season/year, making the costs of potential failure next year even higher.

Anyone involved in agriculture is at base a gambler and likely has a high tolerance for risk. When it comes to beef production, managing that risk by minimizing potential losses while doing as much as possible to reduce costs and improve efficiency is the key to success. While the above paragraphs may cause some to cast doubt on the value of a bull breeding soundness exam, the benefits of performing this management task far outweigh the potential pitfalls of the exam. Identifying a sub-fertile bull is a quick and easy way to improve annual cowherd profitability. The best tools we have available to facilitate this management task are the breeding soundness exam before the breeding season starts and evaluating a bull’s performance at pregnancy check. For my clients, a bull breeding soundness exam is a no brainer, and probably one of the most valuable services I can provide to a commercial beef cow operator.

Written By

Photo of Dr. Harrison DudleyDr. Harrison DudleyClinical Veterinarian and Extension Specialist (919) 513-6608 hbdudley@ncsu.eduCollege of Veterinary Medicine - NC State University
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