Extension Program Improves Reproductive Efficiency in Beef Herds

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Stan Dutile

For many beef cattle producers, evaluating breeding soundness of their herd bulls is often an overlooked practice. Selection of bulls based on genetic potential is one of the most progressive ways to improve the beef herd. However, bulls that do not properly settle cows contribute to reproductive inefficiency and lost income — no matter how genetically superior they may be. Performing an annual bull breeding soundness exam (BBSE) on every bull in the herd is the only way producers can predict with relative certainty that their bulls can adequately service the cow herd during the breeding season.

Some producers believe their bull is “good to go” because he has sired calves previously or passed a breeding soundness exam in prior years. Making this assumption can be a costly mistake. Just because a bull has sired several calves does not mean he is a satisfactory breeder. The LSU AgCenter in the Acadiana region of south Louisiana has been working for over 25 years to better educate local cattlemen to this fact.

The annual Acadiana Bull Breeding Soundness Exam started in 1996 as a cooperative effort utilizing producer input and coordinated by LSU AgCenter Lafayette Parish livestock agent Stan Dutile with support and sponsorship from Mike Dominique and Dominique’s Stockyard; local veterinarians, such as Fontenot Veterinary Clinic; and the Lafayette Cattlemen’s Association. Initially offered only in the spring, an annual fall BBSE was added in 2016 at the request of the St. Landry Cattlemen’s Association, who subsequently became additional sponsors.

Although bulls can undergo a breeding soundness exam at any time, the most logical time for cattlemen to have one performed on their bulls is just prior to the start of the breeding season. Because most cattlemen in south Louisiana follow a spring calving program, the spring exam is usually conducted in late February or early March. The fall exam is then usually held in early November for producers implementing a fall calving season.

A standard BBSE usually consists of a physical exam, scrotal measurement, evaluation of reproductive organs, and semen collection and evaluation. During the early years of the program, many bulls were observed to be thin and in poor body condition. As a result, beginning in 2010, a body condition score (BCS) was assigned to each bull, encouraging producers to provide improved nutrition for thin bulls. For the BCS, a bull’s body condition is scored on a numbered scale. A score of 1 denotes an emaciated animal and 9 is obese.

In addition to the soundness exam, for an additional fee producers can also have their bulls vaccinated, dewormed and treated for external parasites. Since 2014, an additional testing option for trichomoniasis, a venereal disease that causes spontaneous abortions, has also been offered.

Lessons Learned

After 25 years of operating the Acadiana BBSE program, the data gathered is telling. Currently, more than 1,200 bulls have been tested. Of this number, 197, or 16.2%, were unable to successfully pass the exam. Various reasons for failure included:

  • Poor sperm motility (live versus dead sperm cells).
  • Reduced morphology (percentage of normal cells versus misshapen cells).
  • Poor or damaged reproductive organs (small testicles or penile injuries or deformities, etc.).

Additionally, during each exam, any physical problems that might adversely affect a bull and hinder his ability to effectively breed cows were called to the attention of the respective producer. Physical problems observed over the years included:

  • Eye problems (cancer of the eye, blindness or eye injury).
  • Foot problems (lameness, corkscrew toe or corns).
  • Sheath problems (too long and thus subject to injury).
  • Bulls being too thin (low BCS score).

Within the group of bulls unable to pass the exam, the vast majority failed and were officially rated as unsatisfactory. A much smaller number within this group that did not pass could not be successfully collected and were listed as deferred with a recommendation to be retested later.

Importantly, very few bulls unable to pass the exam were ever actually found to be completely infertile. Instead, most of these bulls could be classified as subfertileable to get a few cows pregnant, but most likely unable to settle their herd mates without repeated breedings over extended periods of time, resulting in fewer calves and reduced income for the producers.

For bulls that successfully pass the exam, producers must remember that there is no practical way to estimate a bull’s true mating ability except to observe him servicing cows. Each individual bull’s libido, or sex drive, is vital in that bull’s ability to breed and settle many cows. Producers should continually monitor each bull throughout the breeding season.

Finally, since assigning BCS began, body condition has improved over the years for bulls brought to the BBSE. For bulls to maintain their stamina over the course of a breeding season, they should ideally start the season with a BCS in the 5 to 6 range, with 6 being preferred. Bulls will almost always lose weight over the course of the breeding season. Cattle producers participating in the BBSE have apparently taken note, as bulls coming through the 2021 to 2022 Acadiana BBSEs have increased their average score by nearly a full point, up from just above BCS of 4 in 2010 to nearly a BCS of 5 today.

Stan Dutile is a livestock agent based in Lafayette Parish.

This article appeared in the fall 2022 issue of Louisiana Agriculture.

 Cows stand in a pasture. 

A strong or high percentage calf crop is the primary goal for all cow-calf producers. Photo by Stan Dutile

A bull’s foot has a growth between its toes. 

A corn between the toes (interdigital hyperplasia) of a bull was observed during a bull breeding soundness exam. This condition can lead to lameness and may be heritable in some breeds. Photo by Stan Dutile

 A bull’s eye diseased eye is shown.

Cancer eye (ocular squamous cell carcinoma) was observed in this bull during the bull soundness exam. The condition can be heritable. It is controlled by culling animals with early signs of cancer eye. Photo by Stan Dutile

Two men examine a bull stuck in a metal chute.

A veterinarian prepares to collect a bull sample at the annual BBSE. Photo by Stan Dutile

12/15/2022 5:34:41 PM
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