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WHAT TO LOOK FOR IN BULLS DURING BREEDING SEASON
FEATURE ARTICLE
WHAT TO LOOK FOR IN BULLS
Editor’s Note: Article Courtesy of Noble Research Institute DURING BREEDING SEASON
Bull management is often overlooked coming second to cow management; when it should be the other way around. Fertility issues with one cow only affect one calf. Fertility issues with one bull could affect up to 30 calves, or lack thereof. As we know, percent calf crop weaned is the single most important factor influencing profitability and is directly tied to the herd bull’s breeding capability. We are sometimes guilty of not paying attention to bulls when they have their “work clothes” on, when they are out with the cows. Problems with the bull during the breeding season are oftentimes not detected until after the breeding season or the pregnancy diagnosis at weaning. Thus, management of bulls to optimize breeding performance should include time during the breeding season.
Understanding how many bulls you need in each breeding herd is important so that you can accurately evaluate breeding performance during the breeding season. In larger commercial cow-calf operations, multiplesire breeding herds are commonly used, whereas seedstock operations typically use single-sire breeding herds. Multiple-sire breeding herds are easier to manage with less risk of reproductive failure, but they are more difficult to evaluate in terms of genetic improvement in your calf crop. Single-sire breeding herds can be a great tool for evaluating genetic improvement in your calf crop, but they are more difficult to manage with more risk associated due to potential reproductive failure from the bull. There are many benefits to using either system, but understanding the disadvantages of each system is important when observing bulls during the breeding season.
Disadvantages of a Single-Sire Breeding Herd
• Requires more breeding pastures and managing of forage, water and fencing • Increased risk of reproductive failure from a bull due to potential health, injury, or poor semenquality during the breeding season • Potentially requires a backup bull(s) in case the herd sire needs to be pulled
Disadvantages of a Multiple-Sire Breeding Herd
• Risk of getting fewer calves out of a particular sire due to social dominance • Increased risk of injury from other bulls due to fighting • Challenge of bringing in and using younger virgin bulls
Once you understand some of the things that can go wrong with either type of breeding herd, you can begin making careful and close observations during the breeding season to increase the success of your cows conceiving. I would like to break it down into three areas to watch for during the breeding season: bull health and injury, bull behavior, and cow behavior. 1. Bull Health and Injury
Many factors can contribute to the health or injury of a bull during the breeding season, such as nutrition, disease, infection, lameness, and heat stress. Fertility issues associated with these factors are oftentimes not detected until after the breeding season or pregnancy diagnosis at weaning, and by then, it’s too late. Observations leading to diagnosis of problems affecting fertility include poor nutrition, lameness, or illness, which negatively impacts a bull’s mating ability; can cause physical damage to the testes, which could negatively impact semen quality and serving capacity (the ability to service several cows in a short period of time); and can cause transmissible diseases, which directly affects the cow.
Bulls will typically lose body condition during the breeding season, younger bulls more severely than older bulls, even with a proper bull:cow ratio. Loss of too much body condition can compromise the immune system, negatively affect sperm production and motility, and reduce energy needed for mating and serving capacity. Proper stocking rates with by Ryon S. Walker, Ph.D., Noble Research Institute, livestock consultant Many factors can contribute to the health or injury of a bull during the breeding season, such as nutrition, disease, infection, lameness, and heat stress.
adequate good quality forage is critical throughout the breeding season.
Reproductive diseases in bulls often times come unnoticed until after the breeding season. Diseases such as Leptospirosis and Vibriosis (bacterial diseases) and Trichomoniasis (protozoal disease) can cause abortion at different stages of pregnancy after infection and is transmitted directly between animals. While correcting the problem during the breeding season is impossible, following a good herd health program will reduce, or eliminate the risk of transmitting these and other diseases.
Bulls can develop infection just like any other animal. This can be caused by a puncture wound from a broken fence, metal objects laying around the pasture or sticking out of the ground, boards with nails lying around, etc., or by bacterial infections, such as foot rot. Puncture wounds around the hoof area are common and can cause an abscess that is oftentimes very difficult to treat and accommodate.
Lameness in bulls is one of the biggest problems that producers deal with during the breeding season. Lameness typically results from fighting with other bulls, mounting of cows, objects in the pasture, and the unknown. Lameness due to physical activity or infection is oftentimes easily noticed and can prevent bulls from servicing cows due to discomfort and pain. In addition to physical structure, physical damage to the testes can also result in lameness and should always be observed.
Lastly, exposure of bulls to increased ambient temperatures prior to or early on in the breeding season can negatively impact spermatogenesis and potentially reduce fertility due to heat stress. Testicular temperature of bulls must consistently be 3.6 to 10.8 degrees Fahrenheit (2 to 6 degrees Celsius) cooler than the body temperature. High relative humidity can affect a bull’s ability to effectively dissipate heat through the skin when exposed to increased ambient temperatures. Ample shade and clean water is the best way to reduce the incidence of heat stress during the summer. Observe how the bull moves, walks and stands, how he carries his head, and his body condition. The more you observe, and the more you pick up on what is normal and not normal for a bull, the faster you can replace him in the breeding herd. 2. Bull Behavior
Paying attention to bull behavior during the breeding season is just as important as observing bulls for sickness or lameness. How a bull behaves and reacts, especially in a pasture full of cows, will tell you a lot. Behavior differences in bulls can be different or extreme.
One important behavioral trait is libido. Libido measures how aggressive a bull is at servicing cows when multiple cows are in heat at the same time. To observe this, ask yourself the following questions: Is the bull with cows that are in heat? Secondly, if there are multiple cows in heat, is he getting multiple cows bred or just staying with one cow? Libido is a measureable trait that is positively correlated to pregnancy rate. A bull with poor libido used in a single-sire breeding herd can result in a lower pregnancy rate or longer calving season for that herd.
In multiple-sire breeding herds, social dominance will likely happen and can have negative impacts on the breeding season. If your dominant bull is running off all the other bulls, is the genetically superior one and always throws the best calves, sometimes that is OK as long as all of the cows are getting bred. If he is one that is not genetically superior and you have never liked his calves, then you have a problem. At that point, you may need to use him in a single-sire breeding herd with your lower quality cows or just cull him. You want to avoid having young bulls in the same breeding herd as your mature bulls, especially if there is a dominant bull in the group. This could lead to very few cows conceiving or injury to the younger bull. Know the dominant bull so you can properly manage him through the breeding season, if he must stay in the herd. 3. Cow Behavior
Cows will tell you a lot during the breeding season as well. While maybe not as critical as watching what the bull does, they will give you an idea of how good of a job the bull has done at servicing his cows. What percentage of the cows are still coming into heat at different stages throughout the breeding season? No doubt daily heat detecting is very labor intensive, but that is why we prefer the bull to do that job for us. (continued on page 20) The more you observe, the more you pick up on what is normal and not normal for a bull.
(continued from page 19)
Keep in mind, a cow cycles approximately every 21 days. Let’s assume we have a 75-day breeding season. If a bull is doing his job, we should expect 50 to 65 percent of those cows to conceive in the first 21 days of the breeding season (first estrous cycle), followed by approximately 75-80 percent of the whole herd conceiving by the end of the second 21-day estrous cycle, and then approximately more than 90 percent of the whole herd by the end of the third 21-day estrous cycle. If you still have 20 percent or more of your cows cycling after 60 days with the bull, something is wrong. Another question to ask is: If there are cows in heat and no bull, where is the bull? If he is off by himself eating or laying under a shade tree, then we have bull behavioral problems as mentioned above.
Traditional thinking trains us to be satisfied with
our results when we have met the industry average. Non-traditional thinking should redirect our focus more on the causes of some of these failures and put more emphasis on correcting or minimizing the problem. Ask yourself what happened. Was it because of nutrition? Were cows too thin going into the breeding season or are cows on a negative plane of nutrition during the breeding season? Are there health issues causing cows to abort during early pregnancy? Or is there a bull issue: infertile, infection, lameness, or behavioral? Being aware of these things will help a producer to avoid potential fertility wrecks.
Observations can lead to diagnosis of problems sometimes early enough to save your breeding season. So spend more time monitoring and observing your bull for physical and behavioral issues throughout the breeding season and make sure he is getting the job done.
The Texas Junior Brangus Breeders Association (TJBBA) is raffling off a show heifer to raise funds for their TJBBA State Show each June. 1 ticket is $100, only 200 tickets will be sold - contact a TJBBA director or advisor to purchase ticket(s) Heifer is donated by Myron Saathoff and will be on display at the TJBBA State Show June 24-27. The drawing will be held June 27 at the Bryan Co. Expo Center in Bryan, Texas during the TJBBA State Show. R10429832 | DOB: 5/25/2019 | Sire: Skyhawks Abe 99D2 | Dam: Skyhawks Ms Pres 915E
