FEATURE ARTICLE
WHAT TO LOOK FOR IN BULLS DURING BREEDING SEASON Editor’s Note: Article Courtesy of Noble Research Institute
by Ryon S. Walker, Ph.D., Noble Research Institute, livestock consultant
Bull management is often semen quality during the breeding season • Potentially requires a backup bull(s) in case the overlooked coming second to cow herd sire needs to be pulled management; when it should be Disadvantages of a Multiple-Sire the other way around. Fertility Breeding Herd issues with one cow only affect • Risk of getting fewer calves out of a particular one calf. Fertility issues with one sire due to social dominance bull could affect up to 30 calves, or • Increased risk of injury from other bulls due lack thereof. As we know, percent to fighting calf crop weaned is the single most important factor influencing profitability and is directly tied to the herd • Challenge of bringing in and using younger virgin bulls bull’s breeding capability. We are sometimes guilty Once you understand some of the things that can of not paying attention to bulls when they have their go wrong with either type of breeding herd, you can “work clothes” on, when they are out with the cows. begin making careful and close observations during Problems with the bull during the breeding season the breeding season to increase the success of your are oftentimes not detected until after the breeding cows conceiving. I would like to break it down into season or the pregnancy diagnosis at weaning. three areas to watch for during the breeding season: Thus, management of bulls to optimize breeding bull health and injury, bull behavior, and cow performance should include time during the behavior. breeding season. Understanding how many bulls you need in each 1. Bull Health and Injury breeding herd is important so that you can accurately Many factors can contribute to the health or injury evaluate breeding performance during the breeding of a bull during the season. In larger breeding season, such Many factors can contribute to the health commercial cow-calf as nutrition, disease, or injury of a bull during the breeding operations, multipleinfection, lameness, and season, such as nutrition, disease, sire breeding herds are heat stress. Fertility issues commonly used, whereas infection, lameness, and heat stress. associated with these seedstock operations factors are oftentimes typically use single-sire breeding herds. Multiple-sire not detected until after the breeding season or breeding herds are easier to manage with less risk pregnancy diagnosis at weaning, and by then, it’s too of reproductive failure, but they are more difficult late. Observations leading to diagnosis of problems to evaluate in terms of genetic improvement in your affecting fertility include poor nutrition, lameness, calf crop. Single-sire breeding herds can be a great or illness, which negatively impacts a bull’s mating tool for evaluating genetic improvement in your calf ability; can cause physical damage to the testes, which crop, but they are more difficult to manage with more could negatively impact semen quality and serving risk associated due to potential reproductive failure capacity (the ability to service several cows in a short from the bull. There are many benefits to using either period of time); and can cause transmissible diseases, system, but understanding the disadvantages of each which directly affects the cow. system is important when observing bulls during the Bulls will typically lose body condition during the breeding season. breeding season, younger bulls more severely than 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 18
May 2020
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
