Bull Battery Nutrition and Management in Preparation for the Breeding Season


Source: Nebraska Cattleman Magazine

By Kacie McCarthy, Ph.D., Assistant Professor and Beef Cow-Calf Specialist, University of Nebraska-Lincoln

Currently, we may be dealing with cold weather conditions and calving season, but breeding season is right around the corner, and we want to make sure our bulls are ready. When I think about preparing bulls for the next breeding season, a few things come to mind: 1) How is their body condition? 2) What have they been consuming in terms of feed before, during, and after the previous breeding season? and 3) When do we have our breeding soundness exam (BSE) scheduled?

Within a year of a breeding bull’s life, dramatic and dynamic changes occur in body weight and plane of nutrition. Factors that generally contribute to weight loss in yearling or mature bulls may be due to workload and nutritional management. A survey of North Dakota producers revealed that stocking rates varied from four cows per bull up to 80 cows per bull (and bulls can experience dramatic weight loss – between 100 to 400 pounds. So how are we managing these bulls to maintain or regain that lost weight and condition?

Evaluating body condition scores (BCS) provides an opportunity to make management decisions during different production stages or after the breeding season. Like maintaining BCS of the cow herd, bulls should be in an adequate BCS of 5 to 6 as we move into and through winter, which allows for greater BCS and potentially semen quality in the subsequent breeding season. Much like cows, bull body condition needs to be evaluated as fat cover over the front ribs, brisket and tail head, also making sure to take into account gut fill.

When it comes to younger bulls that we purchased or managed at the ranch, we often recommend getting those bulls used to their new environment and ensuring they are maintained on a good plane of nutrition prior to turn out. Generally, mature bulls can be maintained on a 100 percent forage diet that consists of roughly 7 percent crude protein (CP) and about 50 percent total digestible nutrients (TDN). That would target a daily intake of about 1.5 to 2.0 percent of body weight or roughly 40 pounds of dry matter per day. With young or thin bulls, a diet may consist of roughage at 2 percent of body weight but a higher CP and energy-dense diet (7.5 to 9.0 percent CP and 55 to 65 percent TDN, respectively) to help encourage gains. For yearling bulls, we have provided some examples of diets for maintenance as well as targeting gains in a 60- or 90-day time frame. Those example diets can be found in our NebGuide for Breeding Bull Management (https://extensionpublications.unl.edu/assets/pdf/g2332.pdf). A good vitamin and mineral program may be a consideration for successful animal growth and breeding performance. As you develop rations or need help from your local Extension personnel, understanding the quality of your forages and supplements will be important to consider.

Management and preparation prior to the breeding season also includes scheduling a BSE to ensure fertility. Because a variety of factors can impact a bull’s fertility, testing both young and older bulls 60 days prior to the breeding season is strongly encouraged to know where all your bulls stand and allow time for new herd sires to be acquired well in advance. Keep in mind that sperm production is a continuous process. If a bull has sustained an injury over winter or from the past breeding season, the results of a BSE will change; however, in general, it takes roughly 60 days for sperm production to recover. Conversely, a bull that successfully passes a BSE doesn’t mean he may not fail a subsequent BSE, so testing bulls annually or a month or two prior to the breeding season is recommended.

While we may not be to breeding season yet, preparing during the off-season is just as important. With cold weather, ensuring that bulls have protection from wind and frozen ground (bedding) all help prevent frostbite and infertility issues that may occur. Also, keeping up with herd-health practicums like deworming and vaccination programs are additional things to consider.

Nutritional management of our young and mature bulls is essential for proper development and maintenance. Meeting those nutritional requirements can ensure bulls are achieving their full growth potential and can be ready to perform once the breeding season is upon them.

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