Consequences of Overconditioning Beef Bulls Pedro Fontes, Assistant Professor Animal and Dairy Science University of Georgia (Published in Progressive Cattle)
Feeding high-energy diets to young bulls right up to the point of breeding season can have a negative effect on breeding ability, semen quality and embryo development. Sire overconditioning is a prevalent issue in the beef industry. Because pre- and post-weaning growth are important in the cattle business, we often place considerable emphasis on identifying bulls with superior genetics for weaning and yearling weights. To help us identify these superior bulls, high-energy diets are often utilized to allow young bulls to express their genetic potential. Nevertheless, bulls are often
reserves to handle a busy breeding season while minimizing the risk of reduced fertility associated with overconditioning. Additionally, it is important to keep in mind that bulls can lose over 100 pounds during the breeding season. Adapting young bulls that were developed in a predominantly concentrated diet to a forage-based diet before turning them out to breed cows can help mitigate these losses and optimize bull performance during the breeding season.
not only fed high-energy diets to express their genetic potential at the time of yearling weight collection, but also until the time of sale, resulting in overconditioned bulls. While “fat sells” when it comes to selling bulls, research has shown that excessive conditioning can negatively affect semen quality. An observational study evaluating over 1,600 breeding soundness exam records revealed that only 45% of extremely overconditioned bulls (with a body condition score [BCS] of at least 4 on a scale of 1 to 5) passed the breeding soundness exam, compared to 81% of bulls with an adequate BCS of 3. Moreover, when an experimentally controlled study compared the impact of feeding young bulls a moderate-gain diet primarily based on forage (control) to a high-energy diet comprising 80% concentrate and 20% forage (high- gain) for approximately 160 days, similar results were observed. Bulls fed the high-gain diet were heavier and had greater backfat thickness. However, they exhibited a greater percentage of secondary sperm defects and reduced sperm motility compared with the control bulls. Additionally, high-gain bulls had greater scrotal circumference and suboptimal regulation of scrotum surface temperature, which may be linked to increased fat deposition in the neck region of the scrotum, potentially explaining the decrease in semen quality. In summary, while high-energy diets should be used to enable young bulls to express their genetic potential for post-weaning growth, it’s crucial to avoid overfeeding them to an extent that fertility is compromised. This can be accomplished by closely evaluating body condition scores while developing bulls. Bulls should be managed to have a body condition score of 6 on a 1-to-9 scale before the beginning of the breeding season. This ensures they have sufficient energy
What the professionals have to say “I visited Stavick Simmental on 1/7/26 to scrotal measure bulls and was very impressed with what I saw. The bulls are developed on a simple, back-to-basics ration and allowed to grow naturally. They are in excellent condition—sound, athletic, and well-muscled without being over-conditioned. Scrotal measurements were strong, ranging from 32 cm to 40.5 cm, with minimal fat and very good testicular quality. The Stavicks also maintain one of the most aggressive Johne’s control programs I have seen. They are willing to cull deeply and decisively, prioritizing herd health above all else. Stavick cattle work because the Stavicks work. Any animal that doesn’t meet expectations—structurally, functionally, or from a health standpoint—is removed. Mike has always been extremely detail-oriented and uncompromising when it comes to conformation and quality. He knows exactly what he wants and is always focused on the future of the herd. As their veterinarian, it’s a pleasure to work with cattlemen at this level. As a bull buyer, you can purchase with confidence. Owen and Liv carry on that same commitment to quality—though Mike may still think he has the upper hand."
– Holly Roe-Johnson, DVM
“While each individual seedstock operation defines their own goals for bull development, it is a process that takes years to refine. Stavick Simmental judiciously looks back each year to refine their process. They are very specific that bulls should be developed in a manner that maximizes their fertility and provide higher reliability of their durability. This year’s bulls have been the lowest input group of bulls assembled to date. Even with that, they have posted some impressive average daily gains and shown their genetic potential for growth. While we all know that anything can happen with these animals, they have been developed to be ready to work for their new owners!”
- Tyler Melroe, M.S., Consulting Nutritionist
4
Made with FlippingBook - Share PDF online