Determine when a herd sire should stay or go

A producer’s herd sire may be one of the trickiest animals on the farm to manage. A breeding age bull eats a lot, needs a separate pen when it isn’t breeding season and at times can have a bit of an attitude problem. Despite the challenges of keeping a herd sire around, he’s responsible for a majority or all of a producers’ calf crop. So, how do cattle producers decide when it’s time to cull the bull?

Livestock experts recommend taking several factors into consideration. Every breeding season, producers should check their herd sires for fertility, structural soundness and genetic merit. Additionally, the herd should be assessed to determine if new bloodlines need to be introduced.

Breeding Soundness Exam

A breeding soundness exam (BSE) indicates the fertility of the herd sire. “In order to proactively catch an infertile bull, producers need to have a breeding soundness exam performed on the bull 60 to 90 days before every breeding season,” Elizabeth MacConnell Picking, University of Missouri Extension ivestock Specialist, said. 

The BSE should test the quality of the sperm, the quantity of sperm, the direction the sperm is moving and if the sperm contains any mutations. Information from the BSE gives producers valuable insight into the viability of their herd sire. 

It could be disastrous for a cattle operation to use a herd sire that was infertile. It’s possible to lose an entire calf crop. 

“I cannot emphasize enough how important breeding soundness exams are for cow/calf production,” Heidi Ward, DVM, Ph.D., veterinarian and assistant professor associated with the University of Arkansas Cooperative Extension Service, said.

A variety of factors including heat stress, scrotum injury or respiratory infection can cause temporary poor fertility in a herd sire. In many of these cases bulls recover fully and are still viable herd sires.

Last year, due to the stretch of frigid weather some cattle producers had bulls that suffered frost bite on their scrotums. Frost bite on a bull’s scrotum causes inflammation and kills sperm. In some cases, the bulls rebounded, in others the damage was too severe and their sperm quality never improved. 

If the BSE is conducted 60 to 90 days prior to breeding season, then producers have time to make important herd management decisions. 

“With a round of spermatogenesis (the growth and maturation of new sperm cells) taking 61 days, this gives the producer time to make arrangements to recheck a bull’s semen or replace him before the breeding season starts,” Picking explained.

Structural Soundness Evaluation

Herd sires must be structurally sound to get their job done. They must be free of arthritis, joint injury or sore feet. Any physical ailment that will keep him from being able to mount and breed a female is a reason to cull him. 

“Producers should watch for lameness in their bulls and carefully consider structural correctness and hoof shape and angle when selecting sire replacements,” Picking shared.

Genetic Merit Assessment

When purchasing a bull select a herd sire that will improve the genetics of the entire herd. Cattle producers can assess the value of a bull by studying his EPDs. The bull’s EPDs can help guide producers in their selection of a herd sire that will meet their production goals and ultimately generate higher selling calves.

If a producer has kept the herd sire’s daughters as replacements, then they may want to make the decision to cull their herd bull. Managing the replacement females separate from the herd sire may be more work than a producer wishes to endure.


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