Fenceline Chatter: Jenschke: Bull breeding soundness should be tested after Winter Storm Uri

Lonnie Jenschke
Texas A&M Extension Service

Following the February winter storm that produced record low temperatures across a large portion of the state, there is concern among the experts about the presence of frostbite on some breeding bulls. Others have expressed concern about reduced sperm production and quality, even if no frostbite was observed on the scrotum.

“While it is difficult to estimate the extent to which a specific operation’s bull battery may or may not have been affected by abnormally low temperatures and extended snow and ice cover, one thing remains certain … a pre-breeding BSE is the only way to objectively evaluate a bull’s readiness to breed prior to turnout,” Smith said.

Lonnie Jenschke

Bull testing should be a priority

Producers are encouraged to request a complete BSE that includes evaluation for motility, morphology and physical defects as well as testing for Trichomoniasis, Gill said. Most often a quick screening for sperm motility constitutes a “fertility test” on bulls.

Morphology is as important to a sperm’s ability to fertilize an oocyte and is often not looked at during routine BSEs conducted in the field. The value of a complete BSE cannot be overemphasized, he said.

Early observations indicate a higher-than-normal rate of BSE failure or deferment to re-test in bulls with visual signs of frostbite, Hairgrove said. It appears that a large portion of those are likely due to physical/structural defects to spermatozoa that can be attributed to damage that occurred during storage in the epididymis.

“From a conceptual standpoint, the damage most likely occurred due to excessive testicular heating in response to the frostbite,” Smith said. “Similar consequences would be expected during times of extreme heat stress, such as is often the case throughout the summer months in Texas.

“We also preliminarily expect younger bulls to have been more resilient to the extreme cold, as they have a greater ability to raise their testes to regulate scrotal temperature and prevent frostbite. However, we do not yet have the objective data to support that notion.”

Don’t panic, but take action

The experts said it could be that many of the bulls that fail a BSE or are deferred to re-test may recover and pass a BSE without requiring a full 60-day cycle of spermatogenesis to do so.

“This extreme weather event is one of many reasons why working with your veterinarian to conduct a pre-breeding BSE on all bulls is always advised, regardless of past performance,” Smith said. “This is also true for recently purchased bulls that underwent a BSE prior to the winter storm.

“A key takeaway from this is to not panic and not immediately cull all bulls that fail a BSE or are deferred for re-test,” Gill said. “Once results are known on the initial tests, plans can be made to locate additional sires if needed, or a plan can be developed to rotate sires in and out during the breeding season.”

The experts said that, following the re-test, they expect some of the deferred bulls to pass a BSE.

Lonnie Jenschke is the Erath County Extension Agent – Ag/NR for the Texas AgriLife Extension Service. He can be emailed at l-jenschke@tamu.edu