ANGUS BEEF BULLETIN EXTRA

January 20, 2022 | Vol. 15 : No. 1

Keep the Boys Warm

Avoid scrotal frostbite to prevent bull infertility.

Bull buyer's resource

Bulls are quite the investment. During the winter, they need some more TLC to ensure they can do their jobs. Cold weather can result in bull infertility the next breeding season. Ahmed Tibary, professor at Washington State University’s College of Veterinary Medicine, says risk for scrotal frostbite increases when the ambient temperature falls below freezing. Wind, wet areas or sweat on the bull’s testicles, and bulls lying on frozen ground are also risk factors. Bulls need bedding or windbreaks to protect their vulnerable reproductive organs from cold damage. Don’t forget about protection from wind chill during transport, either.

“Bulls with pendulous testicles seem more predisposed to freezing. If a bull can’t pull his testicles up close enough to his body to keep them warm during cold weather, there is more risk for damage,” Tibary explains.

This means older bulls with lower-hanging scrotums are more frequently and more adversely affected than younger bulls. If a bull can’t move his testicles up and down to compensate for temperature changes, he will be infertile, since sperm production and viability depend upon proper temperature.

Impaired fertility
Minor frostbite involving areas ½ inch (in.) to 1 in. in diameter at the bottom of the scrotum is common, and generally has a short-term detrimental effect on semen quality. The more severe the frostbite and the closer it occurs to the breeding season — as in a late winter storm — the higher probability that fertility will be impaired.

“The primary insult to testicular function occurs as a result of heat produced by the inflammatory response, not the cold itself,” says Tibary. “Cold weather causes two extremes in temperature in the scrotum. First there is supercooling at onset of frostbite, then superheating as the frozen tissue thaws and inflammation occurs. Supercooling is temporary, while superheating can last 10 days after the initial injury. Inflammation causes swelling, and testicle swelling always produces lowered semen quality.”

Bulls can recover from scrotal frostbite if there are no adhesions, and the sperm tract is not damaged. The lower part of the scrotum usually suffers first. This area remains unprotected when a bull draws his testicles against his body for warmth. If there is damage in the epididymis, sperm will not be viable.

Moderate to severe frostbite affecting 10% to 30% of the scrotal surface will need a minimum of two months and perhaps as long as 12 months for recovery to restore normal fertility, if no adhesions occur between the testes and scrotum. If adhesions occur, the loss of normal fertility may be irreversible, he warns.

After a cold winter, especially after periods with wind, stockmen should check bulls for signs of damage with a breeding soundness exam (sometimes referred to as a BSE). Blisters and scabs will be obvious for about three weeks after frostbite. Scabs fall off in about a month, leaving reddish-pink scar tissue, he says. If there is evidence of frostbite, check the extent of injury. In many cases, only the lower tip of the scrotum is affected, and permanent damage to the testicles is not as likely.

“If a testicle is pliable and appears normal, there’s a good chance the bull is not damaged. But if there’s been serious freezing of the tissue, the scrotum will show signs of scarring — a scabby area on the bottom third, up the back, where the scrotum was exposed to wind,” he explains.

“We see quite a few lesions of scrotal frostbite in breeding soundness examinations in February and March — typically a skin discoloration or scab. If frostbite was recent, there may be swelling at the bottom of the scrotum,” says Tibary. “This is the area covering the tail of the epididymis.”

Damaged testicles produce abnormal sperm cells that will be obvious in a semen sample. Common advice is to wait at least 40 days before taking a semen sample, to determine if sperm cell structure has been affected. If the sperm-producing cells have degenerated or died, some of these abnormal cells will appear in the semen.

Since the effects can be long-lasting, preventing frostbite in the first place is the smart and efficient way to care for bulls.

Editor’s note: Heather Smith Thomas is a cattlewoman and freelance writer from Salmon, Idaho. Photo by Shauna Hermel.




Angus Proud

In this Angus Proud series, Editorial Intern Jessica Wesson provides insights into how producers across the country use Angus genetics in their respective environments.



Angus Proud: Bubba Crosby

Fall-calving Georgia herd uses quality and co-ops to market calves.


Angus Proud: Jim Moore

Arkansas operation retains ownership through feeding and values carcass data.

Angus Proud: Les Shaw

South Dakota operation manages winter with preparation and bull selection.


Angus Proud: Jeremy Stevens

Nebraska operation is self-sufficient for feedstuffs despite sandy soil.