Scrotal Frostbite in Bulls
Windbreaks and bedding protect bulls from scrotal frostbite.
Cold weather, especially with wind chill, can result in bull infertility the next breeding season. Fertility may be temporarily or permanently affected. George Perry, professor and extension beef reproduction specialist at South Dakota State University, says spermatogenesis — the generation of sperm — in a bull takes 61 days.
“Anything that affects sperm production will take 61 days to totally clear the system and have normal cells and healthy sperm after the bull recovers,” he explains.
If frostbite was severe, it may take several months before the bull is fully recovered.
“A few years ago we checked a bull that had frostbite in February, and by June he was fine. Where the sperm is in the production cycle can make a difference in what will happen to it when frostbite occurs,” says Perry.
Scabs on the scrotum indicate frostbite damage, he says. “Even when the scabs are gone and the skin heals, there can be residual effects on fertility due to misshapen or deformed sperm for the entire 61 days following recovery. We have to give those bulls enough time after they are completely healed to make sure they are producing good sperm.”
A bull lowers his testicles in hot weather, and draws them up closer to the body in cold weather to keep them warm enough. Severe scarring from scrotal frostbite may interfere with raising and lowering the testicles. Perry explains that anything that affects the neck of the scrotum also affects the countercurrent exchange for temperature. This is a sensitive area, and if there is frostbite on the neck of the scrotum, the bull may not be able to extend or contract the scrotum enough to properly control temperature, which can have a negative effect on fertility.
Perry recommends that bulls be given access to windbreaks and enough bedding to avoid frostbite. The scrotum has very little protection compared with the rest of the body — just bare skin with a fine hair covering. If bulls lie on frozen ground or snow, they are basically putting the testes on ice. If it’s windy, testicles are exposed to wind chill. Bedding serves as insulation.
“Frostbite implies minor frost damage. Tissues may also suffer severe frost damage. The main thing stockmen need to realize is the length of time it takes to recover. Even when you can no longer see scabs — and the skin has healed — that’s when normal sperm production resumes and the time starts for the 61-day period before the healthy sperm is mature and the bull is fertile again,” says Perry.
Bulls with severe damage, however, may not be fertile until later in the summer.
If damage is severe enough, the bull will be permanently infertile. Impaired bloodflow to the testes can decrease function. This would be similar to severe freezing on a finger or any other extremity, says Perry.
“This is good reason to remember that breeding soundness exams need to be performed each year before you turn bulls out with cows,” he cautions. Just because a bull was fine last year doesn’t mean he will be fertile this year. Some people just check the new bulls going into the herd and don’t check the older bulls.
“After suffering frostbite, if the bull doesn’t have normal sperm at the time he’s checked, you might give him another 60 days and check him again. You definitely want to have him checked before you turn him out,” Perry recommends.
Editor’s Note: Heather Smith Thomas is a cattlewoman and freelance writer from Salmon, Idaho.