lisa pedersen

Lisa Pederson

During the winter months a beef producer’s main attention is given to the cow herd in terms of  nutrition and Body Condition Score (BCS), and the bulls in the herd sometimes don’t get the consideration they deserve.

Every year the producer needs to make sure the BCS of the bulls at turnout are in the range of 4 to 7, but this year there is another factor to consider – the fertility level of the bull, according to Lisa Pederson, Extension livestock specialist at the Central Grasslands Research Extension Center in Streeter, N.D.

“This year we are likely to see a lot of bulls with scrotal frostbite,” Pederson said.

To better understand the situation, a basic understanding of the semen development in a bull is needed. The fancy name for this process is spermatogenesis. The semen development time in a bull is 61 days, according to Pederson, which means that anything that has occurred in the past two months will impact semen quality and the ability to pass the Breeding Soundness Exam (BSE). She compared semen development to a factory, where anything that happens during the production along the factory line results in a “lemon,” and we certainly don’t want any lemons when it comes time to breed cows.

Pederson cited figures from a study published in the Canadian Veterinary Journal that focused on the effect of scrotal frostbite on semen quality in a study involving 1,557 bulls. They graded frostbite by the number of scabs that were a penny or larger or smaller than a penny. Severe frostbite was when a bull had one or more scabs larger than a penny on their scrotum and slight frostbite was one or more scabs smaller than a penny.

Those bulls that had a BSE in January thru March had 0 percent with satisfactory semen quality, 29 percent with questionable semen quality and 71 percent unsatisfactory semen quality. But later tests in May and June now indicated 53 percent had satisfactory levels, 11 percent questionable quality semen and 37 percent unsatisfactory.

The take home message from this is a producer needs to protect their bulls’ testicles from the cold by providing wind breaks and/or deep bedding.

Pederson stressed the need for a BSE within a month of breeding season.

“That gives us enough time to find alternative bulls, if our bulls happen to not test well,” she said. “It is also an appropriate amount of time for them to have that BSE exam be accurate when you turn them out.

“Don’t save pennies to waste dollars by skipping your Breeding Soundness Exam.”

Most veterinarians charge from $50 to $100 for a BSE and while that seems like a lot of money, she said, think about this.

“If your cows breed just 21 days later because your bull failed the Breeding Soundness Exam, that ends up being about 50 pounds of weaning weight. If calves sell for $1.50 a pound, that is $75 per head that is lost and you could have paid for that Breeding Soundness Exam with just one calf,” she explained.

She closed her presentation by noting that the semen test is only good for the day it was taken, and semen development takes 60 days.

Pederson made her remarks during a recent NDSU Extension webinar on Cold-weather Cattle Management that was given on March 12.