Semen quality is essential in breeding success
Semen is semen, right? Producers thaw the straw, inseminate the cow and life is good.
“Maybe not,” said Dr. Lisa Herickhoff, owner of Membrane Protective Technologies, Inc., an assisted reproductive technologies firm, during the American Wagyu Association “Shaping the Future” annual convention in Charleston, S.C.
“We don’t talk about male fertility very often. We just talk about sperm cells and say, ‘Use that straw of semen.’ But, there is variability in straws of semen, and if producers don’t pay attention to it, they are going to have higher costs of pregnancy and missed pregnancies,” explained Herickhoff.
Bull studs will evaluate the motility and morphology of semen.
“Those are important, but only part of the picture,” she said.
Semen variability factors
“When we talk about older bulls, semen variability levels off. But, when we talk about younger bulls, every lot of semen is going to be different,” noted Herickhoff.
She mentioned bull studs often discard up to 40 percent of the ejaculates from young bulls because of quality issues.
The next factor is when the semen was collected.
“Was it collected in the middle of summer or was it collected in winter? It’s going to make a big difference,” she pointed out. “This is because seven or more days of temperatures above 90 degrees will decrease semen quality if the bull is housed outside.”
Likewise, freezing temperatures can affect semen quality.
“It’s going to take quite a bit of time – 45 to 60 days – to recover,” she told Wagyu enthusiasts at the convention. “So, look for semen that has been collected early in the summer or later, after a cold snap.”
Semen quality is also affected by a bull’s health.
“Semen quality is affected by illness, and it doesn’t have to be related to reproduction,” shared Herickhoff. “It could be something like a foot abscess, which was treated with antibiotics, and now, all of a sudden, we have poor semen quality.”
“Also, dietary, mineral and antioxidant imbalances will change semen quality,” she noted.
Herickhoff explained there are several things producers can do to avoid this.
“Producers can ask the bull stud for data on a straw of semen they’re considering buying or they can send it off to a third-party lab to be analyzed before they use it,” she said. “This is their best bet of insurance so they know, before they put it in a cow, how many of the sperm cells in a straw are actually available to fertilize, how many of them have good quality DNA that hasn’t been broken during handling, how many of them have an intact acrosome and how many have good morphology and are motile.”
If a person finds semen that works well, they should look at the cane code so they can buy more of the same lot, Herickhoff advised. The cane code will have the date it was produced, the bull’s name, the country where it was produced, the stud code, which can be cross-referenced on the National Association of Animal Breeders website and the breed.
Breeding soundness exams
According to Herickhoff, when it comes to bull fertility, breeding soundness exams (BSE) are the right place to start.
“I’ve heard this referred to as a fertility soundness exam, and it’s probably a better way to look at it because we want to make sure we are looking at the whole animal,” she said.
“For bulls that are going to be used for pasture breeding, a BSE will knock off the bottom 10 to 15 percent of inadequate bulls – bulls which don’t have good enough semen quality or don’t have good enough legs to mount cows,” she added.
While it’s true testicular size is directly related to fertility in both the bull and his female offspring, be knowledgeable, Herickhoff warned. Research shows the testicle size of American Wagyu is smaller than genealogy standards by roughly 36 percent.
“If a producer has a veterinarian who is not familiar with looking at their breed, they will want to say, ‘Hey, these guys are going to measure three to four centimeters smaller than most typical breeds.’ Make sure veterinarians are well informed of their specific breed,” she said.
Herickhoff noted it’s important to understand the confirmation traits of each breed of cattle because certain breeds have smaller testicle size and would not have passed a breeding soundness exam.
However, American Wagyu have good quality semen, which will go up even higher when discussing about animals in the 12- to 14-month-old range.
If a veterinarian doesn’t pass a bull on a breeding soundness exam, Herickhoff advises, “Unlike being in school, it doesn’t mean they have to stay back a year. Instead, it means a vet can come back in about 45 days and retest.”
Indeed, fertility is fundamental.
“Herd and breed improvement must include fertility factors,” she concluded. “Even if a person is not a seedstock producer, they will need to think about fertility in order to get calves on the ground and to sell carcasses.”
Burt Rutherford is the senior editor for Beef Magazine. He can be reached at firstname.lastname@example.org.