Polled Potential

02:15AM Jan 24, 2014
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( Photo: Dairybullsonline )

Polled genetics can transform the dairy industry

Violent. Gruesome. Barbaric. These are just a few of the words that have been used to describe the common practice of dehorning by people who oppose the act.

The opposition largely comes from animal rights groups such as People for the Ethical Treatment of Animals (PETA), Mercy for Animals and the Humane Society of the U.S. (HSUS), each of which has shown videos of poor dehorning practices with narration from celebrities to help sway the court of public opinion.

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Thus far, consumers have not started a huge outcry condemning dehorning, but public perception could be the straw that breaks the dairy producer’s back when it comes time to look at alternatives.

One way to alleviate the problem is to use polled genetics.

"If we can eliminate the need to physically or mechanically dehorn animals, it would be an advantage to those individual dairy producers, and it is a good story that we can tell the consuming public," explains Mark Rodgers, a registered Holstein breeder.

He has been breeding polled cattle for the past 16 years at the Andersonville Dairy in West Glover, Vt. Prior to that, he grew up with polled Jerseys.

"When I went into the Holstein business, I thought polled was something that was special to Jerseys," he says. "I wasn’t even aware that there were polled Holsteins."

At his 200-cow dairy, not all the calves are polled, so calves that are dehorned are done so under approved protocol from the National Dairy FARM Program.

Dehorning occurs before eight weeks of age with a butane dehorner. Calves receive anesthesia prior to the process to help numb the pain.

Unfortunately, not all dairies do this type of protocol or train their help properly, Rodgers says.

D14024 Scoop and Run (2)

Using polled genetics reduces the need for dehorning tools, such as this scoop and iron that is sometimes used, along with local anesthesia.

"Rather than try to train everybody or convince everybody of the proper means and methods of dehorning, it is much simpler to use polled breeding," Rodgers adds. "It is like I tell everybody, ‘polled is polled in every language; you don’t have to interpret it.’ You don’t have to write dehorning instructions in six different languages because the calf is born with no horns."

Rodgers is currently using semen from the top three homozygous polled bulls available, but he is also trying to create the next best homozygous polled bull.

Breeding superior homozygous polled bulls could be exactly what it takes to get more dairy producers, and commercial dairy producers in particular, to have more interest in using polled genetics.

"They are sometimes leery to restrict their choice of bulls to the (heterozygous) polled bulls because only 50% of the calves will be polled," says Ben Dorshorst, assistant professor of genetics at Virginia Tech.

Of the two copies of every gene that an animal possesses, a heterozygous polled bull has one polled gene, while a homozygous bull has two polled genes. A homozygous polled bull will have 100% polled progeny, regardless of whether the dam is a carrier of the trait. That’s because all progeny receive one polled gene from the sire, which is dominant over the dam’s recessive horn gene.

As it stands right now, there are only 17 homozygous polled Holstein bulls available from semen providers, Dorshorst adds, who has been studying the use of registered bulls and how it pertains to the polled trait. However, there has been an increase in the total number of polled sires available at bull studs. Over the past year, the number doubled to 96 head in December 2013.

"Compared to the number of horned bulls, they are definitely the minority—we’re talking single digits on a percentage basis for the total bulls out there," Dorshorst says. "But it is still a remarkable increase in terms of the proportion of bulls that are polled."

When Dorshorst first started looking at the amount of polled Holstein sires offered by bull studs in April of 2012, there were only 22 sires, so the popularity has certainly been on a rapid incline.

"Genomics have been one big driver for polled having the popularity that it does right now," Dorshorst says. "Genomics have allowed us to more easily find those high genetic value polled individuals to be working with."

The genetic merit of the polled bulls that were available in the recent December evaluation, for instance, had at least one polled bull in the top 10% for the entire Holstein breed in 37 of 38 traits that are evaluated. In April 2012, this number was only 28 of 38 traits.

There may not be as many polled bulls compared to horned, but the quality of those polled bulls is on the rise.

"It is a smaller group of animals that you are choosing from, so it is more difficult solely because of that to find good ones, but the difference is minimal and rapidly decreasing," Dorshorst adds.

Agreeing with that sentiment is Ryan Starkenburg, sire selection manager for ABS, who points out that the gene is present in all dairy breeds. However, it is currently at a low incidence in the total population. 

"It means from a selection standpoint you don’t have as much to select from for a genetic superiority standpoint. As a result, the number of high-ranking animals that also carry polled is certainly more limited," he says.

Starkenburg says he is optimistic of what the future for polled cattle holds. "It would be our hope that over time, the gene frequency in the population will continue to rise as some amount of polled bulls are used and we’ll continue to select the better ones.

"From my discussions with breeders, in general, there is interest in the idea of polled, but not where they want to give up a lot of genetic progress to incorporate polled. As superior polled genetics are available, then it becomes an easier sell to incorporate those into breeding programs," Starkenburg says.

Crossbreeding could also provide an answer for those commercial producers who might be looking to change up their genetics by adding some hybrid vigor and receiving the side benefits of a polled animal.

"There is definitely interest in crossbreeding, and the Norwegian Red has gotten traction," says Les Hansen, professor of dairy genetics at the University of Minnesota.

About 30 years ago, a program was started to breed Norwegian Red cattle to be polled, Hansen says. Now, more than half of the breed in Norway has reached that point. He sees the Norwegian Red and other breeds that have a higher percentage of polled as a popular alternative for crossbreeding.

"I’m excited about the polled [genetics]," Hansen says. "I’m hoping that yet in my lifetime, we’ll have a big shift. ... You can’t do it knee jerk overnight, but I really support this movement."

Horns are a genetic recessive characteristic that is not needed in today’s dairy industry, Rodgers adds.

"Nobody would order a calf with horns," Rodgers explains. "If you had a choice when you were making a checklist, like ordering a new car, you would never check the box that says ‘I want horns.’"

"The breeds have done a pretty good job in identifying undesirable genetic recessives and eliminating them from the population," Rodgers says.

"This is simple because you don’t have to give up on production," he adds, "and you don’t have to give up anything to use polled breeding."