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Is selecting for A2/A2 right for you?

Kathleen O’Keefe for Progressive Dairyman Published on 01 March 2018

Pick up the latest sire directory from any of the major bull studs, and you’ll see that the “bull book” contains more information than ever.

More indexes, more traits, more numbers; it’s quite a job to sift through it. In the midst of all this information, one genetic trait receiving more attention and selection is A2/A2 beta-casein.

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What is A2/A2?

If you’re not familiar with the difference between A1/A1 and A2/A2 milk, here’s a quick primer: Beta-casein, which makes up about 30 percent of all milk proteins, exists in at least 13 different forms, but the two most common forms are A1 beta-casein and A2 beta-casein.

These two only differ in one amino acid, but that difference seems to affect how many people, perhaps as high as 25 percent of the population, digest dairy products. Some studies have asserted that a number of people who think they are lactose-intolerant may instead be sensitive to A1 beta-casein.

Obviously, this is good news to the dairy industry if we can regain consumers who love our products but don’t love the digestive discomfort they cause for some. Providing them dairy goods made solely from A2 milk could be the answer.

This potential niche market for consumer-friendly milk sales has attracted the notice of a growing number of dairy herd owners when considering their sire selection and genetic progress in their herds.

Cows with an A2/A2 genotype are the only ones that produce “A2 milk.” A1/A1 cows and A1/A2 cows will produce A1 milk or milk with a mixture of A1 and A2 beta-casein.

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Certain dairy breeds, such as Jersey, Guernsey and Brown Swiss, have a higher percentage of A2 cattle in their population, while Holstein, Ayrshire and Shorthorns traditionally have been more prominent A1 producers.

For Holstein breeders looking to gain the A2 edge, it’s reassuring to them that the reliability of breeding for A2 is 100 percent. An A2/A2 bull or cow will transmit the gene 100 percent of the time; thus an A2/A2 cow bred to an A2/A2 bull will result in an A2 calf 100 percent of the time.

Using only A2/A2 mating sires across a typical herd of Holsteins would see the frequency of A1 beta-casein in milk halve with each generation.

‘Selection with an eye to the future’

David Hill has seen interest in selecting for the A2 trait accelerate dramatically in the past couple of years. He works in the northeastern part of the U.S. as a consultant with Alta Genetics Advantage herds.

Just over a year ago, he didn’t have any client herds selecting for the trait, but after the past three sire summary runs, he now has several herds choosing exclusively A2/A2 bulls for use. Of the 450 herds enrolled in the program nationwide, he thinks about 40 – or close to 10 percent – are picking only A2/A2 mating sires.

“They don’t have to give up anything in genetic progress because a good number of the top Holstein bulls are A2/A2 now and they can select bulls regardless of what their focus is,” Hill comments.

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Several major A.I. studs began publishing online lists of A2 sires in 2014. Hill elaborates, “It’s not to the point where we would reject a bull coming to stud if he wasn’t A2/A2, but it is a bonus if they test out that way.

Our producers aren’t being paid a premium for A2 milk yet, but they feel it could happen. For them, it’s a selection with an eye to the future.”

Woodvale Farms sees opportunities for A2 milk

Donald Harwood of Woodvale Farms in Perry, New York, agrees with Hill’s assessment. In fact, this was one of Hill’s first herds to select strictly for A2/A2 with the future in mind.

“There is no incentive from our processor at this time for A2/A2 milk or any talk of a bonus for it in the near future. We feel it is something that may be consumer-driven as more information and studies are done that prove the benefits of A2/A2 milk,” Harwood says.

Owned by Donald, Damon and Thomas Harwood and Jason Lowery, the Woodvale operation relocated from Shippensburg, Pennsylvania, 14 years ago in order to expand and to bring more family members into the business.

Their 690-head milking herd consists mainly of Holsteins with a few Brown Swiss and Jerseys sprinkled in and maintains a RHA over 11,300 litres of milk with a 4.0 percent butterfat test and 3.1 percent protein.

Harwood learned about A2/A2 milk through reading articles in breed journals and herd management magazines. Once it caught his interest, he went back and looked at sires they had used in the past and realized that a fair number were A2/A2 bulls.

“From that point on, we made an effort to start specifically selecting bulls with the A2/A2 gene. It was an easy decision to make because it has in no way compromised our genetic progress as so many of the top bulls now have this trait. There are many options – you don’t have to narrow your bloodlines to select for it,” Harwood notes.

While they currently don’t sell any cattle or genetics from the herd, they do have it noted as a possible potential profit line in the future.

Harwood speculates, “Part of the reason we believe in using the A2/A2 gene is if the consumer starts demanding A2 milk, we can then sell cows and heifers to other dairymen looking to supplement their herd with animals carrying that genotype. Our goal is working toward getting as much A2/A2 gene into our herd as possible. If the herd gets to 100 percent, that’s great, but our main goal is to make a quality milk for all consumers to enjoy.”  end mark

Kathleen O'Keefe is a freelance writer in Hammond, Wisconsin. 

What is A2/A2 milk?
A2 is a common form of beta-casein, a component of milk proteins. People who have trouble digesting dairy products seem to be more tolerable of milk proteins in this form.

Cows with the A2/A2 gene are the only ones that produce A2 milk. Guernsey, Jersey and Swiss breeds have a higher percentage of the gene in their populations, compared to Holsteins and other breeds.

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