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A2: genetic fad or future?

Since its 2015 US debut, A2 milk has been a hot topic among dairy producers. Now, the latest A2 buzz comes from consumers. This follows the launch of the A2 Milk Company’s national television advertising campaign, and increased local availability of A2 milk in many grocery stores.

While the curiosity around A2 milk grows, it’s important to evaluate whether this is just another fad in genetic selection, or a real future of the industry.

What is A2 milk?

A2 milk comes from cows with two copies of the A2 gene for beta casein.

Cows’ milk is about 87 percent water and 13 percent solids. Those solids include lactose, fat, protein, and minerals.

To find the A2 gene, we look to the protein in milk. Casein is what makes up the majority of milk protein, and about 30% of that casein is called beta casein. The two most common variants of the beta casein gene are A1 and A2, so any given bovine will be either A1A1, A1A2 or A2A2 for beta casein.

Milk from US cows has traditionally contained a combination of both A1 and A2 beta casein.

Isn’t A2 milk for people with lactose intolerance?

Not necessarily. A2 milk contains the same amount of lactose as non-A2 milk. So a person who has been clinically diagnosed with lactose intolerance will see no benefits from drinking A2 milk.

Some studies have shown the A2 beta casein in milk to be more easily digestible than the A1 beta casein. This means that the discomfort some people experience after drinking milk could actually be linked to an A1 aversion rather than to lactose intolerance.

Since the majority of lactose intolerance cases are self-diagnosed, for those people, A2 milk could be the answer.

How do you get cows that produce A2 milk?

The only way to have a herd that produces A2 milk is through genetic selection.

For a cow to produce true A2 milk, she must have two copies of the A2 gene in her DNA. Each animal receives one copy of the beta casein gene from its sire and one copy from its dam. So for a 100% chance at an A2A2 animal, you must breed an A2A2 bull to an A2A2 cow.

How do you know if your animals are A2?

The only way to know for sure, is a genomic test. Some companies offer A2 genetic testing as an add-on to a full genomic test. Others offer testing for A2 on its own, for as little as $15.

How long will it take to convert your herd to only A2?

This entirely depends on how aggressive your approach is. If your goal is to immediately become 100% A2A2, you can make that happen. To do that, you’d need to genomic test each of your animals, keep only those verified as A2A2, and sell the rest.

A less extreme option for large, multi-site dairies is to genomic test all females, and sort any animals verified as A2A2 all to one site.

But since those aren’t realistic options for most farms, another approach is to limit your sire selection to only bulls confirmed as A2A2. Most AI companies publish this information on their proof sheets and/or websites.

A rough approximation of active AI sires shows about 13% are A1A1, 46% are A1A2 and 41% are A2A2. If you figure that same proportion within your own herd, it would take seven generations of breeding your untested females strictly to A2A2 bulls before you’d reach 99% of A2A2 females.

Pie graph showing that about 41% of bulls in active AI are A2A2. 46% of bulls are A1A2 and 13% of bulls are A1A1.
More than 40% of active AI sires are A2A2.

What do you have to lose by selecting A2A2 sires?

With 40%, or more, of active AI sires verified as A2A2, you have a good number of sire options to use in your breeding program. This also means that less than half of the bulls out there are A2A2, so you will miss out on some sire choices by implementing this as part of your breeding program.

Every time you add a filter to your genetic selection criteria, you limit the amount of genetic progress you can make in your herd.

Should you select for A2 in your breeding program?

If you are offered milk premiums for producing A2 milk, or see that option in your future, then selection for A2A2 sires is a wise decision. However, chasing that bonus, if it isn’t guaranteed will mean you limit your genetic options.

No one can predict the future. So it’s hard to tell yet, whether A2 is just a fad, or the future of the industry.

Regardless of your selection decision around A2 sires, make sure it aligns with your dairy’s customized genetic plan. Emphasize the production, health and conformation traits that match your farm’s current situation and future goals. This will help maximize future profitability and genetic progress in the direction of your goals.

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August sire lists

No matter what genetic plan you’ve put in place on your farm, we have daughter-proven and genomic-proven bulls to meet your goals.

We have access to all you need in one place, in formats that are easy to print. Here you will find lists to download with any of Alta’s Holstein and Jersey specialty sires. Below, are the A2A2, polled, outcross, robot-suited and kappa casein sires. There is also a listing of our milking speed ratings, 100% registry status listings and top wellness trait sires.

Work with your trusted Alta advisor to customize your genetic plan using our Advanced Bull Search or Alta GPS.

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Genetics and A2 milk: what you need to know

As consumers continuously look for new ways to eat healthy, A2 milk is a trend that emerges on their radar. A2 milk has been a common brand in Australia and New Zealand for several years. It only made its entry to the US marketplace in 2015.

It’s a new concept for many people, so before you join in on the A2 hype, here are a few answers to questions you may have.

What is A2 milk?

A2 milk is produced only from cows having two copies of the A2 gene for beta casein.

To explain further, cows’ milk is about 87 percent water. The remaining 13 percent is a combination of lactose, fat, protein, and minerals that make up the solids in milk.

If we focus on the protein within milk, the major component of that protein is called casein. About 30% of the casein within milk is called beta casein. The two most common variants of the beta casein gene are A1 and A2, so any given bovine will be either A1A1, A1A2 or A2A2 for beta casein.

In the United States nearly 100% of the milk contains a combination of both A1 and A2 beta casein.

What is the benefit of A2 milk?

Researchers believe that A2 is the more natural variant of beta casein, and A1 was the result of a natural genetic mutation that occurred when cattle were first domesticated. With that in mind, studies have been done to see if people digest or react to true A2 milk differently than regular milk.

Some of those studies have found that people drinking milk exclusively from cows producing A2 milk were less susceptible to bloating and indigestion – leading some to conclude that A2 milk is a healthier option than regular milk. The exact science behind the difference in A1 versus A2 milk is complicated, but research has shown that digestive enzymes interact with A1 and A2 beta-casein proteins in different ways. Because of that, A1 and A2 milk are processed differently within the body.

Can you breed for A2 milk?

Yes, in fact the only way to have cows that produce A2 milk is to breed for it.

True A2 milk can only be produced from cattle possessing two copies of the A2 gene in their DNA. Each animal receives one copy of the gene from its sire and one copy from its dam. So for a chance to get an animal with the A2A2 makeup, you must breed a bull with at least one copy of the A2 allele to a cow with at least one copy of the A2 allele.

To ensure with 100% certainty that a female will produce A2 milk once she freshens, she must be the result of mating a cow with two copies of the A2 gene to a sire that also has two copies of the A2 gene.

Does A2 milk only come from colored breeds of dairy cattle?

Traditionally, colored breeds of dairy cattle, such as Jerseys and Guernseys have been the poster children for the A2 gene. Those two breeds still have a higher proportion of A2A2 animals. However, some of the popular Holstein sires of recent years have increased the prevalence of A2A2 sires in the black and white breed as well.

You may be surprised that about 40% of the Holstein sires in active AI lineups, including numerous household names, have two copies of the A2 gene. In addition, over 80% of Holstein sires have at least one copy of the A2 gene.

Is A2 milk the answer for people with lactose intolerance?

A2 milk contains the same amount of lactose as non-A2 milk. So in clinically-diagnosed cases of lactose intolerance, A2 milk will not provide the benefits that lactose-free milk would offer.

Since most cases of lactose intolerance are self-diagnosed, some doctors believe the cause of indigestion in those cases is actually linked to an A1 aversion rather than lactose intolerance. In those cases, drinking A2 milk may help prevent the side-effects otherwise experienced from drinking regular milk.

Should you select for A2 in your breeding program?

With this new information at hand, it may seem compelling to produce only true A2 milk. Many A2A2 sires are available, but you still have an opportunity cost by selecting only A2A2 sires.

When A2A2 is a limiting factor in your genetic selection, you’ll eliminate about half of all bulls available. That means you will likely miss out on pounds of milk, extra health and improved fertility traits.

Regardless of your selection decision around A2 sires, make sure it aligns with the customized genetic plan you put in place on your farm so you can maximize profitability and genetic progress in the direction of your goals.

 

Click HERE to view a list of Alta’s current A2A2 sires.

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