cows in field

Value-Added Cow Genetics: Taking a look at A2/A2

By Tamara Scully, NODPA News Contributing Writer

Value-added products are those which generate an additional or increased profit from the farm’s production, achieved by altering the raw product in some way, so that a higher profit can be made. In dairy circles, adding value to milk doesn’t necessarily require a change from its fluid milk stage, however.

Producers can add value by processing and bottling their own milk, whether in its raw or pasteurized - but maybe not homogenized - form. For many consumers, cream-on-top milk is a welcomed throw-back to simpler times. For others, non-homogenized milk represents milk in its pure form, as fat globules are not altered. Although claims of enhanced digestibility of non-homogenized milk don’t appear to have any scientific relevance, some consumers do claim to have less digestive upset from cream-line milk.

Certified organic milk has commanded a price differential on the commodity market, as organic standards disallow many conventional practices which consumers may not approve. But the differential is also tied to health benefits, as practices such as managed grazing can add desirable nutritional properties to the fluid milk.

Certified organic milk isn’t the only option for capturing a retail premium. By creating a functional food - one which has added health value beyond its basic nutritional content - dairy producers can make fluid milk into a value-added product.

Milk produced by cows on forage-only diets is now a widely available niche market, and consumers are willing to pay a higher retail shelf price for milk made without grain. Milk brands wasted no time adding omega 3 fatty acids into their milk and marketing it as a nutritional benefit, despite the fact that the amount of omega 3 fatty acids is less when compared to other dietary sources such as fish. Food Science and Nutrition research found that milk from grass-fed cows had 147 percent more omega-3s than conventional milk and 52 percent more than organic milk. Horizon sells their milk with 32mg of DHA Omega-3 per 8 fluid ounces (224grms) serving. Brad Heins, UMN extension, reports that a seven fluid ounce serving of grassmilk has 100 mg of omega 3; USDA reports that a 3-ounce serving of farmed tilapia delivers about 100 mg of omega-3 and a 3.5 ounce of farmed salmon has 2,260 mg of omega 3.

Amounts of conjugated linoleic acid (CLA) present in milk from grass-fed cows can be twice as high as is found in milk from non-grazing herds, with seasonal variability. Stable throughout processing, and thought to have anti-carcinogenic properties in humans, CLA can have a positive impact on cardiovascular disease, diabetes, inflammation and pancreatic function. Although it is a trans fatty acid, those derived from ruminant animals do not seem to be detrimental to human health.

The fatty acids profile of milk - and the enhanced CLA content of milk from grazing herds - is one reason why milk is considered a functional food. Another up-and-coming quality with the potential to capture a premium, and which may also contribute to milk’s designation as a functional food, is A2 milk.

A2 Milk

More than 80 percent of the milk protein in ruminants comes from casein, while only half of the protein in human milk does. There are four categories of casein in cow’s milk, alpha - which has two subtypes, as well as beta and kappa-casein. Whey makes up most of the rest of bovine milk protein.

All proteins in cow’s milk have genetic variations. Beta-casein has a dozen genetic variants, including the A1/A2 mutations which have been making news over the past several years. These mutations are not anything new: They happened more than 5,000 years ago.

Heritability of the A2 mutation is not complex. If a bull is A2/A2 and a cow is A2/A2, the calf will be A2/A2, inheriting one gene from each parent. But if either parent has even one A1 variant, that A1 gene could be passed along to the calf. A cow can be typed as A1A1, A1A2, or A2A2.

There is no dominance or recessiveness, and therefore both genes are expressed in the cow and in the milk. A2/A2 milk only comes from cows with two A2 genes.

Health claims involving the superior digestibility of A2 milk are making news today, and gaining the attention of dairy farmers seeking to find additional premium pricing differentials, and capture more of their milk’s value in their milk checks.

Producing milk that can be digested by more people without discomfort was the goal when Alexandre Family Farm, in Crescent City, California, began to breed for A2/A2 genetics. Today, they are almost at their goal of raising only A2/A2 cows in all of their four herds.

“We jumped into it ahead of the market,” Blake Alexandre said of the farm’s commitment to A2 milk. “We took a leap of faith.”

That leap - made twelve years ago - has paid off, as they’ve found that milk from their A2/A2 cows is in demand. The milk is processed into their own and private label A2/A2 fluid milk and yogurt, too. They’ve recently entered the powdered A2 milk market as well.

Breeding for A2/A2

Blake transitioned the herd by breeding to A2/A2 sires, and did so at a time when finding those bulls was not an easy task, as the genetics were not yet valued highly. They opted to use only A2/A2 bulls and then further select within that population for other traits important to their herd.

“There’s a pretty good selection now,” across all of the breeds they use in their crossbred herd, Blake said.

Different breeds of dairy cows are more or less likely to carry the A2 gene, and the demand for the gene has increased the sire availability across breeds, according to Chad Debow, associate professor of dairy cow genetics at Penn State University.

Using A2/A2 sires and breeding only A1/A2 cows is the fastest way to convert the herd to fully A2/A2 genetics, he said. You can use A1/A1 cows, but the process of transitioning the herd will take longer, as there is no chance of a calf obtaining an A2 gene from an A1/A1 mother cow. You will always get an A2/A1 calf from this pairing, rather than having a 50-50 chance of an A2/A2 calf from the initial breeding.

Approximately 80 percent of Guernsey cows have A2A2 genetics and it is reported that all Guernsey bulls sold by AI companies are A2A2. Debow estimates that Jerseys are now at 85 percent A2A2 genetics, while Norwegian Reds and Brown Swiss breeds are both well above 50 percent. And a majority of Holstein’s sires are now A2A2, with less than 10 percent A1A1 sires being used by AI companies.

But does selecting for A2/A2 genetics come with any other genetic pitfalls? So far, none of those have been found.

“We do not believe A2A2 is genetically linked to other traits,” Debow stated. “In our data, the A2A2 cows perform as well as their A1 counterparts.” Cows can be tested directly for A2 genotypes, Debow said, with genotyping companies such as Zoetis providing this service. Genomically testing cows is also an option, which allows traits such as production and fertility to also be ascertained. A simple test for milk proteins - including beta-casein - may cost about $25.00 per animal. “In most instances, genomically testing will cost a bit more than A2 only, but you get a lot more information from the genomic test and that is what I recommend,” he said.

Milk can be tested for A2 genes, as methods available for testing milk for the beta-casein protein variant have been available since the 1960s, Dr. Peggy Tomasula, research leader of the Dairy and Functional Food Research Unit of the USDA’s Agricultural Research Service, confirms. These tests are now much easier for the laboratories to run, so DNA testing of the cow is not needed if you want to test for A2A2 genetics.

Premium Product?

Just a few years ago, Tomasula addressed the functional properties of A2 milk at the 2019 Northeast Pasture Consortium conference. At that time, A2 milk was in the news thanks to The a2milk Company, of New Zealand, which had recently begun selling their milk in the United States.

The A1 variant of milk produces histidine, an amino acid which has immunomodulating properties, at position 67 in the chain of 209 amino acids which make up the beta-casein protein. A2 milk has the amino acid proline in place of the histidine. This is the only difference between the two genes.

The A1 histidine mutation causes the protein to break differently during the digestion process, and allows the formation of the BCM7, which is related to the opiate family, to break free during the digestive process.

Tomasula explained that the release of $CM-7 during digestion of cow’s milk is thought to be the cause of gastrointestinal upset and inflammation which occurs in some of the human population. Lactose intolerance has been blamed, perhaps incorrectly, for many milk digestibility issues, although no conclusive studies on A2 digestibility have been widely accepted and the FDA has not approved any claims about the benefit of A2 milk. Several long term studies are being conducted in the United States on digestibility differences between A2 and A1 milk, and both are expected to conclude in 2023.

The Alexandre’s believe that the demand for their A2 milk is evidence that consumers are receiving benefits by drinking their milk, and have heard from many customers who state they can now enjoy milk without digestive upset.

The rising demand for healthier food products should enhance the market for A2 milk, and recent global dairy market reports expect the A2 market to expand in the United States and internationally over the next several years. Just how much of an opportunity A2 milk might provide remains to be seen and its potential is not yet evident based on retail shelf prices.

In the Northeast region, the supermarket shelf price of A2 milk appears to be less than that of Organic Valley’s GrassmilkÔ, Horizon Organic DHA Omega 3 milk, and also less than some brand’s certified organic milk price. It is more expensive than conventional milk.

A2 genetics may provide opportunities to differentiate fluid milk and dairy products, and many - such as Alexandre Family Farm - have already opted for A2/A2 cow genetics. Research continues into the A2 gene, its possible role in enhancing milk digestibility, and the role it may play in dairy herds - and dairy premiums - moving forward.