Dairy Genetic Testing

Testing for dairy genetics can be tested across many different cattle breeds.

There are 3 main types of genetic testing used for milk genetics:

1. Beta Casein ( A2 Genotyping)
2. Kappa Casein
3. Beta Lactoglobulin

Beta Casein test is the most common test done on Dexters for milk genetics. It is in reference to one of the proteins in a cow's milk. The test is looking at the specific amino acid that is located on the 67th position on this protein. There are two types, A2 and A1. There are some variants for each type as you can see below:

1. A2 ( additional variants A3, H1, H2, I, J, K and L)
2. A1 ( also known as N) ( additional variants B, C, F and G)

The reason why A2 beta casein has been coined as better than A1 beta casein is because of the much higher levels of “bioactive peptide beta -Casomorphin 7” produced from the digestion of A1 milk variants, than found in digestion of A2 milk. Higher levels of this peptide are associated with negative impacts on human health in such things as sudden infant death syndrome, histamine release, lymphocytosis, and other health factors.

Kappa Casein test is not done as often as the Beta Casein ( A2) test. This test is looking for the gene that determines how much protein is in the milk. Milk with higher levels of this of kappa casein are better for cheese production to to the high protein amount.

For test record purposes there are 2 types:

1. A= this type has a lower concentration level of Kappa Casein in the milk
2. B= this type has a higher concentration level of kappa Casein in the milk

Test results can be AA, BB or AB. The level of Kappa Casein increases in this order AA ( least), AB (middle) and BB (highest amount.) So if you want a milk cow for producing cheese products you may want to invest in some testing for Kappa Casein to see if they produce the BB gene.

This Beta-lactoglobulin test is not done very often either in Dexter breeders. This test is looking for the gene that determines milk production and whey protein content. So this test will help tell you the likelihood of a cow's milk yield production and fat/whey content.

For test record purposes there are 2 types:

1. A= gene has higher levels of beta-lactoglobulin (relative)
2. B= gene has lower levels of beta-lactoglobulin (relative)

Test results can be A/A, A/B or B/B. The level of beta-lactoglobulin increases from B/B (low), A/B ( middle) and A/A ( high amounts.) Lower levels of beta-lactoglobulin are associated with better ability to make cheese products.

Much of the technical information and testing codes on this topic was found on UC Davis VGL DNA tests