We have been breeding for A2A2 genetics since 2006. We test each generation to ensure the A2A2 genetics are being expressed.
What is A2A2 genetics? A2-A2 milk carries the A2 type of β-casein. Most commercially available milk contains both the A2 and A1 protein. The A2-A2 gene is the oldest casein protein and can be found primarily in the heritage breeds, such as Jersey, Brown Swiss, and Normande.
The A1 gene was a mutation that eventually became widely spread among dairy breeds, and is predominantly found in Holsteins. But, even among cross breeds of heritage bovines, the A1 gene is still found. That is why we test each generation.
- The A1 mutation causes a change in a single amino acid in the a-a chain, the amino acid at number 67 is histidine in A1 and proline in A2 milk. This polymorphism leads to a key conformational change in the secondary structure of expressed β-casein protein.
- Digestion of A1 milk yields a compound called beta-casomorphin-7 (BCM7). No such compound in the digestion of A2 milk.
- In hydrolyzed milk with variant A1 of beta-casein, the BCM-7 level is 4-fold higher than in A2 milk.
- New Zealand researchers claimed that A1 milk contains beta-casein which is harmful to human beings. The results of the NDRI research also indicated that A1 milk that is served to infants and old age people damages the immune system.