Tag: Dairy genetics

Recent studies suggest A2 milk may offer a more comfortable digestive experience for some individuals compared to conventional milk containing both A1 and A2 proteins. But since A1 and A2 milk look and taste the same, figuring out how do I know if my milk is A2 requires a deeper investigation.

According to a 2023 study published in *Frontiers in Animal Science*, the frequency of the A2A2 genotype in genotyped Australian Holstein cows increased from 32% in 2000 to 52% in 2017. This demonstrates that not only *can* Holsteins be A2A2, but the trait is becoming more prevalent due to selective breeding.

Originally, almost all cows produced milk containing only the A2 beta-casein protein. Today, producing A2 milk requires a multi-step process involving identifying, selectively breeding, and segregating a herd of cows to ensure the milk is free of the A1 beta-casein protein.

Genetic research shows that the A2 beta-casein protein is primarily found in older, heritage cattle breeds rather than a single specific one. This discovery has led to a growing interest in knowing exactly what breed of cow has A2 milk, which contains only the A2 protein and is often associated with easier digestion.

Up to 2.25% of cows in certain breeds carry a genetic mutation that causes a fishy odor in their milk, but this is just one of several potential culprits. Understanding why does my raw milk smell fishy is crucial for ensuring milk quality, taste, and safety.

Beta-casein, which makes up about 30% of the protein in cow's milk, exists in two major forms: A1 and A2. Knowing how to tell the difference is crucial for those sensitive to A1 protein, as it involves scientific testing and understanding cow genetics rather than relying on taste or appearance.

Casein makes up roughly 80% of the total protein in cow's milk. However, simply asking, "Does all cow's milk have casein?" overlooks the crucial genetic variants that determine the specific types of this protein present, which can influence digestibility for some individuals.