Dairy science · 6 min read
Research note · 3 September 2025 · revised 1 December 2025
Understanding A2 Milk in Gir Herds
Darvi Genetics Research Desk · Darvi Genetics field desk
Abstract
Beta-casein genotypes, laboratory verification, and what A2A2 status means for breeders and dairy brands.
A2 milk refers to milk from cows that produce only the A2 type of beta-casein protein. The distinction is genetic, not processing-based.
§01Genotypes
“Beta-casein genotypes, laboratory verification, and what A2A2 status means for breeders and dairy brands.”
Animals may be A2A2, A1A2, or A1A1. Only A2A2 animals exclusively produce A2 beta-casein. Claims should rest on laboratory genotyping of individual animals or bulk tank verification protocols.
§03Gir advantage
Many Gir populations show favorable A2 allele frequencies, but assumption is not certification. Progressive programs genotype foundation animals and track inheritance.
§04Practical breeding
When A2 is a market or product goal, mating plans should prioritize verified A2A2 sires and dams while still balancing type, health, and production.