The composition of A2 proteins varies amongst different breeds with Holstein Friesian having the lowest proportion and Guernsey has the highest proportion of A2 proteins in milk. Many Indian subcontinent breeds like Shahiwal, Gir, Rathi, Red Sindhi, Kankrej, Tharparkar are good source for A2 milk. In Indian breeds Gir species is the best choice due to its less interbreeding.