A1 cow breed include Holstein, Friesian and Ayrshire, which are often present abroad. However, Desi cow breeds like Gir, Rathi, Kankrej, Sahiwal, etc. produce A2 milk. A1 and A2 beta-casein are two types of proteins found in different milk types. BCM-7 is an opioid peptide which is released during the digestion of milk from imported cow breeds. As it is not absorbed properly by the human body, it might trigger undesirable health effects like type 1 diabetes, neurological impairment, autoimmune disease, heart diseases. (You can refer a book by name ‘Devil in the Milk’ by Keith Woodford, for relation between A1 protein and lifestyle diseases) Therefore, milk from Desi cows is beneficial for people as it has hypoallergenic properties and many other health benefits.