I do believe this. I live in the UK where there is regional variance in the taste of milk. I believe this is due to factors such as the breed of cattle, the type of cattle feed (which is sometimes season dependent) and processing techniques. Supermarket milk is commonly from Friesian cows, but sometimes from Ayrshire cows (especially in Scotland) or from Jersey cows (especially in South West England). My personal favourite is non-homogenised milk from Ayrshire cows.