The cows are the heaviest milkers of all zebu breeds and display a well-developed udder. They did eventually allow milkers, balers, propane gas and pneumatic tires. Polled Dorsets are a medium-sized sheep that are long lived and prolific, heavy milkers. The milkers were not allowed to bring the milk in direct from the farmyard. British Alpines are excellent milkers, well known for their extended lactations.