East Friesians are used as either a purebred milking breed or as a crossing breed for other milking sheep. They can raise the average number of lambs born, as well as milk production, when crossed with other milk sheep breeds. They are not a very hardy or adaptable breed, but their cross-breeds can be. Crossing them with the Awassi breed has been a notable success in Mediterranean or semiarid environments. East Friesians crossed with the Lacaune breed have been a success in the Wisconsin environment. East Friesians were not introduced into North America until the 1990s, but since then, on account of their high milk yield, they have rapidly become the breed of choice among commercial sheep milk producers, although generally not in purebred form.