CHEYENNE -- With fierce-looking horns and shaggy black hair, the yaks that live on Willis Larson's ranch look like a cross between domesticated cattle and sasquatch walking on all fours. But despite the intimidating impression that they first offer, the scraggly coated bovines are actually tamer than cattle and train easily for use as pack animals, Larson says. Yaks also produce a low-fat, flavorful meat that has begun to attract health-conscious people looking for an alternative to beef. When he talks about his yaks, Larson's voice softens and he speaks about the complexity of each animal's personality. "They're clowns, and...