What's good for horses is good for cows, and maybe even humans. That is one reason oats is a popular feed, although for cows the price doesn't fit into the least-cost ration formulation.
Carrots is another example.
Horses love them, and a regular feeding of carrots makes their haircoat glossy. But not too many dairy farmers feed carrots to their cows, not even to their prize cows. Cost and labor in handling small carrots is one reason. In this country we do not feed cows the bigger root vegetables, such as rutabagas, mangles or cowbeets, as farmers still do in Europe. Instead of feeding carrots, we add a carotene supplement to the feed ration.