Breeds of livestock differ in size and production characteristics, which dictate their nutrient requirements, dry matter intake, and digestive ability. These factors influence which plants, and in what proportion, an animal chooses to include in its diet.
Research on redberry juniper illustrates the differences in dietary preference among breeds. Spanish goats ate juniper more readily than Angora goats, while Ibex goats (a wild breed from Europe) ate more than both domestic breeds. These differences may be explained by the degree of breeding selection. Ibex goats are largely feral and have experienced virtually no selective breeding by humans. Angoras have been highly selected for hair production, and Spanish goats are raised primarily for meat production. When selecting for these performance traits, managers may have inadvertently selected physiological traits that influence diet selection, such as the ability to handle various secondary plant compounds. Livestock selection and breeding may have also affected the kind of terrain animals can effectively forage. Breeds of cattle developed in mountainous terrain may graze rugged rangeland more uniformly than breeds developed in gentler terrain. An animal’s ability to navigate rough terrain is an advantage of using livestock to manage vegetation compared to conventional methods.