Green mass of grasses and shrubs was the base of the diet of horses, cows, sheep, goats and other herbivores in the process of evolution. Ancestors of domesticated herbivores had little chance to find any amount of plant seeds, grain, root vegetables or other high calory feeds that could affect the evolution of their digestive system.
Modern high-tech farms use up to 80% of the green mass of cereals and legumes (structural feeds) in farm animals' diet while concentrates are added mainly to balance the composition of the ration. Increased volume of herbal fodder in farm animals' diet can significantly extent period of productive life, improve reproduction and save on veterinary expenses.