What is the main source of energy for ruminants?

The main source of energy for ruminants is volatile fatty acids (VFAs), which are produced during the fermentation of fibrous plant material in their stomachs, particularly in the rumen. As ruminants break down cellulose and other complex carbohydrates through microbial fermentation, VFAs like acetic, propionic, and butyric acid are generated. These VFAs are then absorbed into the bloodstream and serve as a primary energy source for the animal's metabolism. Additionally, ruminants also obtain energy from the digestion of proteins and fats, but VFAs are the most significant contributor.