Digestive enzyme
Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. Digestive enzymes are found in the digestive tracts of animals (including humans) and in the traps of carnivorous plants, where they aid in the digestion of food, as well as inside cells, especially in their lysosomes, where they function to maintain cellular survival. Digestive enzymes of diverse specificities are found in the saliva secreted by the salivary glands, in the secretions of cells lining
Methanogens in digestive tract of ruminants
Methanogens are a group of microorganisms that can produce methane as a byproduct of their metabolism.They hold an important place in the digestive system of ruminants. The digestive tract of ruminants contain four major parts, they are abomasum, rumen, omasum and reticulum.The food with saliva is first passed to the rumen for breaking them into smaller particles and then it moves to the reticulum where the food is broken into further smaller particles and the indigestable particles are sent back for rechewing and then to rumen.  The majority of the anaerobic microbes assisting the cellulose breakdown occupy the rumen. They initiate the fermentation process.The animal observes the fatty acids, vitamins and nutrient content on passing the partially digested food from rumen to omasum which, decreases the pH level and thus initiates the release of enzymes for further break down the food which is later passed to the abomasumthat absorbs remaining nutrients before excretion.This process takes about 9–12 hours.