Major objective of this lecture is to present on Digestion in Ruminants and Rodents. Here briefly describe on Digestive System of Ruminants: Feed on plant – cellulose; Need cellulase to digest it; But ruminants do not produce cellulase. However their digestive system are specially adapted to carry out cellulose digestion. Here also focus on Ruminants. Ruminants has a stomach with 4 chambers: rumen, reticulum, omasum and abomasum. Finally describe on Abomasum of Ruminants and Rodents.