Which part of alimentary canal is involved in killing of bacteria and formation of faeces?
And
Why have ruminants developed the habit of ‘chewing cud’?
Stomach and mouth are involved in killing of bacteria while large intestine helps in formation of faeces.
Ruminants chew their cud again to break it down even more as plant materials on which they feed are more complex and raw which takes more time to be broken down and digest. As during taking in food, they are in danger of getting hunted, they eat at faster rate and as much as possible which does not give them enough time to chew their food . So, their food gets stored in a part of their stomach until the animal finds a safe place to eat. Then the animal brings up the food or cud to chew.