By-products can play an important role to minimize the gap between animal requirements and available animal feeds. Therefore, it is important to find out unconventional sources of feedstuffs for ruminant rations. Rumen contents as a low cost by-product which got from slaughterhouse as wastes contain considerable amounts of nutrients and after some certain inexpensive treatments can be used in livestock feeding. These wastes considered a very big pollution source and unused these materials increase the availability to get sour through microbiological active material, which easily fermented expels many unpleasant odors and gases. Also, it is considered a good medium for growth and reproduction of flies, encourage rodents and insects multiplication. Many studies were carried out using these wastes as unconventional feed for ruminants.