Practical implications of comparative digestion in farm animals

Monogastric (non-ruminant) animals cannot digest fibrous feed (cellulose, hemicellulose) and depend on high quality, low-fiber concentrate diets. Among the monogastrics, horses and rabbits, due to their well developed caecum is less efficient than in the rumen. Therefore, horses should be fed good quality forages. On the other hand, ruminants, because of efficient microbial fermentation in the rumen, have acquired the ability to digest a wide range of roughages, including poor quality cereal straws and other crop residues. Ruminants can also utilize non protein nitrogen from sources such as urea as a dietary crude protein and convert it to a protein of high biological value (microbial protein).
The unique digestive features of ruminants enable them to utilize agro-industrial by products and wastes which cannot otherwise be used by monogastrics, including man. As ruminants depend largely on the fermentation products of the rumen (VFA's and microbial protein), conditions in the rumen should be optimal at all times to support efficient fermentation. This can easily be achieved by taking care of the nutrient requirements of rumen microbes. Recent developments in ruminants nutrition have emphasized that these animals should be fed in such a way that their capacity to utilize roughages and non-protein nitrogen is exploited to the greatest extent possible, and at the same time high quality feeds (such as good quality feeds and starches) should be protected from rumen fermentation so that they escape from the rumen and are efficiently digested and abosrbed in the small intestine. Unlike ruminants, monogastrics cannot synthesize amino acids and vitamins B and K. Therefore they depend on feed resources for these nutrients.