Important Anti-Nutritional Substances and Inherent Toxicants of Feeds

Abstract

Review was carried out on important ant- nutritional factors and toxins in animal feed, their effect on animals and possible mechanisms to reduce toxicity.  The major anti- nutrients found in plant protein sources are saponins, cyanogenic glycosides, tannins, phytic acid, oxalates, protease inhibitors, chlorogenic acid and amylase inhibitors.  Anti-nutritional factors are compounds which reduce the nutrient utilization and/or feed intake of plants or plant products used as animal feeds. Numerous Anti-nutritional factors (ANFs) in forages can cause toxicity in livestock. Some of these toxins are produced by the grasses, legumes and other forages. The tannin-protein complexes are astringent and adversely affect feed intake and  cause negative animal responses. Saponins  can affect animal performance and metabolism through erythrocyte haemolysis, reduction of blood and liver cholesterol, depression of growth rate, bloat (ruminants), inhibition of smooth muscle activity, enzyme inhibition and reduction in nutrient absorption. Phytic acid forms  protein and mineral-phytic acid complexes and  reduces protein and mineral bioavailability, inhibits the action of gastrointestinal tyrosinase, trypsin, pepsin, lipase and amylase. Oxalic acid on the other hand binds calcium and forms calcium oxalate which adversely affects the absorption and utilization of calcium in the animal body. The positive  effect of tannin in animal feeding includes; increased efficiency of protein utilization, reduction of parasite burden, reduction of proteolysis during ensilage, bloat prevention, increase quality of animal products, reduction of emission into the environment and defaunate rumen. Saponins have shown a variety activities such antitumor, cholesterol lowering, immune potentiating, anticancer, antioxidants.  A number of methods can be employed to reduce the toxic effects of antinutrients in animal feed.