Importance of trace minerals and relevance of their supplementation in tropical animal feeding system: A review

Trace minerals are required by animals in smaller quantity and based on the established functions atleast 9 trace minerals are essential (Fe, Cu, Zn, Mn, I, Co, Se, Mo, Cr). Trace minerals activate several enzymes responsible for various biochemical functions and some are integral part of enzymes/hormones/vitamins.Trace mineral deficiency impaires productivity in livestock. Body trace mineral status, immunity and reproductive functions have direct relationship Cu, Co, I, Se, Zn and Mn are likely to influence these functions. The trace mineral content in plants is governed by geochemical nature of soil and species of plants besides agro-climatic conditions. The requirement of trace minerals in livestock is dependent on level of production, physiological status and feeding system. Legume fodders, cultivated green fodders and tree leaves are good sources of Fe, Zn, Cu, Co and Mn, and oil-cakes and bran are good sources of Zn, Mn and Cu. Chemical form of inorganic source and anti-nutritional factors (silica, tannins, phytate) greatly influence the bioavailability. Chelated or organic forms of minerals (Cu-lysine, Zn-methionine) have better bioavailable and improved immunity and reproduction. In tropical regions, mostly Cu and Zn are deficient in most fodders, whereas the level of Mn, Co and Fe is either adequate or high. Low reproductive efficiency of livestock in most regions is generally attributed to the deficiency of Cu, Zn and Mn. Supplementation of the most deficient minerals as area-specific mineral mixture improved production and reproduction of animals. Chromium is an essential element because of its role in glucose utilization, reducing muscle fat content and increasing the Leanness of meat. Boron, lithium, silicon, nickel arid vanadium though may not be dietary essential but on supplementation in controlled conditions have shown beneficial effects.