THE VALUE OF MINERAL ZINC IN ANIMAL PHYSIOLOGICAL FUNCTIONS

Résumé

Zinc is one of the most important trace elements in the body, and it is indispensable to the growth and development of microorganisms, plants, and animals. This review work looks at the value of zinc in animal physiological functions. In domesticated species, experimental zinc deprivation was produced first in chicks and pigs. Zinc - responsive disorders were induced by excess dietary calcium in poultry attributed to a potent and complex interaction with the major source of phosphorus in feed grains (phytate). Fetal growth is especially affected by lack of zinc. Zinc deprivation increases the expression of the gene for the appetite-regulating hormone cholecystokinin and also increases the susceptibility of endothelial cells to oxidant stress. The role of zinc is probably multi-factorial. Zinc regulates genes involved in signal transduction, responses to stress, reduction—oxidation reactions, growth and energy utilization. It is also a potent inducer of metallothionein (MT), a zinc and thiol - rich metalloprotein that scavenges free radicals and could act as a reduction— oxidation sensor or active signalling switch in cells. Zinc aids in proper assimilation of vitamins, normal growth and development. Zinc supplementation also cured and prevented parakeratosis, a thickening and hardening of the skin found in pigs given grain-based diets, rich in calcium. It is therefore important that the value of zinc in animal physiological functions be assessed and deficiency corrected in some chronic animal diseases.