Role of Vitamin A in Vision, Fertility and Immunity of Ruminant

Vitamin A is necessary for animals because it supports many body processes. The major functions of vitamin A are crucial for maintaining the health and the productivity of cattle, sheep, goats and other ruminants. Vitamin A exists in several forms like retinol which is the primary form, retinyl esters which is the storage form of retinol and retinoic acid, retinaldehyde are the activated form of vitamin A. With recent studies, retinol has become recognized for its anti-ageing property and also helps in development of muscles, forming pre-adipocytes and reducing reactions to allergens in milk proteins. Vitamin A in preformed form comes only from feeds made from animal sources. Several poly isoprenoid plant pigments called carotenoids can transform into retinoids which gives them vitamin A activity. In animals, enzymatic changes can only change a little bit of the carotenoids into retinol or retinoic acid precursors. Whether they are fully used or not it depends among other things like, how protein is bound, the kind of animal, its diet and vitamin A levels. Usually, ruminant diets are mainly based on roughages and grain cereals and these lack vitamin A. Because herbivores cannot make enough retinol, it is usual to give them extra vitamin A in the form of retinyl acetate. It is well understood that providing enough of this vitamin, whatever the method used, is important. The amount of vitamin A needed depends on environmental conditions, genes and the food being eaten. Gaining a full knowledge of how vitamin A is metabolized in ruminants helps to determine nutrition needs and point out possible health risks comes from not getting enough of the vitamin and offering smart recommendations for addressing deficiencies strategies.