Protein is absolutely essential for growth, reproduction and maintenance in monogastrics and ruminants. Mature animals require less protein on the basis of percentage of the feed offered than young ones. Excess protein is utilized as an energy source. To full fill requirements of proteins you should feed Amino Power, which great source of supplementing proteins.
Vitamin A is the most important vitamin in cattle nutrition. It is the only one that normally must be added to cattle diets. It is necessary for bone development, sight, and maintenance of healthy epithelial tissues (i.e. lining of digestive and reproductive tracts). A deficiency can cause an increased susceptibility to disease, night blindness and reproductive failure.
Vitamin A contains carotenoids. Carotenoids are broken down in the body to vitamin A. Thus forages are not analysed for vitamin A but carotenoids, which are measured in milligrams per kilogram or pound: mg/kg or mg/Ib. Animals on green grass can store vitamin A in the liver and draw on it for 2-3 months.
To fulfil requirement of Vitamin-A water-soluble vitamin A should be given to cattle. Grovit -A is a very good supplement to overcome deficiency of Vitamin -A.
Vitamin D is called the sunshine vitamin because ultraviolet light acting on a compound on animal skin changes that compound into vitamin D. Vitamin D is found in sun-cured forages. Animals kept outdoors or fed sun-cured hay do not usually suffer a deficiency, whereas animals kept indoors and fed silage may do so.
Vitamin D is involved in the uptake to Ca and P, so that a vitamin D deficiency resembles a Ca and P deficiency: rickets in the young animals, weak bones in older animals, and a decreased growth rate.
Vitamin E and selenium have similar and interrelated functions in the body. Use supplements containing vitamins D and E in addition to vitamin A. They may not always be necessary but cost little to add.