Vitamins and minerals are crucial for the growth and productivity of cows. However, benefit only occurs when supplementing correct deficiency. If there is no deficiency, supplementing animals may have poisoning.

Vitamins

As far as research has shown, oversupply of water soluble vitamins would not harm the cows. Any excess will be excreted in the urine. However, fat soluble vitamins (Vitamin A, D, E and K) are stored in the cow's body and oversupply of Vitamin A and D may cause food poisoning.

Vitamin A

• Vitamin A is required by the retina and it is good for eyesight and is needed for tissue and bone formation, growth, milk production and reproduction.

• Vitamin A maintains healthy epithelium, so deficiencies may increase mastitis infection.

• Cows generally require about 100,000 international units (IU) of Vitamin A.

• Cows fed with good quality forage seldom faced Vitamin A deficiency.

Vitamin D

• Vitamin D is formed in the skin when stimulated by sunlight.

• It is required for calcium and phosphorus metabolism in the body.

• It stimulates calcium absorption in the small intestine.

• Cows generally need around 50,000 IU of vitamin D a day.

• Excess Vitamin D may cause calcification of soft tissues, especially aorta.

Vitamin E

• Vitamin E helps to improve immune function to help fight off infection.

• Cows need around 1,000 IU of Vitamin E a day and higher amounts may be required during calving time.

• Lack of Vitamin E may cause poor reproductive performance and low conception rates.

Minerals

Essential macrominerals

• Macrominerals are those that required in quantities of grams per kilogram of dry matter (g/kg DM). They include calcium, phosphorus, magnesium, potassium, sodium and chlorine.

Essential microminerals

• Microminerals are those that required in quantities of milligrams per kilogram of dry matter (mg/kg DM). They include cobalt, copper, iron, iodine, zinc and so on.

Generally, mineral deficiencies are less likely to occur if green forages are part of the diet. High producing herd fed diets high in cereal grain or maize silage may need additional minerals.