The major minerals in livestock nutrition are:

Sodium and ChlorideNa and Cl

These minerals are included in rations and are calculated as so many grams per ton.


Calcium is clearly linked with phosphorus in the metabolism of animals. Calcium and phosphorus together make up over 90% of the ash of the animal body, and 99% of calcium and 80% of phosphorus is found in the bones and teeth of an animal.


Good grassland and especially legume herbage is high in calcium, as are roughage foods – hay and silage. The calcium content of both and the roughage made from grass can be increased by the application of agricultural lime to the pasture or veld. Steamed bone flour and mono-calcium phosphate both have a high calcium content and are added to concentrate rations to increase the supply of calcium. Cereal grains are low in calcium.


Metabolism: the chemical processes that occur within a living organism in order to maintain life.  
Malformation: an abnormally formed part of the body.

The malformation of the bones in young, growing animals and humans, causing the condition called rickets. Children who suffer from lack of calcium

often develop bent and deformed legs.

  • The weakening and bending of bones in adult animals especially during their pregnancy and lactation.
  • Milk fever in dairy cows, particularly good milkers that have just calved. The calf suckles the cow and removes milk from the udder, and calcium is transferred from the blood to the new milk. The lack of calcium in the cow’s blood affects the brain causing spasms, coma and death. The condition can be cured by injecting 250 – 500ml of a solution called Calcium Borogluconate directly into a vein.
  • The animal will recover within about 20 minutes. This disease is badly named because it is not a fever and the animal does not develop a high temperature.


This mineral is essential for the formation of sturdy bones in the growing animal. It is an important part of the protein in the nucleus of the cell and blood, and there are large amounts present in milk.

A dry Friesland cow requires 17 grams of calcium and 17g of phosphorus a day.

A Friesland cow giving 35kg of milk requires 115g of calcium and 87g phosphorus a day.


The sources of phosphorus are the opposite to those of calcium. Grass and roughage are low and cereal grains are high in phosphorus. The total mineral (also called the total ash) calcium and phosphate contents of some common foodstuffs are given below:

 Total Ash %Calcium %Phosphorus %
Lucerne Hay8.12.00.23
Cotton Seed Meal6.70.301.20
Soybean Meal5.50.210.92
White Fish Meal21.57.14.0
Dicalcium Phosphate85.026.520.5
Steamed Bone Flour87.032.013.6


The important thing in animal feeding is to feed the correct amounts of both calcium and phosphorus. Feeding too much calcium can cause a deficiency of phosphorus and too much phosphorus will lead to a deficiency of calcium. The balance between calcium and phosphorus is most important in breeding cows and particularly high yielding dairy cows. Too much calcium and a deficiency of phosphorus cause infertility. Such cows do not become pregnant when they are served by the bull. A good level of phosphorus should be maintained in the cow’s ration particularly during the 2 – 3 months after calving when the cow is giving the most milk.

Calcium, phosphorus and vitamin D all seem to work together in the chemistry of the breeding cow.


Although this is an essential mineral for all species, deficiencies occur only in ruminant animals. In an adult cow, magnesium is found in the following proportions:

59%in the bones;
40%in the soft tissue; and
1%in the body fluids the blood plasma in particular.

In an adult animal, the magnesium in the bones is locked up and unavailable to the rest of the body so that magnesium has to be included in the ration. Magnesium is associated with calcium and phosphorus in the metabolism of the animal. Deficiency of magnesium does cause one serious disease called Grass Staggers, or Hypomagnesaemia Tetany. This is particularly serious in the United Kingdom. This disease usually occurs in milking cows in the spring season, when the young, growing grass is low in magnesium. The milking cows lose more magnesium in their milk than they can

 Convulsions: a sudden, violent, irregular movement of the body, caused by involuntary contraction of muscles and associated especially with brain disorders.  
Perspiration: the process of sweating.

replace from the grass and develop a magnesium deficiency in their blood. This in turn affects the brain and the cow is seized with violent convulsions, quickly goes into a coma and dies.

The time between the onset of the symptoms and the death of the animal can be as short as one hour. Provided the symptoms are seen, the disease can be cured quickly by injecting the animal with a solution containing both calcium and magnesium. This restores the level of magnesium in the animal’s blood.

Epsom salts, which is magnesium sulphate is dissolved in water and given to animals as a laxative.


These two minerals are considered together as they are fed to animals in the form of common salt, the chemical Sodium Chloride (Na C1).Sodium is found in the soft tissues and body fluids in the form of sodium ions, Na+. It is an important ion in blood. Chloride is an important part of the gastric juices.

Sodium Chloride, or salt, is lost from the body as perspiration. A deficiency of salt in the body causes poor growth, low milk yields and weight loss in animals, because the lack of salt interferes with the digestion of carbohydrates and proteins in the small intestine.

The absorption of salt from food is very efficient, and a deficiency should occur only with lactating animals or in very hot weather. Salt is put into urea blocks used as a winter feed for cattle on the veld because it limits the amount of the block the animals eat. Both roughage and cereal foods can be low in salt, and some salt is included in most concentrate rations. Water that contains up to 2% salt is safe for cattle to drink.


This is an essential compound for cattle but all foods including grass contain far more potassium than animals require. Excess potassium is passed out of the body in the urine.


Sulphur is present in the body as part of protein so that a low sulphur intake can cause a deficiency of protein. Extra sulphur should be fed to the animal to help the manufacture of protein in the body.


The Trace Elements in animal nutrition are:

ElementsChemical Symbol

These minerals are required by animals in very small quantities and their requirements are expressed as parts per million – p.p.m.), or milligrams per kilogram (mg/kg).


Iron is important to the animal because it is an essential part of the blood, particularly in hemoglobin which carries the oxygen in the bloodstream. A lack of iron causes the condition called anaemia in both animals and humans. This results in a loss of the red blood cells and can cause death. Milk is deficient in iron so it is a routine practice to inject young pigs with an iron solution at 3 days old to prevent them from developing anaemia.

Iron is stored in the bone marrow of the animal. Cereals, green crops, meat and eggs are fairly rich in iron.


Rations that contain less than 10 p.p.m. of manganese can cause poor growth in animals and a delay in heifers coming on heat. Too much manganese can interfere with the metabolism of other minerals in the body.


In ruminants, copper is linked with iron in the formation of hemoglobin in the blood. Normally, 1.0

p.p.m. is enough in a ration for cattle, 0.75 p.p.m. is the normal level in the blood.

In the feeding of pigs, however, copper is used to speed up the growth of pigs up to bacon weight, and 175 p.p.m. is put into pork and baconer rations. Although nobody is quite sure why this higher level of copper makes pigs grow faster, it is thought to improve the efficiency of the digestion of carbohydrates and proteins; and thus the animal makes better use of its food.

A deficiency of copper in cattle causes the animal to scour badly and pine away.


This mineral is used to manufacture a hormone called thyroxin by the thyroid gland in the neck. The hormone is connected with the general chemistry of the animal’s body. A deficiency of iodine causes the thyroid gland to swell up, a condition called goiter, which occurs in both animals and humans. As this interferes with the production of thyroxin, cattle give birth to hairless calves and sheep produce dead lambs. Infertility can be caused in both cattle and sheep.

Where sheep are grazing on heavily fertilized star grass pastures, chemicals produced in the grass  can reduce the amount of iodine taken up by the animals causing a deficiency in their diets. Too much iodine does not affect animals.


This mineral is used by the bacteria in the rumen of cattle and sheep to manufacture vitamin B12 and a lack of cobalt causes a lack of vitamin B12.


Zinc is used to increase the growth rate of pigs and a deficiency of zinc causes skin diseases in cattle and pigs.


This is closely associated with Vitamin E in the body and a deficiency of either selenium or Vitamin B can cause white muscle disease in calves and lambs. The muscles waste away and the animals die. Any excess of selenium in a ration is highly poisonous and it should not be added to foodstuffs. Animals suffering from white muscle disease can be injected with a special solution containing the correct quantity of selenium.

3.       VITAMINS

These are organic compounds found in very small quantities in food and are essential for normal health and growth. They are not a single class of compound like minerals. These are many different compounds. They are classed together because they have one thing in common – they are required by the animal in very small quantities. Vitamins are measured in what are called International Units (I.U.).

Vitamins are divided into Fat Soluble and Water Soluble Vitamins.


  • Vitamin A
    • Vitamin D
    • Vitamin E
    • Vitamin K


  • Vitamin B complex
    • Vitamin C


This vitamin occurs in egg-yolk, milk and liver (cod liver oil). It is also found in plants in the form of the green pigment carotene, which is converted into vitamin A in the wall of the gut of an animal and stored in the liver. Both Vitamin A and carotene are very sensitive to oxidation, hence the bleaching of weathered hay.

Well-compacted green silage is a good source. Normally, grazing animals will store enough of the vitamin in the liver to last the winter. Carrots and yellow maize are also rich sources of Vitamin A. A deficiency of this vitamin will cause a lowering of resistance to disease, un-thriftiness, and blindness in animals and night blindness in humans. The colour of body fat of cattle and milk fat of cows is mainly due to carotene. The high butterfat in milk of Channel Island breeds in cattle is mainly due to carotene. Pale cream and butter at the end of the winter, before cows are turned out, demonstrates this fact clearly. Colostrum is 5 to 10 times richer in carotene and Vitamin A than normal milk.


Vitamin D is associated with Vitamin A in fish liver oils. Cod liver oil is a rich source, as is egg yolk. However, vegetable foods are a very poor source of Vitamin D. In the animal, Vitamin D is closely bound up with calcium and phosphorus depositions in the bones, and lack of it can cause rickets in young stock, as well as soft-shelled eggs in poultry.

Vitamin D appears to be important in the conversion of calcium and phosphorus into milk minerals, and large doses before calving have sometimes prevented milk fever in dairy cows.

The chief source of Vitamin D in farm animals is sunlight as the ultra violet radiation from the sun acts on chemicals under the skin, which produce the vitamin.

Cow’s milk has been shown to be ten times richer in Vitamin D in Summer than in Winter when there is less sunlight.


This vitamin occurs in the germ oil of cereals and in green foods, especially leaves. It is also present in egg-yolk, and limited amounts are found in milk. A deficiency of vitamin E causes sterility in rats and poultry, but this has not been confirmed in the case of livestock. It has also been associated with the development of muscular dystrophy in calves and lambs, causing death through the failure of the heart muscle.


This vitamin is present in cereals. Its deficiency causes capillary weakness and poor blood-clotting in chicks. However, a deficiency does not normally occur in farm animals. It can synthesize Vitamin K in the rumen.


Dystrophy: Dystrophy: poor nourishment or malnourishment.  
Low hatchability: A large proportion of the eggs laid by hens which suffer from a deficiency of Vitamin B, fail to hatch out.

This vitamin consists of a number of organic compounds; i.e. vitamins B1 through to Vitamin B 12. The compounds are widely distributed in foods, although some foods may contain one or more without containing all twelve.

Yeast and cereal bran contain several vitamins of this complex, as do milk (Riboflavin), liver and kidneys.

Ruminants can synthesise most of the Vitamin B complex in the first stomach.

Deficiency diseases in humans are Beri-Beri, Pellagra and Dermatitis. In poultry, a deficiency of Vitamin B Complex causes low hatchability and Curly Toe disease. Adult cattle do not suffer from the deficiency.


Vitamin C is widely distributed in plants, but animal products including milk, are poor sources. Vitamin C is easily destroyed by heating in air. The small amount found in milk can be lost by passing over a cooler.

From 1795, the disease known as Scurvy was eliminated from the British Navy by the issue of one ounce of lemon juice daily. The disease was caused by a lack of Vitamin C in the diet.

Rats, dogs and birds are able to synthesise Vitamin C, but humans and monkeys cannot do this. Farm animals do not appear to suffer from a deficiency of Vitamin C as they are able to synthesise Vitamin C in their tissues.

Vitamins are measured in International Units. Although each vitamin has a specific function, there is also a relationship of function. Deficiency of Vitamin A or E causes sterility. Vitamins A, D and C influence bone formation. Vitamins A, B, D and E affect growth while Vitamin C and A are associated with resistance to infection.

4.    WATER

Most foods are mixtures of compounds, some fairly simple and others very complex. The simplest compound is water which is present in all animal foods, and varies in extent from about 10 – 20% in dry foods like cereals and roughages, to 70 – 90% in succulent foods like grass, silage, cabbage and other green crops. Water is essential for all plant and animal growth and metabolism. To build up one part of dry matter, a plant transpires up to 1 000 parts of water, as neither plants nor animals

can make use of any food until it has been made completely soluble. About two-thirds of the weight of the body of an animal consists of water and some animal products are very rich in water; milk contains about 87.5% and eggs 66%. Water is essential for the formation of blood, digestive juices and all the other body fluids. A starving animal may lose nearly all its glycogen and fat, half of its body protein and about 40% of its body weight and still live.

The loss of 10% of its water causes serious disturbances in the body and the loss of 20% of its water will cause death.

Water may be consumed directly by animals, or as the moisture contained in succulent feed. However, all stock should have access at all times to a good supply of clean drinking water. The following daily requirements are a guide:

Horses50 litres per head per day
Cattle – fattening, at winter temperatures44 litres per head per day
Cattle – fattening, at temperatures over 27°C70 litres per head per day
Dairy Cows44 litres per head per day
Plus9 litres per 4.5 liters of milk produced
Pigs3 litres per kg of dry meal fed
Sows – dry4.5 litres per head per day
Sows – suckling young25 – 30 liters per head per day

Young cattle and sheep should have access to clean water at all times.

There are a number of factors which affect the water intake of cattle and these are:


Water consumption increases with feed intake. An animal will eat the maximum amount of food when it has a good supply of water. This is particularly important with dairy cows and steers being fattened in pens.


A high water intake is associated with high levels of protein or non- protein in the feed. On the other hand, cattle eating a large quantity of succulent feed will use less water than when eating dry feed.


A high level of minerals, particularly salt, in the food will increase water consumption by cattle. In some areas, the water itself contains mineral salts, making it alkaline or ‘brak’. The maximum safe level of salts in drinking water for cattle is about 1.5%, and if necessary, cattle become used to drinking such water. Sea water contains about 3% of mineral salts.


Water intake by cattle increases as the temperature rises, especially when the air temperature rises above 20°C.


Water intake is affected by the temperature of the water available to the animal. Cattle will drink less if the water is very cold or very warm. If possible, water troughs should be placed in the shade.


Cattle should have access to water at all times but if this is not possible they should be allowed to drink at least once a day. Cattle can survive by drinking every other day, but this should only happen in an emergency.


Lactating cows will drink more water than a dry cow.