Feeding Tips For Pork Farming

Pigs are non-ruminants, with a simpler digestive system than sheep, cattle and horses. Pigs will not graze exclusively on pasture, in the way cattle, sheep or horses do, but under some farming practices, with the right plant species, grazing can be significant. Protein however is always a particularly important component in pig food. Crude fibre should not exceed 5% for large pigs and around 3% for smaller pigs.

Porcine Nutrition and Feeding

Protein is particularly important for pigs. If protein is not included in their diet, there is a strong tendency for animals to not thrive, and often cannibalism may follow. There are 20 to 25 different amino acids found in proteins. Of these, the following ten must always be included in a pig’s diet:   Lysine, Isoleucine, Leucine, Methionine, Phenylalanine, Threonine, Valine, Arginine, Histidine and Tryptophan. Lysine is the most important amino acid in pig feeding.  If a ration contains 1 (one) part Tryptophan, it must contain 3.25 parts of Lysine.  Fish meal, which is an animal protein, is high in Lysine.  Of the vegetable proteins, soybeans have the highest proportion of Lysine, which accounts for the fat that it is commonly found in pig rations. Up to 60% of the protein needs of pigs can be met with protein-rich cereals such as maize, wheat, barley and sorghum. Additional protein may be supplied through legumes (for example soybeans) and animal products (for example fish meal, milk).

Minerals and trace elements

The most important minerals to be included in a pig’s diet are calcium, phosphorus and sodium chloride.


Calcium is required for the formation of bones, teeth and milk production in lactating sows.  A lack of calcium can cause rickets in young pigs.


Phosphorus is used in the formation of bone and for milk production.  It is a constituent of nucleo-proteins and blood.  The ratio of calcium (Ca) to phosphorus (P) should be 1.5 (Ca) to 1 (P) in the ration.

Sodium Chloride

Sodium Chloride, or salt, occurs in all parts of the body, mainly in the soft tissues and blood.  A deficiency of salt can cause retarded growth because it affects the ability to digest carbohydrates and protein.

Minor or trace elements required in pig nutrition are:


A deficiency of iodine in the feed can cause malfunction of the thyroid gland and also infertility in adult stock. An excess can however reduce the growth rate of young pigs.


Iron is required for the formation of haemoglobin in the blood (the red part of the blood).  A deficiency of iron can cause anaemia, particularly in pigs that are suckling.  The milk produced by sows is low in iron and only small amounts are passed on to the suckling pigs.  Young pigs require 7mg of iron a day and the normal practice is to inject the little pigs with 150 – 200mg of iron in the form of a soluble preparation before they are four days old.  Piglets that have become chilled in the farrowing house can show symptoms of anaemia because the function of the liver has been upset.


Copper is associated with iron in the formation of haemoglobin in the blood and the prevention of anaemia. High levels of copper in the ration of fattening pigs have been shown to increase their growth rate. The exact reason for this is not yet known although the copper is thought to benefit micro-organisms in the intestine and increase the absorption of nutrients.  A high level of copper is 125 - 200 parts per million (ppm = mg/kg or g/ton). Baconer meal, for example, contains 175 ppm of copper.


A deficiency of this mineral can cause dermatitis (a skin complaint).  A zinc deficiency can be induced by feeding too much calcium.  Zinc is added to pig rations in the form of zinc carbonate to give 50 to 100 ppm of zinc in the ration.


This is involved in the formation of Vitamin B12.

In addition, Magnesium, Manganese, Selenium and Molybdenum are essential trace elements normally added to pig rations in very small quantities.

Vitamin requirements

Vitamin A

Vitamin A is associated with the yellow pigment called carotene. Sows can store the vitamin in the liver.  Even limited periods of grazing will provide pigs with enough of this vitamin. Pigs that are intensively housed must however be fed a supplement.  Deficiency of Vitamin A over a period of 2 - 3 lactations will cause a severe drop in litter numbers and can cause pigs to be born blind.

Vitamin D

Vitamin D can be manufactured under the skin from sunlight in animals that are on range.  This vitamin is connected with the metabolism of calcium and phosphorus and can act as a buffer is the Ca/P ratio is wrong.  A deficiency can cause rickets.

Vitamin B complex

There are twelve separate vitamins in this group. A deficiency of one or more can cause pigs to be born with nervous disorders, trembling and unsteady gait.

Vitamins used to be supplied in rations in the form of Brewers' Yeast and cod liver oil. Today, stabilised manufactured vitamin powders are added to ration mixes to provide the correct quantities of all the essential vitamins.

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