INTRODUCTION
| Non-ruminant: an animal with a single stomach. |
Pigs are non-ruminants and their feeding is different to that of most farm animals. There are a number of factors that the farmer has to think about when working out rations for his pigs, and these are summarised below.
- Pigs have a simple digestive system and cannot digest much fibre. Modern pigs are fed almost entirely on concentrates;
- They have no protective coats like those of sheep and cattle and are affected by temperature changes. They eat less in hot weather and more in cold weather;
- Modern pigs are housed intensively and are dependent entirely on the feeder for all their nutrients. Although pigs will eat anything, including each other, the farmer must make sure that they are fed a ration, balanced for all their nutritional requirements. Some animal protein must be included in their diet, especially during the early stages of growth;
- Crude fibre in the ration should not be more than 5% for large pigs and 2 – 4% for small pigs;
- Pigs for pork or bacon do not have a ‘store’ period when an animal is growing slowly. Pigs are killed before they are fully grown, and must be fed for growth and fattening at the same time. The aim of the farmer must be to produce rapid, uninterrupted growth in his animals;
- During the first 4 months in the life of a pig, the bones of the skeleton and the muscle tissues develop faster than the fat tissue; after 4 months of age, this process is reversed and fat develops faster than muscle which forms the lean meat. This explains why pigs can be fed ad lib meal (as much as they can eat) up to pork weight, but have to be rationed in the later stage of bacon production. See the diagram below:
Figure 1: Feeding of Pigs for Weight Comparison
- The main consideration in pig keeping is the cost of the food which is 80% of the cost of producing a pork or bacon pig; and
- Pigs can be marketed at different weights and ages and these are:
| TABLE 1: SHOWS THE TYPE OF PIGS WITH COMPARISON TO WEIGHT AND AGE | |||
| Type of Pig | Age (weeks) | Live-mass kg | Cold Dressed Mass |
| Weaner | 8 | 18 | |
| Small Porker | 12 | 34 – 47 | 25 – 35 |
| Medium Porker | 14 | 48 – 60 | 35 – 45 |
| Large Porker | 18 | 61 – 74 | 45 – 55 |
| Baconer | 22 | 75 – 94 | 55 – 72 |
| Overmass | 35 | 95 – 115 | 72 – 85 |
| Manufacturing | Boars, sows and heavy, overfat pigs |
Factors that will affect the type of pigs that the farmer produces are:
- The type of housing available
- The type of food available: Whether the farmer is feeding concentrates or boiled swill, or concentrate to pigs, running outside.
- The local marketing of pigs, whether, they are being sold on contract or privately: The skill of the pig man in feeding, managing and selecting pigs for slaughter. The breed of pig kept on the farm.
The 4 basic rations fed to pigs are:
- Creepfeed Meal or Pellets;
- Sow Meal;
- Porker Meal and;
- Baconer Meal
These meals are made up of:
Cereals: Maize, Wheat, Wheat Offals, Maize Offals.
Animal Protein: White Fish Meal, Meat Meal, Meat and Bone Meal.
Vegetable Protein: Soybean Meal, Pea/Bean Meal.
Minerals
Vitamins
Additives
2. ENERGY REQUIREMENTS
These are expressed as Total Digestible Nutrients or T.D.N. which is the sum of the percentages of the
- Digestible Protein
- Digestible Nitrogen Free Extractive (Carbohydrate)
- Digestible Fibre
- Digestible Oil X 2,25 (to allow for its higher energy value)
T.D N. for a food is calculated by analysing the food in a laboratory for each of the above nutrients, and multiplying the results by digestion coefficients; these are obtained from tables based on digestion trials, and there are different tables for cattle, sheep and pigs. (See the Feeds and Feeding Course). The result is given as a percentage of the food. The T.D.N of some common pig foods are:
| TABLE 2: THE T.D.N. OF SOME COMMON PIG FOODS | |
| T.D.N. | |
| Maize | 80% |
| Wheat | 80% |
| Barley | 76% |
| Maize Bran | 68% |
| Wheat Bran | 66% |
| Soybeans | 88% |
Most pig meals have a T.D.N. of 66 – 73%.
Energy in pig meals can also be expressed as Metabolisable Energy or M.E. This is the total energy intake of the animal less the energy lost through the faeces, urine and gases expelled by the animal. The total energy of any food is measured by burning the food in a special container, and this is done in a laboratory. Foods that have a high T.D.N. also have a high N.E.
The energy in pig rations is supplied by the cereals and oilseeds in the ration, but in pig feeding the type of cereal fed to the pig, can affect the type of fat formed by the pig. Pigs naturally produce a soft, oily type of fat with a poor appearance, which shrinks on cooking. This type of fat is difficult to cure during the bacon cure and is undesirable.
During the process of digestion, fats in a food are broken down into glycerol and fatty acids. Some fatty acids are what are known as saturated and these form fats at normal temperatures. Other fatty acids are unsaturated and these form oils at normal temperatures. The type of fatty acid in a food will determine the type of fat formed by the pig.
Hardy white fat is produced by feeding barley, wheatings, pea and bean meal.
Soft, oily fat can be produced by feeding too much maize, oats, soyabean meal, groundnut meal and rice meal.
Cereals fed to pigs should be ground into a meal using the 3mm screen on a hammer mill. Cereals that have been rolled or crushed will contain pieces that are too large to be digested by the pigs.
3. PROTEIN REQUIREMENTS
It has always been known that animal protein was essential for pigs, particularly young pigs. Pigs fed without some animal protein will not thrive and are likely to become cannibals and eat each other. The reason is the high Biological Value of animal protein. All proteins contain 20 – 25 Amino Acids, and during digestion the protein in a food is broken down into amino acids and then built up again into protein. If some of the amino acids are not fed to the animal, it can manufacture them, whereas, other amino acids must be fed to the animal; it cannot manufacture them. These amino acids, the ones that have to be fed to the animal are called the essential amino acids, and they must be included in the ration: Proteins that contain all the essential amino acids are said to have a high biological value. A point to remember is that the essential amino acids are not the same for all classes of animals, and that some amino acids that are essential for pigs are not essential for cattle; the cattle can manufacture certain amino acids that the pig cannot produce, and vice versa.
| TABLE 3: THE 10 AMINO ACIDS ESSENTIAL IN PIG FEEDING ARE: | |
| PROPORTION IN RATION | |
| Lysine | 3.25 |
| Isoleucine | 3.0 |
| Leucine | 3.0 |
| Methionine | 3.0 |
| Phenylaline | 2.5 |
| Threonine | 2.0 |
| Valine | 2.0 |
| Arginine | 1.0 |
| Histidine | 1.0 |
| Tryptophan | 1.0 |
From this list you can see that lysine is the most important amino acid in pig feeding. If a ration contains 1 part of tryptophan, it must contain 3.25 parts of lysine. Fish meal, which is an animal protein, is high in lysine, and soybeans have the highest proportion of lysine of all the vegetable proteins which is the reason why soyabean meal is used a lot in pig rations.
Protein is measured as crude protein and 60% of the protein needs of the pig are met by the cereals in the ration. The crude protein of the common cereals is:
| TABLE 4: CRUDE PROTEIN CONTENT OF COMMON CEREAL CROPS | |
| CRUDE PROTEIN | |
| Maize | 8 – 10% |
| Wheat | 10% |
| Barley | 9% |
| Sorhum | 9% |
| Soybeans | 38% |
| Fish Meal | 60% |
The protein content of cereals varies from year to year and depends on:
- The fertilizer treatment of the crop. The amount and timing of fertilizer applications will alter the amount of protein in the grain at harvest; poor fertilizer treatment will lower the protein, while a late top dressing of nitrogen will increase the protein content;
- The variety of the cereal being grown; and
- The season; heavy rain will leach nitrogen out of the soil before it can be taken up by the plant. The amount of nitrogen available to the plant affects directly the crude protein content of the grain.
In the case of barley, which is the main cereal fed to pigs in the U.K. and Europe, the crude protein can vary from 7% up to 14% depending on the factors mentioned above. However, as the C.P. content rises, the lysine content falls, so that the quality of the protein remains the same.
| C.P. | LYSINE | |
| Barley | 7% | 0.26% |
| 14% | 0.40% |
A farmer with a large pig unit who is feeding home-grown cereals to his pigs would be very wise to have his cereals analysed for their crude protein content so that he knows exactly what he is feeding.
In order to demonstrate the value of essential amino acids in pig feeding, and particularly the value of lysine, an experiment was carried out using two rations. One ration was made up of barley meal and groundnut meal, and the other ration was barley meal and fish meal. Although both rations had a crude protein of 14% the performance of the pigs getting the groundnut meal was 10% lower than that of the pigs getting the fish meal.
4. MINERAL REQUIREMENTS
The major minerals in pig nutrition are Calcium, Phosphorus and Sodium Chloride (Salt):
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-protein and blood. The ratio of Calcium to Phosphorus should be 1.5 (Ca) to 1 (P) in the ration.
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 of the animal to digest carbohydrates and protein.
Where soybean meal is used to replace fish meal, it should be remembered that the mineral content of soybeans is much lower than that of fish meal.
| TABLE 5: THE MINERAL CONTENT OF FISH MEAL AND SOYBEANS | |||||
| TOTAL ASH (MINERALS) % | CA % | P % | K % | C1 % | |
| Fish Meal | 21.5 | 7.1 | 4.0 | 1.0 | 1.0 |
| Soybean Meal | 5.5 | 0.21 | 0.92 | 1.5 | 0.04 |
Minor minerals or trace elements in pig nutrition are:
IODINE
An excess of iodine in the ration can reduce the growth rate of young pigs, and a deficiency can cause malfunction of the thyroid gland and also infertility in adult stock.
| Haemoglobin: a red protein responsible for transporting oxygen in the blood. |
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 4 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 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 (mg/kg or girt), and baconer meal contains 175 p.p.m. of copper.
ZINC
A deficiency of this mineral can cause dermatitis, a skin complaint, in pigs, and 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 – 100 p.p.m. of zinc in the ration.
COBALT
Is involved in the formation of the vitamin B12.
Magnesium
Manganese These are essential trace elements usually added to pig rations
Selenium in very small quantities.
Molybdenum
5. VITAMIN REQUIREMENTS
VITAMIN A
Associated with the yellow pigment called carotene. Sows can store the vitamin in the liver and even limited periods of grazing will provide them with enough, but sows that are intensively housed must 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
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 if the Ca – P ratio is wrong. A deficiency can cause rickets.
VITAMIN B COMPLEX
There are 12 separate vitamins in this group and a deficiency of one or more can cause pigs to be born with nervous disorders, trembling and unsteady gait.
Vitamins used are supplied in rations in the form of brewer’s 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.
ADDITIVES
The addition of low levels of antibiotics at the rate of 10 – 20 ppm can increase growth rate by up to 10%, lower mortality and reduce feed intake giving an overall increase in food conversion. The biggest affect is in herds of pigs that are being managed inefficiently or those with a high incidence of disease. However, the addition of antibiotics to pig and poultry rations has been banned in many countries because of the risk of the human population of the country building up a resistance to the drugs. The addition of copper to the ration produces the same effect on the growth rate as an antibiotic, but without the risk to people eating the meat.
| TABLE 6: SUMMARY OF SOME OF THE NUTRIENT REQUIREMENTS IN PIG FEEDS | |||
| Creep Feed % | Sow Meal % | Baconer Meal % | |
| T.D.N. | 74 | 66 | 70 |
| Crude Protein | 19 | 15 | 14 |
| Crude Fibre | 3 | 5 | 5 |
| Lysine | 1 | 0.8 | 0.7 |
| Methionine | 0.7 | 0.5 | 0.4 |
| Calcium | 1 | 1 | 1 |
| Phosphorus | 0.9 | 0.6 | 0.5 |
| Salt | 0.9 | 0.5 | 0.5 |
| Vitamin A | 3 000 * | 3 000 | 1 900 |
| Vitamin D | 4 000 ** | 4 000 | 4 000 |
| * International Units ** Upper Limit |
