Gordon King, Animal Science, University of Guelph, Canada

The aim of any feeding program should be to satisfy nutrient requirement at a reasonable cost. This infers provision of a diet balanced for optimum but not usually maximum production. Optimum involves a least cost concept with maintenance of health, proper rate of gain and finish. Each lot of pigs contains individuals with varying requirements for individual nutrients. It is not practical to include sufficient amounts of every nutrient to meet the needs of everyone. If this were done, most of the population would receive excess which, in addition to being costly, could result in less desirable carcasses and even in toxicity. A general guide for growing-finishing pigs might be to provide rations that result in maximum performance for about 85% of animals in a healthy, adequately housed group possessing a genotype for high production and maintained within their comfort zone.

Some of the points to consider are:

Don't forget water

Least Cost Formulation of Rations

Computer program uses data base containing:

Major Energy Ingredients for Pig Diets

Corn - an excellent energy source for pigs. The complementary way in which corn and soybean meal blend to produce a well-balanced diet for pigs makes this combination the standard to which all other mixtures are compared. Corn is presently the major energy source throughout USA and eastern Canada but there are many suitable alternatives. Pigs can digest most cereal grains and, so long as diets are formulated properly, many options exist.

Barley - main energy source for pigs in western Canada and much of Europe.

Oats - excellent for mature animals, particularly if dehulled. Oats are not as good for younger pigs but can provide 20 - 30 % of the total energy source.

Wheat - very good energy source if price is right.

Major Protein Ingredients for Pig Diets

Soya Bean. Usually feed as extracted soya bean meal, the residue remaining after oil removed. This is the major protein source for pigs in north America and throughout much of the world with intensive husbandry. Soya bean meal contains 44 - 49% protein. Whole soya beans can be fed as combined energy (18% oil) and protein (37%) source but usually contain toxins (trypsin inhibitors). The high heat associated with most oil extraction processed denatures the inhibitors since they are proteins. Whole beans must be heat-treated prior to feeding.

Canola (Oilseed Rape). The meal remaining after oil extraction from Tower or Candle varieties, the common types grown in Canada. Canola meal is an excellent protein source for pigs. The earlier varieties of Rape, still grown in some parts of Europe, contain toxic factors (glycosinolates) that make this meal unsatisfactory for pig diets.

Minerals and Vitamins
The specific needs for minerals and vitamins vary considerably with the age and production stage of particular animals. Most producers incorporate the appropriate vitamin-mineral premixed into all diets.

Food Industry By-Products

Feed Additives.

These come in many forms with legislation covering their use varying from country to country and continually under revision.

Preservatives. antioxidants, gelatin coatings for vitamins, organic acids,and similar compounds are sometimes included to prevent or reduce deterioration during storage

Flavouring & Colouring Agents. Sweetening and flavourings are common in early wean diets to give milk-like taste. Colours are sometimes used to distinguish diets, particularly if feed is medicated.

Texturing agents may be added to promote pelleting. Eg. molasses to assist passage through screens; beet pulp to improve texture.

Antibiotics - to inhibit or kill bacteria.
Many used, often not pure pharmaceutical grade but rather the dried fermentation product containing antibiotic residues plus mycelium of the producing fungus.
May prevent degradation of nutrients by bacteria during storage. Producers should do all they can to minimize and eventually eliminate the routine need for these.

Antifungal & antiprotozoal compounds. These are mainly anthelmintics.

Other Antimicrobials (those not derived from fungi)
CuSo4 An inexpensive additive that may reduce microbial action during storage. Aarsenicals are also used or this.

The incorporation of various enzymes into pig diets is a relatively new concept. However, if their production costs can be reduced through biotechnological synthesis or some other practical procedure, the practice might become universal. Some prospects are: proteases to make protein more available; b-glucanase to break down complex cereal starches to glucose; cellulase to digest plant cell walls; and phytases to liberate tightly bound phosphates. Any of these enzymes could liberate specific nutrients from plant materials so these are available to the animals in greater quantities.

Usually dried mixtures of lactobacillus and other microflora which, when added to diet, multiply in gut to displace less desirable and possibly pathogenic species. Most are trade secrets.

Gut Acidifiers.
Citric and fumaric acids maintain acidity of duodenum without altering body's acid:base balance. Distressed pigs, such as those at weaning, may have impaired gut function so stomach secretes less acid to control bacterial flora in the intestine. Acidifiers compensate for this.

Immune Stimulants.
Killed or attenuated microorganisms, often given to sows prior to parturition to promote passive immunity in piglets. Some may also give direct to piglets to promote active immunity.

Chelating Agents.
Claim is that trace elements bound to chelating agents are protected from binding to other components that may prevent absorption, and then released for absorption at critical part of intestine.

Emulsifying Agents
Necessary if fat included in diet.

Metabolic Modifiers
Compounds such as beta-agonists or recombinant porcine somatotrophin alter metabolism, promoting deposition of more muscle. Certainly the pork chops from pigs treated with rpST have less fat and, in the opinion of most marketing specialists, more consumer appeal. The use of such pharmaceuticals is certainly a grey area at present but some of the presently available or even new compounds might evolve into practical methods to modify growth and carcass composition.

The Extension Swine Husbandry Staff at North Carolina State University produce a number of Nutrition Related Topics, including a Swine Nutrition Guide, that provide an informative coverage of nutrition and feeding topics.

Some additional information on nutritional requirements and feeding practices are available in the Swine Care Handbook prepared by the National Pork Producers Council.

Return to Pork Production.