Nutrition

By LeRoy G. Biehl.

Excellent nutrition in all phases of the swine production cycle is the key to top performance and feed efficiency. Although the pig's diet can vary tremendously in the kind and amounts of feed-stuffs, certain basic nutrient requirements must be met if reproduction and growth are to occur.

Nutrients in swine diets can be divided into five classes: Water, energy, protein, minerals and vitamins.

Water is an essential part of the diet, and absence of water will cause death sooner than if the diet lacks any other nutrient. Clean water should be provided free choice at all times.

Energy in swine diets usually is made up of carbohydrates or fats. In the United States, corn is the major source of energy in swine rations. Other sources include wheat, oats, barley and fats such as tallow or vegetable oil.

Protein is the building block for muscle and is added to swine diets as a supplement. Soybean meal is the most common source of protein supplement, although cottonseed meal, fishmeal and tankage are additional protein sources. Low protein diets result in unthriftiness in growing pigs and poor milk yield in sows.

Minerals usually are divided into two classes, macrominerals which are required in relatively large amounts and micro or trace minerals which are required in small amounts. Calcium, phosphorus, sodium and chlorine are the macrominerals added to the common grain-soybean meal ration.

Depending on the stage of production, calcium and phosphorus should be added at recommended levels for maximum growth and good bone development. The calcium/ phosphorus ratio should never exceed 2:1 with the optimum ratio near 1.2:1.

Supplements Vital

Adequate calcium-phosphorus supplementation is especially important to gestating-lactating sows and gilts. Bone growth of the fetus and milk production deplete the mother's supply of calcium and phosphorus from her bones.

Deficient diets can result in broken legs and spines. These usually occur immediately following weaning. Affected sows are unable to rise and frequently die. Excellent mineral supplementation of the ration during pregnancy and lactation will prevent these losses.

Sodium and chlorine are added to the ration in the form of salt. Usually 0.35 percent or 7 lbs. per ton of feed for all animals is adequate for all stages of production. Excessive salt without adequate water can cause convulsions and rapid death as a result of sodium poisoning. Water deprivation for 12 to 24 hours can cause "salt poisoning" to occur, even in pigs consuming normal rations.

Iron, zinc, manganese, copper, iodine, and selenium are microminerals commonly added to swine diets. Magnesium and potassium are required by the pig but traditional swine rations usually have them in sufficient quantity.

Vitamins are essential for enzyme and cell metabolic function and are added to swine rations for maximum production. The typical grain-soybean meal ration should be supplemented with vitamins A, D, E, K, riboflavin, niacin, pantothenic acid, choline and B₁₂. Biotin, folic acid, and pyridoxine are required by the pig but adequate amounts usually are provided in natural feedstuffs and do not need to be added to the diet.

Feeding Life Cycle

Swine require different concentrations of nutrients and amounts of feed depending on the stage of production. This is often referred to as the "life cycle of feeding" and is divided into: Gestation, lactation, starter, grower and finisher.

Feed intake must be limited in gestating sows to prevent them from becoming overweight. Four to five pounds of properly fortified feed is adequate for the pregnant sow, although during colder weather additional feed may be needed. Adding fat to the diet in late gestation may save more of the smaller pigs by increasing the energy stores in the baby pig and the fat content of the sow's milk.