Vitamin Requirements of Swine
John C. Rea and Trygve L. Veum
Department of Animal Sciences
Vitamins are essential nutrients for swine. The trend toward complete confinement swine production, however, has focused more attention on the need to supplement practical rations with adequate dietary sources of vitamins. This guide will help swine producers overcome vitamin deficiencies in rations. It is a summary of important aspects of vitamin requirements of swine, with emphasis on meeting the needs of hogs fed practical swine rations in Missouri.
Vitamins are specific chemical compounds or organic nutrients whose major function is to regulate body processes. Vitamins do not form a part of the animal's tissue and are required in smaller amounts than other nutrients such as protein, calcium, phosphorus, carbohydrates and fats. Each vitamin functions in a particular way, and the function of the various vitamins in the body differs widely.
As a starting point, feed manufacturers and hog producers should use the National Research Council's (NCR) "Nutrient Requirements of Swine" as a basis for vitamin supplementation.
Table 1 lists the Missouri vitamin recommendations for growing pigs on a nutrient added per ton basis. All of these recommendations are above 1988 NRC requirements.
Missouri recommended vitamin additions per ton of feed (growing-finishing pigs)
|Nutrient||Unit||Addition per ton|
|Vitamin A||Mil. IU||5.0||3.0|
|Vitamin D||Thou. IU||500.0||300.0|
|Vitamin E||Thou. IU||20.0||10.0|
The vitamins swine producers need to pay particular attention to when formulating practical growing swine rations in Missouri are the following: A, D, E, riboflavin, niacin, pantothenic acid, choline and B12. In addition to these vitamins, the following are needed but are generally in adequate amounts in Missouri rations for growing pigs: K, C, biotin and folic acid.
Table 2 lists recommended vitamin additions for breeding swine. Recent research indicated sows receiving supplemented folic acid have larger litters farrowed. With sows in complete confinement, adding folic acid along with choline and biotin at the levels shown seems justified.
Missouri recommended vitamin additions per ton (breeding swine)
|Nutrient||Unit||Addition per ton|
|Vitamin A||Mil. IU||5.0|
|Vitamin D||Thou. IU||500|
|Vitamin E||Thou. IU||25|
Vitamin needs of swine are met either from that contained in the feed or from synthesis in the body of the animal. Determinations have been made of the vitamin content of many swine feeds. These are average figures and, in some cases, are influenced drastically by the method of harvesting, processing and storing.
Vitamin A functions in the growth of both skeletal and soft tissues of the body: in vision, reproduction and disease resistance. Vitamin A does not occur in plant products but the plant pigment carotene can be converted to vitamin A in the intestinal wall of the pig. Yellow corn is the only cereal grain that contains significant amounts of carotene. Forages are good sources of carotene, but they are seldom used in today's practical rations. One milligram of B-carotene is equivalent to 500 IU of biologically active vitamin A for the pig.
Good sources of carotene or vitamin A are found in yellow corn (although 60 percent may be destroyed in several months of storage by light, high temperature, air, etc.), green forages, sun-cured legumes, dehydrated alfalfa meal, cod-liver oil and fish oils. Both carotene and vitamin A are readily destroyed by the following:
- Storage and exposure to air.
- Exposure to light and high temperature.
- Exposure to metals such as iron hasten destruction.
- Exposure to rancid fats.
- Grinding, which helps destroy the carotene in corn.
For these reasons on a practical basis, we should assume that pigs in dry lot receive very little, if any, vitamin A in their diets.
Weak, malformed, blind and eyeless pigs may be farrowed by sows deficient in vitamin A.
Vitamin D functions in the pig's body to increase the absorption of calcium and phosphorus from the intestines. It is necessary for good bone growth and calcification. Vitamin D2 sources include sun-cured hays, irradiated yeast and dehydrated alfalfa meal. Sources of D3 include fish-oils and fish meals and formation of D3 in the skin by sunshine. Swine exposed to sunshine in the summer should not need dietary vitamin D. During the winter months and in confinement rearing, it is important that rations be supplemented with vitamin D.
Vitamin E is required for normal reproduction and growth. Common swine feeds are good sources — green pastures, cured hay, alfalfa meal, whole grains and germ parts of grain. In Missouri, vitamin E deficiencies are not common, but as a safeguard, it can be added cheaply in a premix.
Deficiency symptoms have been diagnosed in some of the northern midwest states. Michigan State University has reported several vitamin E — selenium deficiencies in swine herds. In areas where selenium levels are low, reports of vitamin E shortages have been more common.
There is a definite relationship between vitamin E and the trace mineral selenium. Adding recommended selenium levels reduces the need for vitamin E. Apparently selenium is needed for good use of vitamin E. Loss of vitamin E in normal feeds due to handling and storage, less use of pasture and alfalfa meal, and extensive use of some drugs are believed to contribute to the vitamin E deficiencies in some herds.
Trace mineral selenium can be added legally to rations at a level of 0.3 part per million. This should reduce problems from marginal vitamin E levels.
Under ordinary circumstances vitamin K is supplied in adequate amounts in normal swine diets and the microbial synthesis in the intestines. The major function of vitamin K is its blood clotting role.
From time to time, cases are reported that seem to indicate a shortage of vitamin K in swine rations. The presence of mold in feed has been found to interfere with normal use of vitamin K by pigs. In Nebraska studies of moldy feed, the addition of 2 grams of menadione sodium bisulfite per ton corrected vitamin K deficiency symptoms in affected pigs. Check moisture levels at the time grains are stored and again in the spring and process to reduce mold risk.
With normal feeds vitamin K should be adequate in Missouri swine rations, but it may be included where mold is present or past experience indicates a need for additional vitamin K.
Vitamins generally are classified according to solubility. The four vitamins discussed (A, D, E and K) are fat-soluble, and the remaining mentioned are water-soluble. Of the latter group, biotin, vitamin C and folic acid generally are not of practical concern in growing swine rations because adequate amounts appear to be synthesized by the animal. Thiamine and vitamin B6 are supplied in more than adequate amounts by the feed in normal swine rations. Recent research shows an increase in pigs per litter from adding folic acid to sow rations.
- Riboflavin functions in the animal's enzyme system. It is heat-stable but is destroyed by alkali and light. It is available in good amounts in legume hays, dairy byproducts and in fair amounts in tankage and soybean oil meal. Cereal grains are a rather poor source of riboflavin.
- Niacin functions as a co-enzyme. It is resistant to heat and is quite stable in feeds. Fish meals, corn distillers solubles and wheat bran are good sources of niacin. It may be in a bound or unavailable form in cereal grains, especially corn.
- Pantothenic acid is stable in heat and light. Common feed sources are milk products, alfalfa meal, wheat bran and fish solubles. Practical diets tend to be borderline in pantothenic acid. Corn is a poor source. "Goose-stepping" is a common symptom of pantothenic acid deficiency.
- Choline is required for small pigs. It can be synthesized from methionine. This increases the methionine requirements in choline deficient diets. Sources are meat and bone meal, soybean oil meal, fish meal and grains. Practical swine grower rations should contain adequate levels of choline, particularly for heavyweight hogs. Research has shown that feeding pregnant sows supplemental choline generally increases numbers of pigs born and, in some experiments, pigs weaned.
- Vitamin B12 is required for growth, hemoglobin and red blood cell formation. It is available in animal byproducts and commercial preparations. Plant products are deficient, and where rations are formulated based primarily on corn and soybean-oil meal, supplemental sources need to be supplied.
- Folic acid is an essential B-vitamin for swine. Green leafy plants are an excellent source. Bacteria in the pigs' lower gut also can synthesize folic acid, making feces a source of this vitamin. Confinement practices of raising hogs has reduced both of these vitamin sources so research now indicates supplemental sources of folic acid should be added to the feed. Recent research has shown a mild increase in pigs born when folic acid is added to sow rations.
Table 3 lists clinical and sub-clinical symptoms of vitamin deficiencies. Some of these are more specific than others. Some deficiencies don't occur on practical swine rations. However, studies have been made using semi-purified rations that are lacking in specific vitamins, and deficiency symptoms have been determined.
Symptoms of vitamin deficiency in swine
|Vitamin||Clinical symptoms1||Sub-clinical symptoms2|
|Vitamin A||Poor growth, unsteady gait, birth of abnormal pigs, hyperkeratinization of skin, xerophthalmia||Low liver vitamin A, elevated cerebrospinal fluid pressure, low plasma vitamin A|
|Vitamin D||Poor growth, leg weakness||Rickets, low plasma Ca and P, elevated plasma alkaline phosphatase|
|Vitamin E||Sudden death, paleness||Liver necrosis, mulberry heart, pale musculature, edema, jaundice|
|Vitamin K||Sudden death||Internal hemorrhages, slow blood clotting time|
|Thiamine||Poor growth, loss of appetite, sudden death||Enlarged flabby heart, abnormal electrocardiogram, elevated blood pyruvate|
|Riboflavin||Poor growth, red exudate around eyes, birth of dead or weak pigs||Lens cataracts, increase of blood neutrophils|
|Niacin||Poor growth, necrotic enteritis||Normocytic anemia|
|Pantothenic acid||Poor growth, goose stepping, posterior paralysis, birth of small, weak pigs||Sciatic nerve degeneration|
|Vitamin B6||Poor growth, epileptic convulsions||Low blood hemoglobin, high plasma iron, high urinary xanthurenic acid|
|Vitamin B12||Poor growth, irritable, birth of weak pigs||Low serum B12, low lymphocyte count, enlarged liver|
|Choline||Birth of pigs with spraddle legs||Fatty liver, kidney necrosis|
|Folic acid||Poor growth||Normocytic anemia|
|Biotin||Dermatitis, cracked hoof|
1Observations made on the animal
2Determined from tests of postmortem examination
Producers buying complete mixed feeds or commercial supplements to feed with home-grown grains generally must rely on their company to provide adequate amounts of vitamins. Those formulating and mixing complete rations need to pay particular attention to meeting vitamin needs. Missouri recommendations are that vitamins that are short of borderline in feeds should be provided in a commercial vitamin pre-mix at levels shown in Tables 1 and 2.
Vitamin pre-mixes don't add much to the total cost per ton of feed, and there is less chance for error providing these vitamins in this form rather than relying on average amounts of feed, particularly with variations in processing and storing and changes in management of hogs.