Farm animal nutrition: Vitamins

Vitamins are essential organic compounds, which are needed for normal bodily functions. Usually animals cannot synthetize all of the required vitamins, so they must have them in the feed. Each vitamin has a task which no other compound can replace. Common tasks for vitamins are metabolism management, antioxidative activity, hormonal activity, enzyme activity and energy formation.

Vitamins can be divided to fat-soluble and water soluble compounds. K, A, D and E vitamins are fat-soluble: they are stored in fat, transferred in lymph, and are slow to excrete from the body. Vitamins B and C are water-soluble: they infuse directly to blood, circulate freely in the body, and are excreted through urine. Since they are not stored, the animal needs them daily from the feed. Most feeds do not include enough vitamins, so they must be added.

Fat-soluble vitamins: A, D, E, K

 

Vitamin: A
Required for: Important for vision, especially night vision, bone formation, renewal of epithelial tissue, fertility. Also an antioxidant.
Sources: The precursor for vitamin A are carotenoids in plants. Six micrograms of beta carotenoid creates one microgram of retinol (vitamin A).
Deficiency symptoms: Decreased vision, blindness

Vitamin: D
Required for: Immunological system, genetic expression, metabolism of phosphorus and calcium
Sources: The precursor for vitamin D exists in the skin. It turns into D-vitamin in sunlight or UV-light, and absorbs then into the body. D-vitamin can also be ingested from the feed. Non-active forms of D-vitamin are transferred to the liver and finally to kidneys, where it is transformed to calcitriol (the active form).

Deficiency symptoms: Rickets, soft bones

Vitamin: E (common name for tocopherol and tocotrienol compounds)
Required for: Acts as an antioxidant, protecting the unsaturated fatty acids in cell membranes from oxidization. Supports blood circulation, immunology and fatty acid synthesis.
Sources: Plant feeds, especially vegetable oils and whole grain products
Deficiency symptoms: Anemia, bleeding, changes in the lungs

Vitamin: K
Required for: Blood clotting
Sources: Vitamin K is formed in the large intestine. Usually animals can synthetize enough of it in any diet. The synthetic vitamin K is water-soluble, but in the liver it is transformed into a fat-soluble form.
Deficiency symptoms: Anemia, bleeding, changes in the lungs

Water-soluble vitamins: B and C 

 

Vitamin: B

• Vitamin B₁ (thiamine)
• Vitamin B₂ (riboflavin)
• Vitamin B₃ (niacin or niacinamide)
• Vitamin B₅ (pantothenic acid)
• Vitamin B₆ (pyridoxine, pyridoxal, or pyridoxamine, or pyridoxine hydrochloride)
• Vitamin B₇ (biotin, "vitamin H")
• Vitamin B₉ (folic acid)
• Vitamin B₁₂ (various cobalamins; commonly cyanocobalamin in vitamin supplements)

Required for: Coenzyme in energy-releasing reactions, coenzyme in RNA and DNA formation, neurological functions (thiamine),  redox-reactions (riboflavin, niacin), formation of phospholipids (biotin)
Sources: B vitamins are often bound to proteins, so they are metabolized as proteins. They are not stored in the body, so the animal needs to have a constant supply of vitamin B. B₁₂ is an exception, it can be stored to some extent. B-vitamins are also formed in the rumen and large intestine.
Deficiency symptoms: Symptoms depend on which vitamin B the animal is lacking. There can be  e.g. weight loss, neurological dysfunction, convulsions, skin infections, hypertension, diarrhea, lesions and anemia. Deficiency of thiamin may cause cerebro-cortical necrosis.

Vitamin: C
Required for: Acts as an antioxidant together with Fe or Cu, collagen metabolism, steroid metabolism. Increases stress tolerance. The amount needed varies greatly between species. Animal's age, production level, gestation, health, diet and nursing affect the needed amount as well.
Sources: Vitamin K is formed in the large intestine. Usually animals can synthetize enough of it in any diet. The synthetic vitamin K is water-soluble, but in the liver it is transformed into a fat-soluble form.
Deficiency symptoms: Scurvy (swollen and bleeding gums, internal haemorrhage)

Pigs and poultry 

 

Animals, which are raised indoors or fed other than plant-based feed likely need additional vitamins in their diet. Pigs and poultry commonly never see sunlight, and thus form very little or no vitamin D. Due to their concentrated, synthetic and/or animal based diet, but pigs and poultry get no vitamins A and E, which are common in plants. They may also need riboflavin, niacin, B₁₂ and pantothenic acid added to their feeds. Poultry need also vitamin K, since they are fed solely on grains and plant proteins.