Vitamins and Horses
Vitamins are chemicals required in small amounts to promote and regulate and a multitude of body functions. There are two types, fat and water-soluble. The fat soluble vitamins are A, D, E, and K. The water soluble vitamins are the B vitamins and vitamin C. This article goes over vitamin sources, availability, and situations that may indicate possible vitamin problems in horses.
The horse produces vitamin's C, D, and the B vitamin, niacin. Microorganisms in the horses large bowel produce all the B vitamins and vitamin K. Between the vitamins produced in the bowel and those in the feed stuffs, symptoms of vitamin B or K deficiencies are rare in the horse. Generally they occur only when the there is interference with their production or utilization, for instance during prolonged antibiotic administration. Vitamins A and E are entirely supplied by the diet with green forages being a good source of both. Green forages are also good sources of vitamin B1, B2, folacin and K. Under normal feeding conditions vitamin deficiency or toxicity is unlikely cause clinical signs of disease, however recent work suggests that horses may not receive enough of some vitamins under certain conditions for optimal health. for more on Vitamin E
Situations where specific vitamin supplementation for healthy horses may be beneficial are:
- Feeding poor quality hay or hay stored more than 6 months: Vitamin A, E deficiency with low B vitamins.
- Feeding a high concentrate - low forage diet: Vitamin A, E deficiency with low B vitamins.
- Horses that undergo regular difficult work: Increase need for many vitamins particularly E
- Frequent stressful situations: Increase need for many vitamins particularly E
- Nervous or hyperactive horses: Increase need for many vitamins particularly E
- Horse in Training: Increase need for many vitamins particularly E
- Pregnancy and growing: Increase need for all vitamins particularly A and E. Caution folic acid supplementation may actually be harmful in pregnant mares.
Disease situations where complete vitamin supplementation might be useful:
- Horses not eating well: Generalized Deficiency
- Prolonged antimicrobial therapy: Interferes with B vitamin synthesis and uptake. Caution folic acid supplementation may actually be harmful in pregnant mares.
- Anemic Horses: increase need of all vitamins. Unlike in humans, iron deficient anemia is rare in horses.
- Fighting off infection
- Tissue destruction or inflamation
- Genetic predisposition for an increase need of particular vitamins, particularly E.
In all these situations a good complete balance supplement may be indicated. See "Dosage" below.
Do older horses, 18 or more years, or horses suffering from Cushinoid Disease need more vitamins. This is uncertain but the answer is, probably. How much of which type is unknown. Certainly the single best tonic for older horses is a lot of good green grass. If this is not available or if the older horse seems to be having more difficulty keeping weight and condition, vitamins can be supplemented, after a thorough review of the whole nutritonal and management program.
B Vitamin Deficiency B vitamin deficiency is rare in horses on appropriate roughage. Symptoms are wide ranging as this interferes with proper metabolism of all tissues. Symptoms include poor appetite, anemia, unthriftiness, poor growth, weight loss, congenital deformities, and a poor hair coat. Caution folic acid supplementation may actually be harmful in pregnant mares.
Vitamin activity is decreased by, heat, light moisture, grinding, processing, air and even the presence of other vitamins and minerals. Losses during storage are greatest with A, D, K, and B1 (thiamine). Of these only vitamin A is completely dependent on food stuffs. When moisture is high, Vitamin A may degrade at the rate of close to 80% every 3 months in hay. Vitamin supplements should not be mixed with other minerals and should be bought in dry forms only. Buy small amounts so that you replace them frequently.
Supplementation of vitamin A (30 to 60 IU / kg or 15 to 30 / lb of body weight daily) and vitamin E (2 IU per kg or 1 per lb body weight daily) may be beneficial to offset those not receiving enough fresh green forage. It should be noted that this level of vitamin E is substantially above the requirement levels recommended by NRC but have shown to have a benefit on tissues and resistance to infection.
Let's say we have a 1000 lb horse that only has clean but poor quality hay available for forage. Using the above formulas the vitamin A requirement would be: 1000lbs_X_22_=_22,000 IU of vitamin A. The supplement I have has 5000 IU vitamin A per capsule so the dosage would be: 22,000_/_5000_=_appx._4_capsules. Each capsule contains 60 mg vitamin E so will be supplementing: 4_X_60_=_240_mg vitamin E. The recommended level for vitamin E is: 1_X_1000lbs_=_1000 mg. so the above supplement is 760 mg short on vitamin E. Four capsules of the multivitamn and either a single 500 or 1000 IU capsule of vitamin E would get us very close to what is right for optimum health.
With antibiotic administration, a lb (.45 kg) of brewers yeast or a good complete vitamin supplement a day per 1000 lb (450 kg) of horse may be indicated to supplement the B vitamin decrease caused by the antibiotics. Folic acid supplementation may actually be harmful in pregnant mares.
Commercial vitamin supplements should have about this profile:
Vitamin: Amount of Vitamin per Ounce (30g) of Supplement:
A: 40,000 IU
D : 4,000 IU
E : 1,000 IU
Thiamine(B1): 75 mg
Riboflavin (B2): 40 mg
Niacin: 120 mg
Pantothenic acid: 48 mg
Pyridoxine (B6): 12 mg
Biotin : 1.5 mg
Folacin: 20 mg
Cobalamine (B12): 120 mg
Choline: 600 mg
These recommendations can be used for growing, reproducing, athletic, nervous, and hyper active horses and those not eating well. The supplement should be fed at the rate of 1 oz per 1000 lbs (450 kg).
Excess B vitamins are readily excreted by the kidneys. Excessive intake of these vitamins is rarely detrimental to anything but your pocketbook. Excessive intake of the fat soluble vitamins A and D is detrimental. Vitamin A excess will cause anemia and a dull hair coat while vitamin D excess will cause bone abnormalities. Vitamins K and E though fat soluble do not appear to be toxic.