Nutrient Requirements of Horses Presentation Part 5: Vitamins #8895-C

Vitamins Needed in very small quantities Serve as catalysts for numerous reactions & transformations in body tissues – Catalysts - start off a reaction & allow it to proceed at a more rapid pace

Vitamins Synthesize some vitamins in their bodies Others must be present in diet Two groups exist: – Fat-soluble vitamins – Water-soluble vitamins

Vitamins Fat-soluble vitamins: Vitamins A, D, E, & K Ability to store them so they have reserve supply Water-soluble vitamins: B complex vitamins Vitamin C Cannot be stored Must be consumed or synthesized daily

Fat-Soluble Vitamins – Vitamin A If deficient in vitamin A, they may experience: – Impairment of vision (excessive watering of eyes) – Night blindness Watering occurs because cornea is too dry – Cornea - transparent part of the coat of eyeball that covers iris & pupil

Fat-Soluble Vitamins – Vitamin A Other signs of deficiency consist of: – Rough, dry skin – Skin lesions – Brittle hair coat – Poor hoof growth – Digestive disturbances – Respiratory illness

Fat-Soluble Vitamins – Vitamin A Utilize carotene or synthetic vitamin A to meet needs Fresh green forages include carotene Converted to vitamin A in wall of intestine

Fat-Soluble Vitamins – Vitamin A Carotene & vitamin A are both unstable in: – Sunlight – Oxygen – High temperatures Hay exposed to sunlight & rain for a year will lose 90% of its carotene

Fat-Soluble Vitamins – Vitamin A Carotene content in correctly stored hay diminishes in six months Liver stockpiles vitamin A – Gives 3-6 month supply to bank upon before they need to consume more carotene

Fat-Soluble Vitamins – Vitamin A Too much vitamin A: – Becomes toxic – May cause fragile bones – Causes intestinal lining to slough

Fat-Soluble Vitamins – Vitamin D Does not have to be acquired in the diet Comes from substance in their skin that takes the sun ’ s ultraviolet rays & converts it to vitamin D Bodies absorb it

Fat-Soluble Vitamins – Vitamin D 30 minutes of daily sun can meet requirement Also acquired from sun-cured hay

Fat-Soluble Vitamins – Vitamin D Sign of deficiency in growing horses is rickets – Rickets - Deformed bones with swollen joints and frequent fractures in adult horses Be careful not to over supplement – Excess can cause toxicity

Fat-Soluble Vitamins – Vitamin D Excessive calcium deposits in soft tissues (heart, muscle, arteries) result if given too much vitamin D Liver stores extra vitamin D so most rations do not need supplementation – Unless they do not receive any sun at all

Fat-Soluble Vitamins – Vitamin E Occurs in: – Green, growing forage – Quality hay – Cereal grains – Wheat germ oil May be synthesized artificially

Fat-Soluble Vitamins – Vitamin E Vitamin E & selenium work together to prevent appearance of white muscle disease – White Muscle Disease - Degenerative disease of the skeletal muscles

Fat-Soluble Vitamins – Vitamin E Associated with: – Development of muscles – Transport of oxygen – Red blood cell stability – Fertility

Fat-Soluble Vitamins – Vitamin K Essential for normal blood clotting Bacteria found in digestive tract & plants synthesize it Green forages are good sources

Fat-Soluble Vitamins – Vitamin C Liver synthesize vitamin C Not needed in the diet

Water –Soluble Vitamins Ten water-soluble vitamins are part of B vitamin complex Bacteria in digestive tract synthesize these vitamins If horses are under stress, vitamin B may need to be supplemented

Water –Soluble Vitamins Thiamin - essential to carbohydrate metabolism Deficiency results in loss of appetite 3 mg of thiamin per kg of feed is sufficient

Water –Soluble Vitamins Vitamin B-12 key to red blood cell synthesis Supplementation usually unnecessary & wasteful