Vitamin A

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    Vitamin A Chemical Structure
    Vitamin A Chemical Structure
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    Vitamin A, also known as retinol, is consumed from feedstuffs in the form of beta-carotene, which is converted to vitamin A once inside the body (Briggs, 1998; Frape, 2010).

    Vitamin A is well known for its role in vision, especially night vision (Ellis and Hill, 2005; Frape, 2010). It also plays a part in maintaining the health of the cells that line all systems of the body (e.g., skin, respiratory tract, eyes, reproductive tract).

    Vitamin A is also important in bone and muscle growth and contributes to the immune system response to infection (Cunha, 1991).

    A deficiency in vitamin A results in a poor hair coat, reproductive and respiratory infections, night blindness, excessive tearing of the eyes, weight loss, and diarrhea (Briggs, 1998; Cunha, 1991; Ellis and Hill, 2005; Frape, 2010).

    Beta-carotene (the natural form of vitamin A) is abundant in green forages such as alfalfa and grass.

    Fresh hay and pasture contain beta-carotene, but dull hay or hay stored for longer than 6 months typically does not have adequate amounts of beta-carotene to meet the horse’s requirement (Frape, 2010).

    Vitamin A is required at the amount of 18,000 IU daily for a 600Kg horse. 10 times this level may result in toxicity.

    Sources of Vitamin A are Green forages and yellow vegetables such as carrot.

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