B-vitamins are a group of 8 water soluble vitamins that play important roles in cell metabolism. They cannot be produced by the body itself, but can be produced by bacteria, fungi and plants. In the horse, microorganisms in the gut (mainly the hind gut) are capable of synthesizing B-vitamins. Equine nutrient requirements have only been established for thiamin (B1) and riboflavin (B2). In this article we will look at the function, dietary sources and requirements for thiamin (vitamin B1). Function Thiamin is a sulfur-containing vitamin that plays…