The equid has been estimated to derive 70% of energy from volatile fatty acids (VFA) production. Hind gut fermentation in the equid degrades structural carbohydrates to VFA's that are oxidised by the liver as a source of energy. Maximising this potential source of energy is an important consideration when attempting to improve the utilisation of fibre feeds by the equid. It is generally accepted that the acetate:propionate:butyrate are produced in a ratio of 76:18:5 by horses consuming forage diets (Moore–Colyer 2000). This optimum can be unbalanced by the inclusion of high levels of cereal–based concentrates in the diet. Therefore to maximise hindgut function it is important to maximise the use of high–energy fibrous feeds such as alfalfa and sugar beet pulp (USBP), while reducing the inclusion of concentrate feeds. This experiment sought to determine the effect of feed preparation, namely particle size on VFA profiles from a range of alfalfa : unmolassed sugar beet pulp diets.