Impact dehulling oat grain to improve quality of on-farm produced feed. I. Hullability and associated changes in nutritive value and energy content

High hull content of oat (Avena sativa L.) limits its use as on-farm feed. Dehulling, used in the oat processing industry, can be performed on-farm, to increase nutritive value and energy content. A laboratory model of an impact oat dehuller, similar to a commercial device, was used to study the effects of rotation speed, grain characteristics and moisture content on hullability and groat energy content. Grain of oat cultivar Salo [from official variety trials, MTT Agrifood Research Finland, Jokioinen (60°49'N), 1996–2000] was assessed for quality prior to dehulling. Impact dehulling rotation speed ranged from 200 to 500 r min-1 at 50 r min-1 intervals, with moisture content of grains ranging from 10% up to 18%. Dehulling improved oat energy content markedly. Hullability was better at higher rotation speeds. 350 r min-1 was determined to be adequate to result in improved quality as no marked additional improvements were demonstrated by increasing rotation speed further. As the proportion of hulless groats increased with higher rotation speeds, nutritional and energy content of groat yield improved consistently. The higher the grain moisture, the higher the proportion of grains retaining hulls. Impact dehulling proved to be a potentially useful method to increase energy content of oat grains on-farm