Impact dehulling oat grain to improve quality of on-farm produced feed : 1.Hullability and associated changes in nutritive value and energy content

Abstract

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.

Impact dehulling oat grain to improve quality of on-farm produced feed : 2.Groat breakage and storability

“…Background information for the experiments are shown in Kangas et al (2001) and Peltonen-Sainio et al (2004). Grain from each year was pre-purified by sorting with 1.5 mm sieves to remove immature grains, small particles, dust and weed seeds prior to all measurements and analyses.…”

“…However, partially dehulled oat groats have resulted in similar results to those for naked oat in feeding experiments (Pettersson et al 1987(Pettersson et al , 1997. Hence, onfarm dehulling of conventional oat is considered to be a valid alternative to growing naked oat (Peltonen-Sainio et al 2004).…”

“…Three 250 g sub-samples were dehulled at rotation speeds of 200, 250, 300, 350, 400, 450 and 500 r min -1 with an impact oat dehuller (Rivakka, Nipere Ltd., Finland, http://www.nipere.fi) as demonstrated by Peltonen-Sainio et al (2004). After dehulling, a 50 g sub-sample representing groat yield was ana-Vol.…”

“…Oat (Avena sativa L.) grain is excellent in nutritional quality and has high metabolised energy content compared with other small-grain cereals, but only when hulls surrounding the caryopsis are removed (Peltonen-Sainio et al 2004). High hull content of oat is a major reason for predomination of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) as feed crop in many countries (Burrows 1986).…”

“…Mechanical dehulling causes groat damage (Symons andFulcher 1988, Doehlert et al 1999). Groat breakage may cause economic losses by increasing proportion of wastage (Peltonen-Sainio et al 2004), but it can also activate endogenous lipase and lipoperoxidase in oat groat. Oat lipase is mainly localised in the aleurone layer and embryonic tissues (Ekstrand et al 1992), both of which are likely to be damaged during rough dehulling.…”