INFLUENCE OF PROCESSING ON IN VITRO DIGESTIBILITY OF RYE, CORN, BARLEY AND OATS

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Abstract
Studies were conducted to determine the influence of processing waxy barley, normal barley, high fat oats, normal oats and corn on in vitro dry matter disappearance (IVDMD). The processing treatments compared were dry ground, dry heated, ground reconstituted, reconstituted whole grain, grain steamed at 0 and 6.8 kg/cm2 and cooked grain. In addition to the previously mentioned treatments, corn was also popped and roasted. Processing had little effect on IVDMD of the oat and barley varieties although cooking at high moisture levels tended to be beneficial for all varieties. There were no differences in IVDMD between high fat and normal oats. Statistical analysis of the data for waxy and normal barley indicated a variety-treatment interaction (P < 0.05) with the dry ground and steam pressure (6.8 kg/cm2) treatments being responsible for the interaction effect. Cooking reduced (P < 0.05) IVDMD of rye compared to other treatments except rye steamed at 6.8 kg/cm2. All other treatment effects for rye were statistically similar. Reconstituting corn, either ground or whole improved IVDMD compared to dry ground corn while moist or dry heat treatment of corn tended to reduce (P < 0.05) IVDMD compared to dry ground corn. These results suggest that there is little benefit in processing rye, barley and oats, but corn digestibility may be improved substantially by reconstituting ground corn. There are indications that high fat oats and waxy barley may be slightly more digestible compared to normal oats and normal barley. Further in vitro and in vivo studies of these oat and barley varieties are necessary to determine their true value as feedstuffs. Key words: In vitro, rye, corn, barley, oats, processing