COMPARISON OF METHODS FOR DRY MATTER DETERMINATION OF HIGH MOISTURE GRAIN CORN

Abstract

Comparisons were made between methods of determining the dry matter (DM) content of high moisture (HM) ground ear corn, preserved five months earlier with volatile fatty acids (VFA), and HM shelled corn at harvest. The effect of fine grinding (1 mm diameter screen) of HM shelled corn samples prior to DM determination also was examined. There were no differences in DM content of HM shelled corn between toluene distillation, oven-drying, or semi-automatic moisture testing. With HM ground ear corn, DM values obtained by toluene were greater (P < 0.01) than for the other methods. Fine grinding of the samples resulted in increased DM content (P < 0.01). However, differences between methods were apparently confounded by the presence of VFA. Air-drying HM shelled corn at 65 C for 24 hr, prior to DM determination, resulted in a 3% (P < 0.01) increase in DM content. However, there was a significant interaction (P < 0.01) with the effect of fine grinding; hence, the most accurate DM determinations were obtained when the samples were finely ground after air-drying. The least accurate sample preparation was from finely ground corn which had not previously been air dried. Moisture was apparently lost during grinding due to equilibration with atmospheric moisture.