Comparison of two methods for determining dry matter in different types of forages

The study compared the Association of Official Analytical Chemists method for determining dry matter (DM) at 275 Odegrees National Forage Testing Association. Nine commercial and research laboratories provided 156 dry and ground samples of corn silage (n = 45), hays (grasses, legumes and mixture; n = 67) and haylage (n = 44). Although the range of variation was similar between the two methods, the average DM content measured using the 221 degreesF method was about 2 percentage units higher than the 275 degreesF method. The relationship between DM determined at 221 degreesF and 275 degreesF had the same regression coefficient for all forages, but haylages had a larger intercept than hays and corn silages. Accurate near infrared reflectance spectroscopy equations were developed for the new 221 degreesF method for corn silages and hays (SECV = .31%). The haylage equation had a larger standard error of calibration (SECV = .53%). Haylage also had the lowest 2 correlation between the two drying methods (R-2 = .68).