Comparison of on-farm forage-dry-matter methods to forced-air oven for determining forage dry matter1

The objective of the study was to compare 3 different on-farm methods of determining DM in forages using traditional forced-air oven (FAO) as a standard for comparison. Silage samples (60 corn silage, 35 grass silage) were analyzed by microwave (MW), Koster Moisture Tester, Q-Dry (a new automatic convection system to measure DM), and FAO using standard or manufacturers' methods for each system. A linear relationship was observed for corn silage between FAO and MW (β = 1.014; R2 = 0.961), Koster Moisture Tester (β = 1.028; R2 = 0.885), and Q-Dry (β = 0.982; R2 = 0.921), where β is slope of the regression line and R2 is coefficient of determination. In addition, grass silage showed a significant relationship between FAO and MW (β = 1.021; R2 = 0.961), Koster Moisture Tester (β = 1.245; R2 = 0.950), and Q-Dry (β = 0.965; R2 = 0.952). All methods resulted in similar DM determination, exhibiting a strong, linear relationship with FAO (P < 0.01), and all have advantages and disadvantages. Microwave and Q-Dry showed the strongest correlations to FAO. These data suggest that MW and Q-Dry are the best on-farm alternatives to traditional oven drying for DM determination.