A Comparision of Methods to Determine Dry Matter in Silages

¹ Sheep Research Farm, Agriculture and Agri-Food Canada, La Pocatière, QC, Canada G0R 1Z0
² Experimental Farm, Agriculture and Agri-Food Canada, Kapuskasing, ON, Canada P5N 2Y3
³ Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2

Dry matter (DM) contents of 90 silages were determined by 1) toluene distillation (corrected for volatile fatty acids and ethanol in the distillate), 2) gas chromatography, 3) Karl Fisher titration, and 4) oven-drying at 65°C. The mean DM content of silage as determined by Karl Fisher titration (33.6%) was higher than values obtained by other methods. Values of DM determined by gas chromatography (31.8%) were similar to those determined by toluene distillation (31.3%) but higher than those obtained by ovendrying (31.0%). The highest correlation (r = 0.9928) among DM values was between those determined by gas chromatography and those determined by Karl Fisher titration. However, higher values for DM content obtained with the Karl Fisher titration method and the potential health hazard of toluene utilization suggest that gas chromatography is a better choice to determine precisely DM content in silages. Karl Fisher titration is a simple and rapid method that requires less sophisticated equipment than does gas chromatography and would be more practical for some laboratories. Oven-drying could be acceptable to determine DM in a large number of samples used for farm purposes.

Key Words: silage • moisture • dry matter • Karl Fisher titration

Submitted on January 23, 1996
Accepted on May 10, 1996