Relationship between oven and toluene dry matter in grass silage

Dry matter (DM) contents of 205 silages were determined by toluene distillation and oven drying at 100°C. The toluene distillation method gave values up to 11% higher than the oven drying method, the largest differences occurring with silages of high volatile fatty acid concentration, low lactic acid concentration and high ammonia nitrogen content expressed as a percentage of total nitrogen. Highly significant ( P < 0.01) correlations were shown between toluene dry matter and oven dry matter for various ranges of ammonia nitrogen, and equations are presented which allow toluene dry matter to be readily estimated on a routine basis for grass silage.