Comparison of oven drying and toluene distillation in the determination of the dry‐matter content of silage

The dry‐matter content of 30 silages has been determined by oven drying and by distillation with toluene, values obtained by the latter method being corrected to allow for volatile materials present in the aqueous distillate. The toluene distillation method gave values up to 22.1% higher than the oven‐drying method, the largest differences occurring with silages of low dry matter and high volatile fatty acid concentration. Even when volatile fatty acid content was low, the toluene distillation results were some 12% higher, due to the appreciable volatility of lactic acid under the conditions of the oven‐drying method used. The implications of these results on intake and digestibility studies with ruminant animals are discussed.