Studies on the Chemical Composition and the Quality of Silage. : VII. Relation between the Methods for Determining Dry Matter and Volatile Matters in Silage

The presence of various volatile matters in silage has long been known. The authors have made a comparison between methods for determining dry matter in silage. The determinations in these tests included the toluene distillation method, and the drying methods with infrared ray and with oven. One of the two oven drying methods tested was a usual one and the other was a simplified one, in which a 20 to 40 g. of fresh and finely cut silage was directly weighed before drying in a large weighing bottle(6cm×5cm). Of fifty silage samples, the contents of organic acids, total nitrogen, ammonia nitrogen, and dry matter as well as the pH values were determined. The results obtained are summarized as follows: 1)Fifty silage samples(14 chinese milk-vetch, 13 Italian ryegrass, 6 oat, 5 corn, 3 sweet potato vines, 5 mixed hay crops and 4 others) contained 11.3 to 47.5(mean 20.7±7.6g.) of dry matter by the distillation method, 0.07 to 3.86(1.40±0.95g.) of volatile fatty acid, 0.09 to 1.16(0.58±0.29g.) of total N and 6.5 to 407.4(110.6±98.3mg) of ammonia N, per 100 g. 2)The losses(D. M. by the distillation method-mean value of D. M. by the drying methods) were significantly correlated with volatile acid content, r=+0.69, with butyric acid content, r=+ 0.70, with ammonia N, r=+0.64, with pH, r=+0.46 and with appraisal marks of silage, r=-0.60. Therefore, the percentage of underestimating dry matter in poor silages is higher than that in good silages. 3)The quantity of dry matter estimated by the infrared ray drying was generally larger than that by the oven drying, but lower than that by the distillation method. Even in employing the distillation method, however, further investigation will be necessary to determine the real quantity of dry matter in silage.