1985 Volume 31 Issue 2 Pages 248-256
Two experiments were carried out to evaluate the loss of dry matter in silage occurring during the oven drying. In experiment I, the dry distillation of 27 silages was conducted by an apparatus designed to collect the volatile matters produced during the drying and the volatility of volatile matters in the silages was examined. The Silage samples made from Italian ryegrass were collected from different dairy farms in Okayama prefecture. These samples consisted of various fermentation qualities, ranging in pH value from 3.84 to 5.33 and in the score by Flieg's method from 14 to 100. For the dry distillation, about 100g of each sample chopped to about 5mm length was accurately weighed and then dried in the oven of the apparatus for 16h. During the drying, the oven temperature was maintained at 100℃ and the rate of air flow was kept constant at 12 1 per h. The contents of volatile matter in the silages used and in distillates produced by the dry distillation were analyzed quantitatively. Volatilities of volatile matters and of dry matter during the drying of silages were calculated from the amounts of volatile matters present in the silages and their distillates. In the silages examined, the mean value of volatility of total volatile fatty acids (VFA) was 73.5%, ranging from 15.2 to 111.7%. And mean percentage volatilities of acetic acid, propionic acid, i-butyric acid and n-butyric acid were 70.3, 64.4, 40.0 and 80.4, respectively. Lactic acid was also recovered in the distillates from all the silages and its volatility ranged from 0.5 to 3.7% with a mean value of 2.1%. Furthermore, all silages and their distillates contained considerable amounts of ammonia and ethanol. The volatility of ammonia during the drying process ranged from 0.3 to 99.9% with a mean value of 20.7% and that of ethanol ranged from 15.3 to 109.2% with a mean value of 67.3%. Statistical analysis showed that the volatility of volatile matters was significantly influenced by the fermentation properties of the silages. On the other hand, the mean value of dry matter volatility of the silages by the dry distillation was 3.56%, ranging from 1.10 to 7.80%. And mean values of apparent dry matter and corrected dry matter contents in the samples were 30.34 and 31.39%, respectively. Significantly negative correlations were found between the volatility of dry matter and the fermentation quality or dry matter content of the silages. In experiment II, conditions of drying silage samples were examined for their influences on the volatility of volatile matters in the silages by the dry distillation. Silage samples used for this experiment were made from Italian ryegrass without additive (A), and with the 2% glucose (B). The volatility of volatile matters in each sample was evaluated by drying for 8, 16 and 24h at 100℃, and by drying at 60, 80, 100 and 110℃ for 16h. In general, with the increase in the time and temperature, the volatility of volatile matters in the samples increased. However, each volatile matter had a volatility pattern according to the drying conditions. Namey, ethanol and n-butyric acid indicated a higher volatility, whereas lactic acid and i-butyric acid showed a lower volatility. Furthermore, volatilities of acetic acid and ammonia were highly influenced by the drying conditions. From these experiments, it was confirmed that the considerable loss of dry matter owing to the volatilizing of volatile matters could occur during the oven drying of silage and the extent of the loss could be significantly influenced by the fermentation properties and drying conditions of the silage.
