Abstract
An experiment was conducted to find the drying method of analytical sample for the accurate evaluation of nutritive value of silage. Silages used for the experiment were made from Italian ryegrass without additive (C-silage), with 0.4% formic acid (F-silage) and with 1% glucose (G-silage). The silages were fed individually to 3 wethers by a 3×3 Latin square design for digestion trials. On the other hand, the silage samples of analytical use were treated as follows: freeze dried at a 5 micron pressure for 24 hours and then ground in a Wiley mill to pass a 0.5mm screen (F); oven dried with forced air at 60℃ for 8 hours and then ground in the Wiley mill to pass the 0.5mm screen (L); oven dried with forced air at 100℃ for 8 hours and then ground in the Wiley mill to pass the 0.5mm screen (H). Residual mosisture in freeze dried samples was determined by vacuum drying to constant weight over P_2O_5 at 40℃ at a pressure of less than 20 microns (V), while the moisture in oven dried samples was determined by oven drying to constant weight at 105℃ (O). The chemical composition of these samples was determined by proximate analysis and the apparent digestibility of the silages was calculated from results of the trial and analysis. Furthermors, in vitro digestibilities for the dry matter and crude protein of each sample were determined by artificial rumen method and WEDEMEYER method. Resultant silages had different fermentation qualities and contained various amounts of organic acids, ammonia and ethanol according to treatments at the ensiling. The contents of dry matter, crude protein, crude fat and nitrogen free extract (NFE) were appreciably higher in the silages dried by FV method than in the silages dried by LO and HO methods. Digestibilities of dry matter, crude protein, crude fat and NFE determined by wethers were significantly higher in FV dried silages than those in oven dried silages. Such tendencies were detected in the in vitro digestibilities of dry matter and crude protein. The values of digestible crude protein (DCP) and total digestible nutrients (TDN) of the silages evaluated by FV method were significantly higher than those evaluated by oven drying methods. And further, these nutritive values by LO method were higher than those by HO method. The results may show that the FV method is more advantageous to the oven drying methods for the accurate evaluation of nutritve value of silage.
