Evaluation of the Dacron Bag Technique as a Method for Measuring Cellulose Digestibility and Rate of Forage Digestion2

Abstract

The rates of digestion of the cellulose in four forages were determined by suspending dacron bags filled with the forages in the rumen of sheep fed the same forages. Alfalfa gave a digestion curve which was different from those of bromegrass or two samples of timothy hay. Coefficients of variation were very high for digestibility values at early time periods (6 to 24 hours). The digestion curves obtained using the dacron bag technique were similar to digestion curves obtained using an in vitro fermentation. In a second trial, the effects of the forage ration fed to the animal on the digestibility of different forages suspended in that animal's rumen was determined using the dacron bag technique. Alfalfa as the ration fed to the animal significantly increased the digestibility of all four forages in dacron bags over digestibilities obtained when the grass hays were fed. The cellulose digestion at various times in dacron bags had little relation to in vivo digestibility coefficients except in the case of cellulose where the 36 and 42 hour digestibilities in dacron bags were significantly correlated with the cellulose digestibility coefficient (r=0.52 and 0.54, respectively).