Relationship of in Vitro Cellulose Digestibility of Undried and Dried Mixed Forages to Their in Vivo Dry Matter Digestibility

Abstract

The digestibility by rumen bacteria in vitro of the cellulose in 30 samples of mixed alfalfa-bromegrass forages in the undried and dried state were determined and compared to in vivo dry matter digestibilities determined using dairy cows. In 12 hour in vitro rumen fermentations, the cellulose digestibility of the undried forages was significantly higher (7%) than that of the dried forages. When the in vitro cellulose digestibilities were correlated with in vivo dry matter digestibilities the correlation coefficients were 0.859 and 0.711 for the undried and dried samples, respectively. Both coefficients were highly significant. These results suggest that the in vitro rumen fermentation technique might be useful in predicting dry matter digestibility of fresh forages but use of the undried forage rather than dried samples in the determination is recommended.