Abstract
The in vivo artificial rumen (VIVAR) technique was compared with the Wisconsin artificial rumen, the Tilley and Terry two-stage and the Van Soest and Wine digested neutral detergent fiber (NDF) methods of estimating forage digestibility. Dry matter disappearance (DMD) was determined after in vitro fermentation with rumen fluid inoculum for the Wisconsin procedure, and after a subsequent pepsin or neutral detergent treatment in the Tilley and Terry, and Van Soest and Wine digested neutral detergent fiber methods, respectively. Forage DMD was determined by the VIVAR procedure using stainless steel containers with gas vents and small glass jars (without gas vents) placed in the rumen during the fermentation stage. The glass-jar VIVARS were exposed to a pepsin treatment after the rumen fermentation. Of the four methods, the two-stage techniques (Tilley and Terry and NDF) were superior, indicating that further digestion beyond a rumen microbial fermentation is necessary to estimate in vivo forage digestibility. Although the VIVAR technique was improved by including a pepsin digestion, its performance was still relatively poor, compared with the Tilley and Terry method. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.