To test the repeatability of a gas production method for assessing the in vitro fermentation of forages using micro-organisms derived from a rumen simulation technique (rusitec) or from sheep rumen liquor

Abstract

When forage in vitro digestibilities are determined on different occasions, they can be different and this is generally related to differences in rumen liquor from which the microbial inoculum was obtained. Experiment 1 of the present study, using rumen liquor only, investigated whether fermentation kinetics of forages as determined by in vitro gas production assays (Theodorou et al, 1994) made on different occasions are repeatable. It was argued that kinetics of fermentation were likely to be more sensitive to quality of rumen micro-organisms than digestibility assessment.In previous experiments (Barbi et al, 1993, 1994a 1994b) to minimize the reliance on fistulated animals in feed evaluation, RUSITEC fluid was used to replace strained rumen liquor as the inoculum for the gas production method (PTT) of Theodorou et al (1994). Experiment 2 investigated whether the day-to-day repeatability of gas production assays using RUSITEC fluid was comparable to that using sheep rumen liquor.