Use of the rumen simulation technique (rusitec) to provide micro-organisms for assessing forage rate-of-fermentationin vitro:effect of soluble carbohydrate inputs to rusitec

Abstract

In previous experiments (Barbi, Owen & Theodorou, 1993; Barbi, Owen & Theodorou, 1994), to minimize the reliance on fistulated animals in feed evaluation, effluent fluid from thein vitrorumen simulation technique (RUSITEC - Czerkawski & Breckenridge, 1977) was used to replace strained rumen liquor as the inoculum for the Pressure Transducer Technique (PTT - Theodorou, Brooks, Dhanoa, McAllan & Gill, 1993). In Barbiet al(1993), two different dilution rates in RUSITEC were compared, whereas in Barbiet al(1994), the effect of increasing the solid food input to RUSITEC was assessed. In both experiments low microbial activity in the RUSITEC effluent fluid affected the PTT results, reducing rates and extent of fermentation profiles to below those in the rumen-liquor inoculated control cultures.In the present study, mixtures of glucose and xylose, as sources of liquid-phase nutrients, were infused, in differing quantities, into RUSITEC vessels. Also, the effect of adding or not adding a source of solid nutrient (hay) to the effluent collection vessels, was investigated. The objective, in both treatments, was to increase the cellulolytic microbial activity of RUSITEC effluent fluid.