Comparison of Types of Fermentation Vessels for an In Vitro Artificial Rumen Procedure

Three types of containers (125-mi Erlenmeyer flasks, 122 x 28 mm glass centrifuge tubes, and 200 x 25 mm glass screwcapped tubes) were compared as fermentation vessels for a modified Tilley and Terry two-stage in vitro artificial rumen procedure.This in vitro technique estimates true dry matter digestibility.Four forages (orchard-grass, alfalfa, bromegrass, and timothy) with wide differences in digestibility and three sample sizes (250, 375, and 500 rag) were utilized for the comparison.Digestibilities were consistently low with the centrifuge tubes.Results with screwcapped tubes were comparable to those with Erlenmeyer flasks.Tubes utilize water bath space more efficiently and do not require a constant supply of CO2 during fermentation to maintain an anaerobic condition.Small but significant differences in digestibility occurred between sample sizes.