Animal Feed Science and Technology 123–124 (2005) 243–253 Ranking of in vitro fermentability of 20 feedstuffs with an automated gas production technique: Results of a ring test A.H. van Gelder a , M. Hetta b , M.A.M. Rodrigues c , J.L. De Boever d , H. Den Hartigh e , C. Rymer f,1 , M. van Oostrum g , R. van Kaathoven h , J.W. Cone a,∗ a Division of Nutrition and Food, Animal Sciences Group of Wageningen UR, P.O. Box 65, NL-8200 AB Lelystad, The Netherlands b Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Science, P.O. Box 4097, SE-90403 Umea, Sweden c Departemento de Zootecnia, Universidade de Tras-os-Montes e Alto Douro, Apartado 202, P-5001 Vila Real, Portugal d Departement Dierenvoeding en Veehouderij, Scheldeweg 68, B-9090 Melle, Belgium e Schothorst Feed Research B.V., P.O. Box 533, NL-8200 AM Lelystad, The Netherlands f Nutritional Sciences Research Unit, ADAS Drayton, Alcester Road, Stratford upon Avon CV37 9RQ, UK g BLGG, P.O. Box 115, NL-6860 AC Oosterbeek, The Netherlands h CCL BV, P.O. Box 107, NL-5460 AC Veghel, The Netherlands Abstract A ring test was completed to determine within laboratory repeatability, and reproducibility among laboratories, of a gas production technique for measuring fermentation kinetics of feeds in rumen fluid. Eight laboratories in different European countries received 20 feed samples. All used the same gas production equipment and method. Gas production profiles were fitted to a multiphasic model and the most important parameters were statistically compared. Although the within laboratory repeata- bility of, and levels of, calculated parameters differed among laboratories, in most cases there was a high correlation between pairs of laboratories (r = 0.93–1.00), although in some cases the correla- tion was only moderate (r = 0.73–0.87). Within laboratory gas production profiles were influenced by Abbreviations: CP, crude protein; DM, dry matter; NDF, neutral detergent fibre; OM, organic matter ∗ Corresponding author. Tel.: +31 320 237354; fax: +31 320 237320. E-mail address: john.cone@wur.nl (J.W. Cone). 1 Present address: University of Reading, P.O. Box 237, Reading RG6 6AR, UK. 0377-8401/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2005.04.044