One in vitro method to simulate ruminal nutrient degradation and fermentation is the rumen simulation technique (RUSITEC), allowing investigation of a large number of treatments in a relatively short period of time. Although it was developed decades ago, till today no standardised method exists, which impairs the comparison of research data. Therefore, in an interlaboratory study involving nine animal science research groups from Germany and Switzerland, the variability between laboratories was assessed. In a first step, each laboratory incubated the same feeds according to their established RUSITEC protocols. In a second step, all participants followed a standardised protocol which allowed analysing the variability between groups when incubating the same diets. Data analysis of the first step using appropriate statistical models depicted considerable variation and large differences between laboratories for most response variables of rumen nutrient degradation and fermentation. Strict adherence to a standardised protocol in the second step largely reduced this variation for almost all response variables. Our study clearly shows that standardisation of all steps of the RUSITEC has potential to improve the comparability and reliability of RUSITEC research data. Furthermore, the study highlights the importance of standardising in vitro methods to successfully reduce and replace animal experiments with ruminants.
Klevenhusen et al. (Sun,) studied this question.