A proposed methodology to standardize the determination of enzymic activities present in enzyme additives used in ruminant diets

There is increasing interest in using enzymes that degrade plant cell walls in ruminant diets to enhance production efficiency. Despite strong evidence from several studies suggesting a beneficial effect of enzyme supplementation on nutrient utilization and animal performance, overall the results have been somewhat inconsistent. One of the main problems faced by researchers is the lack of adequate biochemical characterization of the products used, which leads to a poor understanding of their mode of action. Of these biochemical characteristics, enzyme activities are the most important, but they are not always evaluated prior to use. Furthermore, as many arbitrary units of expression for these activities coexist, direct comparisons among studies are essentially impossible. In this paper, we propose a methodology that we feel accounts for the requirements of accuracy, simplicity and safety of use. In addition, a rationale for the standardization of the assays as a function of the conditions under which the enzymes are expected to act is presented. The standardization of these assays will benefit researchers, the feed industry, regulatory organizations, and ultimately the consumer, as it will result in the development of better, safer and more consistent enzyme additives for use in ruminant diets. Key words: Cellulase, enzyme additives, methodology, ruminants, xylanase