Courses in introductory biochemistry invariably encompass basic principles of enzymology, with reinforcement of lecture-based material in appropriate laboratory practicals. Students undertaking practical classes are more enthusiastic, and generally display improved performance, when the specific experiments undertaken show direct relevance to their core degree area. Herein is described an enzyme-based practical of particular relevance to students undertaking primary degrees in biotechnology, environmental science, nutrition, as well as animal and veterinary science. The practical entails assay of phytase, an enzyme that is now routinely included in monogastric animal feed in order to ameliorate the negative nutritional and environmental consequences of its substrate, dietary phytic acid. The practical is technically straightforward, requiring relatively basic laboratory equipment and reagents that are both easily obtained and relatively inexpensive. To be an effective digestive supplement, the enzyme must display a combination of physicochemical properties, which provide sufficient scope for an interesting and multifaceted post-laboratory discussion.