After completing his PhD on growth modelling in calves in 1996, he worked as a research scientist for TNO Nutrition & Food Research Institute. Since 2016 he holds a personal chair at the Animal Nutrition Group and since 2021 he is chairholder of the Animal Nutrition Group. His research focuses on digestive physiology and macronutrient metabolism in various species, mostly pigs and calves. Prof. Gerrits has focused on interactions between nutrition, health and welfare. In whole-body metabolism studies, he combines indirect calorimetry with stable isotope tracer technology. Understanding of digestion kinetics is a key item in his research across species. In pigs, his research has focused on the quantitative impact of suboptimal health on nutrient digestion and metabolism. Twenty-one PhD students have completed their PhD under his supervision with 10 more underway. His publication record comprises more than 130 papers in peer-reviewed journals.