As a researcher at Feed Analytical Laboratory, Department of Animal Nutrition, Faculty of Agriculture, main research topic of Kristina Kljak is feed evaluation. Her research is focused on maize grain, its physical-chemical properties and utilization in animal nutrition. For that topic, her research includes proximate analysis, protein fractions of maize, starch and detergent fiber analysis, in vitro digestion analysis of starch and protein for monogastric animals and ruminants, grain hardness, feed particle size distribution, feed buffering capacity. Large part of her research is focused on antioxidants and antioxidant activity of maize hybrids, with accent on carotenoids and their relationships with color of maize grain. She also conducted several in vivo studies with poultry to investigate carotenoid utilization from various feeds.