U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Document Type


Date of this Version

January 2007


Published in Crop Protection 27 (2008) 851–854.


Various species of rodents and lagomorphs were used in bioassays to determine the effectiveness of protein hydrolysates (specifically hydrolyzed casein and gelatin) as herbivore repellents. Mixed sex groups of captive rabbits, pocket gophers, voles, and mountain beavers were offered hydrolyzed casein or gelatin test diets in single-choice tests following a training period with a hydrolysate-free diet. The effectiveness of either hydrolyzed casein or gelatin was dependent on the species. Hydrolyzed casein was identified as an effective repellent for mountain beavers and pocket gophers as these species showed a strong avoidance of hydrolyzed casein diets. Rabbits demonstrated slightly higher avoidance of the gelatin diets versus hydrolyzed casein. However, hydrolyzed casein and gelatin displayed little potential as repellents for voles as both products were readily consumed. Rather than universal application for all pest herbivores, test diet preferences suggest that repellent application depends on the pest species.