INVESTIGATIONS OF FEEDING INFLUENCES ON T HE DEVELOPMENT OF INCISORS LENGTH IN RABBITS, CHINCHILLA AND RATS

1. Rabbits and chinchilla have similar developments of teeth length. C ompared with lower incisors the upper incisors show a higher growth, w hereas the incisors of rats are characterized by a higher growth in th e lower than the upper jaw. 2. The attrition of upper incisors mainly depends on growth of the antagonist in the lower jaw. Feeding hay or c arrots exclusively high (rabbits, chinchillas) or highest (rats) rates respectively of attrition are observed. It shows that hardness of fee dstuffs has not the importance as be supposed. 3. Minimum increases of teeth length, that are the lowest differences between growth and attr ition, were observed on upper incisors of rabbits and chinchillas fed with hay or carrots and on lower incisors when fed concentrates (compl ete pelleted feed or mixed feed with native components). 4. Compared t o animals with usual development of teeth length, the reason of distur bances of teeth health in form of ''elephant teeth'' is fewer an overg rowth than a decreased attrition (because faulty conformations of teet h reduce the attrition on each other). Offering hay or carrots in clin ic manifestations have only a small effect.