This study investigated the effects of age on behavior controlled by temporal contingincies and also describes bar press responding by an animal infrequently used in the operant laboratory: the Syrian hamster. A review of the literature revealed a paucity of research on aging and temporal control thus providing an impetus for the study. The performance of four young (12months) and four old (24+months) male Syrian hamsters on Fixed-Interval schedules o f reinforcement was analyzed according t o post-reinforcement-pause duration, response rate, running rate, and cummulative record measures. Failure of the behavior to stabilize consistently over time precluded the interpretation of age differences. The discussion presents rationales for the inconclusive results and describes the atypical behavior of the hamsters.

published_or_final_version / Anatomy / Master / Master of Philosophy

published_or_final_version / Biochemistry / Master / Master of Philosophy

published_or_final_version / Biochemistry / Master / Master of Philosophy

Fifty twelve-month female Sprague-Dawley rats were used to study a lysine requirement for tissue maintenance. Animals were randomly assigned into five groups with dietary lysine levels ranging from 0.097 to 0.317 percent and fed for 60 days. Liver composition and carcass composition were determined, and a lysine requirement was also predicted. Results showed that the group fed 0.317 percent lysine had significantly increased liver fat content and decreased protein content. Neither liver moisture content nor total liver nitrogen content was related to dietary lysine levels. There was no significant finding on the analysis of carcass composition. The data indicated that the mature rat had a requirement for lysine lower than 0.097 percent in the diet. It was suggested that either adequate lysine was provided by wheat gluten in the diet, or the mature rat did not require lysine in order to maintain tissue level of protein. In future studies, it was necessary to use a diet with lysine levels lower than 0.097 percent to determine the minimum lysine requirement, and a concurrent baseline group for comparison with the treatment animals. / M.S.