Meeting Abstract
Working previously with house sparrow (HOSP; Passer domesticus) nestlings near fledging, we found that (1) dietary carbohydrate induces intestinal disaccharidase activity, (2) dietary lipid depresses disaccharidase activity, and (3) aminopeptidase-N activity may be induced by increasing dietary protein. In the current study, we tested younger HOSP nestlings and also a non-passerine – Northern bobwhite (NOBO; Colinus virginianus) chicks – to see if the previously observed responses to multiple dietary signals were common among avian species. In order to disentangle the effects of varying substrate levels, three diets were used: one high in carbohydrate (HC), one high in protein (HP), and one high in lipid (HL). Maltase, sucrase, and aminopeptidase-N activities were determined in birds fed these diets, and ratios of maltase activity to aminopeptidase-N activity (M/A ratios) were then calculated. The M/A ratio tests for specific enzymatic responses to differing levels of substrates and can reflect tradeoffs in enzymes that might occur if intestinal apical membrane space is limiting. We found that lipid depressed carbohydrase activity in both avian species, and aminopeptidase-N activity was significantly higher in HOSP nestlings and NOBO chicks that had been fed the HP diet. M/A ratio was highest in birds fed the HC diet, although the ratio was highest in HOSP fed the HC diet due to enzymatic induction per gram of intestinal tissue, while the ratio was highest in bobwhites fed the HC diet mainly due to larger intestines. Overall, the enzymes studied responded to multiple dietary signals, and, for the most part, the patterns of response were similar. Funded by NSF IOS-1354893 to WHK & UNSL/CONICET to EC-V.
