Ammonotely in a neotropical frugivorous bat as energy intake decreases.
We tested the role of increased ammonia in urine as an energy- and/or nitrogen (N)-saving mechanism in the great fruit-eating bat Artibeus lituratus (Phyllostomidae). We compared N excretion in two groups of bats fed energy-rich (2.75 kJ g(-1) wet mass) or energy-poor diets (0.7 kJ g(-1) wet mass). Within each diet, bats were assigned to different N contents. In order to function as an energy-saving mechanism, ammonia production should increase with decreasing energy intake. To function as an N-saving mechanism, ammonia production should increase with decreasing N intake. Because we varied both diet energy density and N content, our study design allowed us to test these two possibilities simultaneously. Bats had higher food intake rate and, consequently, higher N intake rate on the energy-poor diet, but energy intake rate was lower. Most bats on the energy-rich diet were ureotelic whereas on the energy-poor diet bats were ureotelic, ammonotelic or ureo-ammonotelic. Bats fed the energy-poor diet had a higher excretion rate of ammonia and a higher percent of N excreted as ammonia. Percent N ammonia and ammonia excretion rate were inversely related to energy intake, but they were not related to N intake. By favoring ammonia production over urea, bats on the energy-poor diet may save up to 1% of their basal metabolic rate. Consumption of energy-dilute fruits by fruit bats might affect the way in which N wastes are excreted, favoring the excretion of ammonia N when food intake is accompanied by the ingestion of large volumes of water.
Estación de Biología de Chamela, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 21, San Patricio, Jalisco 48980, México. gherrera@ibiologia.unam.mx
L Gerardo
LG
Herrera
Jazmín
J
Osorio
Carlos A
CA
Mancina
D000641:Ammonia / Q000378:metabolism* / Q000652:urine; D000818:Animals; D002685:Chiroptera / Q000378:metabolism*; D004435:Eating; D002149:Energy Intake; D009584:Nitrogen / Q000378:metabolism
D000641:Ammonia; D009584:Nitrogen