Ammonia and urea excretion rates of juvenile Australian short-finned eel (Anguilla australis australis) as influenced by dietary protein level

This study aimed to determine excretion rates of ammonia and urea of Australian short-finned elvers as influenced by varying dietary crude protein intake. Elvers (2.3±0.02 g) were fed diets containing dietary crude protein levels of 25% (P25), 35% (P35), 45% (P45) and 55% (P55) dry matter equivalent to 14.17, 19.24, 20.57 and 26.39 g CP/MJ, respectively (pairs of diets P25, P35 and P45, P55 were isoenergetic). Elvers were fed twice a day to a total of 6% BW/day and nitrogenous excretory products (ammonia- and urea-nitrogen) measured during the following 24 h and peak excretion rates occurred 4–8 h following both the morning and afternoon feed. Daily ammonia-nitrogen excretion was significantly (P