The largemouth bass (LMB) is a high-value fish for aquaculture and sports fisheries in the United States. In teleosts, ammonia is a major component of nitrogen excretion, which is produced from protein metabolism. In feeds, digestible non-protein energy aids in sparing protein use for energy thereby enhancing protein retention efficiency. Reduced catabolism of protein would also reduce ammonia excretion by the fish to receiving waters.
An experiment was conducted in the Aquatic Animal Nutrition Lab (AANL) at Kentucky State University to assess the effects of diet formulation on ammonia production by juvenile LMB. A control diet (Diet 1) was formulated to contain 45% crude protein and 12% lipids and was modified to contain 7% lipids and no supplemental amino acids (Diet 2). After a week of conditioning, each diet was fed once daily to quadruplicate groups of three LMB stocked in 110-L glass aquaria operating as a recirculating system. Water quality was kept within acceptable ranges for LMB and water flow was interrupted during water samplings for total ammonia-N (TAN). TAN readings from each aquarium were performed every three hours for a total of 12 hours. The experiment was repeated once after two days of water recirculation.
No statistically significant differences (P>0.05) in TAN levels in the rearing water were found during the study, despite the linear increases in TAN concentration over time (Figures).