Mixed feeding schedule switching between high and low protein diets for Asian seabass (Lates calcarifer)

Abstract

Mixed feeding schedule (MFS) switching between high (HP) and low (LP) protein diets has been used to improve growth and feed utilization in various fish species. In the current study, the optimal MFS was investigated in Asian seabass (Lates calcarifer) over the duration of an 8-week feeding trial. The fish (18.7 ± 0.1 g initial weight) were fed alternating between one day of HP and one day of LP diet (1 H/1 L), two days of HP and one day of LP (2 H/1 L), three days of HP and one day of LP (3 H/1 L), two days of HP and two days of LP (2 H/2 L), or three days of HP and two days of LP (3 H/2 L), and these treatments were compared to continuous feeding with HP (positive control, 403 g/kg protein and 86.1 g/kg lipid of feed basis) or with LP only (negative control, 333 g/kg protein and 55.7 g/kg lipid of feed basis). Twenty-one experimental units comprising fifteen fish each were set under a completely randomized design. At the end of experiment, growth performance and feed utilization parameters were similar between fish fed HP, 2 H/1 L and 3 H/1 L, followed by 3 H/2 L treatment, and all the fish in the alternating feed groups ingested a higher amount of HP than LP (P < 0.05). Economic analysis suggests that the most profitable schedule was 2 H/1 L among the tested feeding regimens. Specific activities of chymotrypsin, amylase, cellulase, lipase; and the amylase to trypsin ratio, indicated significant improvement in nutrient utilization and protein-sparing effect in the alternating treatments. There were no negative effects on muscle quality or carcass composition by the preferred alternating treatments (2 H/1 L and 3 H/1 L). Findings from the current study can be used to decide a practical feeding schedule for the commercial production of Asian seabass.