Pre-soaking feed pellet significantly improved feed utilization in Asian seabass (Lates calcarifer)

- Pre-soaking of feed pellets was optimized for feed utilization in Asian seabass.
- Pre-soaking improved digestive efficiency by activating chymotrypsin and lipase.
- No negative effects were found in blood, muscle or carcass parameters.
- Economic analysis supports the use of pre-soaked feed pellet for this species.

Effects of water pre-soaking a commercial dry feed pellet on growth, feed utilization, specific activity of digestive enzymes, fecal thermal properties, hematological parameters, muscle quality and carcass composition were investigated in Asian seabass, Lates calcarifer. The 2 months old fish (6.02 ± 0.04 g body weight) were subjected to four dietary treatments with three replications under a completely randomized design. The dietary treatment pellets were pre-soaked with 0, 0.25, 0.5 or 0.75 (v/w) fold amounts of water per pellets, here termed soaking ratios. After rearing for three months, there were no differences in survival (95% on average) or in growth performance (specific growth rate 1.64% body weight day− 1 on average) of the fish across the four dietary treatments (P > 0.05). Superior feed utilization (feeding rate, feed conversion ratio, and protein efficiency ratio) was observed in the fish receiving the last treatment. This treatment significantly increased the specific activities of chymotrypsin and lipase, but not those of pepsin, trypsin, or amylase, relative to the baseline control. An improved feed utilization was well supported by the thermal properties of feces, assessed in relation to the available nutrients. Data on hematological parameters, muscle quality and carcass composition indicated no negative effects on the fish reared with this dietary treatment. Findings from the current study indicate an optimal pre-soaking ratio of 1:0.75 w/v of pellet to water, for enhancing the feed utilization in Asian seabass.