Pre-soaking of the feed pellets: a trick for successful feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758).

Abstract

Pre-soaking of the feed pellets in water can improve feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758), but the pre-soaking has not previously been optimized. This study aimed to optimize the water amount used for pre-soaking the pellets. The experiments followed a completely randomized design with three replications of each dietary treatment group. Initially 10-day-old green turtles (20-22g body weight) were treated in an indoor aquaculture system for 3months. The dietary treatment pellets were pre-soaked with 0.3, 0.5 or 0.7 (v/w) relative amounts of water that are here termed soaking ratios. At the end of experiment, there were no significant differences in survival (96% on average) and growth (average body weight 75.34g and specific growth rate 2%/day, on average) of turtles in three dietary treatments (p>0.05). Feed utilization was the best in turtles fed with 0.7 pre-soaked ratio, as indicated by significant reductions (p<0.05) in the feeding rate (7.44% body weight/day) and the feed conversion ratio (1.12g feed/g gain). Digestion was also improved by the induction of faecal digestive enzymes as well as the faecal thermal properties. The rapid growth did not negatively affect the general haematological parameters of reared turtles. These findings indicate that the pre-soaking of feed pellets at the optimal soaking ratio (1:0.7 w/v of pellet to water) can contribute through improved feed utilization of green turtles.