Optimal Feeding Frequency for Captive Hawksbill Sea Turtle (Eretmochelys imbricata)

SIMPLE SUMMARY: Head-starting programs of hatchlings before release of yearlings to natural habitat are an alternative approach for restoring the population of critically endangered sea turtles. Hawksbill sea turtle has been reared in captivity programs in several countries, while the feeding regimens have never been optimized. In the current study, the feeding frequency of hawksbill sea turtle was optimized in indoor experimental conditions. Two-month-old turtles were fed at different frequencies: one meal daily at 12.00 h, two meals daily at 08.00 and 12.00 h, two meals daily at 08.00 and 16.00 h, two meals daily at 12.00 and 16.00 h or three meals daily at 08.00, 12.00, and 16.00 h. At the end of an 8-week trial, two meals daily with long time interval (at 08.00 and 16.00 h) were optimal, based on assessment criteria of growth, feed utilization, digestive enzyme markers, available and unavailable nutrients present in the feces, hematological parameters, and carapace elemental composition. This finding could be directly used as a feeding guideline supporting the head-starting programs of this species. ABSTRACT: Hawksbill sea turtle (Eretmochelys imbricata) has been reared in head-starting captivity programs, while the feeding regimens have never been optimized. In the current study, the feeding frequency of hawksbill sea turtle was investigated in indoor experimental conditions. Two-month-old turtles (38.98 ± 0.02 g) were distributed to triplicates of five treatments containing three turtles each and they were fed at different frequencies: one meal daily at 12.00 h (1M12), two meals daily at 08.00 and 12.00 h (2M8–12), two meals daily at 08.00 and 16.00 h (2M8–16), two meals daily at 12.00 and 16.00 h (2M12–16), or three meals daily at 08.00, 12.00 and 16.00 h (3M8–12–16). At the end of an 8-week trial, growth performance (specific growth rate 2.39 ± 0.02% body weight day(−1)) and feed consumption (feeding rate 2.00 ± 0.43 g day(−1)) were highest for turtles fed 2M8–16, followed by 2M12–16 or 3M8–12–16 relative to the other treatments (p ˂ 0.05). These treatments had significantly higher trypsin specific activity and trypsin/chymotrypsin ratio, and vice versa for lipase specific activity and amylase/trypsin ratio, relative to the remaining treatments. These match well with the fecal thermal properties that indicate amounts of available and unavailable nutrients present in the feces. Hematological parameters and carapace elemental composition showed no negative effects to turtles in 2M8–16 treatment. Therefore, two meals daily with long time interval were optimal for feeding hawksbill sea turtle. Findings from the current study could be directly used as a feeding guideline supporting the head-starting programs of this species.