Abstract:The relationship between the feeding strategy and the growth of sea cucumber Apostichopus japonicus has been an important issue in aquaculture, but the study on the optimized feeding frequency was rare. We conducted a 40-day experiment to identify the best feeding frequency and the mechanisms how feeding frequency affected the growth, the biochemical composition and the energy budget of sea cucumbers. The sea cucumbers were divided into four groups according to the feeding frequencies: F1 (1 time/day), F2 (2 times/day), F3 (3 times/day), and F4 (4 times/day). Each group had 3 duplicates. The artificial feed was made by authors themselves. During the experiment, the unfed feed and feces of sea cucumbers were collected then dried at 70℃. The food consumption, initial body weights and final body weights were recorded. The results showed that the F3 and F4 grew faster and their final body weights were significantly higher than those of F1 and F2 (P<0.05). Food consumption increased along with the feeding frequency. Food consumption of F4 was 3.67 g/(d•ind) which was the highest among all groups. Food consumption of F3 and F4 was significantly higher than that of F1 and F2 (P<0.05), but there was no significant difference between F3 and F4 (P>0.05). The food conversion efficiency increased along with the feeding frequency and it was 9.70% in F4, but the digestion rate showed the opposite trend. The feeding frequency did not much affect the biochemical composition of sea cucumbers. The remained food energy in feces was more than 50% of the total food energy in all 4 groups, and it was significantly lower in F1 and F2 than in F3 and F4 (P<0.05). The proportions of food energy consumed in respiration in F1 and F2 were higher than those in F3 and F4 (P<0.05). Our data suggested that the optimal feeding frequency was three times per day for sea cucumbers reared indoors. The poor growth performance of F1 may be caused by their high excretion and respiration expenditure in energy.
