Optimal feeding frequency for bigfin reef squid (Sepioteuthis lessoniana)

摘要

Bigfin reef squid (Sepioteuthis lessoniana) has been successively cultured through multiple generations, but little is known about the factors affecting feeding regimens. In the current study, optimal feeding frequency of five-week-old bigfin reef squids was investigated in laboratory conditions. The squids (1.48 +/- 0.03 g initial weight) were assigned to four feeding frequencies: two (2TD), three (3TD), four (4TD) or five (5TD) times daily, and they were fed with post-larval stage of Pacific white shrimp (Litopenaeus vannamei) over the three weeks of experiment. At the end of the feeding trial, the squids receiving 4TD and 5TD had the highest growth and feed utilization, and the least size variation among the treatment groups. Significant decrease in chymotrypsin-specific activity was observed in squids receiving 5TD relative to 2TD (p < 0.05), while a moderate level was observed across the remaining treatments. This matched the available and unavailable nutrients present in faeces, assessed from thermal responses. Mantle quality, in terms of RNA concentration, was the highest in squids fed 4TD or 5TD, while protein concentration and RNA/protein ratio did not differ across the four feeding frequencies tested. Also, the most crude lipid was observed in squids fed 5TD, followed by 4TD that were superior to 2TD or 3TD treatments, while crude protein and ash did not differ. These findings indicate that feeding four or five times daily is most appropriate. This practical feeding protocol can be used for mariculture of this species.