The Effects of Dietary Protein Sources on the Growth and Survival of Scylla tranquebarica (Fabricius, 1798) Megalopa to Early Crab Instar

Abstract

The effects of different dietary protein sources on the growth and survival of Scylla tranquebarica (Fabricius, 1798) megalopa to early crab instar were elucidated. Four isoproteic (51 %) and isolipidic (10 %) diets were formulated using fish meal (FM) as the main protein source, combined with squid meal (FM:SQ), scallop meal (FM:SC), or bloodworm meal (FM:BW) at a ratio of 3:2. The 2-day-old megalopa were reared in triplicate in 35 L black rectangular tanks and fed the experimental diets for 14 days. The larval stage composition, survival, and growth performance were evaluated on days 7 and 14. On day 7, the production of crab instar 1 was significantly higher in the FM, FM:SQ, and FM:SC treatments compared to FM:BW (P < 0.05). On day 14, the proportion of crab instar 2 and the mean total biomass were significantly higher in the FM:SQ and FM:SC treatments (P < 0.05). These two treatments also exhibited significantly lower feed intake and feed conversion ratios than the others, with the highest protein and lipid efficiency ratios (P < 0.05). In conclusion, combining fish meal with squid or scallop meal improves megalopa growth and survival during the transition to the early instar stage.