GROWTH AND FATTY-ACID COMPOSITION OF PACIFIC OYSTER (CRASSOSTREA-GIGAS) SPAT FED A SPRAY-DRIED FRESH-WATER MICROALGA (SPONGIOCOCCUM-EXCENTRICUM) AND MICROENCAPSULATED LIPIDS

Pacific oyster (Crassostrea gigas) spat were fed for 28 days on either a 100% ration of spray-dried freshwater microalga Spongiococcum excen tricum, or an 80% ration of S. excentricum and 20% gelatin-acacia micr ocapsules (GAM) containing various lipid sources. Replacement of S. ex centricum with any lipid significantly increased the ash free dry weig ht (AFDW) of spat. GAM containing squid oil or mixtures of squid oil a nd either coconut oil, corn oil, or linseed oil produced spat with sig nificantly higher AFDW than GAM containing vegetable oils only. Spat f ed a live reference diet (Chaetoceros muelleri) had significantly high er AFDW than spat fed any of the S. excentricum/GAM-diets. There was n o correlation between AFDW of spat and the energy content of GAM, howe ver, AFDW was positively correlated with levels (% of total fatty acid s) of the fatty acids 20:5n-3 and 22:6n-3 in GAM. The fatty acid profi le of spat generally reflected that of the diet after 28 days and unfe d spat retained high % levels of 20:5n-3 and 22:6n-3, indicating the i mportance of these fatty acids for spat growth. (C) 1997 Elsevier Scie nce B.V.