Growth and fatty acid composition of Pacific oyster (Crassostrea gigas) spat fed a spray-dried freshwater 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 excentricum, or an 80% ration of S. excentricum and 20% gelatin-acacia microcapsules (GAM) containing various lipid sources. Replacement of S. excentricum with any lipid significantly increased the ash free dry weight (AFDW) of spat. GAM containing squid oil or mixtures of squid oil and either coconut oil, corn oil, or linseed oil produced spat with significantly higher AFDW than GAM containing vegetable oils only. Spat fed a live reference diet (Chaetoceros muelleri) had significantly higher AFDW than spat fed any of the S. excentricum/GAM-diets. There was no correlation between AFDW of spat and the energy content of GAM, however, AFDW was positively correlated with levels (% of total fatty acids) of the fatty acids 20:5n-3 and 22:6n-3 in GAM. The fatty acid profile of spat generally reflected that of the diet after 28 days and unfed spat retained high % levels of 20:5n-3 and 22:6n-3, indicating the importance of these fatty acids for spat growth