Baker’s yeast as a substitute for microalgae in the hatchery rearing of larval and juvenile tropical oyster (Crassostrea belcheri, Sowerby 1871)

Abstract

ABSTRACTIn this study, baker’s yeast, Saccharomyces cerevisiae, was used as a partial substitute for microalgae in the hatchery rearing of larval and juvenile tropical oyster (Crassostrea belcheri). Dietary microalgae were replaced with graded levels (0%, 25%, 75%, and 100%) of untreated and treated yeast in the feed of oysters from the early umbo (6 days postfertilization) to the eyed larval stage (18 days postfertilization); then the same diets were formulated with untreated barker’s yeast and fed juvenile oysters for 3 weeks. The results showed that a partial substitution of microalgae with untreated or treated baker’s yeast is unsuitable for feeding oyster larvae up to the eyed stage. With juvenile oysters, there were nonsignificant differences (P > 0.05) in mean shell width and length during the study period. The replacement of 25% microalgae with baker’s yeast showed mean daily growth rates (DGR) as high as that obtained with 100% microalgae, while the other treatments showed lower DGR (P > 0.05). Nonsignificant differences were found among the treatments in terms of mean percentages of survival at the end of the experiment (P > 0.05). The percentage of juvenile oysters larger than 0.75 cm was highest (P < 0.05) when 25% microalgae was replaced with baker’s yeast, while the highest percentage of juvenile oysters smaller than 0.32 cm was observed with diet where 75% microalgae was replaced with baker’s yeast (P < 0.05). From the experiments, it was concluded that a partial substitution of microalgae with untreated or treated baker’s yeast was unsuitable for feeding oyster larvae, while a 25% substitution with untreated yeast could be used for rearing juvenile oysters.