Comparison of live microalgae and Spray-dried algae powder effects on growth, digestive and antioxidant capacity of juvenile pearl oyster Pinctada maxima

The pearl production through the pearl oyster Pinctada maxima’s culture has developed slowly over the past decades due to over-fishing of wild populations and mass mortality at juvenile stages. Indoor farming is an alternative mode for P. maxima juvenile cultivation to improve survival rates. In pursuit of optimizing healthy management under the indoor farming mode, the objective of this investigation was to compare the growth performance, digestion, and antioxidant capacity of juveniles fed with different microalgae-based diets (live Isochrysis zhanjiangensis, Platymonas subcordiformis, Chaetoceros muelleri; and spray-dried I. zhanjiangensis, P. subcordiformis, C. muelleri powder). The juvenile survival rates fed with spray-dried microalgae powder (except C. muelleri powder) were not significantly different from those fed on live microalgae. However, the growth performance of juveniles fed with spray-dried microalgae powder could have been better than the live one. The digestive enzymatic activities were consistent with growth performance, and diets affected the antioxidant capacity. The spray-dried I. zhanjiangensis powder can serve as a substitute for live microalga in P. maxima juvenile indoor farming and is recommended under controlled conditions. The findings from this study would provide essential data to improve health management for P. maxima juveniles in indoor farming conditions.