Effects of Artemia sp. Enrichment with Essential Fatty Acids on Functional and Morphological Aspects of the Digestive System in Acipenser gueldenstaedtii Larvae.

The aim of this study was to compare the physiology and morphology of the digestive tract of Russian sturgeon (Acipenser gueldenstaedtii) larvae fed Artemia sp. nauplii enriched or non-enriched with essential fatty acids (EFA). Physiology was evaluated by digestive enzyme activity analysis, while morphology was assessed with histological methods. The larvae were divided into two groups, in which fish were fed either pure Artemia sp. nauplii or Artemia enriched in EFA. Both groups had similar survival rates, but fish fed EFA-enriched Artemia displayed higher, body weight and length. At the end of the experiment (22 dph): 1) the activities of lipase and leucine aminopeptidase were similar in both groups; 2) the activities of trypsin, alkaline phosphatase and γ-glutamyltransferase were insignificantly higher in fish fed pure Artemia; 3) the activity of α-amylase was significantly higher in the EFA-enriched feeding group; 4) lower hepatocyte lipid vacuole diameters and hepatocyte proliferation were measured in the EFA-enriched group. Lipid accumulation was observed in the anterior intestine of fish fed pure Artemia on the 15 th and 22 nd dph. The epithelial turnover was significantly lower in the EFAenriched group, in the posterior intestine on the 15 th dph, but no differences occurred between the groups on the 22 nd dph, in either anterior or posterior intestine. In conclusion, the study revealed a positive effect of the EFA-enriched Artemia-based diet on the physiology and morphology of the digestive system of Russian sturgeon larvae.