Effect of Dietary Supplementation with Kappaphycus alvarezii on Growth, Survival and Immune Response of Penaeus vannamei Challenged with Vibrio parahaemolyticus under RAS and Biofloc Culture Systems.

A 60-day trial was carried out to assess the effect of Kappaphycus alvarezii as a dietary feed supplement on the growth and disease resistance of Penaeus vannamei reared in RAS and biofloc systems against Vibrio parahaemolyticus. The experimental diets were formulated as isoproteic diets (35 ± 0.5% crude protein) and supplemented with K. alvarezii at three inclusion levels (5%, 10% and 15%), while an unsupplemented basal diet as the control. The findings showed that the addition of 5 % of K.alvarezii to the diet significantly enhanced final weight, weight gain, Feed Conversion Ratio (FCR) and Feed Efficiency Ratio (FER) compared to the other groups. Diets for shrimp that included K.alvarezii resulted in a higher crude protein content in the whole body of shrimp compared to the control. After the feeding trial, P.vannamei was challenged with V.parahaemolyticus for 15 days to assess the immune response. The result of the immunological parameters was significantly higher than that of the control group. The maximum survival rate against V. parahaemolyticus was shown in K.alvarezii supplemented diets. The addition of K.alvarezii to shrimp diets improved the histological features of hepatopancreatic tissues, especially at 10% and 15% levels. The results showed that shrimp fed a diet containing K. alvarezii showed enhanced growth and immune response profiles. Overall, the study suggested that incorporating K.alvarezii into the feed of P.vannamei improves the growth and immune response against V.parahaemolyticus.