Hemato-immunological parameters can be influenced by microalgae addition and fish feed supplementation in the integrated rearing of Pacific white shrimp and juvenile Nile tilapia using biofloc technology

This study evaluated the effects of microalgae (Scenedesmus obliquus) addition and fish feed supplementation on hemato-immunological parameters of Pacific white shrimp (Penaeus vannamei) and juvenile Nile tilapia (Oreochromis niloticus) cultured in integration using biofloc technology for 62 days. The experiment was designed as a factorial design with two factors, totaling four experimental groups: (1) No addition of microalgae and no addition of fish feed; (2) no addition of microalgae and addition of fish feed; (3) addition of microalgae and no addition of fish feed; and (4) addition of microalgae and addition of fish feed. In all groups shrimp were fed according to a feeding table. Shrimp (2.16 ± 0.01 g) and fish (1.53 ± 0.12 g) were cultured under densities of 400 shrimp m−3 and 522 fish m−3 in 800 L and 90 L (useful volumes) tanks maintained under water recirculation. Microalgae was added two times a week for a final concentration of 5 mg L−1 in the units, while a commercial fish feed was provided at the rate of 1% of the fish biomass daily. At the end of the trial, the fish and shrimp were sampled for the hemato-immunological analyses. As regards the shrimp, there was a significant effect of the interaction on total hemocyte count (p < 0.05), in which the highest value occurred in the group with microalgae/no fish feed addition. There was also a significant effect of microalgae addition on serum protein (p < 0.05), with the highest values occurring in the treatments that employed microalgae. In the case of the fish, the monocyte count was significantly affected by the fish feed addition (p < 0.05), the highest values being observed when the feed was provided. There were also significant effects of the interaction and of microalgae addition on mean corpuscular volume and mean corpuscular hemoglobin concentration (p < 0.05), with the highest values occurring in the group that received microalgae but no fish feed and in the groups that did not receive microalgae, respectively. Overall, these results suggest an enhanced immunological status for the shrimp due to increases in total hemocyte count and high serum protein concentration when microalgae was added and an improved nutritional status for the fish that received feed due to increased circulating monocytes, along with possible greater erythrocyte stability when microalgae was added.