Symbiotic supplementation on the hemato-immunological parameters and survival of the hybrid surubim after challenge with Aeromonas hydrophila

This study evaluated the effects of dietary supplementation with two symbiotics in the hybrid surubim (Pseudoplatystoma corruscans x P. reticulatum) prior to and after challenge with Aeromonas hydrophila. The fish were divided into unsupplemented fish, supplemented fish with Weissella cibaria and inulin, and supplemented fish with Lactobacillus plantarum and inulin. Twenty days after being fed symbiotics, the fish were sampled for immunological, haematological, and microbiological analysis pre-challenge. After this period, they were challenged with Aeromonas hydrophila, and after 96 h the fish were sampled for blood collection and survival. Fish fed W. cibaria and inulin from the pre-challenge showed the highest values of lysozyme activity. Fish fed L. plantarum and inulin presented a higher number of thrombocytes and granular leukocyte PAS(+) than the other fish. After challenge, fish fed both symbiotics presented an increased red blood cells number. Fish fed L. plantarum and inulin showed an increased total leucocyte count (WBC), neutrophils, and monocytes number as well as total immunoglobulin. The W. cibaria- and inulin-supplemented fish showed improved haematological and immunological parameters and reduced cumulative mortality after the challenge.