Effects of salinity gradients on the skin and water microbial community and physiological responses of tilapia (Oreochromis niloticus) in the pre‐slaughter

• Published in: Aquaculture research Vol. 52; no. 10; pp. 4638 - 4647
• Main Authors: Uehara, Silvio Akira, Walter, Eduardo Henrique Miranda, Cunha, Daniele Mello, Calixto, Flávia Aline Andrade, Furtado, Angela Aparecida Lemos, Takata, Rodrigo, Mesquita, Eliana de Fátima Marques
• Format: Journal Article
• Language: English
• Published: Oxford Hindawi Limited 01-10-2021
• Subjects: animal welfare; Bacteria; Blood cells; Dehydration; Eosinophils; Freshwater fishes; haematological; Hematocrit; Hematology; Hemoglobin; Heterotrophic bacteria; Hyperglycemia; Leukocytes; Leukocytes (basophilic); Leukocytes (eosinophilic); Leukocytes (neutrophilic); Lymphocytes; Marine fishes; microbiological contamination; Microorganisms; Monocytes; Muscles; Neutrophilia; Oreochromis niloticus; Parameters; Physiological responses; Physiology; Proteins; Salinity; Salinity effects; Salinity gradients; Salts; Simulation; Skin; Slaughter; Slaughtering; Thrombocytopenia; Tilapia; Transport
• ISSN: 1355-557X; 1365-2109
• DOI: 10.1111/are.15298

This study investigated the use of salt as a mitigating agent for bacterial contamination and physiological responses of tilapia in a simulation of pre‐slaughter transport. Bacteria concentration, haematological parameters and muscle dehydration were evaluated. Adult tilapia (568 ± 141 g) were fasted for 24 h and subjected to a simulation of transport for 4 h in four salinities: 0, 7, 14 and 21 g of salt L−1. The concentration of 21 g of salt L−1 resulted in the lowest concentration of aerobic mesophilic heterotrophic bacteria on the skin of tilapia and in the transport water. Salinity did not influence the haematological parameters of haematocrit, monocytes, eosinophils, basophils, haemoglobin and mean corpuscular haemoglobin concentration. The concentrations of 14 and 21 g of salt L−1 had the lowest plasma protein values and led to lymphopaenia and neutrophilia. The concentration of 7 g of salt L−1 had values similar to baseline level for lymphocyte, neutrophil, white blood cell counts and plasma protein. Hyperglycaemia and thrombocytopaenia occurred in all treatments. Increased dehydration of muscle tissue with increased salinity was observed. The concentration of 7 g of salt L−1 promoted the fewest physiological changes. However, it is recommended the transport at high salinity of 21 g of salt L−1 for bacterial control.