Effect of <i>Tamarindus indica</i> (Linn, 1753) pulp and leaf-fortified diets on experimental <i>Aeromonas hydrophila</i> infection in <i>Clarias gariepinus</i> (Burchell, 1822)

Abstract

Intensification of aquaculture is associated with infectious diseases with consequent increase in the use of synthetic antibiotics. The rise in antibiotic-resistant bacteria is of global criticism. The role of Tamarindus indica as antimicrobial agents has been reported. This study evaluated the utilization of tamarind pulp and Leaves in the diets of Clarias gariepinus as antimicrobial agent against Aeromonas hydrophila infection. Ten experimental diets consisting of 0.5, 1.0, 1.5, 2.0% of basal diets each of tamarind pulp or leaf meal and 0.0% (untreated control) and 0.2% oxytetracycline (treated control) were fed to C. gariepinus for 12 weeks. After the feeding trial, fish were subjected to bath challenge with Aeromonas hydrophila and observed for 28 days to determine mortality and relative percentage survival. The surviving fish after 28 days post-challenge were sampled for haematological studies. Data were analyzed using oneway analysis of variance at P = 0.05. All experimental groups of the fish on tamarind-treated diets exhibited significantly lower (P ˂ 0.05) mortality compared to the groups fed with the control diets. 100% relative percentage survival was exhibited by the groups of fish on 1.5-2.0% pulp and 2.0% leaf diets. Higher white blood cell counts were obtained from tamarind-treated groups compared to the untreated control diets. The heterophil of the challenged fish fed diet with oxytetracycline was significantly lower (P ˂ 0.05) than fish fed 2.0% tamarind leaf diet. Inclusion of tamarind in the diets of the challenged C. gariepinus did not alter the monocytes, eosinophil and basophil significantly (P > 0.05) compared to those on the control diets. Fortifying the diets of Clarias gariepinus with 2.0% tamarind pulp and leaf meal significantly enhanced protection against Aeromonas hydrophila infection, hence these inclusion levels are recommended as alternatives to oxytetracycline in the control of motile aeromonas septicaemia.

Keywords:  Clarias gariepinus, tamarind, synthetic antibiotics, Aeromonas hydrophila infection, relative percentage survival