Woranong Thongsombat, Nantarika Chansue, Anchalee Sirichote, Sathit Aroonseang, Suganya Chanthachum, Nongnut Assawawongkasem, and Jirasak Tangtongpirot

pp. 69 - 81

Abstract

The objective of this study was to determine the effects of guava leaves in treatment or prevention of bacterial infection using methanol extracted guava leaves. Three hundred and eighty four fancy carps (Cyprinus carpio) with average weight of 25.5 g. were acclimated for 14 days before the experiment. Fish were divided into 32 groups of two replicates each with 6 fish. All experiments were done in replicate. Guava leaves were macerated and extracted by methanol distillation and evaporation to produce 12.99% of dried
leave weight. The exposures were divided into oral route using 5% (MIC) and 10 % (2xMIC). And 1000 ppm (MIC) and 2000 ppm (2xMIC) for dip and bath methods. MIC by agar dilution method was 1000 ppm. At the 1000 ppm concentration dipped for 5 minutes, fish lost consciousness but this was reversible when returned to freshwater, which may due to the antinociceptive effect. All fish died when dipped at 2000 ppm concentration. The relative percent survival (RPS) of 5% feed mix group was significantly higher than the 10% feed mix group and higher when fed for longer time. All groups receiving guava leaf extract had significantly higher percent phagocytosis and percent chemotaxis than the controls (P<0.05). The results indicated that
guava leaf extract can stimulate the non-specific immune responses and decrease the mortality rate of the bacterial infected carp. The effects were enhanced by the longer period of exposure