Abstract:
Two hundred and seventy (270) Clarias gariepinus juveniles, average body weight of 9.2g + 0.12, were used to investigate the probiotic effect of Lactobacillus plantarum on the growth and immune modulation of the fish. The Fish were randomly distributed into six groups each at a rate of forty five (45) fish per treatment. The test diets were fed to the fish in 18 aquaria with three replicates per treatment. Diet 1 was the control diet (basal diet). Diet 2 was the basal diet containing additional 109cfu/ml of antibiotic (oxytetracycline). Diets 3, 4, 5 and 6 were the basal diet plus 103cfu/ml, 105cfu/ml, 107cfu/ml and 109cfu/ml of (Lactobacillus plantarum) respectively. The fish were fed to apparent satiation twice daily for seventy (70) days. A challenge test was conducted using thirty (30) fish from each group (10 fish / replicate) by introducing 2ml/L broth culture of pathogenic Salmonella typhi into the culture water. The mortality rate was estimated for 14 days post challenge. The results revealed that the four groups fed Lactobacillus plantarum supplemented diets showed significant increase in body weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio. In terms of immunity, there was significant increase (P > 0.05) in the total leukocyte count, differential leukocyte count as well as haematocrit values of all the fish fed Lactobacillus plantarum supplemented diets when compared with the control and fish fed antibiotic supplemented diets. It may be concluded that Lactobacillus plantarum can be used as a growth promoter, an immunostimulant and disease control agent in Clarias gariepinus juveniles.
