The positive contributions of PowerLac™ supplementation to the production performance,feed utilization and disease resistance of Nile tilapia Oreochromis niloticus (L.)

The objective of this research was to determine the optimum dietary supplementation level of a probiotic (PowerLac^?), for improving Nile tilapia Oreochromis niloticus growth performance and feed utilization, as well as enhanced protection against disease. For laboratory experimentation, a completely randomized experimental design, consisting of four treatments of a dietary probiotic (PowerLac^?, containing Lactobacillus lactis D1813) supplementation at different levels (0.25, 0.5, 1.0 and 2.0 g kg^?1), against a control (0 g kg^?1), was performed for 8 weeks (of culture period). For field experiments, three treatments of different dietary probiotic supplementation levels (0.25, 0.5 and 1.0 g kg^?1), plus a control, were employed for 22 weeks (of culture period). Under controlled experimental conditions, in the first experiment, significantly higher fish final body weight, growth and lower food conversion ratio (FCR) were achieved by treatments with dietary probiotic supplementations of 0.25 and 0.5 g kg^?1 (P < 0.05). In strong partial support of this, at field experimentation level, a dietary PowerLac^? supplementation of 0.5 g kg^?1 showed the most pronounced results, as indicated by the higher growth, and protein and lipid retention, as well as lower FCR, and reduced mortality following the Aeromonas hydrophila challenge test (P < 0.05).