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).