Evaluation of probiotic effects on the growth performance of Nile tilapia (Oreochromis niloticus) in a high-density biofloc system.

Abstract

Biofloc technology (BFT) is an aquaculture production system that has gained popularity with tilapia producers. Probiotics provide benefits for the host and/or the environment. Probiotics have been reported in some cases to enhance growth performance, improve water quality, and prevent infections. One of the administration routes for probiotics is to apply them through the feed. When a probiotic is combined with a biofloc system, the production yield may be improved through better fish growth, disease resistance, or enhanced survival. This research aimed to evaluate the growth performance of Nile tilapia Oreochromis niloticus fed commercial top-coated probiotics. Two growth trials were conducted, Trial A had fish with a mean initial weight of 71.4 ± 4.4g, and fish in Trial B had a mean initial weight of 5.34 ± 0.42g. Tilapia were offered commercial feed (38 % protein floating tilapia feed, Optimal Aquafeed, Omaha, NE) in both trials, in the first fish feed was top coated with two probiotics, AP193 (Bacillus spp.; provided by Dr Mark Liles, Auburn University) final concentration of 1 x 107 CFU g-1, and BiOWISH® Feedbuilder Syn3 (BiOWISH Technologies ® Cincinnati, OH, USA) in a final concentration of 3.6 x 104 CFU g-1. In Trial B, feed was top coated with two different concentrations of BiOWISH® Feedbuilder Syn3 (BiOWISH Technologies, Cincinnati, OH, USA) at the final concentrations of 3.6 x 104 CFU g-1 and 7.2 x 104 CFU g-1. The same commercial feed was used as a reference, resulting in 3 experimental treatments with three tank replicates each. The results of both growth trials indicated no significant differences in growth performance (except FCR (feed conversion rate) that showed significant differences in Trial B, where both concentrations of BiOWISH® Feedbuilder Syn3 showed improvement), survival, water quality, solids management, and bacterial composition of water and fecal matter. Even though growth performance results presented no significant differences, results could differ based on the concentration and the route of the probiotic administration, but most importantly, their impact on the microbial community of the culture water developed in the biofloc system. According to the data collected, testing on a larger scale with different probiotic doses is necessary to achieve an effective dosage to improve tilapia culture.