Supplementing the diet of Nile tilapia (Oreochromis niloticus) with trub, a brewing byproduct, enhanced growth performance, increased fillet protein content, improved immunological response, and lowered intestinal pH

The study aimed to assess the impact of trub as a feed additive for juvenile Nile tilapia (Oreochromis niloticus). To this end, an experimental doseresponse growth assay was conducted with varying dietary levels of 0 %, 1 %, and 2 % trub, each treatment having six repetitions, over a 50-day period. The experimental diets were well-received by the tilapia. Inclusion of 2 % trub in the diet led to improved zootechnical performance (final weight 62.77 ± 9.24, final biomass 1129.86 ± 62.41, weight gain 53.61 ± 8.69, daily weight gain 1.09 ± 0.18) increased protein (15.60 ± 0.29) and phosphorus (2.17 ± 0.22) concentrations, and decreased lipid (8.21 ± 0.76) content in the carcass. Diets with 1 % and 2 % trub enhanced the immunological response, red blood cell count, haemoglobin levels, white blood cell count, lymphocytes, thrombocytes, and lowered blood glucose levels. The highest level of trub inclusion reduced the intestinal pH, but no significant difference was observed in the intestinal microbiological analyses. The results suggest that trub supplementation positively impacted zootechnical indices, haemato-immunological parameters, and fish carcass proximate composition, supporting its incorporation up to 2 % in the diet for juvenile Nile tilapia.