Dietary effects of Saccharomyces cerevisiae on Nile tilapia (Oreochromis niloticus) juveniles challenged with Aeromonas hydrophila

Abstract

A 14-week study was conducted to examine the dietary effects of Saccharomyces cerevisiae on growth performance, hematological response and, resistance of Oreochromis niloticus juveniles to Aeromonas hydrophila as a pathogenic organism. The study had 5 treatments and 3 replicates in a complete randomized design. The growth study which was run for 12 weeks, with the fish fed twice per day at 3% body weight. The experimental diets contained Saccharomyces cerevisiae at 0, 20, 25, 30 and 35 ml/kg, represented as T1 (control diet), T2, T3, T4 and T5, respectively. The study had growth parameters monitored, after which the fish were challenged with Aeromonas hydrophila through intramuscular injection and, kept for another 2 weeks to monitor the clinical signs and the mortality rate. The study revealed that diet T5 supported better fish growth and survival rates. All the challenged fish were sluggish after being challenged. The highest relative percentage survival was obtained in treatments T4 and T5, while T1, T2 and T3 had the least relative percentage survival.  Higher values of hemoglobin packed cell volume, red blood cell, and white blood cells were recorded in the treated diets with the highest recorded in T5, while the least was obtained in T1. In conclusion, diet T5 was observed to support growth rate, improved blood constituents and increased the resistance of Nile Tilapia exposed to Aeromonas hydrophila. Therefore, diet containing S. cerevisiae at 35 ml/kg could be recommended to the fish farmers for the production of disease resistant and fast growth Oreochromis niloticus.