EFFECTS OF LOW LEVELS OF MANNANOLIGOSACCHARIDES IN FEED ON GROWTH AND INTESTINAL SALMONELLA REDUCTION IN JUVENILE RAINBOW TROUT (Oncorhynchus mykiss)

Low levels of added mannanoligosaccharides (MOS) in the feed for juvenile rainbow trout significantly promote growth rate, food conversion and overall culture results. Three levels of added MOS: 0.05%, 0.10% and 0.15% were incorporated in commercial pelleted feed and fed three and later two times per day. The experiment started with juveniles of 48±2.1 grams and lasted 90 days. The best growth result was obtained with the smallest (0.05%) MOS level, if compared to the control group and 0.1% and 0.15% MOS supplemented feed. The growth was improvedby11.5% with 0.05% MOS. The best feed conversion ratio (FCR) of 1.29 was found with 0.05% MOS supplement compared to 1.54 in the control group. FCR in 0.1% and 0.15% MOS treatments was 1.46, also significantly better than in the control group. The experiment shows that 0.05% MOS in trout feed is not fully successful in total elimination of salmonella colonies from fish intestine. But this is achieved with 0.1% MOS after only 30 days of experiment. The results of experiment point that smaller levels of MOS, if compared to previous research, are beneficial for rainbow trout juvenile culture.