The U.S. catfish industry, the largest aquaculture sector, faces significant constraints, including high feed costs, limited broodstock reproduction, labor shortages, and competition from imported frozen fillets. Additionally, mortality resulting from pathogenic diseases has affected the catfish industry and hindered aquaculture production. Mannan oligosaccharides (MOS) are prebiotics that have shown great benefits in promoting a healthy digestive system by stimulating beneficial bacteria in the host.
In a complete randomized design, a 14-week study of seventy-five juvenile channel catfish with an average weight of 5.6 g in twelve recirculating tanks with three replicate tanks per diet were examined to determine the effects of supplementing a standard soybean diet with four graded levels of MOS [Diet 1 (0%), Diet 2 (1%), Diet 3 (2%), and Diet 4 (3%)] on growth performance, digestive enzymes, and intestinal morphology of channel catfish. The data obtained were subjected to analysis of variance, and a significant difference was determined at P<0.005. Culturing temperature and pH were within the optimal range for catfish, ranging from 7 – 8, and 22 - 24°C, respectively. Fish survival was lowest when catfish were fed Diet 4, but it was not significantly different between diets (p>0.005). Growth was significantly affected by dietary treatments, with the highest fish growth in Diet 2 and the lowest in Diet 4 (p<0.005). The specific growth rate of fish followed a similar trend. Although Diet 2 showed the lowest feed conversion among the diets, the effect was not significant. Likewise, the feeding rate per day was not significantly different between the diets (p > 0.005).
Other growth performance data, including hepatosomatic and viscerosomatic indices, were also evaluated, indicating that Diet 2 resulted in the best performance in channel catfish. The study highlights the potential of including 1% MOS to improve growth and survival in practical diets for channel catfish