Dietary Plant-Based Mixture Improves Feed Efficiency, Gross Profit, Physiological Performance, Gene Expression and Gut Health of Nile Tilapia (Oreochromis niloticus)

The goal of this study was to evaluate the effect of the supplemental plant-based blend Phyto AquaNity (PAN) on growth, profitability and health status of Nile tilapia (<i>O. niloticus</i>) cultured in hapas. Juvenile fish of average weight 73 g were stocked in 2-m³ hapas in triplicates at a density of 20 fish m^-3 (40 fish hapa^-1). Four extruded diets were formulated following isonitrogenous (30% CP), isoenergetic (17 MJ kg^-1) standards, with incorporation levels of 0, 0.25, 0.50, or 1.00 g of PAN kg^-1 diet. Fish were fed the experimental diets at a daily rate of 2-3% of their body weight (BW) over 80 days. From this study, results showed that growth performance and tissue composition were not significantly impacted by these treatments. Feed intake exhibited a significant reduction while feed efficiency was improved in the groups fed 0.5 g kg^-1. Diets supplemented with PAN were also more profitable than the control diet, with 0.5 g kg^-1 indicating the highest return (9.24% increase). Digestive enzyme activity and hepatic enzyme activity were significantly improved with an increase in the level of PAN up to 0.50 g kg^-1. In addition, immune parameters (lysozyme activity, alternative complement and phagocytic cells) and antioxidant enzymes (superoxide dismutase, glutathione peroxidase and catalase) were significantly enhanced with increasing PAN level up to 0.5 g kg^-1 (<i>p</i> < 0.05). Gene expression of cytokines was also upregulated in fish fed with PAN at levels of up to 0.5 g kg^-1 (<i>p</i> < 0.05). Moreover, the results showed that higher levels of PAN promoted the growth of beneficial bacteria while reducing the load of pathogenic bacteria. Additionally, intestinal fold length and goblet cell count were significantly increased in the group fed PAN up to 0.5 g kg^-1. A quadratic regression analyses performed on feed efficiency, profitability, hepatic enzyme activity and gut microbial load revealed that 0.60-0.65 g kg^-1 of feed were the optimal dosages. Regarding immunological and antioxidant responses, the optimal dosages ranged between 0.75 and 0.85 g kg^-1. Overall, about 0.60-0.85 g PAN kg^-1 feed is suggested for optimum performance, profitability, gut health and overall health status of Nile tilapia, depending on the target objective for which this product is added.