Exogenous β-Propeller Phytase and Prebiotic Mannan Oligosaccharide (MOS) Supplementation of Formulated Diets Applied to Juvenile Nile Tilapia, Oreochromis niloticus: Impact on Growth Performance and Nutrient Digestibility

Abstract

The growth of the aquafeed sector is highly dependent upon the availability of fish feed with a balanced nutritional composition. The use of prebiotics and probiotics can be an effective solution to increase the bioavailability of feed components. In this study, we evaluated the effect of dietary supplementation with β-propeller phytase (0, 600, 1200, 1800 and 2400 U/kg) from Bacillus and mannan oligosaccharide (MOS) (0, 2, 4 and 8 g/kg) on growth performance and nutrient digestibility of Nile tilapia over 45 days. The findings showed that adding phytase significantly (p < 0.05) increases the growth performance and nutrient digestibility; the 1200 and 1800 U/kg PHY levels showed the maximum weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) and best feed conversion ratio (FCR). Furthermore, phytase increases carcass mineral composition (phosphate and calcium). At the end of the experiment, there were no significant differences among all feeding groups in survival rates (above 90%). Regarding MOS inclusion, insignificant differences were seen in WG, SGR and SR. However, significant effects of MOS were observed on FCR, feed intake (FI) and PER when supplemented at 4 and 8 g/kg of feed. Taken together, our results suggest that supplementation of Nile tilapia feed with adequate amounts of β-propeller phytase from Bacillus and MOS increases growth performance and nutrient digestibility.