Lactobacillus-fermented wheat bran, as an economic fish feed ingredient, enhanced dephytinization, micronutrients bioavailability, and tilapia performance in a biofloc system

Abstract

Fermentation of animal feed has been approved for its contribution to the nutritional quality, lowering feed costs and pollution when treated with appropriate microorganisms. Fermentation could significantly improve micronutrients bioavailability of aquafeed. Therefore we aimed to use the wheat bran as an economic feed for tilapia fish (Oreochromis niloticus) in a biofloc system after fermentation with dephytating Lactobacillus sp. Lactobacillus rhamnosus KU985435 was selected according to phytase production and growth intensity as it showed good enzyme activity (343 U/L) and growth intensity (2 × 1010 CFU/ml). Total protein, carbohydrates, and antioxidants were higher in the fermented wheat bran. In contrast, a potential reduction in phytic acid content was detected (from 4.2 to 0.07%) compared to the control. The green edible alga, Chlorella vulgaris, was added twice daily to improve fish growth and health. Final body weight, weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio were significantly higher for fish received fermented wheat bran compared to control. Also, crude protein content was higher, and crude fat was lower in the whole fish body. Interestingly, fish fed with fermented wheat bran recorded the highest values of hemoglobin and RBCs count with the lowest values of cholesterol and triglycerides. Finally, histopathological examination of fish bones significantly confirmed restoring the normal trabecular thickness and interconnectivity with narrow inter-trabecular space and mineralization of most trabeculae. In conclusion, wheat bran could be incorporated as an economic fish feed after fermentation with the appropriate dephytating lactobacilli.