Influence of fish meal replacement with graded levels of corn gluten meal on performance, feed efficiency, body chemical analysis and economic revenue of the Nile tilapia fish Oreochromis niloticus

The current experiment was conducted to inspect the influences of partial replacement of fish meal (FM) with Corn gluten meal (CGM) on tilapia growth, feed utilization, biometric indices, body composition and economic revenue. The experimental groups were divided into five equal groups, each with five replicates. The D₁ fish group was fed a FM-based diet, whereas the other four fish groups were fed FM diets substituted with several levels of CGM, as follows: 15, 30 and 40% of total FM level (D₂, D₃, and D_4, respectively). After 10 weeks of the feeding trial, the growth findings showed that diets containing higher CGM replacement levels (D₃ and D₄) enhanced feed intake, weight gain, and weight gain % significantly (P ˂0.05) compared to the other diets. Other performance and feed utilization measures showed no statistically significant differences among the tested diets. Weight gain, feed conversion ratio, and FM replacement with CGM showed a strong positive correlation tends; R² = 0.98 and 0.92, respectively. The poly-nominal regression indicated that the optimum FM replacement level with CGM is at 45% of the total FM content. Moreover, the biometric indices revealed that tilapia fish fed graded inclusion levels of CGM as a substitute to FM had normal health status. In terms of chemical body composition, fish fed FM diet replaced with a high amount of CGM (D₄) diet had the highest crude protein, ash, and NFE content and the lowest crude fat levels. In conclusion, the current results prove that CGM is a viable feed component for Tilapia. Moreover, it may substitute 45% of the total FM content without affecting the performance or health status of O. niloticus.