Evaluation of the use of whole guava (Psidium guajava) meal replacing wheat bran for Nile tilapia (Oreochromis niloticus) diets: Digestibility, growth, hematobiochemical, and intestinal histology

Wheat ( Triticum aestivum ) is a product widely used in fish feed and can have a high market value, and cheaper ingredients, such as fruit residues, have been researched as alternatives. This study aimed to investigate how whole guava ( Psidium guajava ) meal (WGM) as a substitute for wheat bran (WB) could affect juvenile Nile tilapia ( Oreochromis niloticus ) digestibility, intestinal histology, and growth, hematology, and biochemical (plasma and liver) parameters. The first experiment evaluated the apparent digestibility coefficients (ADC) (crude protein, crude energy, and dry matter) of the test diet (70 % reference diet plus 30 % WGM). Fish (n = 60) were allocated to these two treatments (in triplicate). In the second experiment, fish (n = 300) were distributed in five treatments (in quadruplicate) and were fed for 45 days with graded levels of WGM replacing WB in diets: 0 (control), 50, 100, 150, and 200 g kg −1 . The ADC of WGM was 60 %. As the level of WB replacement by WGM increased, the fish reduced the weight gain, intestinal villus height, hemoglobin, and hepatic aspartate aminotransferase (AST) activity and increased the feed conversion ratio and plasma AST activity. With 200 g kg −1 of substitution of WB by WGM, simple columnar epithelium showed an intense reaction on the cell surface. In conclusion, replacing 50 g kg −1 of WB with WGM is suggested for manufacturing practical diets for Nile tilapia. • Whole guava meal (WGM) replacing wheat bran (WB) reduced nutrient digestibility in Nile tilapia. • WGM inclusion above 50 g kg −1 impaired growth performance and intestinal villus height. • Hematological and metabolic disruptions were observed with the increase of WGM inclusion. • Replacing 50 g kg −1 of wheat bran with WGM maintained growth and health.