Corn substitution by mesquite bean flour (Prosopis juliflora) maintains growth and improves protein metabolism of Nile tilapia juveniles (Oreochromis niloticus).

The objective of this study was to evaluate the potential of mesquite bean flour (Prosopis juliflora) as an energy ingredient in extruded diets for juvenile Nile tilapia (Oreochromis niloticus). Two experiments were carried out: the first consisted of a study to evaluate the chemical composition and digestibility of the energy and nutrients of MBF; the second consisted of a growth test, in which juveniles consumed diets containing different proportions of corn substitution by MBF, in which zootechnical, hematological, physiological, and metabolic variables were evaluated. It was observed that MBF has a chemical composition similar to corn, as well as the apparent digestibility of energy and nutrients. The higher sucrose/starch ratio of the ingredient stands out, as well as the difference in digestibility (p < 0.05) between the predominant carbohydrates 87.63 and 99.25% for starch and sucrose, respectively. In the growth assay, no difference was observed between zootechnical variables (p > 0.05), and sucrase and alkaline phosphatase activities were increased (p < 0.05), which was not observed for amylase and lipase (p > 0.05). The hematological variables did not change (p > 0.05). Metabolic variables indicate a reduction in gluconeogenesis from amino acids, as can be seen by the reduction in liver transaminase levels (ALT and AST) and glutamate dehydrogenase (GDH), as well as the greater availability of free amino acids in plasmas (p < 0.05). Thus, it can be said that MBF has a high nutritional value and can totally replace corn in diets for juvenile tilapia and the metabolic findings indicate a potential protein-sparing effect.