Supplementation of orange peel fragment submitted to solid state fermentation: effects on growth performance and hematological status of Nile tilapia (Oreochromis niloticus)

Abstract

Abstract: Agro-industrial residues contain active biomolecules that can positively influence growth performance and modulate immune responses. Bioprocess techniques such as solid-state fermentation (SSF) can optimize the content of bioactive compounds in agroindustry by-products, developing potential feed additives for animal production. In this sense, the present study aims to develop potential feed additives for aquaculture using orange juice industry residue as substrate for SSF. The peel fragment (frit) obtained from the agro-industrial processing of orange juice (var.Pêra) will be subjected to SSF and protein precipitation. The precipitation of protein biomolecules from the fermented product will be done using the salting-out method with ammonium sulfate 60% (PSA 60%). Three processing methods will be tested: raw frit (FB) subjected to FES (FB + FES), FB subjected to PSA (FB + PSA 60%), and raw FB subjected to FES and PAS (FB + FES + PSA 60%). After that the products will be applied in Nile-tilapia diets. Juvenile Nile-tilapia (450, 10 g) will be randomly distributed in 15 tanks (500 L) in a stocking density of 30 fish/tank and fed the experimental diets for 30 days. The experimental design used will be completely randomized, consisting of five treatments: control diet without FB supplementation, control diet with FB supplementation, control diet with FB supplementation + FES, control diet with FB supplementation + PSA 60% and control diet with supplementation of FB + FES + PSA 60%, and three repetitions. At the end of the supplementation period, growth parameters: final weight, weight gain, feed intake, feed conversion, percentage of survival; and hematological parameters: number of erythrocytes, percentage of hematocrit, hemoglobin rate, mean corpuscular volume and mean corpuscular hemoglobin concentration will be evaluated. Growth performance data will be submitted to analysis of variance, at a 5% significance level. In case of significant differences, the Tukey test will be performed (P < 0.05). For hematological parameters, the data will be submitted to the Kruskal-Wallis test and complemented with the Mann-Whitney comparison test.