Effect of product from orange peel fragment as a source of bioactive compounds, on digestibility, growth performance, immune response, antioxidant capacity, transport induced strees and resistance to bacterial challenge

Abstract

The research aims to develop a product from orange peel fragment as a source of bioactive compounds (proteins and enzymes) and its application on diets for Nile Tilapia, seeking to evaluate the effects on digestibility, growth performance and health when submitted to bacterial and transport challenges. The research will be consisted in four studies: study I comprises the development of products from the orange residue (frit), in which enzymatic activities, antioxidant activity, amino acid profile and total protein concentration will be determined. In study II, the digestibility coefficient of dry matter, protein, lipid, energy, minerals (phosphorus and calcium) and amino acids of the products (crude product, P160 and P180 and P260 and P280) will be determined. In study III, the growth performance will be evaluated, with the rations added to the products chosen in study II, and for that purpose 540 juveniles of tilapia will be used, distributed in 36 aquaria (250L), in a completely randomized design with four treatments and nine repetitions. After the end of the growth perfomance (30 days) the growth parameters will be evaluated. In study IV, after a 30-day feeding period with the experimental diets plus the products chosen in study II, the hematological profile, the antioxidant enzymes activity (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase) will be evaluated lipid peroxidation in the liver of fish, before and after challenges. For the bacterial challenge, eight fish/treatment will be used, which will be infected by Aeromonas hydrophila for a period of 14 days. In this challenge, lysozyme activity, burst respiratory, oxidative neutrophil metabolism (NBT in blood) and complement system will be evaluated before and after infection. The expression of the TNF-± and IL-1² in the spleens of fish will also be performed after infection. For transport induced stress nine fish/treatment will be used. Data of growth performance and digestibility will be subjected to analysis of variance, at the 5% significance. In case of significant differences, the Tukey's test (P <0.05) will be performed. For health parameters, the data will be submitted to the Kruskal-Wallis test, and complemented with the Mann-Whitney comparison test. (AU)