Nile tilapia fed enzyme complex added at different levels and processing steps

Abstract

Enzyme activity in solid-state fermentation complex added to diets before and after extrusion process and its influence on Nile tilapia (Oreochromis niloticus) performance were evaluated. The following enzymes were analyzed: b-glucosidase, pectinase, xylanase, endoglucanase, amylase, protease, and phytase. The fish were fed five experimental diets: a control diet (without enzyme), two test diets supplemented before extrusion (400 and 800 ppm SSF), and two test diets after extrusion or “on top” (400 and 800 ppm SSF). The experiment had a completely randomized design with four replicates and seven fish per tank. Average initial weight was 10.37 ± 0.95 g, and fish were fed four times a day to satiation for 56 days. The following performance parameters were evaluated: final weight, weight gain, feed conversion, survival, specific growth rate, and body composition. The results were compared using ANOVA and Tukey’s test at p<0.05. All the enzymes showed partial or total losses of activity when subjected to the extrusion process, except phytase. No differences were observed for survival, water quality parameters, and body composition. On-top inclusion provided a better performance, which is observed through increases in final weight, weight gain, and feed conversion. As a result, 800 ppm of enzyme complex SSF should be added "on top", that is after extrusion, to improve tilapia performance and, consequently, contribute to the fish farming financial efficiency.