Dietary Effects of Sodium Propionate Supplementation on Growth, Digestive Enzyme Activity and Immune System Gene Expresion of Tropical Gar Juveniles (Atractosteus Tropicus)

Abstract

The effect of sodium propionate (SP) added to balanced diets was determined for Atractosteus tropicus juveniles on growth, survival, digestive enzyme activity, and expression of genes associated with the immune system. Five treatments (0, 0.5, 1.0, 1.5, and 2.0%) were evaluated in triplicate during a 61-day feeding trial. 180 organisms (3.65 ± 0.12 g) were distributed in 15 tanks of 70 L. The juveniles were fed five times daily with 6% in relation to the biomass of the organisms. Juveniles fed with 0.5% of SP showed higher final weight, absolute weight gain (AWG), and specific growth rate (SGR). Fish fed with 1.5 and 2.0% SP showed highest survival rate (91.6%). Control group (0%) showed greater activity of lipases and trypsin. The highest activity of alkaline proteases and chymotrypsin was found in treatments with 0 and 0.5% SP, while addition of 1.5% of SP promoted highest activity of acid proteases, and highest relative gene expression of ocln, muc2, and nod2. The inclusion of SP in the diet of A. tropicus juveniles may benefit the activity of digestive enzymes, as well as the expression of genes related to the function of intestinal barrier and therefore increasing the survival of organisms.