The Effects of a Functional Palatability Enhancer on the Growth, Immune Response and Intestinal Microbiota of Penaeus vannamei Chronically Exposed to a Suboptimal Temperature (22 °C)

Shrimp farming is practiced worldwide in tropical and subtropical regions, where shrimp often experience suboptimal temperatures during part of the production cycle, resulting in slower growth. A concentrated functional palatability enhancer (FPE) containing a mixture of chemoattractants was tested. A 12-week experiment at a suboptimal temperature (22 °C) was conducted with Penaeus vannamei (3.25 ± 0.02 g) in a clear water system (400 L with 40 shrimp per tank) with flow-through seawater. A standard diet was supplemented with 0, 1, and 2 g kg−1 of FPE (STD, STD+1, and STD+2) with four replicates for each one. The inclusion of 1 g kg−1 of FPE (STD+1) significantly increased the average final weight by 11.24% and weekly weight gain by 14,00% when compared to STD. The highest tested dose (2 g kg−1) did not result in further improvement in growth performance compared to the control. In addition, the total hemocyte count (THC) remained at an optimal level for the species in the STD+1 treatment under suboptimal temperature conditions compared to the other treatments. We also observed a decrease in Vibrio spp. bacterial counts in STD+1 compared to STD+2. Therefore, the lowest tested dose was shown to positively influence the rearing of P. vannamei at suboptimal temperatures.