Effects of a functional palatability enhancer on growth performance, digestive physiology, and immune response in the Pacific white shrimp (<i>Penaeus vannamei</i>) fed low-quality fishmeal diets

This study investigated the effects of a functional palatability enhancer on the growth performance, digestive enzyme activity, immune response, gut histology, and thermal shock resistance of the Pacific white shrimp (Penaeus vannamei). Shrimp were fed four experimental diets for 56 days: a negative control without the palatability enhancer, two diets supplemented with the additive at 0.08% and 0.2%, and a positive control formulated with higher quality fishmeal. Shrimp fed palatability enhancer supplemented diets exhibited significantly higher final body weight, weekly weight gain, and daily growth coefficient compared to the negative control (p < 0.05), with performance comparable to the positive control (p > 0.05). No significant differences in feed intake, feed conversion ratio, or survival were observed (p > 0.05). The palatability enhancer modulated the activity of digestive enzymes, with increased chymotrypsin activity at 0.08% inclusion and increased trypsin activity at 0.2% inclusion (p < 0.05). Total hemocyte count was also elevated in the 0.08% palatability enhancer group (p < 0.05), suggesting a potential for enhanced immune function. No significant effects were observed on gut histology or thermal shock resistance (p > 0.05). These findings suggest that the palatability enhancer can effectively enhance growth performance in the Pacific white shrimp, potentially by modulating digestive processes and improving nutrient utilization efficiency, offering a potential cost-effective alternative to using higher quality protein sources in shrimp diets.