Tyramine mediates growth performance, immune response, and physiological regulation of Litopenaeus vannamei through dietary administration

Abstract

In this study, the effects of feeding diets containing tyramine (TA) to Litopenaeus vannamei at levels of 10 (TA10), 50 (TA50), and 100 (TA100) mg/kg on growth performance, immune parameters, hemolymph glucose and lactate level, biogenic amine synthesis, and resistance against Vibrio alginolyticus were investigated. Results showed that shrimp fed with TA-containing diets had significantly higher feed efficiency and percent weight gain for a period of 56 days. The total hemocyte count increased in TA10, TA50 and TA100 after 7 and 28 days, and increased in TA100 after 14 days. The phenoloxidase activity increased in TA100 after 7 days, and respiratory bursts increased in TA100 after 7 and 14 days. In terms of resistance against V. aliginolyticus infection, the phagocytic activity increased in TA10, TA50 and TA100 after 7–28 days. The clearance efficiency increased in TA10, TA50 and TA100 after 7 and 14 days, and increased in TA 100 after 28 days. Shrimp fed with TA50 and TA100 for 28 days then challenged with V. aliginolyticus had a higher survival rate compared to those fed the basal diet at 48 h–168 h post challenges. The hemolymph glucose level was significantly decreased after being fed with TA10 at 28 days and TA100 for 56 days, while the octopamine synthesis in shrimp was improved after 14 days of being fed with TA50 and TA100, and after 28 days of being fed with TA100. These findings suggest that administering a TA diet regulated the growth performance, immune response and V. aliginolyticus resistance in L. vannamei.