Dietary thiamine requirement of Pacific white shrimp, Litopenaeus vannamei

This study investigated the dietary thiamine (vitamin B1) requirement of Pacific white shrimp ( Litopenaeus vannamei ) for optimal growth performance, feed utilization, and innate immunity. Six test diets were formulated to contain 3.32, 20.8, 38.7, 60.2, 80.7, and 108 mg/kg of graded thiamine levels (designated as T0, T20, T40, T60, T80, and T100, respectively). A total of 360 shrimp (6.03 ± 0.03 g) were randomly assigned into 24 acryl tanks (240 L) to be quadruplicated per treatment, and feeding was done in six equal portions daily for 58 days. The T20 diet fed group exhibited significantly higher growth performance compared to shrimp fed T0 and T100 diets. Feed conversion ratio and protein efficiency ratio were not significantly different among experimental groups. A significantly higher phenoloxidase activity was exhibited in T20 dietary group than T0 and T100 groups. Lysozyme activity was significantly enhanced in T20, T40, T60, and T80 groups than in T0 group and antiprotease activity was not significantly affected. Antioxidant parameters: superoxide dismutase activity and glutathione peroxidase activities were significantly elevated in T20 dietary treatment group. Significantly upregulated proPO gene expression was observed in T20 and T40 dietary treatment groups, although penaidine 3a and insulin-like growth factor-1 relative gene expressions were not significantly different. Glucose, total cholesterol, triglyceride, and total protein levels in hemolymph were not significantly different. Intestinal histology observations did not show significant differences in villi heights. A piecewise regression of weight gain percentage (WG%) estimates the optimal dietary thiamine requirement of L. vannamei at 19.7 mg/kg.