Effects of betaine fortified in the feed on growth performance and resistance to Vibriosis was conducted in P. vannamei of average initial weight 2 gram. In the 6-week feeding trial different feed formulae were tested. Formula 1 feed control was without betaine fortification while in formula 2 through 5 contained betaine at 1.0, 2.0, 3.0 and 4.0 percent, respectively. Determination of weight gain was carried out at 2 week intervals. The results showed that there was no significant difference among treatments in survival, feed conversion ratio or feed intake although average individual weight gain showed a difference with higher weight gain in those given 4 percent fortified feed compared with control. A similar result was obtained for specific growth rate, which was higher for 4 percent betaine than the control. The feed with 4 percent betaine fortification resulted in the best performance on immune response while the best capacity to eliminate V. harveyi in plasma was noted in the treatment with 3 percent betaine supplementation. In conclusion, betaine has been shown to be effective in its application to enhance growth and immunity, and this might help support the sustainability of the shrimp industry.
