Ulva ohnoi as a feed additive for Pacific white shrimp post-larvae cultured in a biofloc system

The use of macroalgae as feed additives has attracted great interest in past years because of their nutritional, immunostimulant, antiviral, antibacterial, and growth-promoting properties. Thus, this study aimed to evaluate the use of dry biomass of macroalgae Ulva ohnoi in the diets of Penaeus vannamei post-larvae cultured in a biofloc system on growth performance, post-larvae microbiology, and resistance to thermal shock. U. ohnoi was included in the diets at three levels (0, 0.5, and 2% inclusion) and added to diets to replace kaolin. Post-larvae (0.068 ± 0.01 g) were cultured for 46 days in 60-L tanks at a density of 2000 post-larvae m⁻³ and fed six times daily. Shrimp fed with 0.5% of Ulva ohnoi in the diet showed a significantly higher final mean weight, weight gain, and specific growth rate than those in the control group. The post-larvae fed with the diet containing 2.0% of U. ohnoi exhibited a significantly higher total heterotrophic bacteria count than the post-larvae of the control group. Considering that the performance of shrimp fed with diets containing U. ohnoi was similar, the inclusion of 0.5% is recommended because shrimp growth was higher in this inclusion compared with the control.