Brown seaweeds added in the diet improved the response to thermal shock and reduced Vibrio spp. in pacific white shrimp post-larvae reared in a biofloc system

摘要

This work aimed to evaluate the effect of the combined use of the brown seaweeds Sargassum filipendula (S) and Undaria pinnatifida (U) dry biomass, as a feed additive, on growth performance, bacterial count and thermal shock resistance of Pacific white shrimp reared in a biofloc system during the nursery phase. Four combinations of seaweeds were evaluated: 0.5S:2U, 0.5S:4U, 1S:2U and 1S:4U (%), and a control diet. Shrimp post-larvae (PLs, initial weight +/- 0.006 g) were reared for 7 weeks in 400 L polyethylene tanks, partially filled with water from a biofloc matrix tank, at density of 3000 PLs m(-3), and were fed 6 times a day until reaching +/- 1 g. The presence of Vibrionaceae in PLs was significantly lower in those that were fed diets containing 0.5S:4U and 1S:4U. For thermal shock resistance (from 29 degrees C to 13.5 +/- 0.1 degrees C for 1 h, and returned to 29 degrees C), PLs fed the diet containing 1S:2U showed lower cumulative mortality than those fed the other diets. Among all treatments, no significant difference was observed in growth performance and total heterotrophic bacteria count in the PLs. S. filipendula and U. pinnatifida showed a combined effect on shrimp thermal resistance and reduction of Vibrio spp. in PLs.