Supplementing Green Alga Ulva intestinalis Linnaeus in Feed of Litopenaeus vannamei Boone, 1931 Reduced Growth Performance and Red Color of Cooked Shrimp

Abstract

Supplementing shrimp feed with algae has captured interest because it may benefit their growth and health, and even enhance the color of cooked shrimp. In the present study the effects of supplementing Ulva intestinalis in the diet of Pacific white shrimp Litopenaeus vannamei were investigated. Diets of 40 % protein and 10 % lipid were prepared with six different concentrations (0, 6, 12, 18, 24, and 30% [w/w]) of U. intestinalis powder. The experimental diets were given to satiation to stage-30 shrimp post larvae (mean body weight of 0.12±0.01 g) five times per day. After a 12-week cultivation period, the shrimp fed the 0% algae diet (control) had higher final body weight (12.27±0.19 g), daily weight gain (0.42±0.18 g·day^-1) and specific growth rate (8.25±2.16 %·day^-1) than the groups fed with U. intestinalis. However, the feed conversion ratio (1.80±0.63) and protein efficiency ratio of the control and the groups fed with U. intestinalis diets were not significantly different except for the 30% algae treatment, in which these two parameters were higher than the control. Feeding the alga to the shrimp resulted in reduction of redness (a*) (p<0.05) after cooking, while lightness (L*) and yellowness (b*) were unaffected in all but one case (b* was significantly reduced in the 30% alga treatment). The shrimp fed 12-24% algae had significantly higher Ca, P and Mg in cooked shrimp than those of the other groups. We conclude that supplementation of U. intestinalis powder in the shrimp diet reduced their growth, while the cooked shrimp had reduced redness.