Effects of different dietary macsumsuk levels on growth performance and stress tests in juvenile whiteleg shrimp (Litopenaeus vannamei) (Boone, 1931)

Abstract

The effects of dietary Macsumsuk® as the feed additiveon the growth and stress tolerance of Litopenaeus vannamei (Boone, 1931) were examined in 15 culture tanks of 36L. Five isonitrogenous (48% CP) diets containing 0, 0.3, 0.6, 1.2 and 2.4% of Macsumsuk® (M0, M0.3, M0.6, M1.2 and M2.4) were fed to triplicate groups of shrimp averaging 0.1 ± 0.01 g (mean ± SD) for 60 days. Weight gain (WG) and specific growth rate (SGR) of shrimp fed M0.6, M1.2, M2.4 diets were significantly higher than those of shrimp fed M0 and M0.3 diets (P<0.05); however, there was no significant difference in WG among shrimp fed M0.6, M1.2 and M2.4 diets, among shrimp fed M0.3 and M0.6 diets and among shrimp fed M0 and M0.3 diets. Feed efficiency (FE) and protein efficiency ratio (PER) of shrimp fed M1.2 and M2.4 diets were significantly higher than those of shrimp fed M0, M0.3 and M0.6 diets (P<0.05). Meanwhile, there was no significant difference in FE and PER among shrimp fed M1.2 and M2.4 diets and among shrimp fed M0, M0.3 and M0.6 diets. For the salinity stress test, % cumulative mortality of shrimp fed M1.2 diet was significantly lower than those of shrimp fed M0 diet at 4 and 5hrs (P<0.05). For the oxygen stress test, % cumulative mortality of shrimp fed M1.2 diet was significantly lower than those of shrimp fed M0 diet at 1 and 1.5 hrs (P<0.05). Meanwhile, % cumulative mortality of shrimp fed M2.4 diet was significantly lower than those of shrimp fed M0 diet at 1, 1.5 and 2 hrs (P<0.05). The broken line analysis of weight gain revealed that optimum growth of shrimp was being performed by shrimp at 1.06% of Macsumsuk®. Thus, the optimum dietary Macsumsuk® level could be greater than 1.06%, but less than 1.2% of the dietary Macsumsuk®.