Effects of dietary administration of Macsumsuk ® on growth and stress to low salinity and low dissolved oxygen in whiteleg shrimp, Litopenaeus vannamei (Boone, 1931) juveniles

An 8‐week study was conducted to explore the results of Macsumsuk ® as a feed additive on the stress tolerance and growth of Litopenaeus vannamei in 15 culture tanks of 36 L each. Three hundred shrimp averaging 0.1 ± 0.01 g were fed with five isonitrogenous (48.38 ± 0.38% CP) diets (in triplicate groups) containing kaolinite (Macsumsuk ® ) at 0%, 0.3%, 0.6%, 1.2% and 2.4%, namely Mk 0 , Mk 0.3 , Mk 0.6 , Mk 1.2 and Mk 2.4 . Specific growth rate (SGR) and weight gain (WG) of shrimp fed diets Mk 1.2 and Mk 2.4 were significantly better than those of shrimp fed diet Mk 0 ( p  < .05). However, SGR and WG of shrimp fed diets Mk 0.6, Mk 1.2 and Mk 2.4 were not significantly different. Protein efficiency ratio (PER) and feed efficiency (FE) of shrimp fed diets Mk 1.2 and Mk 2.4 were significantly better than those of shrimp fed diets Mk 0 , Mk 0 . 3 and Mk 0.6 . Furthermore, the survival of shrimp fed diet Mk 2.4 was significantly lower than that of shrimp fed diet Mk 0.6 ( p  < .05). Cumulative mortality of shrimp fed diet Mk 1.2 was significantly lower than that of shrimp fed diet Mk 0 at 1–1.5 hr post‐stress to low dissolved oxygen (from 6.1 mg/L to 2.9 mg/L) and 4–5 hr post‐stress to low salinity (from 32‰ to 1‰) ( p  < .05). The optimum dietary Macsumsuk ® level for juvenile L. vannamei was determined as 1.97% by the polynomial regression analysis of weight gain.