Effects of dietary mannan oligosaccharide on growth performance, gut morphology and stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei

► MOS supplementation significantly enhanced the weight gain and specific growth rate of Litopenaeus vannamei. ► Dietary MOS significantly increased the intestinal microvilli length of L. vannamei. ► Dietary MOS significantly increased the activities of phenoloxidase and superoxide dismutase in haemolymph L. vannamei. ► Dietary MOS significantly enhanced the resistance against NH3 stress in L. vannamei.