Effects of polysaccharides, oligosaccharides and protease on growth, digestive enzyme activities and serum nonspecific immunity of white shrimp (〖WTHX〗Litopenaeus vannamei)〖WTHZ〗

Abstract:

A 6 week feeding trial was conducted to study the effects of supplementation of polysaccharides, oligosaccharides and protease in diets on growth performance, serum nonspecific immunity and digestive enzyme activities of white shrimp (Litopenaeus vannamei). Graded levels of 0.0% (control group), 0.2% β glucan, 0.05% astragalus polysaccharides, 0.4% mannan oligosaccharides and 175 mg/kg protease PT were supplemented to diet. Each diet was randomly fed to four cages of white shrimp with initial average weight (4.55 ±0.08) g in 20 cages（2.5 m×1.2 m×1 m）for 6 weeks. Compared with control group, weight gain rates (WGR) of shrimp fed with 0.2% β glucan, 0.4% mannan oligosaccharides and 175 mg/kg protease PT were increased by 16.19%, 12.78%, 11.25% (P<0.05), and feed conversion rate (FCR) decreased by 0.10, 0.09, 0.09(P<0.05). There were no significant differences in contents of muscle moisture, ash, crude fat and crude protein among treatments (P>0.05). In respect of serum nonspecific immunity, phenoloxidase were significantly increased by all additives groups compared with control group (P<0.05), but no difference was found in MDA among groups（P>0.05）. Shrimp fed with diet adding 0.4% mannan oligosaccharides had a significantly higher lysozyme and alkaline phosphatase activity, meanwhile activities of superoxide dismutase of 0.2% β glucan and 0.4% mannan oligosaccharides groups were enhanced compared with control group (P<0.05). In respect of digestive enzymes activities, hepatopancreas protease activities of 0.05% astragalus polysaccharides and 175 mg/kg protease PT groups, intestine protease activity of 175 mg/kg protease PT group, stomach protease activity of 0.2% β glucan and 0.4% mannan oligosaccharides groups, hepatopancreas lipase activity of 0.2% β glucan, 0.4% mannan oligosaccharides and 175 mg/kg protease PT were all significantly higher than those of control group (P<0.05). Results above showed that the addition of 0.2% β glucan and 0.4% mannan oligosaccharides in diet could improve the growth performance, serum nonspecific immunity and digestive enzyme activities; addition of 175 kg/kg protease PT could improve the weight gain rate and digestive enzyme activites; addition of 0.05% astragalus polysaccharides had no influence on weight growth rate, serum nonspecific immunity and digestive enzyme activities.