Effects of adding organic acid complex in diets on growth,nutrient utilization,serum biochemical indexes and intestinal microflora of Litopenaeus vannamei
Due to the risk of drug residues and resistance,antibiotics have been banned from being used as feed additives in aquatic feeds.Some organic acids have been reported to improve the growth and health of shrimp,presenting the potential to substitute antibiotics.For their synergistic effects organic acids complex may play more functions than a single organic acid.Therefore,this study investigated the effects of dietary organic acid complex on growth performance,nutrient utilization,hepatopancreas enzyme activity,serum non-specific immune enzyme activity and intestinal microbial composition of Litopenaeus vannamei.Firstly,a control diet was formulated to contain 10%fish meal,then microencapsulated organic acids complex(OC,fumaric acid and tributyrin as the major components)was added with 0,0.05%,0.10%,and 0.15%inclusion to form four isonitrogenous and isolipidic diets as OC-0,OC-5,OC-10,OC-15.A total of 1 000 shrimp(1.0±0.1 g)were randomly allocated into 20 cages(5 cages per group,50 shrimp per cage)and fed with the above four diets for eight weeks.Compared to the OC-0 group,the weight gain of OC-5 and OC-10 groups increased by 18.7%and17.9%,and the feed conversion ratio decreased by 16.1%and 18.5%,respectively.In body composition,the addition of OC reduced the crude fat significantly,and the crude protein contents of OC-5 and OC-10 groups were significantly higher than that of OC-0 group.Dietary supplementation of OC had no significant effect on nutrient digestibility,but significantly increased hepatopancreas amylase activity and serum SOD activity.The analysis of intestinal microbiota showed that dietary OC(0.10%)increased the abundance of intestinal flora in L.vannamei.In summary,organic acid complexes in diets can promote the growth and feed utilization of L.vannamei,and the appropriate addition amount of OC is 0.10%.
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