Aquaculture Reports (Jul 2020)
Beneficial impacts on growth, intestinal health, immune responses and ammonia resistance of pacific white shrimp (Litopenaeus vannamei) fed dietary synbiotic (mannan oligosaccharide and Bacillus licheniformis)
Abstract
The impacts of dietary mannan oligosaccharide (MOS) and Bacillus lincheniformis (B. lincheniformis) on growth performance, immune responses, intestinal health and ammonia resistance of Litopenaeus vannamei were explored. Four resultant diets (control diet (CON), 0.2 % MOS (MOS), 0.1 % B. lincheniformis (BL), 0.2 % MOS plus 0.1 % BL (SYN)) were produced to feed shrimps for 8 weeks. Results showed that significantly higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and protein productive value (PPV) were found in shrimp fed the SYN diet (P < 0.05). The villus number (VN) and villus height (VH) of shrimps fed the SYN diet were significantly higher than those of shrimps fed the CON diet (P < 0.05). Moreover, significantly thicker submucosa (SM) of shrimp fed the MOS diet than that of shrimps fed BL and CON diets were found (P < 0.05). Intestinal acetic acid content was significantly higher in shrimps fed supplemented diets (P < 0.05). Meanwhile, the propionic acid content in shrimps fed BL and SYN diets were significantly higher than those in shrimps fed the other diets (P < 0.05). The expression levels of catalase (CAT), glutothion peroxidase (GPX), superoxide dismutase (SOD), penaeidin -3a (Pen-3a) and heat shock protein (Hsp-70) were significantly upregulated by supplemented diets at some time points (P < 0.05). The survival rates of shrimps fed supplemented diets after ammonia challenge were significantly higher (P < 0.05). The expression levels of CAT, SOD, Pen-3a and Hsp-70 in shrimps fed supplemented diets were upregulated after ammonia challenge. In conclusion, dietary synbiotic could enhance growth performance, feed utilization and intestinal morphology, while dietary MOS and/or B. lincheniformis supplementation could positively influence the intestinal SCFAs content, increase immune responses and ammonia resistance of Litopenaeus vannamei.
