The goal of this study was to investigate the effects of dietary supplementation with b-glucan and microencapsulated probiotics (Bacillus subtilis or Pediococcus acidilactici) on growth performance, body composition, haemolymph constituents, and intestinal morphology and microbiota of the Pacific white shrimp Litopenaeus vannamei. Four treatment diets [basal diet (C), b-glucan-containing diet (b-glu), b-glucan plus B. subtilis-containing diet (b-glu+Bs), and b-glucan plus P. acidilactici-containing diet (b-glu+Pa)] were fed to L. vannamei for 90 days. Shrimp fed the b-glu and b-glu+Pa diets exhibited similar growth performance and body protein content, which were significantly higher than those of shrimp fed the control diet (P < 0.05). No significant differences in haemolymph triglyceride, cholesterol, protein, haemolymph urea nitrogen or chloride were detected among the experimental diets. However, dietary b-glucan alone increased the haemolymph glucose level and osmolarity (P < 0.05). Synbiotic supplementation had greater effects on intestinal microbiota and morphology than dietary b-glucan alone. For example, b-glu+Bs increased the number of intestinal lactic acid bacteria and decreased the number of Vibrio spp. (P < 0.05), and b-glu+Pa increased the height of intestinal villi.

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This study investigated the effects of dietary inulin and Jerusalem artichoke (JA) on intestinal microbiota and morphometry of Nile tilapia fingerlings. Five treatment diets were designed to supplement inulin at 0 (basal diet), 2.5 and 5.0 g/kg, and JA at 5.0 and 10.0 g/kg. Nile tilapia larvae were fed experimental diets from the first feeding through the fingerling stage (84 days). The cultivation-dependent technique showed that dietary inulin at 5.0 g/kg and JA (at both levels) increased lactic acid bacteria and Bifidobacterium spp., but decreased Vibrio spp. (p < .05). PCR-DGGE targeting 16S ribosomal RNA gene revealed that dietary inulin and JA generated different profiles of microbial community compared with fish fed a basal diet. Compared with fish fed the basal diet, a greater intestinal villi height was observed in fish fed 5.0 g/kg inulin and JA at both levels (p < .05). A larger relative goblet cell number were observed in the anterior intestine of fish fed 5.0 g/kg inulin or JA (p < .05). Overall, dietary inulin (5.0 g/kg) and JA (5 and 10.0 g/kg) since the first feeding had effects on modulating the intestinal microbiota and morphology of Nile tilapia fingerlings. K E Y W O R D S intestinal morphology, inulin, Jerusalem artichoke, Nile tilapia, PCR-DGGE, prebiotics

This study investigated the effects of the co-supplementation of vitamins C (0, 500, and 1000 mg kg À1 ) and E (0, 62.5, and 125 mg kg À1 ) on the growth performance, haematology and the modulation of blood stress indicators and immune parameters in hybrid catfish (Clarias macrocephalus 9 Clarias gariepinus) under combinations of thermal and acidic stress. Supplementation of vitamins C and E influenced the growth, haematological indices, serum chloride, plasma protein and immune parameters (lysozyme, total immunoglobulin and alternative complement haemolytic assay) (P < 0.05). Although vitamins C and E did not prevent a significant reduction in serum chloride, they minimized not only the modulation of blood glucose and plasma protein, but also the reduction in immune parameters (P < 0.05) owing to stress. Our results demonstrated that co-supplementation of 500 mg kg À1 vitamin C and 125 mg kg À1 vitamin E, or 1000 mg kg À1 vitamin C alone, for four weeks and co-supplementation of both vitamins at low levels (vitamins C at 500 mg kg À1 and E at 62.5 mg kg À1 ) for eight weeks had beneficial effects on the growth, amelioration of stress-mediated adverse changes in the physiological and immunosuppressive responses of hybrid catfish under stressful conditions.