Prebiotics in Finfish: An Update - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 383

study with Photobacterium damselae subsp. piscicida (IP) displayed no significant effect of
inulin (10 g kg −1 ) compared with the control group (non-supplemented diet). In a recent study,
Cerezuela et al . (2013a) investigated the effect of inulin (10 g kg −1 ) on intestinal morphology
and allochthonous intestinal microbiota. Intestinal morphology evaluations by light and trans-
mission electron microscopy revealed signs of damage in the anterior intestine (disruption and
damage to the intercellular space and microvilli and enterocyte vacuolization); these results
are in accordance with those reported in Arctic charr fed inulin (Olsen etal . 2001) but contrary
to those reported for Atlantic salmon (Bakke-McKellep et al . 2007). Dietary administration of
inulin significantly increased villi height, intestinal diameter and the number of intraepithelial
leukocytes, but reduced the number of goblet cells and microvilli height. The increased villi
height is in accordance with that reported in gilthead sea bream fed MOS (Dimitroglou et al .
2010a). DGGE analyses revealed that the intestinal microbiota of the fish fed inulin contained
significantly fewer (12 ± 0.43) operational taxonomic units (OTUs) than detected in control
fed fish (17.33 ± 0.94).
Cerezuela et al . (2013b) investigated the effect of inulin administration on intestinal gene
expression in gilthead sea bream, and revealed that IL8 (proinflammatory cytokine), β-actin,
occludin and transferrin expression were significantly increased with inulin supplementation.
The authors suggested that the increase in IL8 is related to modulation in the intestinal micro-
biota; however, as no information exists on this topic in fish, further investigations are needed.
In a study with sharpsnout ( Diplodus puntazzo Cetti, 1777; ∼100 g), Piccolo et al . (2011;
2012) assessed the effect of MOS, FOS and inulin on growth, ADC, somatic parameters,
body composition and fillet fatty acid composition. Supplementation of MOS and FOS
(8gkg −1 of both prebiotics) did not affect growth performance (Piccolo et al . 2011) and
similar results were reported when MOS and inulin were used (Piccolo et al . 2012). ADC of
dry matter, protein, lipid and energy was not influenced by MOS and FOS supplementation
(Piccolo et al . 2011). Somatic parameters - viscerosomatic index (VSI) and mesenteric fat
index (MFI) - decreased but not significantly (Piccolo et al . 2012). Crude lipid decreased
significantly while crude protein and ash were not affected. Some fatty acids (16:0, 18:1 n-9
and 20:5 n-3) were significantly affected by MOS and inulin; otherwise no clear effect on
fatty acid composition was apparent.
14.8.2 White sea bream
The white sea bream is considered one of the 'new species' in the Mediterranean aquaculture
industry. In the study of Dimitroglou et al . (2010b), white sea bream larvae were fed 20 g kg −1
MOS supplementation (incorporated in Artemia ) from 24 to 43 days post hatching (dph). The
results indicated that larval growth performance and survivability were not affected by the
MOS supplementation at the early life stage. However, light microscopy and TEM evalua-
tions revealed that MOS supplementation significantly improved the intestinal morphology by
increasing villi surface area and microvilli length by 12% and 26% respectively, compared
to the control. Salinity challenge experiments showed that MOS significantly increased larval
stamina and survival (higher LT 50 ) at both 0 mg l −1 and 60 mg l −1 salinity by 13% and 23%,
respectively. The reason for this observation was not fully elucidated but the authors suggested
a possible explanation may be related to improved gut morphology. In marine teleosts the GI
tract plays an important role in osmoregulation, thus the better stamina of MOS fed larvae
in the salinity challenge may be related to improving intestinal morphology. This improved