Prebiotics in Finfish: An Update - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 380

These studies indicate that dietary supplementation of MOS can influence several aspects:
intestinal lipid, intestinal morphology, localized immunological responses and potentially
intestinal microbiota, which provide protection against enteric bacterial pathogens in fish.

14.7.2 Hybrid striped bass ( Morone chrysops × Morone

saxatilis )
Hybrid striped bass is an important game fish and food fish in the United States and commer-
cial production has steadily increased over the past 25 years to 4000-6000 tonnes per annum
during the past decade (FAO FIGIS 2013). Several studies have investigated the application of
prebiotics in hybrid striped bass (Table 14.5). It has been reported that dietary GroBiotic ® -A
can improve hybrid striped bass HK macrophage extracellular superoxide anion production
and resistance to Streptococcus iniae and Mycobacterium marinum (Li and Gatlin III 2004;
2005). More recently in vitro and in vivo experiments have been conducted by Burr et al .
(2010) in order to investigate the effect of four prebiotics (GroBiotic ® -A, MOS, GOS and
inulin) on hybrid striped bass. In the in vitro experiment, the intestines of three fish fed the
commercial diet (without prebiotic supplementation) were aseptically removed inside an
anaerobic chamber. The intestinal contents were diluted and incubated with the experimental
feeds at 25 ∘ C. The experimental diets were based on the commercial diet with an inclusion
of5gkg −1 and 10 g kg −1 of each of the prebiotics. After 24 and 48 h of incubation at 25 ∘ C,
supernatants were removed for volatile fatty acid (VFA) analysis and DNA was extracted
for PCR-DGGE analysis. The results showed that propionate production was low compared
to acetate and butyrate for all samples. Additionally, there were no significant differences
in propionate, acetate and total VFA among the samples after 48 h incubation. Compared
to the control, butyrate production significantly increased after 48 h but only for samples
containing 5 g kg −1 GroBiotic ® -A, 10gkg −1 MOS, and 5 g kg −1 GOS. Microbial cluster
analysis showed that community composition in all samples had high similarity coefficients
(

80%) at 24 and 48 h and the dominant bands were identified as Clostridium perfringens
and Fusobacteria. In the in vivo experiment, fish were fed experimental diets supplemented
with 10 g kg −1 of each prebiotic for 8 weeks. Weight gain, FCR and PER were unaffected
by prebiotic supplementation. Similarly, body proximate analysis revealed that ash, moisture
and lipid levels remained unaffected by prebiotic supplementation; however, body protein
content was significantly higher in the GroBiotic ® -A fed fish compared to the control fed
fish. PCR-DGGE analysis revealed that microbial patterns of fish fed inulin, MOS and
GroBiotic ® -A had very high similarity indices. Similarity coefficients of fish fed GOS were
less than 80% compared with the other prebiotic treatments, and the microbial community
of the fish fed the control diet was unique compared to fish fed prebiotic supplemented diets.
The main genera identified were: Clostridia , Bacillus , Enterococcus , Lysinibacillus and
Staphylococcus . This study showed that prebiotics did not affect the growth performance of
the cultivated fish but the prebiotics modulated the intestinal microbiota to some extent.

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14.8 SPARIDAE

14.8.1 Gilthead sea bream
The gilthead sea bream is probably the most important fish species in the Mediterranean region
with an estimated 97,000 tonnes produced in 2011 (FAO FIGIS 2013). Despite this, very few