Probiotic Applications in Cold Water Fish Species - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 245

resulted in the control of larval gut microbiota by decreasing Gram-negative populations, as
well as increased larval survival and growth (Daga etal . 2013). Live prey is an appropriate vec-
tor for probiotic delivery to fish larvae (Gatesoupe 1994) and bioencapsulation of bacteria in
rotifers can be achieved within 20-40 min (Makridis etal. 2000). Villamil etal. (2010) showed
that a 1 h treatment of P. acidilactici supplementation to rotifer culture led to better probiotic
retention in rotifers, and in the gut of fed turbot larvae, compared to 24 h. Finally, Villamil etal .
(2002) conducted in vitro experiments to determine the effect of a LAB strain on non-specific
immune functions. As with live cells, heat-killed Lc. lactis stimulated the immune response of
turbot macrophages, but a higher concentration was required compared to live cells.
Probiotics may also influence growth and nutrition of turbot juveniles. Increased protein
degradation in the distal segments of the turbot (25-30 g) GI tract has been reported after
oral intubation with Vibrio proteolyticus (10 10 ml -1 ) for a 3 week period. The higher nitro-
gen digestibility, followed by higher ammonia contents, evidenced the involvement of the
microbiota in water-soluble nitrogen contents by the contribution of bacterial proteases and
aminopeptidases and potentially the stimulation of endogenous enzyme activities which would
account for higher protein digestion, as supported by the elevated fraction of smaller soluble
proteins (De Schrijver and Ollevier 2000).
Overall to date, increased larval growth was reported in three studies involving
allochthonous strains, while increased survival was demonstrated in five studies conducted
under normal rearing conditions (Table 9.4).
9.5 PERCIDAE
9.5.1 European perch ( Perca fluviatilis )
European perch is a valuable candidate for aquaculture diversification in Europe but farming
profitability is compromised by high mortality rate during the larval and early juvenile devel-
opmental stages as well as the lack of therapeutic strategies to control outbreaks in culture
(Mandiki et al. 2011). Hence, the development of prophylactic strategies may contribute to
the expansion of European perch culture. Evaluating two administration pathways, Mandiki
et al . (2011) applied a commercial three-strain Bacillus mixture to Artemia and/or rearing
water (5 × 10 4 CFU ml -1 per day) of European perch larviculture, resulting in higher larval
growth rate and Ig levels only via treated live feed. However, a lower dose was applied via the
rearing water.
9.6 CONCLUSION
Aquaculture production is vulnerable to adverse impacts of disease and environmental condi-
tions. The demand for environmentally friendly and sustainable aquaculture has led to increas-
ing research on probiotics for aquatic animals. As presented in this chapter, beneficial effects
have been demonstrated following probiotic applications to cold water fish, emphasizing the
potential of probiotics in aquaculture production. Probiotic supplementation via the rearing
water has been successful in cold water larviculture. This delivery vector is relevant since
the intestinal tract, skin and gills are generally accepted routes of entry for bacterial infec-
tion, such as furunculosis and vibriosis (Groff and LaPatra 2000; Birkbeck and Ringø 2005;