Prebiotic Applications in Shellfish - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 410

15.3.1 Growth and survival
One of the main objectives of prebiotic studies is to induce direct improvements in culture
success. Improvements in growth and/or survival have previously been reported in shellfish
species with the use of prebionts (Genc et al. 2007; Zhou et al. 2007; Hai and Fotedar 2009;
Sang et al. 2009; Sang and Fotedar 2010; Sang et al. 2011a; 2011b). The extent of growth
and/or survival enhancements is dependent on the developmental stage, the prebiotic type, the
dosage, the duration of application and the culture conditions (Table 15.1). MOS applied singu-
larly, and in combination with Bacillus probionts, has been reported to enhance culture success
in larval European lobster (Daniels et al . 2010). Greater improvements in growth performance
were achieved with the combined dietary application of MOS and Bacillus spp.; however, this
trend was not apparent in respect to survival where both MOS and MOS + Bacillus spp. fed
larvae showed equally elevated levels of survivability compared to the control (Daniels et al.
2010). Comparatively using a different culture technique (green water), during European lob-
ster culture, provided markedly different results in growth and survival (Daniels et al . 2013)
to those seen in the earlier study. In this study survival and growth were similar in larvae fed
prebiotics and probiotics both individually and in combination, though these results were sig-
nificantly greater than non biotic fed larvae. Similar varying enhancements in survival have
been shown with the combined use of other prebiotics and probiotics (Li P. et al. 2009). Posi-
tive effects of MOS on growth performance have also been documented in western king prawn
(Hai and Fotedar 2009), tiger shrimp (Genc et al. 2007), C. destructor (Sang et al. 2011b) and
tropical spiny lobster ( Panulirus ornatus ) (Sang and Fotedar 2010). However, in a study on
freshwater crayfish ( Astacus leptodactylus ), Mazlum et al. (2011) reported that varying lev-
els (1.5, 3.0 and 4.5 g kg -1 ) of dietary MOS had no significant effect on final weight or FCR.
MOS has been demonstrated to enhance survival in Marron Cheraxtenuimanus when provided
at 2 and 4 g kg -1 (Sang et al. 2009; Sang et al. 2011a), Pacific white shrimp ( Litopenaeus
vannamei ) at 2, 4, 6 and 8 g kg -1 feed (Zhang et al. 2012), tiger shrimp at 3 and 4.5 g kg -1
feed (Genc et al. 2007) and tropical spiny lobster at 4 g kg -1 feed (Sang and Fotedar 2010).
These studies however demonstrated no effect, in comparison to control individuals, on sur-
vival or growth at lower MOS supplementation levels. Contrary to these studies, survival was
unaffected in western king prawn fed MOS at 5 g kg -1 (Hai and Fotedar 2009). Enhance-
ments in survival with alternative prebiotic dietary supplements have also been documented
(Table 15.1), for example in white shrimp ( Fenneropenaeus indicus ) fed inulin supplemented
diets (Hoseinifar et al. 2010). The enhancements in growth and survival documented with pre-
biotics can in part be ascribed to a suite of interrelated developments in GI morphology, GI
microbiology, GI enzyme activity and immune status, as described in the following sections.
15.3.2 Immunomodulation and disease resistance
It has been suggested that the innate immune response is biologically linked to gut health
(Gómez and Balcázar 2008; Perez et al. 2010). As the establishment of a commensal and/or
defensive microbiota is a key factor in the exclusion of potential opportunistic pathogens and
sustaining health, there is clearly a delicate balance between the immune system and the GI
microbiota (Gómez and Balcázar 2008). Furthermore it is becoming increasingly clear that
the host-microbiota interactions at the mucosal interface play key roles in regulating both
localized and systemic immunological status. In shellfish the innate/non-specific immune
system is the primary defence mechanism against pathogenic microorganisms in which
haemocytes (coelomocytes in lower invertebrates) play key functions (Lee and Söderhäll