Prebiotic Applications in Shellfish - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 402

with consumer demand and sustaining natural stocks. However increasing production creates
complications as intensification can decrease water quality, increase stress and increase bacte-
rial loading which ultimately reduces culture success and can lead to epidemic losses in stock
(Robohm et al. 2005). Aquatic borne diseases are a major problem facing the development
of commercial aquaculture and have resulted in significant economic losses and many indus-
trial failures (Balcázar etal. 2006); indeed, disease problems caused Thai shrimp production to
drop by 40% between 1994 and 1997 (Moriarty 1999). Alongside the quest to control bacterial
epidemics by means other than chemotherapeutics, recent years have seen the search for alter-
native strategies to help prevent infectious aquatic diseases in crustacean species. The use of
probiotics - live dietary supplements which can positively affect host health through manipu-
lation of gut microbiota (Fuller 1989) - has been explored ( Chapters 7 and 11 ). However, due
to the limitations of probiotics, such as the viability of live bacteria in feed products and the
viability and colonization of bacteria within the GI tract, the prebiotic concept has been devel-
oped (Roberfroid 2007). Prebiotics have shown potential for increasing growth and survival
of shellfish by improving feed conversion, immune status and/or stress tolerance. Furthermore
prebiotics have been shown to modulate the GI microbiology and enhance GI morphology,
which may enable improved feed conversion and consequently growth. This chapter provides
an overview of the types of prebiotics used in shellfish culture to date and their effects on organ-
ism development and physiology. Most research on shellfish has been conducted on penaeids
due to the size and value of the penaeid culture industry, constituting more than half of all
crustacean culture (FAO 2010).
15.2 USE OF PREBIOTICS IN SHELLFISH AQUACULTURE
Compared to the diverse range of prebiotics used in finfish aquaculture ( Chapter 14 ), there
are relatively few prebiotics documented in shellfish aquaculture. The prebiotics used in
shellfish culture to date include oligosaccharides such as mannanoligosaccharide (MOS),
fructooligosaccharide (scFOS and FOS), oligofructose, isomaltooligosaccharide (IMO) and
xylooligosaccharide (XOS) and the polysaccharide inulin (Ringø et al. 2010; Chapter 14 )
(Table 15.1). Studies have applied these prebiotics via incorporation into dry feeds (e.g. Genc
et al. 2007; Sang et al. 2009; Hai and Fotedar 2009) and live feed such as Artemia and rotifers
(e.g. Daniels et al. 2010; Hoseinifar et al. 2010).
15.2.1 Mannanoligosaccharides
MOS is the most well documented prebiotic in shellfish culture and has shown potential in
a range of shellfish species including shrimp, freshwater crayfish and lobsters (Genc et al.
2007; Hai and Fotedar 2009; Sang et al. 2009; 2011a; 2011b; 2014; Daniels et al. 2010; 2013;
Sang and Fotedar 2010; Mazlum et al. 2011; Zhang et al. 2012). While relatively few stud-
ies have been conducted, these studies have demonstrated improved growth and/or survival
with the dietary addition of MOS at different stages of development. In the freshwater crayfish
( Cherax destructor ), MOS was supplemented to juveniles via a formulated feed and admin-
istration increased specific growth rate (SGR) and average weight gain (Sang et al . 2011b).
Similar results have been observed in post larval tiger shrimp ( Penaeus semisulcatus ) (Genc
et al. 2007), juvenile black tiger prawn ( Penaeus monodon ) (Sang et al. 2014) and juvenile