الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Until recently, the addition of low doses of antibiotics to animal feeds was common practice in terrestrial animal production because of its growth-promoting effect; animals fed diets containing antibiotics grow 4 to 5% faster than control animals (Ferber, 2003). Also in aquaculture, antibiotics have been traditionally used as prophylactics (Cabello, 2006). Because of the risk of antibiotic resistance development, there is a growing awareness that antibiotics should be used with more care. As a consequence, the use of antibiotics as growth promoters in animal production is prohibited in Europe since 2006 (European Parliament and Council Regulation No 1831/2003). However, there are good indications that this ban could result in a higher frequency of pathogenic bacteria such as Salmonella spp., which in turn could lead to a higher frequency of infections (in animals as well as consumers) (Phillips et al., 2004). Hence, alternative methods to control the level of pathogenic bacteria are important with respect to the improvement of animal well-being as well as of consumers’ health.Over the last decade research has focused on the application of using probiotics and prebiotics to replace antibiotic growth promoters in fish farming industry (Irianto and Austin, 2002a; Vine et al., 2006; Wang and Xu, 2006; Gatlin III and Peredo, 2012). In a practical sense, probiotics are defined as live microorganisms that are used as dietary supplementations in aquaculture and could enhance the growth and health of the host (Gatesoupe, 1999 and Kesarcodi-Watson et al. 2008). Gibson and Robefroid (1995) defined prebiotics as ‘nondigestible food ingredients that beneficially affects the host by selectively stimulating growth and/or activity of one or a limited number of bacteria in the colon’ through the combination of probiotics and prebiotics in so-called synbiotics. Gibson and Robefroid (1995) reported that the use of the synbiotics concept may give the benefit of both pre- and probiotics on growth of fish mainly due to the synergistic effect and may improve the survival of the probiotic organism, because fermentation can be implemented more effectively as its required specific substrate is readily available, hence, the simultaneous presence of probiotic and prebiotic reward the host in a proper manner (Collins and Gibson, 1999).