Immunomodulating Feed Additives in Fish Feeds for Marine Flatfish Species

Tierärztliche Hochschule Hannover Abteilung Fischkrankheiten und Fischhaltung Immunomodulating feed additives in fish feeds for marine flatfish species INAUGURAL – DISSERTATION zur Erlangung des Grades einer Doktorin der Naturwissenschaften - Doctor rerum naturalium - ( Dr. rer.nat. ) vorgelegt von Vanessa Isabelle Fuchs Münster Hannover 2020 Wissenschaftliche Betreuung: Prof. Dr. Dieter Steinhagen Abteilung Fischkrankheiten und Fischhaltung Stiftung Tierärztliche Hochschule Hannover Prof. Dr. Bela H. Buck Marine Aquakultur Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung/ Hochschule Bremerhaven 1. Gutachter: Prof. Dr. Dieter Steinhagen Abteilung Fischkrankheiten und Fischhaltung Stiftung Tierärztliche Hochschule Hannover Prof. Dr. Bela H. Buck Marine Aquakultur Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung/ Hochschule Bremerhaven 2. Gutachter: Prof. Dr. Dr. h. c. mult. Harald Rosenthal Professor Emeritus: Universität Kiel Tag der mündlichen Prüfung: 10.06.2020 To my family Contents Chapter 1 General introduction - 7 - 1. Flatfish aquaculture development - 9 - 2. Intensive flatfish production and its challenges - 10 - 3. Functional additives and their mode of action - 13 - 3.1 Seaweeds - 13 - 3.2 Nucleotides - 14 - 3.3 Organic acids and their salts - 15 - 3.4 Probiotics: Bacillus spp - 16 - 3.5 Mannan oligosaccharides - 17 - 3.6 ß-Glucans - 18 - 4. Trends in feed formulations - 19 - 5. Aims, research questions and outline of the thesis - 20 - Chapter 2 The effect of supplementation with polysaccharides, nucleotides, acidifiers and Bacillus strains in fish meal and soy bean based diets on growth performance in juvenile turbot (Scophthalmus maximus) - 25 - Chapter 3 Influence of immunostimulant polysaccharides, nucleic acids and Bacillus strains on the innate immune and acute stress response in turbots (Scophthalmus maximus) fed soy bean and wheat based diets - 45 - Chapter 4 Effect of dietary ß-glucans and MOS on growth, feed conversion, immune and stress response in strarry flounder (Platichthys stellatus) fed soy and wheat proteins as fish meal substitutes - 65 - Chapter 5 General discussion - 89 - References - 103 - Appendix - 123 - Summary - 124 - Zusammenfassung - 127 - Publications and presentations - 131 - Erklärung - 133 - Acknowledgements - 134 - General introduction Chapter 1 General introduction - 7 - General introduction Aquaculture has become the world's fastest growing sector of aquatic animal production (Figure 1) with an average annual growth rate of 5.9% (2001−2010) and 4.8% since 2011, respectively (FAO, 2019). World production of finfish represented 66.6 % (53.4 million tonnes [t]) in 2017 of the total aquatic animals produced in aquaculture (FAO, 2019). Accordingly, about 50% of the total fish production (capture and aquaculture) in 2017 is supplied by aquaculture. Figure 1 Worldwide sea food supply from aquaculture and fisheries between 1950 and 2017 (FAO, 2019) (modified by V.Fuchs) However, the rapid expansion and intensification of aquaculture has simultaneously implicate a rising burden of challenges, such as disease outbreaks in fish production (Thrush et al., 2012). For example, turbot (Scophthalmus maximus) farms have suffered from high losses due to parasitic, viral and bacterial diseases (Fouz et al., 1992; Hellberg et al., 2002; Johansen et al., 2004; Kim et al., 2005; Novoa et al., 1992). Moreover, stressful culture conditions are also harmful for flatfishes affecting physiology, growth, behavior and may encourage the outbreak of diseases (Barton, 2002; Costas et al., 2008; Costas et al., 2011; Gonçalves et al., 2010; Min et al., 2015; Reiser et al., 2010). Therefore, good health management and disease prevention, especially for intensive land-based aquaculture, is of increasing interest and one of the main - 8 - General introduction topics in aquaculture research (Assefa and Abunna, 2018; Segner et al., 2012). Recently, the application of functional additives, such as probiotics, prebiotics, nucleotides or organic acids/acidifiers, represents a promising method for disease control and growth promoting effects in aquatic animals (Dawood et al., 2018). However, further research is needed to assess the effect of such additives for more fish species of commercial interest, such as some flatfish species. 1. Flatfish aquaculture development Worldwide, various flatfish species are produced in aquaculture, predominantly turbot (Scophthalmus maximus) mainly in Spain and China, Bastard halibut (Paralichthys olivaceus) in Korea, Japan and China, Atlantic halibut (Hippoglossus hippoglossus) in Norway and Senegalese sole (Solea senegalensis) in France, Spain and Portugal (Bergh et al., 2001; FAO, 2019; Guan et al., 2018; Morais et al., 2016; Person-Le Ruyet, 2002; Sohn et al., 2019). In Europe, turbot (Figure 2) is one of the six main cultured finfish species alongside Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax) and common carp (Cyprinus carpio) (Janssen et al., 2017). Figure 2 Turbot (Scophthalmus maximus). - 9 - General introduction S. maximus represents an important food resource in the Mediterranean area, especially in Spain, Portugal and France and is mostly favored due to its low-fat level (2 - 4% fat) and firm, white, mild tasting meat. The United Kingdom and France initiated the aquaculture farming of turbot in the early 1970s (Person-Le Ruyet et al., 1991). Turbot production then rapidly developed in Europe, particular in Spain and Portugal, with increasing yields from 38 t in 1985 to 11,000 t in 2017 (FAO, 2017b). To date, turbot farming is also present in other countries such as in Chile since 1991 (Alvial and Manrı́quez, 1999) and China since 2003. Chinese production has been rapidly expanding by an estimated average of 56,000 t per year since 2005 (FAO, 2017b). In contrast, the starry flounder (Platichthys stellatus) (Figure 3) is an emerging newcomer in the aquaculture industry in Korea and in the coastal regions of north China. Since 2003, an ever-expanding production of starry flounder was realized from 4,000 t in 2003 to 16,000 t in 2017 (Guan et al., 2018). Figure 3 Starry flounder (Platichthys stellatus) (Photo: M. Bögner, AWI). 2. Intensive flatfish production and its challenges Turbot is currently primarily produced in intensive land-based culture systems, either in semi- circulating flow-through (the most common technique) or recirculating aquaculture systems (RAS) (Blancheton, 2000; FAO, 2017a; Person-Le Ruyet, 2002). It has been shown that a shallow water depth in ponds or tanks is sufficient for this demersal living species that naturally - 10 - General introduction feeds on other bottom-living fish or invertebrates. Diets for turbots require relatively high protein levels, 500 to 550 g kg-1 (dry matter), with fish meal (FM) preferably as the main protein source (Cho et al., 2005; Day and Plascencia González, 2000; Lee et al., 2003a). Feed conversion efficiency is a crucial factor, because feed represent a minimum of 17% of the total production costs (Person-Le Ruyet, 2002) with an increasing tendency due to the rising prices of feed ingredients (Rana et al., 2009; Tacon and Metian, 2008). Juvenile turbot (> 40 g) show best growth and feed conversion at intermediate salinities (15-27 g L-1) and between 16-19°C, rapidly declining above at 20°C (Boeuf et al., 1999; Daniels and Watanabe, 2010; Gaumet et al., 1995; Imsland et al., 2001) with increasing disease outbreaks (Marcus Thon, personal communication, December, 2012). In contrast, the cultivation of starry flounder is relatively new and currently this species is exclusively cultivated in flow-through land based aquaculture farms (Mirco Bögner, personal communication, November, 2015). This species is a promising candidate for land-based aquaculture due to its acceptable growth rates, wide salinity and temperature tolerance and as well as its high marketability (An et al., 2011; Lim et al., 2013; Min et al., 2015; Song et al., 2014). Starry flounder is generally reared and bred under the same conditions as other commercial interesting pleuronectiformes e.g. Bastard halibut or turbot (An et al., 2011). At present only some studies on the dietary demands in terms of protein and lipid content (Lee et al., 2003; Wang et al., 2017), FM replacement (Song et al., 2014) and diet additives (Park et al., 2016; Schmidt et al., 2017) have been published. More research has been published by Korean and Chinese researchers (in Korean or Chinese literature; access is difficult/impossible) studying the biology of starry flounder or the requirements for its use in aquaculture (Kim et al., 2019; Liu et al., 2008; Shin et al., 2019). In general, marine finfish aquaculture has become more intensive over the last years with the development of new and improved technologies regarding land-based systems (such as RAS) and feed optimization (such as formulation, ingredients, production techniques) (Bendiksen et al., 2011; Dalsgaard et al., 2013; Tal et al., 2009). Intensifying fish production in RAS, a relatively young production sector, offers a sustainable method for culturing flatfish species (Martins et al., 2010). RAS allows the effective management, collection and treatment of nutrient wastes to ensure optimal water quality and, therefore, providing the ability to increase stocking densities and thus fish production (Blancheton, 2000; Orellana et al., 2014; Tal et al., 2009). However, the effort

Load more