38 DECEMBER 2014 • WORLD AQUACULTURE • WWW.WAS.ORG research has focused on monogastric land-based livestock. Current publications describe improvements in inflammatory processes and intestinal health of swine and poultry. For example, a recent study conducted at the Institute of Animal Nutrition and Nutrition Physiology at University of Gießen, Germany, investigated the effects of supplementation with a grape seed and grape marc meal extract1 on performance characteristics and gut health of pigs (Gessner et al. 2013). The tested additive might provide a useful strategy to prevent inflammation in the gut, inasmuch as different parameters involved in inflammation, such as NF-ĸB, were improved markedly. Interestingly weight gain increased by 6.6 percent and feed conversion improved by 4.5 percent. It needs to be elucidated whether or not these benefits were directly linked to saving energy and protein, which were no longer needed for counteracting chronic inflammation. However, it could also be concluded that the animals were apparently healthy and fed according to current recommendations. Available research performed on effects of flavonoids on aquatic species is scarce but promising. Decaffeinated green tea extract improves anti-oxidant status and egg quality of rainbow trout (Asadpour et al. 2012). Malondialdehyde, a marker for oxidative stress, was lower in trout eggs and related to green tea intake, an observation that confirmed previous experiments. In fish, reactive oxidants are produced not only during basal metabolism but can be generated by cold water temperatures or exposure to the factors shown in Figure 1. Inasmuch as the anti-oxidant system of the liver is not activated before late embryonic development, early protection of eggs via an enhanced anti-oxidant system is of particular importance to ensure high reproductive performance. Reduced malondialdehyde content was measured in chicken meat produced from animals fed on diets supplemented with grape pomace rich in flavonoids. This transfer of anti-oxidative effects from feed additives to food products might represent a profitable approach for niche markets, such as aquaculture caviar production, where the application of flavonoids might increase the durability of final products (Fig. 5). However, more information is required and future research needs to focus on the best flavonoid combinations and dosages to improve such valuable food products. In this context, it is crucial to choose the best processing technique of herbal raw materials. For example, Cho et al. (2007) demonstrated that the addition of green tea extract to diets of juvenile flounder had better effects on growth and feed utilization than raw leaves, dry leaves or a tea by-product. Conclusions Future aquaculture will likely face the need to adapt to a reduced availability of valuable feed ingredients, such as fish oil, and to improved genetics with faster and more efficiently growing species. These developments likely will generate a greater risk of inflammatory damage, which can prevent farmers from fully exploiting the production potential of their stocks because controlling inflammation requires energy and protein that will no longer be available for tissue growth. Secondary plant metabolites, such as flavonoids, exhibit strong anti-inflammatory properties and improved anti-oxidant status, production parameters and product quality of terrestrial livestock and aquatic species. More research is required to fully understand the underlying mechanisms and interactions with production factors, such as water temperature and salinity in different production systems. Feed additives based on green tea and grape products are available sources of flavonoids and can contribute to optimized present and future aquafeed formulations. Notes Malte Lohölter, Susanne Kirwan and Bernhard Eckel Dr. Eckel GmbH, Im Stiefelfeld 10, 56651 Niederzissen, Germany 1 Anta®Ox, Dr. Eckel GmbH, Germany Corresponding author: s.kirwan@dr-eckel.de References Asadpour, R. F., Koochaki Panchah, N. Sheikhzadeh, and H.TayefiNasrabadi. 2012. Effects of decaffeinated green tea (Camellia sinensis) on reproductive characteristics and egg quality of rainbow trout (Onchorhynchus mykiss). Bulgarian Journal of Veterinary Medicine 15(4):246-253. Cho, S.H., S.M. Lee, B.H. Park, S.C. Ji, J. Lee, J. Bae and S.Y. Oh. 2007. Effects of dietary inclusion of various sources of green tea on growth, body composition and blood chemistry of the juvenile olive flounder, Paralichthys olivaceus. Fish Physiology and Biochemistry 33:49-57. Gessner, K.G., A. Fiesel, E. Most, J. Dinges, G. Wen, R. Ringseis and K. Eder. 2013. Supplementation of a grape seed and grape marc meal extract decreases activities of the oxidative stress-responsive transcription factors NF-ĸB and Nrf2 in the duodenal mucosa of pigs. Acta Veterinaria Scandinavica 55:18-28. Gjøen, H.M. and H.B. Bentsen. 1997. Past, present, and future of genetic improvement in salmon aquaculture. Journal of Marine Science 54:1009-1014. Gonzalez, R., I. Ballester, R. Lopez-Posadas, M.D. Suarez, A. Zarzuelo, O. Martinez-Augustin and F. Sanchez de Medina. 2011. Effects of flavonoids and other polyphenols on inflammation. Critical Reviews in Food Science and Nutrition 51:331-362. Pettersson, A. 2010. Effects of replacing fish oil with vegetable oils in feed for rainbow trout (Oncorhynchus mykiss) and arctic char (Salvelinus alpinus). Doctoral thesis, Swedish University of Agricultural Sciences, Uppsala. Sweden. Ponzoni, R.W., N.H. Nguyen, H.L. Khaw, N. Kamaruzzaman, A. Hamzah, K.R.A. Bakar and H.Y. Yee. 2008. Genetic improvement of Nile Tilapia (Oreochromis niloticus) – Present and future. Proceedings of 8th International Symposium on Tilapia in Aquaculture 1:33-35. Sargent, J. R., R.J. Henderson and D.R. Tocher. 1989. The lipids. Pages 153-218 In J. Halver, editor. Fish nutrition. Academic Press, New York, New York, USA. Tacon, A.G.J., M.R. Hasan and M. Metian. 2011. Demand and supply of feed ingredients for farmed fish and crustaceans – Trends and prospects. In: FAO Fisheries Technical Paper 564. FAO, Rome, Italy. Weiss, U. 2008. Inflammation. Nature 454:427. Wuerzbach, M., M., Korzekwa, E. Holl and B. Eckel. 2014. Stability of flavonoids in grape pomace. 13th BOKU Symposium Animal Nutrition (Proceedings). Vienna, Austria. 226-230
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