WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2015 33 resulted in a significant decrease in MDA formation in trout fillets. In addition, GST activity was significantly greater in fillets of fish fed the phytogenic feed additive (Table 1). Phytogenics and Growth Promotion Low levels of antibiotics in animal feeds, known as antibiotic growth promoters (AGPs), results in antibiotic resistance and the emergence of so-called ‘superbugs.’ In recent years, antibiotic growth promoters have been banned from aquaculture production in nearly all countries. Farmers who still use AGPs have limited or no access to high-value markets. Phytogenics can act as natural growth promoters that improve diet palatability, stimulate appetite and increase feed consumption and growth performance. Phytogenics also induce transcription, increasing RNA, which leads to an increase in total amino acids available, therefore enhancing the production of proteins in cells. The effect of phytogenics on growth performance was evaluated in a study carried out with channel catfish Ictalurus punctatus at the National Warmwater Aquaculture Center, Mississippi, USA. Catfish fed diets with Digestarom® had significantly enhanced weight gain (from 86 to 109 g) (Fig. 8) and FCR was reduced from 1.50 (control) to 1.36. Furthermore, fish in the control group reduced feed intake during days with large variations of water temperature, while fish fed Digestarom® maintained feed intake at an adequate level. Making Sustainability Profitable Given high feed prices, the pressure to optimize the use of alternative ingredients and consumer awareness about sustainability, it is imperative to improve the digestibility of commercial diets, optimize feed utilization and reduce nitrogen discharges and the use of AGPs. Phytogenic feed additives can improve feed digestibility, especially of proteins and amino acids, thus reducing feed costs and nitrogen output. It also can be a valuable tool for preventive health management, enhancing fillet quality or as a sustainable replacement for AGPs. Therefore, phytogenic feed additives are considered a valuable tool to support the profitability of aquaculture businesses, following guiding principles of sustainability (Fig. 9). Notes Rui Gonçalves, Technical Manager – Aquaculture, Biomin Holding GmbH, Erber Campus 1, 3131 Getzersdorf, Austria rui.goncalves@biomin.net Gonçalo Santos, R&D Manager – Aquaculture, Biomin Holding GmbH, Erber Campus 1, 3131 Getzersdorf, Austria 1 Digestarom® P.E.P. MGE, BIOMIN Holding GmbH, Austria TOP, FIGURE 6. Mortality of white shrimp challenged with Vibrio parahaemolyticus. *Indicates a significant difference between treatments (p<0.05). Source: Biomin trials (2012). BOTTOM, FIGURE 7. Serum immune parameters of white shrimp after Digestarom® P.E.P. supplementation. Source: Biomin trials (2012). TOP, FIGURE 8. Fish body weight of channel catfish as affected by supplementation of the diet with Digestarom® P.E.P. MGE. Bars lacking a common superscript letter differ significantly (p<0.05). Source: Biomin trials (2012). BOTTOM, FIGURE 9. Schematic representation on phytogenics mode of action for aquaculture species.
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