WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2014 69 stress (Akhtar et al. in press). Dietary supplementation of L-tryptophan ameliorates thermal stress and augments growth. Pyridoxine has been used to mitigate stress from pesticide applications and thermal stress (Akhtar et al. 2011). Pyridoxine has multiple roles. Supplementation of nutraceuticals help in mitigating multiple stressors, including temperature, salinity and exposure to pesticides, and augmented growth and modulated non-specific immune functions. Immunoprotection of fish by dietary manipulation to overcome disease has become an important area of research. Some promising nutraceuticals tested for aquafeeds include microbial levan, nucleotides, pyridoxine, tryptophan, vitamin C, mannan-oligosaccharides, yeast extract, n-3 fatty acids and carotenoids. These have helped in immunomodulation in tropical fishes (Jha et al. 2007). Nutrigenomics studies. Nutrigenomic tools involve transriptomics, proteomics and metabolomics, each with specific applications. First, nutrigenomics can help studies to define nutrient requirements, where the expression pattern of specific genes in response to the dietary level of a nutrient is used as response criteria. The physiological effect of different nutraceuticals can be studied with expression of the effector genes. The totality of the side effects of chemicals and antibiotics used in aquaculture can be evaluated with nutrigenomic tools. Flesh quality can be monitored using protein or metabolic biomarkers expressed in the flesh. Nutrigenomics has potential as a research tool that can solve problems of uncertainty and data deficiency in nutrition studies. Flesh quality improvement by nutritional intervention. Flesh quality can be controlled to a large extent by using feed supplements. Modifying the dietary protein-to-energy ratio is useful inasmuch as low-protein feed can reduce fat content and increase product shelf life. The fatty acid profile and flesh coloration can be manipulated by dietary supplementation. Dietary supplements to improve flesh quality should improve lipolysis and protein assimilation, reduction of adipocytes, resistance to air-dipping and activation of liver function, without interfering with growth. The specific quality of final product can be manipulated before reaching the market. It includes increasing consumer acceptability by carotenoid supplementation in salmonids. Fat-free diets for common carp in the last segment of culture improves harvested product quality. Feed development for new species. New species may require new feeds, which have to be developed according to specific requirements at different stages of the life cycle. This often requires systematic research to determine the type, physical characteristics, bulk density and the appropriate process of preparation of new feeds, while keeping economic feasibility in mind. Feed management strategies. Feed management strategies are needed to systematically use feed efficiently and reduce waste. Constraints put forward by environmental regulations to reduce pollution from aquaculture can be overcome by employing tactical approaches in feeding management. It is always economical and environmentally friendly to employ good feed management rather than just using good feed. Good feed management options include development of logical feeding regimes, advanced feeding equipment and accurate allocation of rations. Use of advanced feed manufacturing techniques. Advanced culture systems, such as recirculation units, demand feeds that do not produce breakable faeces, so leaching of nutrients from faeces can be reduced and waste can be filtered easily. Advanced feed production technologies, such as efficient top-coating techniques, may facilitate the supply of nutraceuticals. Effective extrusion can improve acceptability and environmental quality. Conclusion Because aquaculture has immense potential to provide food for the poor, it is essential to make it more efficient and cost-effective. We have noticed a shift in the attitude of farmers as they desire good health of cultured fish, apart from good growth. The inclusion of nutraceuticals or bioactive compounds in the diet of farmed aquatic animals can ultimately improve human health. Technological interventions to produce fish from food industry by-products and plant sources rather from low-cost fish are required. There is an urgent need for action to address the tensions arising from increasing human demand for fish and seafood and rapidly declining marine ecosystem health. Notes V. Tincy*, P. Mishal and A. K. Pal, Division of Fish Nutrition, Biochemistry and Physiology, Central Institute of Fisheries Education, Yari Road, Versova, Mumbai-61, India M. S. Akhtar, Directorate of Coldwater Fisheries Research, Bhimtal-236136, Nainital, Uttrakhand, India * Email: 4tincy@gmail.com; Mobile: 8080376626 References Akhtar, M. S., A. K. Pal, N. P. Sahu, A. Ciji, and D. K. Meena. 2011. Dietary pyridoxine enhances thermal tolerance of Labeo rohita (Hamilton) fingerlings reared under endosulfan stress. Journal of Thermal Biology 36:84-88. Akhtar, M. S., A. K. Pal, N. P. Sahu, A. Ciji, D. K. Meena and P. Das. In press. Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress. Journal of Animal Physiology and Animal Nutrition (Accepted). Allison, E. H. 2011. Aquaculture, fisheries, poverty and food security. World Fish Center, Penang, Malaysia. Baruah, K., A. K. Pal, N. P. Sahu, D. Debnath, P. Nourozitallab and P. Sorgeloos. 2007. Microbial phytase supplementation in rohu, Labeo rohita diets enhances growth performance and nutrient digestibility. Journal of World Aquaculture Society 38:129-137. FAO (Food and Agriculture Organization of the United Nations). 2012. State of World Fisheries and Aquaculture, Food and Agriculture Organization of the United Nations, Fisheries and Aquaculture Department, Rome, Italy. Jha, A. K., A. K. Pal, N. P. Sahu, S. Kumar and S. C. Mukherjee. 2007. Haemato-immunological responses to dietary yeast RNA, ω-3 fatty acid and b-carotene in Catla catla juveniles. Fish and Shellfish Immunology 23:917-927. Manush, S. M., A. K. Pal, T. Das and S. C. Mukherjee. 2005. Dietary high protein and vitamin C mitigate stress due to chelate claw ablation in Macrobrachium rosenbergii males. Comparative Biochemistry and Physiology, Part A 142:10-18. WFC (World Fish Centre). 2009. Climate change: Research to meet the challenges facing fisheries and aquaculture, World Fish Centre, Penang, Malaysia.
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