|Rawles, Steven - Steve|
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract only
Publication Acceptance Date: 11/25/2009
Publication Date: 3/1/2010
Citation: Lochmann, R., Rawles, S.D., Sink, T., Phillips, H., Barrows, F., Bechtel, P.J. 2010. Use of Alaskan pollack viceral meal in diets of channel catfish to enhance the N-3 content of the fillet [abstract]. Book of Abstracts Aquaculture America 2010. p.621. Interpretive Summary:
Technical Abstract: The objective of this study was to determine the potential for using APVM in practical diets of channel catfish to sustain or improve general performance while increasing the n-3 fatty acid concentration of fillets. Replacement of marine products such as menhaden fish meal and oil in diets of cultured fish is a global priority due to dwindling supplies and escalating costs of menhaden and other whole-fish meals and oils. However, products such as menhaden fish meal and oil are the “gold standards” in terms of protein and lipid quality, palatability and digestibility. Although marine products are less critical for performance of omnivorous fishes such as channel catfish (Ictalurus punctatus), eliminating these products from the diets has resulted in fillets with negligible concentrations of n-3 fatty acids, which have well-established benefits for human health. As human consumers become increasingly aware of the n-3 fatty acid content of various foods, fish rich in n-3 HUFA are likely to have a competitive edge in marketing to health-conscious consumers. Underutilized marine by-products such as Alaskan Pollock visceral meal (APVM) that have similar nutritional properties to traditional fish meals and oils may have potential to replace traditional marine products in diets of cultured fish without sacrificing performance or product quality. APVM is a high-lipid product (- 70%) rich in n-3 fatty acids. The protein component will provide some amino acids, but APVM is not a complete protein source. A 14-week feeding trial was conducted with channel catfish fingerlings weighing 11.2 + or - 0.07 g initially. The basal diet was composed of typical ingredients (soybean meal, cottonseed meal, wheat, corn, fat, and vitamins and minerals). The experimental diet contained APVM at 5.5% of the diet in place of poultry fat and a small amount of soybean meal to obtain diets similar in total protein (32%) and energy. Twenty fish were stocked in each of four tanks supplied with flow-through reservoir water and fed once daily to satiation. Fish were weighed every two weeks to track growth. After final weights were obtained, fish remained on their experimental diets for two more weeks prior to taking tissue samples for health assays (alternative complement and lysozyme activity) and proximate and fatty acid analysis. One week later, a stressor (crowding) was imposed on the fish, and serum cortisol was measured to assess the stress response. There were no differences in weight gain or survival between diets, and additional results will be presented at the meeting.