Challenges and Opportunities in Finfish Nutrition

Much of the criticism leveled at aquaculture (e.g., dependency on animal-derived feedstuffs, nutrient-laden effluent discharges, and increased organic contamination in edible products) can be traced to the feeds in use. Accordingly, finfish nutritionists are being challenged to formulate feeds that not only meet the nutritional requirements of livestock but also minimize production costs, limit environmental impacts, and enhance product quality. These challenges not only add considerable complexity to finfish nutrition but also afford opportunities to avoid some of the mistakes made by other industries in the past. From a review of the current status of finfish nutrition with respect to major nutrient classes, we comment on future opportunities and promising avenues of research. Alternative protein sources, specifically those derived from marine bycatch, plants, and microbes, are discussed, as well as methods to facilitate their implementation in finfish feeds. Dietary lipid, its role in fish bioenergetics and physiology, and quality of aquaculture products is reviewed with special emphasis on alternative lipid sources and finishing diets. Carbohydrates and fiber are discussed in terms of nutrient-sparing, least-cost diet formulation and digestive physiology. Micronutrients are reviewed in terms of current knowledge of requirements and, along with other dietary immunostimulants, are given further consideration in a review of nutriceuticals and application in finfish feeds. The status of nutritional research in new aquaculture species is also outlined. By integrating classical approaches with emerging technologies, dietary formulations, and species, finfish nutritionists may identify means to increase production efficiency and sustainability and provide for the continued success of aquaculture

Multiplicity-free theorems of the restrictions of unitary highest weight modules with respect to reductive symmetric pairs

The complex analytic methods have found a wide range of applications in the study of multiplicity-free representations. This article discusses, in particular, its applications to the question of restricting highest weight modules with respect to reductive symmetric pairs. We present a number of multiplicity-free branching theorems that include the multiplicity-free property of some of known results such as the Clebsh--Gordan--Pieri formula for tensor products, the Plancherel theorem for Hermitian symmetric spaces (also for line bundle cases), the Hua--Kostant--Schmid $K$-type formula, and the canonical representations in the sense of Vershik--Gelfand--Graev. Our method works in a uniform manner for both finite and infinite dimensional cases, for both discrete and continuous spectra, and for both classical and exceptional cases

Utilization of soybean meal as an alternative protein source in the Mediterranean yellowtail, Seriola dumerili.

The availability of defatted soybean meal as a substitute for fish meal was evaluated in juvenile (450 g on average) yellowtail fed diets containing several levels of soybean meal (from 20 to 50%). After 153 days, liveweight averages were 980, 925, 795 and 670 g for fish fed diets in which fish meal was partially substituted with 20, 30, 40 and 50% soybean meal, and feed conversion ratios were 2.79, 3.09, 4.57 and 6.52, respectively. Regression analysis showed a negative effect of inclusion of soybean, although fish fed diets containing 20% and 30% of soybean did not present statistical differences and grew significantly more, and had a better feed conversion ratio, than fish fed 40 or 50% diets. Likewise, muscle protein level was lower and lipid content was higher in fish fed 20 or 30% soybean. No differences were obtained for protein digestibility coefficients of experimental diets.Versión de editor