Alternative Lipid Sources in Aquafeeds

The global aquaculture industry is one of the fastest growing food production sectors with farmed seafood currently accounting for about 50% of all fish consumed in the world. It is estimated that aquaculture produces about 65 million tonnes of seafood valued at more than US$78 billion annually. Aquaculture is anticipated to play an increasingly important role in meeting the seafood demand of a growing human population. The rapid increase in aquaculture production worldwide has been fueled by the use of industrially manufactured aquafeeds. Conventionally, marine fish meal and fish oil are used as the major feed ingredients in the formulation of commercial aquafeeds to supply dietary protein and lipid, respectively. It is estimated that aquafeeds currently consume about 90% of the global supply of fish oil and many have predicted that the demand for fish oil from the aquaculture industry will imminently out strip supply. Marine fish oil production has not increased beyond 1.5 million tonnes for the past quarter of a century and in order to further expand, the global aquaculture industry cannot continue to rely solely on this source of lipid. The high demand, impending short supply and often times high prices makes dietary fish oil a bottleneck in the farming of aquatic animals, and there is currently great urgency within the global aquafeed industry in finding suitable alternatives to replace marine fish oils. This article will give an overview of the various alternative lipid sources, grouped according to their main chemical characteristics. Their unique potential advantages and challenges for use in aquafeeds will be highlighted. The physiological effects of various lipid sources and their components on growth, lipid metabolism, health and post-harvest qualities of the farmed fish are briefly discussed. Figure 1. Stacks of imported fish oil in drums are a common sight at aquafeed mills in Asia. Figure 2. The annual world production (1995-2008) of the three major vegetables oils as compared to fish oil. Alternative Lipid Sources Oils and fats are characterized by their unique fatty acid composition. The major vegetable oils have one common characteristic; none contain n-3 long chain-polyunsaturated fatty acids (LC-PUFA). In contrast, marine fish oils have a high content of n-3 LC-PUFA. In consideration of the fact that the dietary fatty acid composition is mirrored in farmed fish fillet, the inclusion of alternative lipid sources in aquafeed can have significant impacts on the nutritional qualities of farmed seafood products. The n-3 …