ABSTRACT
The n-6 polyunsaturated fatty acid (PUFA)-rich vegetable lipid sources considered in this chapter are soybean, corn, safflower, cottonseed, and sunflower oils. All contain high concentrations of 18:2n-6 and relatively low amounts of 18:3n-3. Contemporary lipid extraction from oilseeds and grains relies on organic solvents and removes about 95% of the lipid, and the subsequent distillation process yields a lipid source that is about 99% pure. The vegetable oils are liquid at room temperature and have iodine values above 100. Despite the apparent deficiency in n-3 fatty acids, the majority of formal studies with these lipid sources in aquafeeds failed to identify significant effects on weight gain of farmed aquatic animals. All published studies identified
Abstract .................................................................................................................. 133 5.1 Introduction .................................................................................................. 134 5.2 History .......................................................................................................... 134 5.3 Soybean Seed Processing ............................................................................. 134 5.4 Physical, Chemical, and Nutritional Characteristics .................................... 136 5.5 n-6 PUFA-Rich Oils in Aquaculture ............................................................ 137
5.5.1 Soybean Oil ...................................................................................... 137 5.5.2 Full-Fat Soybean Meals .................................................................... 142 5.5.3 Corn Oil ............................................................................................ 143 5.5.4 Safflower Oil ..................................................................................... 144 5.5.5 Cottonseed Oil .................................................................................. 144 5.5.6 Sunflower Oil .................................................................................... 144
5.6 Reproduction ................................................................................................. 147 5.7 Live Feed Enrichment .................................................................................. 147 5.8 Advantages and Disadvantages of n-6 PUFA-Rich Vegetable Oils ............. 150 References .............................................................................................................. 150
changes in tissue fatty acid concentrations. While there are a substantial number of formal evaluations with soybean and corn oils, there are relatively few with safflower, cottonseed, and sunflower oils. The few studies of n-6 PUFA-rich vegetable lipids on reproduction have documented significant effects of n-6 fatty acid sources on reproduction and to an even greater degree in larval feeding. The n-6 PUFA-rich vegetable oils appear to be high-quality sources of dietary energy and fatty acids during the grow-out cycle in most fish and invertebrates, but should be cautiously used in diets for some broodstock. These lipid sources have not been proven acceptable for the enrichment of live prey items for larval fish and crustaceans.
