NUTRITION, IMMUNE SYSTEM ENHANCEMENT, AND PHYSIOLOGY OF AQUATIC ANIMALS
Location: Aquatic Animal Health Research
Title: Lipid and Fatty Acid Requirements of Tilapia
Submitted to: Annual Meeting World Aquaculture Society
Publication Type: Abstract Only
Publication Acceptance Date: January 13, 2009
Publication Date: February 15, 2009
Citation: Lim, C.E., Aksoy, M. 2009. Lipid and Fatty Acid Requirements of Tilapia. In: Aquaculture America 2009, February 15-18, 2009, Seattle, Washington. p. 194.
Dietary lipids are an important source of highly digestible energy and are the only source of essential fatty acids required for normal growth and development. They are also carriers and assist in the absorption of fat-soluble nutrients, such as sterols and fat-soluble vitamins, serve as a source of phospholipids and participate in the synthesis of hormones, prostaglandins and other metabolically active compounds. Tilapia have been reported to have a dietary requirement for linoleic (n-6) series of fatty acids. The optimum dietary levels of n-6 (18:2 n-6 or 20: 4 n-6) have been estimated to be 0.5 and 1% for redbelly tilapia (Tilapia zillii) and Nile tilapia (Oreochromis niloticus), respectively. This information for other species has not been determined, but it has been suggested that blue tilapia (O. aureus) have a relatively high requirement for n-6 fatty acid. Tilapia may also have a requirement for linolenic (n-3) series of fatty acids. However, the optimum dietary requirement level for n-3 has not been determined. The presence of high levels of either n-6 or n-3 may spare the requirement of the other, although n-6 appears to have better growth promoting effect than n-3. Tilapia appear to possess the ability to desaturate and chain elongate 18:2 n-6 to 20:4 n-6 and 18:3 n-3 to 20:5 n-3 and 22:6 n-3.
Research evaluating various sources of dietary lipids showed that plant oils rich in n-6 and/or n-3 series of fatty acids, such as soybean oil, corn oil, sunflower oil, palm oil products and linseed oil are good lipid sources for tilapia. Beef tallow is a poorly utilized by tilapia when used as the sole lipid source. However, it can be used in combination with other lipid sources providing that their essential fatty acid requirements are met. Information on the nutritional value of fish oil for tilapia is inconsistent. Some studies have shown that the nutritional value of fish oil is similar to that of plant oils, while others reported poor performance of fish oil-containing diets. Fish oil provided good spawning performance for tilapia broodstock reared in saline water, while in freshwater, good reproductive performance was obtained with plant oil (soybean oil). The sparing effect of dietary lipids on protein utilization has also been demonstrated. However, tilapia do not tolerate as high a dietary lipid level as do salmonids. A dietary lipid level of 5 to 12% has been suggested to be optimum for tilapia.
The discrepancy between the results of various studies could be due to various factors such as species, fish sex and size, previous dietary history, source and levels of dietary lipid, composition and nutrient content of experimental diets, feeding duration and practices, and environmental conditions (salinity, temperature, etc.).