November 24, 2006
Fatty acids for aquatic and human nutrition
An eFeedLink Exclusive
The intensification of aquatic production is a palpable trend worldwide. Growing at a compounded rate of 8 percent per annum, aquaculture accounts for almost half of all fish eaten today. By 2030, it is forecast that most of the fish consumed would come from aquaculture rather than captured fishery resources.
Concern over the availability of fast-dwindling fishmeal and fish oil sources for aquatic feed has risen along with the expansion of the industry. The implications this is already beginning to have on aquatic nutrition is unparalleled, and will affect how species can be farmed commercially in an efficient, sustainable and cost-effective way.
Core at the heart of fish nutrition has been the composition of fatty acids, or more specifically, the presence of long-chain omega-3 polyunsaturated fatty acids or PUFA in the fish, which forms the main part of its nutritional value. As fatty acid composition depends very much on the dietary lipid intake of fish species, aquaculturists today need to broaden their understanding of these building blocks of plasma and investigate its alternative sources.
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David Smith, principal research scientist at CSIRO |
Sharing their views on this topic was a gathering of aquaculture experts at the 12th DSM Aquaculture Conference in the Asia-Pacific. The one-day meeting, held in Bangkok on Nov 23, reflects perhaps the disproportionate importance of the Asia-Pacific in world aquaculture production, at over 90 percent of all farmed species.
In formulating lipid nutrition, it is essential to first and foremost consider the group or class of compounds in the context of other lipids, nutrients and energy sources, says David Smith of Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO). Among aquatic species, there are differences in the ability to synthesize omerga-3 or omega-6 series PUFA from unsaturated or monosaturated fatty acids. Optimal total lipid and phospholid content also differs, for instance, among different shrimp species, although the importance of a balanced dietary fatty acid profile is common to all.
Although fishmeal is a good source of lipids containing both EPA and DHA, otherwise known as omega-3 fatty acids, selective use of palm oil, groundnut oil and coconut oil, widely available in tropical regions, may be considered where omega-3 requirements are low, says Smith.
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The use of antioxidants to preserve fishmeal and fish oil from deterioration through oxidation was shared by Tom Verleyen, staff scientist at Kemin Europe. The effects of two categories of antioxidants were discussed, namely metal chelators and chain-breaking antioxidants, including ethoxyquin and gallic acid.
Oxidation reduces the nutritional value of fishmeal and feed intake through the reduction of metabolisable energy. The amino acid profile of the fish is also affected through oxidation. Care should be taken during the drying and cooling stages of fishmeal processing, as oxidative reactions can occur easily then, says Verleyen.
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Essential long-chain PUFA are particularly indispensable for larval nutrition, a topic presented by Marisol Izquierdo of the Grupo de Investigacion en Acuicultura in Spain. Good nutrition for shrimp and feed larvae are crucial at this early stage development, where larvae survival depends significantly on exogenous feed. These essential nutrients include long-chain PUFA, phospholipids, amino acids for gut function and development, and fat-soluble vitamins and pigments, which can keep deformity and poor pigmentation problems at bay.
Touching at the heart of a consumer issue was Alice Thienprasert, who spoke on the health benefits of seafood consumption, a topic which has garnered much interest among the general public in recent years. Citing studies that have linked cardiovascular health, levels of inflammation, depression and post-partum depression among populations, with the level of seafood consumption, Thienprasert presents research that reinforces the health properties of consuming omega-three fatty acids and a balanced proportion of both omega-3 and omega-6 fatty acids. |
DSM Aquaculture Asia-Pacific's Jacques Gabaudan |
Japan, a country boasting the world's highest seafood consumption, was recorded to have the lowest rates of cardiovascular disease, inflammatory and diet-linked depressions. The country was also the focal point of a consumer survey on shrimp purchasing behaviour, conducted by Jacques Gabaudan of DSM Aquaculture Products Asia-Pacific, and Taro Saitoh of DSM Nutrition in Japan. Gabaudan shares what are the most popular species of shrimp among consumers there, the processing formats and the perceptions governing the purchase of fresh and boiled shrimp.
