Individual variation and intraclass correlation in arachidonic acid and eicosapentaenoic acid in chicken muscle

The focus on meat with a composition adjusted to optimize human health and life expectancy, initiates awareness of meat fatty acid composition. Fatty acid analyses are expensive and the number of samples available may sometimes be limited. It is therefore important to know the number of samples and animals needed for planning an experiment with sufficient power to reveal relevant effects of interest. It can be assumed that there will be enhanced focus on the variation in fatty acid composition between individual animals in a standardized environment, and on the potential to breed for a more favourable fatty acid composition.Chicken meat is commonly regarded as a healthy type of meat; it is popular, and hence the consumption has increased [1]. Chicken meat is lean, protein-rich and rich also in other important nutrients. However, the fatty acid composition is strongly dependent on the diet fed to the birds. A typical modern poultry diet is rich in cereals having a high ratio between omega-6 and omega-3 fatty acids. This diet is very different from the natural diet for the same species containing more green leaves that are rich in the omega-3 fatty acid alpha-linolenic acid (ALA). It has been shown that a diet rich in ALA gives increased concentrations of ALA, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) in broiler muscle and improved, i.e. reduced ratio between total omega-6 and total omega-3 fatty acids [2,3]. The utilisation of ALA and linoleic acid (LA) for synthesizing EPA and arachidonic acid (AA) depends on feed concentrations of ALA and LA as well as on other factors. Much AA in the diet may contribute to prostaglandin overproduction in disease situations in humans, but some AA is necessary for virtually every body function. Dietary sources of AA are especially meat, eggs and offal, with smaller amounts coming from milk and fish.Omega-6 and omega-3 fatty acids compete with each other for incorporation into membrane li