Increasing awareness of the health benefits of n-3 fatty acids has led to studies related to the manipulation of the fatty acid composition of animal products. These fatty acids, especially eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3), are abundant in foods of marine origin. Fish consumption is, however, limited by seasonal availability, affordability and consumers' preference. Recent studies on the provision of n-3 fatty acid rich foods have therefore centred on the enrichment of products such as poultry meat through feeding fish oil diets. However, decreased quality (storage and flavour) has been associated with products from poultry fed such diets. Other dietary sources of n-3 fatty acids such as fish meal and plant seed oils result in minor improvement of the quality and low levels of EPA and DHA in the enriched product. Supplementation of high levels of vitamin E or other synthetic antibiotics in diets may increase oxidative stability and hence the storage quality of n-3 fatty acid enriched broiler meat. However, their reported influence on off-flavour is conflicting. Other methods of reducing off-flavour in enriched meat involving the use of processed n-3 PUFA sources although may reduce off-flavour, result in reduced deposition of EPA and DPA. Marine algae (MA) is an attractive source of n-3 fatty acids because it is a primary rich source of DHA and contains naturally occurring carotinoids, which are useful for their antioxidant activity. Investigations into the use of MA and identification of cheaper sources of n-3 PUFA for the enrichment of broiler chicken are needed. In addition, the search for viable methods of reducing off-flavour in n-3 enriched broiler meat should continue. The production of high quality and affordable broiler meat is essential for realising the full benefits associated with the consumption of n-3 fatty acid enriched products.
Authors:Tibor Gaál, L. Wágner, F. Husvéth, H. A. Manilla, P. Vajdovich, N. Balogh, I. Lóth and Katalin Németh S.
The influence of fish oil (highly unsaturated) and beef tallow (highly saturated) with vitamin E (100 IU/kg) supplementation on the antioxidant status of broiler chicken cockerels was investigated. Chicks were fed a control diet with no added fat, 40 g/kg each of fish oil and beef tallow diets, respectively, from 11 to 42 days of age. Tocopherol concentration and the rate of lipid peroxidation, thiobarbituric acid reactive substance (TBARS) in liver, fatty acid composition of the liver lipids, blood serum total antioxidant status (TAS), and reduced glutathione (GSH) content were determined. Vitamin E supplementation of the diet increased liver ?-tocopherol content in chicks regardless of the type of dietary fat. Fish oil diet resulted in higher liver TBARS value while beef tallow diet showed lower values compared to the control diet. Vitamin E supplementation reduced liver TBARS as well as serum GSH, and raised serum TAS for all diets. Serum GSH was the same for vitamin E supplemented diets regardless of the fat supplement. Fish oil diets resulted in a significant increase in hepatic lipid n-3 PUFA content. A significant positive correlation was found between liver TBARS and n-3 PUFA content. No relationships were established, however, between liver TBARS and n-6 PUFA or saturated fatty acids. The results suggest that feeding oils rich in n-3 PUFA increases tissue concentration of these fatty acids, consequently increasing tissue lipid peroxidation and reducing the antioxidative status of broiler chickens. Supplementing high levels of vitamin E with such oils may increase tissue oxidative stability. Serum TAS or GSH may be used as a measure of antioxidative status in chickens.