Research at Stellenbosch University benefit whole poultry industry

The Department of Animal Sciences at the University of Stellenbosch is a strong knowledge partner to the poultry industry of Southern Africa. Research, which is of great value to both producers and consumers of poultry, is done on an on-going basis.

Recent research focussed on the supplementation of broiler diets with Canola oil and the way in which it can help prevent coronary heart disease in humans by reducing plasma lipids.

"Research on the effect of dietary vitamin E on the quality of broiler meat during refrigerated and frozen storage can save the retail industry millions of rands by prolonging the shelf life of chicken by even just one day," says Dr. Louw Hoffman who heads the university research team.

Canola oil in broiler diets reduce the possibility of coronary heart disease

One of the potentially most important sections of the branch of animal science dealing with animal nutrition is the study of the effect of diet on tissue fatty acid composition. This information is mainly of value because an imbalance in the human dietary intake of various types of fatty acids has become apparent. There is much interest in the relative merits of monounsaturated, Omega-6 polyunsaturated and Omega-3 polyunsaturated fatty acids in the human diet and the role they play in the lessening of cardiovascular related diseases. Several sources of information suggest that modern Western diets are deficient in Omega-3 fatty acids compared with the diet on which humans evolved and their genetic parameters were established. It is thus important for human health to increase the consumption of Omega-3 fatty acids.

An increase in the human dietary Omega-3/Omega-6 fatty acid ratio is essential in today's Western diet to help prevent coronary heart disease by reducing plasma lipids. Research by the University of Stellenbosch showed that supplementation of broiler diets with Canola oil can increase the ratio of Omega-6 to Omega-3 fatty acids in broiler carcasses and abdominal fat pads to 5:1, a ratio more suitable for human health.

Increasing the level of Omega-3 fatty acids in the diets was also effective in reducing the level of saturated fatty acids in the carcasses and abdominal fat pads of broiler chickens resulting in "healthier" chickens. Overall, in view of the prevalence of human coronary heart disease, consumption of Omega-3 polyunsaturated fatty acids enriched broilers could be considered as a useful complementary option for the amelioration of coronary vascular disease.

Dietary fatty acids are absorbed by monogastric animals and deposited in tissues without significant modification. There is therefore considerable potential for the manipulation of the fatty acid profiles of poultry tissue by dietary means so as to increase the supply of Omega-3 polyunsaturated fatty acids suitable for human consumption.

Effect of dietary vitamin E on the quality of broiler meat during refrigerated and frozen storage.

Research showed that vitamin E supplementation of broiler feed increases the oxidative stability of broiler carcasses under frozen and refrigerated storage. Carcasses of broilers from birds fed non-supplemented diets could only be refrigerated for three days and frozen for less than a month. Supplementation of as little as 20 mg vitamin E/kg feed doubled the frozen storage time, whereas supplementation of 40 mg vitamin E/kg feed extended storage time by one day in refrigerated broiler carcasses. If this concentration is increased to 160 mg vitamin E/kg feed, storage at 4 °C can be extended to eight days.

This may have important economic implications for the retail industry. This investigation further showed that vitamin E supplementation under these conditions had no significant effect on broiler performance, microbial spoilage, colour deterioration, fatty acid composition or post-mortem pH changes.

Lipid oxidation is a major cause of meat quality deterioration, as products of autoxidation of unsaturated fatty acids affect wholesomeness and nutritional value. Lipid oxidation is an important determinant of shelf life of meats and meat products. Post-slaughter biochemical changes involved in the conversion of muscle to meat are accompanied by a loss of cellular antioxidant defences and an increased propensity of meat lipids to undergo oxidation. This contributes to undesirable changes in a number of quality parameters, including loss of water-holding capacity, texture and flavour.

The lipids in poultry exhibit a higher degree of unsaturation than red meats due to a relatively high content of phospholipids. The degree of unsaturation of the phospholipids of the subcellular membrane is an important factor in determining the oxidative stability of meats, with the oxidative potential increasing as the degree of unsaturation of the lipids in the meat increases.

The production of meat, particularly chicken, with a more unsaturated profile has been the focus of some attention, as such meats are perceived as having a 'healthier' image. Accordingly, poultry meat and meat products are rather susceptible to oxidative deterioration, and oxidation often determines the shelf life of poultry meat products.

Feeding poultry a higher level of natural dietary antioxidants provides the poultry industry with a simple method for improving oxidative stability, sensory quality, shelf life, and acceptability of poultry meats. In addition to the stabilising effect on meat and meat products, a raised vitamin E level significantly enhances feed conversion efficiency, average weight, and net income per bird. by Karin Theron, University of Stellenbosch


April 2004