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
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