Dietary manipulation of oil production in commercial emu
The aim of this research was to optimize emu oil production by manipulation of the dietary protein and energy ratios for greater fat accretion. The research was done at African Emu Ranch in Muldersdrift, Gauteng. Twenty-four, four to five months old emu birds were randomly allocated to three dietary protein treatments, namely a standard control diet containing 170 g crude protein (CP) or a 140 and 200 CP/kg diet, all with similar metabolizable energy content. Proximate analyses were done on representative samples of the diets to confirm the nutrient composition based on AOAC techniques. Water and feed were given ad libitum. The feeding trial spanned eight weeks. The birds were slaughtered and fat yield, anatomical and histological parameters, volatile fatty acid production and carcass weights were recorded. The fat was analyzed for lipid content and composition by means of gas chromatography. Growth rates and average weight gains of the birds in different treatments did not differ. The average dressed out carcass weights for 140, 170 and 200 g CP/kg groups were 16.75, 18.65 and 19.11 kg respectively and differed between treatments. The 200 g CP diet yielded the heaviest carcasses and highest dressing percentage. Volatile fatty acid (VFA) concentrations did not differ between dietary treatments. Acetic acid was the most abundant volatile fatty acid in the distal and proximal intestines. The highest concentration of acetic acid was found in the distal ileum. A small volume of iso-butyric acid was detected in the distal ileum. Total average fat yields for the 140, 170 and 200 g CP groups were 4.1, 4.2 and 4.4 kg respectively, but fat yields did not differ between treatments. The long-chain fatty acid composition of the fat did not differ between treatment groups and consisted of saturated fatty acids (27.74%), monounsaturated fatty acids (51.80%), and polyunsaturated fatty acids (20.45%). Fatty acid composition did not differ between different anatomical fat depots in the carcass. The total mean of lipid produced in the omental and subcutaneous locations were 82% and 92.5% respectively. The results suggest that optimum emu oil production can be achieved by feeding diets with a low protein (optimum level of 140 g) to energy ratio.
Keywords: Emu, nutrition, growth, protein, energy, fat yield