|| Checking for direct PDF access through Ovid
Energy is an expensive component of poultry diets with lipids providing a concentrated energy source to meet these needs. Three separate experiments with broilers (15 d of age), turkeys (15 d of age) and laying hens (60 wk of age) were conducted to determine the AMEn content of 10 lipids with varying fatty acid and free fatty acid concentrations and to compare these values to predicted values based on previously published equations. A corn-soybean meal (broilers and turkeys) or corn-soybean meal-distillers dried grains with solubles (layers) control diet was formulated with test diets created by mixing the control diet with 0, 3, 6, or 9% (broilers and turkeys) or 0, 2, 4, and 6% (laying hens) lipid. Experimental diets were fed over a 5-d acclimation period followed by a 48 h total excretion collection period with AMEn of the diets calculated based upon the GE, nitrogen, and titanium dioxide in the feed and excreta samples. The pen-mean AMEn of each diet was regressed on percentage lipid inclusion level using linear regression with the slope of the line representing the AMEn of each lipid source. As expected, the AMEn values varied widely among lipid sources and species, with broilers having a greater AME compared to turkeys and layers. In general, saturated fatty acids (C14:0, C16:0, and C18:0) were negatively correlated to AMEn while unsaturated fatty acids (namely C18:2) were positively correlated to AMEn. Consequently, the unsaturated: saturated ratio, the polyunsaturated fatty acids: saturated and monounsaturated fatty acids ratio, and iodine value tended to be positively related to AMEn. Compared to broilers and turkeys that were able to efficiently utilize energy from corn oil (purified and crude DDGS corn oil) relative to soybean oil, laying hen AMEn values for corn oils were reduced in comparison to soybean oil. These data indicate that energy values of lipid differ widely due to source and appear to differ relative to a particular species.