The objective of this research was to test the hypothesis that oil in distillers dried grains with solubles (DDGS) and other co-products from the ethanol industry such as high protein distillers dried grains (HP DDG) and corn germ have different nutritional properties in swine diets than liquid extracted corn oil and intact oil in corn. We, therefore, hypothesized that it is not possible to predict the effects of the oil in distillers co-products on carcass quality of pigs simply by measuring the concentration of oil in the co-products, but if the digestibility of oil in the feed ingredients are measured, then diets may be formulated based on the concentration of digestible fat in the diets. The specific objective of the present experiment was, therefore to measure the true ileal digestibility and the true total tract digestibility of fat in extracted corn oil, intact corn oil from high oil corn, DDGS, HP DDG, and corn germ and to compare these values to the digestibility of fat in soybean oil.
The experiment was conducted using 19 barrows with an initial BW of 52.2 kg. All pigs were surgically prepared with a T-cannula in the distal ileum. Diets based on extracted corn oil, high oil corn, DDGS, corn germ, HP DDG, and full fat soybeans were formulated and fed to the pigs for 7 days. Fecal samples were collected from the pigs on d 5 of each feeding period and ileal samples were collected on d 6 and 7 of each period. A total of 11 samples were obtained for each diet. All diets and all ileal and fecal samples were analyzed for fat and the digestibility of fat in each ingredient were calculated.
Results showed that the digestibility of fat was greater in extracted corn oil and full fat soybeans than in the other ingredients. However, HP DDG and DDGS had greater digestibility of fat than high oil corn and corn germ, which indicates that the fermentation process in the ethanol plants increases fat digestibility. It is concluded that the digestibility of fat varies greatly among feed ingredients. As a result, it is not possible to predict the impact of a specific feed ingredient on quality of pork fat just by measuring the concentration of fat in that ingredient. Instead, it is necessary to formulate diets based on the digestible concentration of fat in the diets. The present research provides for the first time, digestibility values for fat in distillers co-products and other feed ingredients. Using these data, it is now possible to formulate diets fed to growing and finishing pigs based on concentrations of digestible fat, which in turn allows producers to predict the effects of a specific diet on the quality of the fat in pigs fed that diet.
