Energy determination of corn co-products in finishing pigs and the use of an in vitro organic matter digestibility assay to predict in vivo energy

Abstract

Twenty corn co-products from various wetand dry-grind ethanol plants were fed to finishing pigs to determine DE and ME and to generate equations to predict energy based upon each ingredient’s chemical analysis. Co-products included: DDGS (7), HP-DDG (3), bran (2), germ (2), gluten meal and feed, dehulled, degermed corn, dried solubles, starch, and corn oil. The control diet was based on corn (97.1%), limestone, dicalcium phosphate, salt, vitamins, and trace minerals. All but two test diets were formulated by mixing the control diet with 30% of a co-product. Dried solubles and oil were included at 20% and 10%, respectively. Eight groups of 24 finishing gilts (n=192, 112.7 final BW ± 7.9 kg) were randomly assigned to a test diet and each diet was fed to a total of 8 pigs. Gilts were placed in metabolism crates and fed an amount equivalent to 3% BW daily for 9 d followed by separately collecting feces and urine for 4 d. Ingredients were analyzed for moisture, GE, CP, crude fat (EE), crude fiber, NDF, ADF, total dietary fiber (TDF), and ash. Gross energy was determined on the feed, feces, and urine to calculate DE and ME for each ingredient. 1 Supported in part by grants from the National Pork Board (No. 08-107). The authors acknowledge Howard Tyler and Leo Timms, Associate Professors in the Department of Animal Science, Iowa State University, Ames 50011. We are also thankful for help from Tom Webber, Cheri Ziemer, Jennifer Cook, Erin Conrad, Kristin Hard, Tricia Wolfswinkle, Tonya Huenink, Chris Olsen, Joel Johnson, Brandy Jacobs, Alisha Hoffman and staff at the Iowa State University Swine Nutrition and Research Farm. 2 These authors contributed equally to the work. 3 Corresponding author: brian.kerr@ars.usda.gov