Title: Effects of corn processing method and dietary inclusion of wet distillers grains with solubles on enteric methane emissions of finishing cattle. Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 2, 2013
Publication Date: April 1, 2013
Citation: Cole, N.A., Hales Paxton, K.E., Todd, R.W., Macdonald, J.C. 2013. Effects of corn processing method and dietary inclusion of wet distillers grains with solubles on enteric methane emissions of finishing cattle. 2013 Livestock and Poultry Environmental Learning Center Conference, Waste to Worth. 1:18. Technical Abstract: The use of wet distiller’s grains with solubles (WDGS) in feedlot diets has increased because of the growing U.S. ethanol industry. However, few studies have evaluated the use of WDGS in finishing diets based on steam-flaked corn (SFC), the processing method used extensively in the Southern Great Plains. The effects of corn processing method and WDGS on enteric methane (CH4), and carbon dioxide (CO2) production and energy metabolism were evaluated in two respiration calorimetry studies. In Exp. 1, the effects of corn processing method (SFC or dry rolled corn – DRC) and WDGS inclusion (0 or 30% of diet dry matter- DM) were studied using a 2 x 2 factorial arrangement of treatments and four Jersey steers in a 4 x 4 Latin square design. In Exp. 2, the effects of WDGS inclusion rate (0, 15, 30, or 45% of diet DM) on CH4 and CO2 production were measured in a 4 x 4 Latin square design. In both experiments, steers were fed at 2 times their maintenance energy requirement. All diets, except the 30% and 45% WDGS diets in Exp. 2, were balanced for ruminally degradable protein (RDP) and fat content. Each period of the Latin squares consisted of a 16-d diet adaptation and 5-d of total fecal, urine, and gas (oxygen consumption, and CO2 and CH4 production) collections. In Exp. 1, steers consuming SFC-based diets produced less (P< 0.05) enteric CH4 (11.6 vs. 14.1 L/kg of DMI and 2.47 vs. 3.04 % of gross energy intake (GEI)) and tended (P < 0.17 ) to produce less CO2 (2,513 vs. 2,645 L/d) than steers consuming DRC-based diets. Inclusion of WDGS did not affect (P > 0.52) CH4 or CO2 production. Nitrogen excretion was not affected by grain processing but calves fed diets containing 30% WDGS had greater (P < 0.01) N intake (114 vs. 140 g/d) and urinary N excretion (40 vs. 54 g/d) than steers fed diets containing 0% WDGS. In Exp. 2, enteric CH4 production was similar for the 0 and 15% WDGS diets (10.9 vs. 11.2 L/kg DM intake: 2.44 vs. 2.46% of GEI) but increased (P < 0.05) in the 30% (13.2 L/kg DMI: 2.85% of GEI) and 45% (17.9 L/kg DMI: 3.73% of GEI) WDGS diets. Carbon dioxide production was not affected by WDGS content of the diets (mean 2,846 L/d) but the CO2:CH4 production ratio decreased linearly (P < 0.01) from 42.6 to 27.0 in 0% and 45% WDGS diets, respectively. Because of greater N intake, total and urinary N excretion increased linearly (P < 0.01) with increasing WDGS inclusion in the diet. Results indicate that cattle consuming SFC-based diets produce less enteric CH4 and retain more energy than cattle fed DRC-based diets. When dietary fat levels were held constant, dietary inclusion of WDGS at 15% of diet DM did not affect enteric CH4 production, WDGS inclusion at 45% of diet DM significantly increased enteric CH4 production and WDGS inclusion at 30% of diet DM had variable effects on enteric CH4 production.