The potential benefit of corn dried distillers' grain (co)products (DDG) in the mitigation of methane production in cattle: An in vitro analysis

Wednesday, July 23, 2014: 11:15 AM
2103B (Kansas City Convention Center)
Mozart A. Fonseca , Texas A&M University, College Station, TX
Dulciene Karla A Silva , Federal Rural University of Pernambuco, Garanhuns, Brazil
Harley D. Naumann , University of Missouri, Columbia, MO
Todd R. Callaway , USDA-ARS, College Station, TX
Luis O. Tedeschi , Texas A&M University, College Station, TX
Abstract Text: The objective of this work was to determine the impact of different levels of DDG on the digestibility of OM and the production of methane (CH4) using an in vitro technique. Nine diets were formulated with Bermuda grass hay, ground corn, and alfalfa hay mixed with DDG (0, 10, 20, 30, 40, 50, 60, 80, and 100% of diet DM). These nine diets and alfalfa hay alone (laboratory control) were ground (1 mm), and incubated with rumen fluid (from grazing cows) and media. Blanks (rumen fluid and media only) were used to adjust the CH4 production. Three replicates and 4 incubation times (3, 6, 24, and 48 h) were investigated in the bottle’s headspace using a syringe for collection. Because these diets had different amounts of potentially fermentable substrate, adjusted CH4 was computed as CH4 concentration divided by the amounts of NDF (CH4NDF, mM/g NDF), NFC (CH4NFC, mM/g NFC), fermentable carbohydrate (FCHO = CHOA + CHOB1 + CHOB2) (CH4FCHO, mM/g FCHO), OM (OM = 100 – Ash) (CH4OM, mM/g OM), and fermentable OM (FOM = OM – Ash – EE) (CH4FOM, mM/g FOM) in the diet sample. The PROC MIXED of SAS (SAS Inst., Cary, NC) was used to analyze the data assuming a repeated measure design. Diets and incubation times were assumed as fixed factors and replicate within diet as random factor. Except for CH4FCHO and CH4NFC, diet effect was significant (P<0.001) for all other adjusted CH4 concentrations, suggesting that FCHO and NFC may not explain differences in CH4 concentration. Regarding incubation time and its interaction with diet, all adjusted CH4 concentration were highly significant (P<0.001).There was a tendency to decrease CH4 concentration as the DDG level increased, but the level of DDG in the diet had to be greater than 50% to yield significant reduction in the adjusted CH4 concentration, CH4FOM and CH4OM (CH4 per unit of OM) when the fat content was greater than 7.39% DM. Significant linear regressions for adjusted CH4 concentration (CH4 = 14.5 − 0.667 × Fat; r2 = 0.64, RMSE = 1.48 mM, n = 46) and CH4FOM (CH4FOM = 83.8 − 3.35 × Fat; r2 = 0.53, RMSE = 9.30 mM/% FOM, n = 46) on fat content of the diets were observed. These in vitro results suggested that under normal ruminal fermentation CH4concentration will decrease as dietary fat increases if ruminal retention time is between 24 and 48 h.

Keywords: abatement, greenhouse gas, ruminant