Methane (CH4) loss from finishing cattle is important as it represents an energy loss that could be used for maintenance and growth, and CH4 is a greenhouse gas with a global warming potential 21 to 25 times that of CO2. Our objectives were to determine hourly CH4 production from growing cattle fed diets differing in corn processing method (dry rolling or steam flaking) and wet distillers grains with solubles (WDGS) inclusion rate. Eight steers (195 kg ± 2.3 in Exp. 1 and 322 kg ± 3.7 in Exp. 2) were fed the following diets: 1) steam-flaked corn (SFC)-based diet with 0% WDGS (SFC-0); 2) SFC-based diet with 15% WDGS (SFC-15); 3) SFC-based diet with 30% WDGS (SFC-30); 4) SFC-based diet with 45% WDGS (SFC-45); 5) Dry-rolled corn (DRC)-based diet with 0% WDGS (DRC-0); and 6) DRC-based diet with 30% WDGS (DRC-30). All hourly CH4 data were analyzed using the MIXED procedure of SAS. Individual animal was the experimental unit. The model included the fixed effect of h, diet, and the h × diet interaction. Hourly differences in CH4 were analyzed using repeated measures. There were numerous h × diet interactions and thus simple-effect means are presented. In steers fed DRC-0 or DRC-30 at 2-times maintenance, the greatest hourly CH4 emissions occur 6 h after feeding (P < 0.01) with a secondary peak between 10 and 11 h after feeding (P < 0.01). For cattle fed SFC-0, SFC-15, SFC-30, and SFC-45 at 2-times maintenance, all diets had peak CH4 emissions 5 and 6 h after feeding (P < 0.01), with a secondary CH4 peak for SFC-45 nine to 11 h after feeding (P < 0.01). Cattle fed all diets at a maintenance level of intake exhibited 1 peak in hourly CH4 production between 3 and 6 h after feeding (P < 0.01). All steers fed SFC-30 and SFC-45 had sustained CH4 production over several hours, irrespective of intake level. Steers fed SFC-45 produced more CH4 beginning 4 h after feeding (P < 0.01) and produced a greater amount of CH4 than any other treatment (P < 0.01). Methane production generally peaked 6 h after feeding irrespective of intake level or diet type. Additionally, when fed above a maintenance level of intake, a secondary peak in CH4 production was observed 9 to 11 h after feeding, and steers fed at a maintenance level of intake had only 1 peak in CH4 production in a 23-h period.
- Finishing diets