Evaluation of the Effect of Corn Oil on Methane Production in Finishing Cattle

Crossbred yearling steers (n=80; initial BW = 369 kg; SD = 25) were used to evaluate the effects of corn oil on methane (CH₄) and carbon dioxide (CO₂) production in finishing diets. Two treatments with four pens per treatment (10 steers/pen) were used in a RCBD-design experiment with four BW blocks. The treatments consisted of a control diet (CON) containing 33 % dry-rolled corn, 33% high moisture corn, 15% wet distillers grains plus solubles, 15% corn silage, and 4% supplement. The corn oil treatment (OIL) displaced corn with 3% corn oil added to the diet. Steers were limit fed for 5 d at the beginning of the trial and weighed on d 0 and 1 to equalize gut fill and were implanted on d 1 with Synovex Choice (100 mg TBA, Zoetis). Steers were harvested on d 127 and carcass data were collected. Continuous measurement of methane and carbon dioxide emissions were collected in an enclosed methane barn over 5d periods, with 3 collection periods per pen. CH₄ and CO₂ were collected by rotating between pens every 6 minutes with an ambient sample taken in between pen measurements. Initial BW, final BW, ADG, HCW, REA, fat thickness, and marbling were not impacted by treatment (P > 0.14) while G:F (P =0.03) increased and DMI (P = 0.03) decreased by feeding OIL. There was a treatment by collection period interaction (P = 0.01) due to a differing magnitude of differences between OIL and CON across time. Feeding OIL decreased (P < 0.01) methane by 32, 9, and 16 g/steer daily during the three collection periods respectively. Methane production (g/steer daily) was lower (P < 0.01) for the OIL fed cattle compared to the CON fed cattle while CO₂ production was not different between treatments. CH₄ g/kg of DMI was decreased (P < 0.01) by 0.09 g for the OIL treatment versus the CON treatment and was lower (P < 0.01) by .07, .02, and .07g across collection periods. CO₂ g/kg of DMI was not different between treatments but was lower (P < 0.02) for cattle on OIL treatment across time. CH₄/ADG kg was decreased (P < 0.01) by 1.3g for the OIL treatment compared to the CON treatment while CO₂/ADG kg was not different between treatments. Feeding corn oil at 3% of diet DM reduced enteric methane production by 14.6% which was partially due to a 4.4% decrease in DMI.