158 Effect of Mootral™ and Forage Amount on Methane Emissions, Growth and Carcass Characteristics of Feedlot Steers

Abstract

Abstract One hundred and forty-four Angus x Simmental steers were allotted by body weight (BW; 363 kg, breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different diets (forage content of 15, 41.5, or 68% corn silage). From day 85 to slaughter, corn silage was included at only 15% of the diet DM. Data were analyzed using the MIXED procedure of SAS. There was an interaction (P = 0.03) between forage content and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage, but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (P ≥ 0.22) of forage content or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. Gain-feed ratio from d 0 to 84 and overall was greater (P = 0.04) for steers fed 68% compared to 15 or 41.5% corn silage. On d 41, steers fed 41.5 and 68% corn silage had increased (P ≤ 0.02) methane emissions compared to steers fed 15% corn silage. There tended to be an interaction (P ≤ 0.09) between forage content and Mootral for methane emissions (g/d) on d 41 and 203, where steers fed Mootral showed lesser methane emissions with 15% corn silage, but not with the 41.5 and 68% corn silage diets. Steers fed Mootral showed lesser (P ≤ 0.03) methane emissions on d 203. Mootral tended to decrease (P < 0.10) fat thickness and yield grade. In conclusion, Mootral decreased methane production in 15% corn silage diets and improved carcass leanness.