259 Evaluation of Methane and Carbon Dioxide Production from Cattle on Different Diet Adaptation Strategies

Abstract

Abstract An experiment was conducted to evaluate impacts of RAMP (Cargill Corn Milling, Blair, NE) on methane (CH4) and carbon dioxide (CO2) emissions, performance, and carcass characteristics of beef cattle during the grain adaptation phase and finishing phase. Crossbred steers [n = 64; initial body weight (BW) = 347 ±7 kg] were utilized in two treatments; RAMP, fed 100% RAMP during step one and then stepped up to a common finisher diet consisting of 65.5% steam-flaked corn (SFC), 22.5% Sweet Bran (SB), 8% wheat straw, and 4% supplement. The second treatment was control (CON) fed 30.5% SFC, 22.5% SB, 8% wheat straw 35% alfalfa hay, and 4% supplement during step one and then stepped up to the common finisher diet. There were 8 steers per pen and 4 paired replications. Replications were stepped up together and rotated through a two-chamber emissions barn in 5-day cycles to measure CH4 and CO2 emissions at three time points: step one of step-up phase, early feeding phase (one week after starting the finishing diet), and later finishing phase (13 weeks after starting the finishing diet). Performance data were analyzed using the MIXED procedure of SAS with treatment and BW block as fixed effects and emissions data analyzed with BW block and treatment as fixed effects and barn chamber as a covariate. Feeding RAMP during step one of the step-up phase led to a decrease in CH4, as g/d (P = 0.03) and a decrease in the CH4:CO2 ratio (P = 0.02). However, CH4 as g/kg of dry matter intake (DMI) was not affected by treatment (P = 0.25). Control steers had a decrease in CO2 as g/day (P = 0.03), but not as CO2 g/kg of DMI (P = 0.31). There were no differences in DMI (P = 1.00) during the step-up phase, averaging 10.3 kg/d for both treatments. For measures taken while all cattle were on the common finishing diet, RAMP did not reduce CH4, as g/d or g/kg DMI (P ≥ 0.27), CO2 as g/d or g/kg DMI (P ≥ 0.37), or CH4:CO2 (P = 0.12). There were no significant differences in DMI (P = 0.49) whole cattle were in the emissions barn during the feeding phase. There were no significant differences for interim (d 66) cattle performance including BW (mean 504 kg; P = 0.84), DMI (mean 9.7 kg; P = 0.27), ADG (mean 2.33 kg/d; P = 0.88), or G: F (mean 0.246; P = 0.30). Feeding RAMP to cattle during the grain adaptation phase resulted in a 12% decrease in methane emissions on a g per day basis without affecting cattle performance. This reduction in emissions didn’t carry over into the finishing phase when a common diet was fed.