Proxies to adjust methane production rate of beef cattle when the quantity of feed consumed is unknown

Abstract

The aim of the present experiment was to evaluate the utility of carbon dioxide production rate (CPR; g CO2/day) and animal weight (WT) data as proxies for feed intake to adjust methane production rate (MPR; g CH4/day) in situations where dry-matter intake (DMI) is not known. This experiment measured individual-animal DMI, MPR and CPR in the feedlot, and then again on restricted quantities of grain and roughage diets in open-circuit respiration chambers. Of the 59 cattle tested in the feedlot, 41 had MPR and CPR recorded, and 59 and 57 had test results on the restricted grain and roughage rations. Methane production relative to DMI by individual animals was calculated as CH4 yield (MY; MPR/DMI) and as residual CH4 production (RMPDMI; calculated as MPR less predicted MPR based on DMI). A second form of RMP: RMPCO2, was calculated by regressing MPR against CPR to determine whether animals were producing more or less CH4 than predicted for their CPR. Carbon dioxide production rate was positively associated with DMI in all three test phases (R2 = 0.25, 0.45 and 0.47; all P < 0.001). The associations for MY with MPR : CPR were moderate and positive, as follows: R2 = 0.49 in the feedlot test; R2 = 0.37 in the restricted-grain test; and R2 = 0.59 in the restricted-roughage test, and with RMPCO2, values of R2 were 0.57, 0.34 and 0.59 in the three test phases (all P < 0.001). The R2 for RMPDMI with MPR : CPR in all three tests were 0.50, 0.79 and 0.69, and with RMPCO2, values of R2 were 0.68, 0.79 and 0.68 (all P < 0.001). The high R2 for MY with MPR : CPR and RMPCO2 and even higher R2 for RMPDMI with MPR : CPR and RMPCO2 in all three test phases showed that CPR can be used to adjust MPR data for DMI when DMI is not recorded. In the feedlot test, where animal WT data were recorded over 70 days, MPR adjusted for WT and WT gain had R2 with MY and RMPDMI of 0.60 and 0.83, respectively (P < 0.001), offering the possibility that animal WT data determined over an extended time period could also be used as a proxy for DMI in adjustment of MPR.

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency

“…The correlation was noticeably high between CH 4 and CO 2 (R p = 0.83 and 0.86). Similar high relationships, R p = 0.78 on average (R p = 0.57 to 0.91), were estimated with yearling beef cattle [16,18,26], dairy cows [28] or with lambs [29], measured either in respiratory chambers or with GreenFeed systems. The two emission rates were also highly correlated with the heifer body weight, slightly more for CO 2 (R p = 0.77 and 0.85) than for CH 4 (R p = 0.68 and 0.70).…”

“…Methane yield (CH 4 /DMI) and the residual methane emission (r wi CH 4 ) were moderately correlated (R p = 0.44 and 0.54). Herd et al [18] found a closer relationship (R p = 0.89) between CH 4 /DMI and r i CH 4 with a limited number of animals.…”

“…According to Herd et al [18], who suggested that CO 2 could be used as a proxy for feed intake for growing beef cattle fed ad libitum, five new feed and methane efficiency traits were calculated, with DMI replaced by CO 2 . The ratio of ADG to CO 2 (ADG/CO 2 ) was first calculated.…”

“…It is possible with the GreenFeed system. To date, there has been a limited number of experiments with growing cattle simultaneously recorded for feed intake and gas emission using GreenFeed systems [14,16,18,26,31,32] with estimated correlation coefficients of R p = 0.58 on average (R p = 0.28 to 0.85) between CH 4 and DMI and R p = 0.65 on average (R p = 0.40 to 0.89) between CO 2 and DMI. The correlations of the current study were in the lower range of these published results.…”

“…The first objective of the present study was to precisely estimate the phenotypic correlation between different feed efficiency criteria and methane production measures of beef heifers fed ad libitum on roughage-based diets. The second objective was to verify if the measure of carbon dioxide could be used as a proxy of feed intake, as suggested by Herd et al [18], for ranking growing cattle on feed efficiency and methane yield.…”