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

Gilles Renand,Aurélie Vinet,Virginie Decruyenaere,Dominique Dozias,David Maupetit

doi:10.3390/ani9121136

Abstract

Simple SummaryFor sustainable meat production, beef farmers must make the best use of grass and roughage while limiting the carbon footprint of their herds. The genetic improvement in feed efficiency and enteric methane production of replacement heifers is possible if the recorded phenotypes are available. Intuitively, the relationship between the two traits should be negative, i.e., favorable, since the energy lost with the methane is not available for heifer metabolism. The measurement of feed efficiency requires several weeks of feed intake recording. The enteric methane emission rate can also be recorded over several weeks. The two traits of 326 beef heifers from two experimental farms were measured simultaneously for 8 to 12 weeks. The correlations between roughage intake, daily gain, and methane were all positive. The enteric methane emission rate was positively related to body weight, daily gain, and dry matter intake. The relationship with feed efficiency was slightly positive, i.e., unfavorable. Therefore, the two traits should be recorded simultaneously to evidence low-emitting and efficient heifers. This study also showed that replacing the feed intake recording with the carbon dioxide emission rate appeared potentially beneficial for selecting these low-emitting and efficient heifers.Reducing enteric methane production and improving the feed efficiency of heifers on roughage diets are important selection objectives for sustainable beef production. The objective of the current study was to assess the relationship between different methane production and feed efficiency criteria of beef heifers fed ad libitum roughage diets. A total of 326 Charolais heifers aged 22 months were controlled in two farms and fed either a grass silage (n = 252) or a natural meadow hay (n = 74) diet. Methane (CH4) and carbon dioxide (CO2) emission rates (g/day) were measured with GreenFeed systems. The dry matter intake (DMI), average daily gain (ADG), CH4 and CO2 were measured over 8 to 12 weeks. Positive correlations were observed among body weight, DMI, ADG, CH4 and CO2. The residual feed intake (rwgDMI) was not related to CH4 or residual methane (rwiCH4). It was negatively correlated with methane yield (CH4/DMI): Rp = −0.87 and −0.83. Residual gain (rwiADG) and ADG/DMI were weakly and positively related to residual methane (rwiCH4): Rp = 0.21 on average. The ratio ADG/CO2 appeared to be a useful proxy of ADG/DMI (Rp = 0.64 and 0.97) and CH4/CO2 a proxy of methane yield (Rp = 0.24 and 0.33) for selecting low-emitting and efficient heifers.

Highlights

Beef producers face serious challenges in ensuring sustainable beef production
Among the strategies to improve the utilization of forage resources and to reduce enteric methane production, the genetic selection of efficient and low-emitting animals is a promising option, since it allows for permanent and cumulative effects, as long as these traits are heritable
The phenotypic correlations estimated in these five experimental populations, in addition to the current results, have shown that the relationship between feed efficiency and methane production traits are tenuous and may depend on the population and diet. These results show that in growing cattle fed ad libitum, (i) CH4 is undoubtedly, but moderately, associated with intake; (ii) CH4 is predominantly independent of residual feed intake and feed conversion; (iii) there is a slight tendency for the methane yield to be negatively correlated with residual feed intake and feed conversion

Summary

Introduction

Beef producers face serious challenges in ensuring sustainable beef production. First, in many beef production systems, a large proportion of the feed is used by the cow breeding herd and forage feed self-sufficiency is a critical issue, especially with the added pressure from rising prices on cereal crops [1]. Among the strategies to improve the utilization of forage resources and to reduce enteric methane production, the genetic selection of efficient and low-emitting animals is a promising option, since it allows for permanent and cumulative effects, as long as these traits are heritable. In two studies with young cattle or lambs measured in respiratory chambers, the estimated heritability coefficients of methane emission rate and yield were slightly lower: h2 = 0.13 to h2 = 0.29 [5,6]. While breeding programs to improve the feed efficiency of growing cattle have been in use in several beef breeds, there is still no breeding program for selecting low-emitting cattle

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