Alternative approaches to predicting methane emissions from dairy cows1

Abstract

Previous attempts to apply statistical models, which correlate nutrient intake with methane production, have been of limited value where predictions are obtained for nutrient intakes and diet types outside those used in model construction. Dynamic mechanistic models have proved more suitable for extrapolation, but they remain computationally expensive and are not applied easily in practical situations. The first objective of this research focused on employing conventional techniques to generate statistical models of methane production appropriate to United Kingdom dairy systems. The second objective was to evaluate these models and a model published previously using both United Kingdom and North American data sets. Thirdly, nonlinear models were considered as alternatives to the conventional linear regressions. The United Kingdom calorimetry data used to construct the linear models also were used to develop the three nonlinear alternatives that were all of modified Mitscherlich (monomolecular) form. Of the linear models tested, an equation from the literature proved most reliable across the full range of evaluation data (root mean square prediction error = 21.3%). However, the Mitscherlich models demonstrated the greatest degree of adaptability across diet types and intake level. The most successful model for simulating the independent data was a modified Mitscherlich equation with the steepness parameter set to represent dietary starch-to-ADF ratio (root mean square prediction error = 20.6%). However, when such data were unavailable, simpler Mitscherlich forms relating dry matter or metabolizable energy intake to methane production remained better alternatives relative to their linear counterparts.

Estimation of the maintenance energy requirements, methane emissions and nitrogen utilization efficiency of two suckler cow genotypes

“…The CH 4 -E : GE intake ratio values obtained in the present study (0.066 to 0.067) fall within the mid-range of each of the two previously quoted studies while the mean value from the current study (0.066) is greater than that of 0.056 (0.038 to 0.074) reported by Kebreab et al (2008) for dairy cows but similar to that of 0.065 ± 0.01 reported by the Intergovernmental Panel on Climate Change (IPCC, 2006) for use in cattle. The mean methane emission per kilogram DM intake in the present study was 22.3 g/kg, which is similar to those (20.4-22.9 g/kg) calculated from the average data of methane emission and feed intake reported for lactating dairy cows (Moe and Tyrrell, 1979;Mills et al, 2003;Ellis et al, 2007).…”

“…However, this industry, like all other livestock production systems, currently is under increasing pressure to reduce manure nitrogen (N) and methane emissions from the meat production. Dry matter intake and N intake have been demonstrated to be the major driver for enteric methane emission Mills et al, 2009) and manure N excretion (Kebreab et al, 2001;Yan et al, 2007) from cattle, respectively. Currently, feed intake for beef cattle across the world is calculated from total energy requirements for maintenance, production and pregnancy using energy feeding systems adopted locally, for example, systems of Agriculture and Food Research Council (AFRC, 1993) in United Kingdom, National Institute for Agricultural Research (INRA, 1989) in France, and National Research Council (NRC, 1996) in United States).…”

Milk production is unaffected by replacing barley or sodium hydroxide wheat with maize cob silage in rations for dairy cows

“…Overall, there was no difference in methane emission between treatments, which is in agreement with Moe et al (1973) and Klevenhusen et al (2011) who compared maize v. oats and maize v. barley, respectively. The DMI has been shown to explain a significant amount of the variation in the methane emission (Mills et al, 2003), and therefore it was expected that MCS would have had the lowest total methane emission in l/day of the three treatments. However, MCS total methane emissions were not different from SHW and barley.…”

Is there a relationship between genetic merit and enteric methane emission rate of lactating Holstein-Friesian dairy cows?

“…Consequently, there is increasing pressure to develop effective mitigation strategies to reduce CH 4 emissions from the livestock sector, especially enteric CH 4 emissions from ruminant livestock. During the last two decades, calorimeter data from research institutes has been used to develop a range of prediction models to facilitate an improved understanding of the effects of diet and animal factors on enteric CH 4 emissions (Mills et al, 2003;Yan et al, 2010;Ellis et al, 2012). In addition, many nutritional strategies designed to reduce CH 4 emissions at an individual animal basis have been evaluated, including the use of dietary manipulation (e.g., improving forage quality, inclusion of concentrates, feed processing) and dietary additives (e.g., inhibitors, electron receptors, ionophores, plant bioactive compounds) (Hulshof et al, 2012;Hristov et al, 2013;Ramin and Huhtanen, 2013).…”