Methane Research Programme

The NZAGRC methane programme is jointly planned and funded in partnership with the PGgRc and aligns with existing MPI programmes funded through SLMACC and New Zealand funding in support of the Global Research Alliance on agricultural greenhouse gases. It aims to reduce emissions by directly targeting the methane producing methanogens through the discovery of small molecule inhibitors and vaccines and indirectly through feeding and changes in animal phenotype. 

 

  • Breeding: Research to understand the genetics of host control of ruminant methane emissions, which aims to develop genetic and genomic selection technologies to reduce methane yield and intensity in sheep. The current stage of the programme involves the development and dissemination of practical tools for selection for lowered emissions. A major part of maximising impact and uptake is to explore relative economic value from increased production and potential increased feed utilisation associated with lowered methane
  • Vaccine (jointly supported by PGgRc): A prototype vaccine (which after further development is aimed at producing a vaccine targeted at reducing methane emissions in cattle and sheep by 20%) is being formulated with the help of a commercial partner
  • Inhibitors (previously jointly funded but now fully funded by PGgRc): Research to develop cost-effective inhibitors that reduce methane emissions by at least 20% in sheep and cattle—without reducing productivity—is now being developed, with a view to bring the technology to market
  • Modelling: A tool to help scientists in the NZAGRC/PGgRc programme to develop hypotheses and predict responses in methane formation is in its final stages
Current progress and research stories

The current objectives within the NZAGRC methane programme have made significant progress this year, with the sheep breeding programme getting closer to delivering breeding values to the national flock.

The effects of fresh forages and feed intake level on digesta kinetics and enteric methane emissions from sheep

K.J. Hammond, D. Pacheco, J.L. Burke, J.P. Koolaard, S. Muetzel, G.C. Waghorn, The effects of fresh forages and feed intake level on digesta kinetics and enteric methane emissions from sheep, Animal Feed Science and Technology, Volume 193, 2014, Pages 32-43, ISSN 0377-8401, http://dx.doi.org/10.1016/j.anifeedsci.2014.04.005.

Abstract

Published data have shown that in ruminants, methane (CH4) yields (g/kg dry matter [DM] intake) decline as feed intakes increase and, although the reduction has been attributed to a shorter digesta mean retention time (MRT), there are few supporting data. This study was undertaken to determine the association between digesta kinetics and CH4 emissions measured from sheep in respiration chambers fed either fresh white clover (Trifolium repens; WC) or fresh perennial ryegrass (Lolium perenne; RG) (Experiment 1), or RG at several feed intakes (Experiment 2). Measurements included CH4, whole tract apparent DM digestibility (DDM), total tract and rumen MRT (TMRT and RMRT, respectively) of solid and liquid fractions, as well as passage rates. In Experiment 1, eight sheep each with a rumen fistula were fed hourly either WC or RG forages, repeated over two periods (four sheep/diet/period) at about 1.6 times maintenance requirements for metabolisable energy (MEm; 1.12kg DM/d). Diet did not affect apparent DDM (726g/kg), CH4 yield (22.3g/kg DM intake), or TMRT of solid fractions (29.4h). However, TMRT for the liquid fraction was shorter (P=0.037) for sheep fed RG (17.4h) compared with WC (23.0h), and rumen digesta analyses suggested a larger rumen liquid pool size when RG was fed (6.05L) compared with WC (3.96L) (P=0.041). Experiment 2 involved 30 sheep offered fresh RG twice daily at about 0.8, 1.2, 1.6, 2.0 and 2.5×MEm. The DDM did not differ greatly across RG intakes (625–648g/kg) but, as RG intake increased (0.49–1.34kg DM/d), there were corresponding reductions (P<0.001) in CH4 yield (27.0–23.9g/kg DM intake), liquid TMRT (31.4–14.2h), solid TMRT (46.4–24.8h), liquid RMRT (18.4–7.5h), and solid RMRT (28.4–15.8h). When CH4 yield was plotted against rumen liquid and solid passage rates, the extent of the relationship was best explained (R2) when RG was fed at different intakes in Experiment 2 (0.71 and 0.66 for liquid and solids, respectively). The 2.7-fold increase in feed intake halved RMRT, but intakes affected passage of the rumen liquid fraction to a greater extent than solids. It can be concluded that reductions in CH4 yield from fresh forages fed to sheep are associated with shorter TMRT and RMRT. Understanding the effects of diet, digestion, feed intake, and feeding frequency on methanogenesis requires more knowledge about rumen digesta kinetics, especially relationships between outflow rates of solid and liquid fractions.

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