<p>&nbsp;</p>
<p class="h5">What research has been done so far?</p>
<p>Since 2003, scientists researching low&nbsp;greenhouse gas forages have received<br />funding from the Pastoral Greenhouse Gas Research Consortium (PGgRc), the<br />New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) and<br />the Ministry for Primary Industries&rsquo; (MPI) Sustainable Land Management<br />and Climate Change (SLMACC) fund. The aim is to establish whether dietary<br />manipulation can provide a practical and cost effective route for reducing<br />emissions of methane and nitrous oxide.</p>
<p>Pasture is the dominant feed for New Zealand&nbsp;ruminants and hence the largest focus in New Zealand has been on measuring emissions&nbsp;from pasture-fed animals. The primary focus of this work has been to establish baseline emissions from pasture-fed animals and to test whether manipulating quality (e.g. digestibility,&nbsp;fibre) can reduce emissions. An element of the work has been to examine the influence of<br />specific chemical constituents (e.g. elevated sugar content) on methane and nitrous oxide emissions.</p>
<p>Work has also been undertaken to examine alternative forages and non-pasture feed options and test whether their incorporation into pasture diets results in a reduction in&nbsp;emissions below those of pasture-only diets.</p>
<p>The majority of work has been carried out using sheep &ndash; a consequence of cost, practicality and&nbsp;availability of equipment &ndash; although some work with cattle has been undertaken. Prior to 2009, methane emissions were mostly&nbsp;measured using the sulphur hexafluoride (SF6) tracer technique. This technique measures emissions from free-ranging animals by sampling exhaled breath in containers placed&nbsp;around the neck of the animal. Since 2009,&nbsp;emissions have been measured almost<br />exclusively in respiration chambers. In these&nbsp;chambers animals are enclosed for 48 hours and exhausted air enriched with methane&nbsp;from exhaled breath is sampled and compared with non-methane enriched ambient air to determine the quantity of methane produced. This is considered to be the standard method for estimating methane emissions from animals as&nbsp;the environment can be controlled, feed intake<br />monitored accurately and measurements made in a stable and reliable manner.</p>
<p>To read more on the substantial work undertaken in this area, download the&nbsp;<strong>NZAGRC-PGgRc Low Greenhouse Gas emitting feeds factsheet</strong> or review the journal articles and science reports below.</p>
<h3>What have we found?</h3>
<h5>Broad conclusions</h5>
<p>There are a number of broad conclusions that can be drawn&nbsp;from the work already completed in addition to specific&nbsp;conclusions from research streams:</p>
<p>1. Enteric methane emissions are generally stable when expressed&nbsp;on a unit of intake basis.</p>
<p>2. It takes large changes in diet to bring about changes in enteric methane&nbsp; emissions.</p>
<p>3. Predicting emissions based on chemical analysis is highly problematic.&nbsp;For example, chicory and forage rape are similar in quality but chicory appears to have no influence on methane emissions while forage rape does.</p>
<p>4. Even where emissions are shown to be reduced (e.g. forage rape),&nbsp;the overall impact at the national scale will be small because the&nbsp;alternative feed makes up a minor component of the overall diet.&nbsp;</p>
<p>5. Although there is no direct link between feed quality and lower&nbsp;emissions at a plant level, continuing to use high quality feed can lower a farm systems&rsquo; emissions intensity (emissions per unit of product).&nbsp;</p>
<p>To read more on specific research findings, download a copy of the<strong> NZAGRC-PGgRc Low Greenhouse Gas emitting feeds factsheet</strong></p>
<h3>What next?</h3>
<h5>Current and future research</h5>
<p>Many different crops have been analysed and, while showing&nbsp;promise in some areas, there are no definitive, easy or dramatic ways to reduce emissions of pasture based<br />livestock by diet alone.&nbsp;</p>
<p>More work is needed to assess the overall emissions impact of feed&nbsp;options. Individual gases can not be considered in isolation.</p>
<p>While reducing nitrogen losses is an immediate priority for many farmers,&nbsp;lower nitrogen intake may in turn lead to higher methane emissions. For example, maize silage has lower nitrogen content but can be of lower&nbsp;quality than other feed options so an animal needs to eat more to achieve&nbsp;optimal performance. Thus, reductions in nitrous oxide are likely to be&nbsp;partially offset by increases in methane emissions.</p>
<p>Current research priorities include undertaking a comprehensive&nbsp;evaluation of the nitrous oxide emissions associated with grazing forage&nbsp;rape and other work to fill in knowledge gaps, and undertaking thorough&nbsp;assessments of promising options such as plantain. Work with plantain&nbsp;is being extended to comprehensively study its impacts on nitrogen&nbsp;partitioning, methane and nitrous oxide emissions, and soil carbon stocks.</p>
<h3>&nbsp;Science articles and reports</h3>