New Zealand
April 18, 2011

The high sugar ryegrasses that reduced animal methane emissions in UK trials are the same varieties grown on New Zealand farms to boost animal productivity, says a seed company that has promoted high sugar grass for the past seven years.

High sugar grass seed wholesaler Germinal Seeds NZ Ltd says the AberHSG (high sugar grass) cultivars appeal to farmers because they boost animal productivity – typically by 1-to-1.5 litres of extra milk per cow per day and lambs gaining up to 412 grams a day of liveweight.

Ewes at Mount Linton Station in Southland graze AberMagic, a high sugar ryegrass that reduces methane gas emissions by 20 percent for each kilogram of weight gain.

“The latest UK results confirm their environmental value, which is a win-win for the farmer and easily achieveable in the course of normal pasture renewal,” said Mr Kerr.

Previous studies have proven that high sugar grass stimulates animal productivity, improves the efficiency of dietary nitrogen utilisation and reduces the excretion of nitrogen from animals.

Mr Kerr said he hopes similar research can be advanced in New Zealand on the effect of forage diets on greenhouse gas emissions from livestock.

The UK results call into question the claim that there are currently no proven, practical and cost-effective farm practices or technologies to reduce agricultural emissions, apart from de-stocking.

A key finding from trials run by Reading University and the Institute of Biological, Environmental and Rural Sciences is that high sugar ryegrass can reduce methane emissions from sheep by 20 percent for every kilogram of weight gain.

A report from the UK’s Department for Environment, Food and Rural Affairs (Defra) said the methane reductions “seem to result from a stimulation in the efficiency of microbial growth in the rumen, leading to an improved capture of N in microbial protein and diverting H away from methane production and into microbial cells”.

Maize silage, naked (hulless) oats and crushed rape seed also reduced the methane output of livestock but the advantage of high sugar grass is its net economic benefit for each tonne of carbon dioxide equivalents mitigated.

“There seems to be no reason why the use of high sugar grass should not be promoted for use in ruminant diets,” said the Defra report.

One of the UK studies was at Trawsgoed Research Farm in Wales where field plots of a control ryegrass and high sugar grasses such as AberMagic, distributed by Germinal Seeds, were fed with and without white clover to 30 lambs at an initial liveweight of 32 kg.

The zero-grazing (cut and carry) trial in mid-2008 found their methane production on high sugar grass was 25 percent less for each kilogram of liveweight gain.

Total bacterial numbers were higher in the rumen of the sheep receiving the high sugar grass, which indicated that their decreased methane emission might be due to the enhanced capture of metabolic hydrogen into microbial protein and thus diverting substrate from the methanogenic archaea.

In a related trial 25 Texel-mule cross lambs were continuously grazed on either normal ryegrass or high sugar grass from April to June 2009 and their methane and ammonia emissions periodically measured in mobile polytunnels placed over the grazed plots.

Methane emission rates were 20 percent lower for lambs grazing high sugar grass than for those grazing the control sward and lambs on HSG gained 40 percent more liveweight a day than lambs grazing normal ryegrass.

Defra said further measurement of emissions from grazing livestock is required to confirm the findings, to understand the mechanism for emission reduction and to assess impacts over a longer grazing season.

AberMagic had produced the greatest yield among the trial grasses and its sugar (water soluble carbohydrate) content was 12 percent higher than in normal ryegrass.

In New Zealand strong yields were also reported from two AgResearch trials with AberHSGs over six years (2000-2006) and the sugar content of AberAvon and AberMagic was 13 percent higher than in the standard ryegrasses Impact and Bronsyn grown in the Manawatu.

A further two-year AgResearch study comparing ryegrass sugar levels found 40 percent more sugar in AberMagic than in Impact in Manawatu plots and similarly a 12 percent sugar difference at Lincoln, according to results presented to the Australasian Plant Breeding Conference in 2009.

Website: http://www.germinalseeds.co.nz/

Published: April 18, 2011