Claims by GE Free NZ that AgResearch’s genetically modified ryegrass is underperforming in trials and is tainting milk are rejected by the science organisation.
AgResearch science team leader Richard Scott said High Metabolisable Energy (HME) ryegrass “looks highly promising” compared to other forages.
“We’re excited about the potential of the HME ryegrass for not only increased animal nutrition and methane reduction but also potential reductions of nitrous oxide emissions.”
The possible reduction in nitrous oxide stems from the plant improving animal nutrition, which reduces urine nitrogen excretion and results in lower nitrate leaching and reduced emissions.
A further aspect being examined is the potential for HME plants to influence the composition of the soil microbes, which could benefit the nitrogen cycle.
“As with methane, we will know more about the scale of potential nitrous oxide reductions when we do animal feeding trials.”
GE Free NZ claims HME is changing the composition of milk, which was also rejected.
Scott said the milk composition of grazing lactating cows can be influenced by changes in forage composition during seasons and by the use of different supplemental feeds.
HME ryegrass increases plant fat levels mainly in the form of oleic and linoleic acids, which are already present in ryegrass.
The HME technology leads to the accumulation of these natural fatty acids.
“Therefore, it is likely HME ryegrass will have an influence on the fat composition of milk of cows grazing HME ryegrass.”
The extent of any change to milk composition can only be assessed by animal nutrition trials on lactating cows, which will be assessed in animal feed trials.
A further claim that United States field trials produced insufficient dry matter yields to conduct the trial, were similarly rejected.
Scott said the five years of trials were intended to assess the shift of traits from containment to field conditions of plant lipid content and gross energy.
A published paper on the transition showed no significant yield penalty for these traits.
HME ryegrass did struggle in extreme hot, dry summer conditions but Scott this occurred in an environment more harsh than the temperate regions where ryegrass is traditionally grown.
Scott said that GE Free NZ claims that HME ryegrass has genes from sesame seed and nasturtium containing para influenza and E coli vectors, are dated.
Scientific methods used to develop earlier versions of HME used proteins and bacterial vector in the preparation and assembly of the genes, but these are not present in the version being trialled.
“The HME ryegrass now in development does not contain this bacterial vector DNA mentioned above, as demonstrated by whole genome sequence analysis of the plant.”
Scott said the potentially significant benefits from improved animal nutrition and environmental gains, outweigh any risks to farming systems.
