by Simon Edwards
New Zealand’s current regulations on genetically modified organisms are denying farmers another potential game-changer for reducing methane belched from our livestock.
For more than 70 years, plant breeders using conventional breeding techniques have aspired – without success – to develop white clover that has good amounts of condensed tannins (CTs) in its leaves, and not just its flowers.
But as described in the just-published paper ‘The hunt for the ‘holy grail’: condensed tannins in the perennial forage legume white clover’, by scientists and researchers with Grasslanz Technology, AgResearch, PGG Wrightson Seeds and AgroParis Tech, molecular biology has provided a pathway. A transcription factor or “master switch” has been identified that can ‘turn on’ the CT pathway present in clover and allow “biologically significant levels” of it to be present in leaf tissue.
The potential is for reduced methane production in livestock animals fed on this clover of the order of 15 percent.
Forage legumes such as white and red clover improve the nutritional value of grazed pasture but can cause bloat. Their rapid fermentation in the rumen also contributes to methane emissions and urinary nitrogen losses. Condensed tannins reduce both of these environmental downsides, as well as reducing internal parasites and improving productivity.
In glasshouse containment (in vitro) trials at AgResearch in Palmerston North, and field tests in the USA, it has been “demonstrated that the condensed tannins produced in white clover leaves can bind protein at a pH 6.5, as found in the rumen, and then release them at pH 2.5, the pH in the abomasum, before entering the small intestine for amino acid absorption,” the paper says.
“Additional in vitro tests have demonstrated that these condensed tannins can reduce methane production by up to 15.7% in the first 6 hours of incubation.”
Animal feeding experiments will be needed to confirm the benefits indicated in the glasshouse and field trials. Other studies have concluded that CT levels in feed need to be between 2 and 4 percent of dry matter to be of benefit to ruminant nutrition, higher than 0.5 percent dry matter to prevent bloat and between 3 and 8 percent of dry matter for a 30-70 percent reduction in rumen ammonia.
But “a potentially intractable challenge” in delivering this new molecular technology will be gaining regulatory approval for its release from containment for general use in grazed pastures, the researchers say.
AgResearch also felt forced to conduct field trials of another high-potential methane emissions solution – its high metabolisable energy ryegrass – in the USA because of the difficulty getting an application through the Environmental Protection Authority here.
While it has been argued that genetically modified plants are no less safe than those bred traditionally and are delivering increased efficiencies and benefits, there is still a reluctance to accept these modern breeding techniques as legitimate and of value (see our story on the recently released research paper on genetically modified crops and forages by Grasslanz Technology CEO John Caradus).
“Regulatory systems are outdated, technocratic and expensive, and rather than regulating the process the focus should be on regulating the benefit – risk issues associated with the end-product of genetic modification,” those behind the condensed tannin break-through say.