Saturday, March 30, 2024

New red clover a value pasture option

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Often relegated to an annual or short-term sward due to its inability to persist among pastures, red clover may be about to enjoy a resurgence, thanks to a new variety’s ability to reduce greenhouse gas emissions – and possibly bring some human health benefits in years to come. Richard Rennie reports.
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FOR Germinal New Zealand plant breeders, the need to develop a new red clover had to extend further than simply providing another high-protein option for farmers to plant as a short-term feed option.

Germinal NZ general manager Sarah Gard says the onus is on the latest generation of plant breeders to also develop feeds that answer the climate change challenge. This can be to offer more efficient conversion of plant protein to animal protein per kilo of dry matter fed, and/or reducing greenhouse gas (GHG) emissions as a new feed crop alternative.

The researchers found a focus on red clovers’ superior conversion of plant nitrogen to animal protein is likely to make it a more viable pasture option in coming years.

Gard says white clover, while perennially more persistent than red, is lower in polyphenol oxidase (PPO), a compound shown to slow the breakdown of plant nitrogen in the rumen.

Red clovers’ higher PPO levels mean animals fed it have more time to capture the plant nitrogen in their rumen and convert it to animal protein, emitting less nitrogen as GHG  in the process.

The difference in red’s ability to have more of its protein captured and converted to animal protein is also significant, with a minimum of 50% targeted by Germinal’s plant breeders, compared to only 25% captured from existing conventional pasture varieties.

“But the challenge was also how we could take what is effectively a more efficient variety, and make it more ‘farm-friendly’, in the sense that it will be more persistent. If you don’t, you only end up producing an option that may well be more efficient, but only to a point – it will have to be replaced sooner, which in itself will incur more carbon emissions,” Gard said.

Germinal’s plant breeding takes place at the Institute of Biological, Environmental and Rural Sciences (IBERS) at Aberystwyth University in Wales.

Germinal’s researchers at IBERS are confident they have arrived with a “win-win” for farmers and the environment. They have developed a red clover with the growth habits and persistence of white clover, capable in trials of delivering yields similar to large-leaved white clover, with tolerance to hard grazing also akin to white clover.

“And they retain those high levels of PPO, ticking all the boxes we required of them,” she said.

The key to the variety’s persistence lies in the plant having a root system very similar to that of a white clover, more capable of withstanding the bashing the plant can get in conventional grazing systems and bouncing back from it.

Gard emphasises the variety has been achieved without sourcing genetics either through gene editing or from outside the red clover genome.

“It has been very much bred through conventional techniques, meaning there are no obstacles about moving the variety here to New Zealand from the UK to trial this year,” she said.

“There is nothing from our UK trials to suggest it should not adapt well to grazing and growing here in NZ, (with) possibly just some minor tweaks to its seasonal growth pattern, but we hope to see it become commercial here in about five years.”

She says varieties developed in the UK tend to grow well in Southland’s colder climate in particular.

“But essentially NZ has three to four different growing climates and we know it is important for us to ensure our varieties are capable of being grown throughout those zones,” she said.

Gard says it is increasingly being acknowledged by the plant breeding industry that the ability of ryegrass to remain the “go-to” pasture plant in parts of the North Island is being challenged by climate change.

Indications from dry spells recently suffered in the UK are that the new red clover variety has held up well.

In casting around for ways to improve red clover, the researchers also thought to look at its potential in other areas as a protein source.

“Much of the human protein supplements you buy will be based around soy and pea protein and both bring their own environmental challenges, usually requiring high-quality land and a level of fungicide/herbicide inputs,” she said.

Those supplement sources also share a poorer amino acid profile compared to red clover.

“So work is under way to look at how we could extend red clover protein for human consumption. It is quite possible it could be cropped for this, with protein that could be extracted possibly through biorefining on the farm,” she said.

Taking the health benefits a step further, red clover is high in compounds, including formononetin and biochanin A, with potential as cancer treatments.

“We are beginning the development of novel red clover varieties where the protein can be easily extracted by optimising biorefining techniques,” she said.

“We can see the day when red clover plays three roles on the farm, as part of the pasture, as a protein ingredient source and as a medicinal crop.”

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