Genetics powers sustainability solutions

Agriculture Victoria research director of genomics and cellular sciences Professor Jennie Pryce introduced the research at the Genetics Australia 2024 Today, Tomorrow and Beyond conference at Geelong, Vic, on March 18.

She said Dr Rob Banks, from the University of New England, described genetic selection as a really cost-effective solution to almost any issue in the plant or animal breeding industries.

"This really sums up to me the power of genetics," Professor Pryce said.

The dairy industry had used genetics to really great effect for more than half a century.

Genetics had improved production efficiency and animal welfare and reduced the industry's environmental footprint.

But the big driver for genetic change had been a technology commercially introduced in 2008 - genomics, Professor Pryce said.

"Now it is literally worth billions of dollars through plant and animal breeding globally," she said.

Genomics had doubled the rate of genetic gain in dairy sires and had helped turnaround declining cow fertility.

Ginfo, a large-scale genotyping project using a reference population of more than 150 commercial dairy herds with excellent records, had boosted the development of genomics in Australia.

Professor Pryce said genomics had underpinned many of the new breeding values, such as heat tolerance, health traits, gestational length and, most recently, the sustainability index.

"Our calculations are the sustainability index will reduce (methane emissions) intensity by about 5-10 per cent," she said.

But genomics could do even more to reduce methane emissions, without taking too much away from cow profitability.

"Which is a really crucial point - so the trade-off is actually very small," Professor Pryce said.

'Green cow' project

Agriculture Victoria senior research scientist Dr Christy Vander Jagt said a new Victorian project, informally called the 'green cow' project, was aiming to identify low methane-producing cows at scale on commercial dairy farms.

This would allow the development of a methane Australian Breeding Value - which would then allow farmers to breed cows for lower methane production.

Methane packed a big punch as a greenhouse gas, Dr Vander Jagt said.

Although it was short-lived compared with carbon dioxide, it was 82 times more potent in the first 20 years after release than carbon dioxide.

So reducing methane emissions was a faster way to address climate change in the short term, while other technologies to reduce carbon emissions in the longer term were being developed, Dr Vander Jagt said.

Dairy cow methane emissions accounted for about 1.7pc of Australia's total greenhouse gas emissions.

These could be reduced through improved management practices, including having more productive cows, breeding cows earlier, improving herd fertility and having healthier, longer lived cows.

Feed additives, such as Asparagopsis (red seaweed) extract, 3-NOP and essential oil mix Agolin, had been shown to reduce methane production and were being trialed at the Ellinbank Dairy Research Institute in Victoria.

Dr Vander Jagt said the 'green cow' project aimed to bring genomics as another solution.

This could cut methane emissions by 30pc by 2050.

Methane emissions in cows were both highly variable and inheritable.

Ellinbank research had revealed cows in the same stage of lactation fed the same diet had highly variable methane emissions ranging from 250 grams per day to 800 grams per day.

But the big challenge was producing a reliable breeding value - and that meant measuring methane outputs on a large number of cows, up to 15,000, and matching that to their genetics.

The 'green cow' project in its first year was aiming to find the most practical and efficient way to measure methane emissions on commercial farms.

It was then looking to recruit commercial farms to partner in the research.

How to measure methane on farm

Agriculture Victoria research scientist Fazel Almasi is researching the best way to measure cow methane emissions at large scale on farms.

The gold standard for methane measurement respiration chambers - essentially large stainless steel boxes on a concrete floor that animals were contained within, but these were expensive and ineffective at large scale.

Another was an apparatus fitted to the cow that released SF6 gas into the rumen and then collected and measured its release.

It had a high correlation with the results from the respiration chambers, but was expensive to run.

It had been used successfully to measure methane emissions from cows at Ellinbank.

The GreenFeed method used portable chambers that could be placed in paddocks to take spot samples of methane emissions from cows feeding from the chambers.

Each cow was identified by its RFID tag and data was collected across multiple visits.

But each unit could collect data from only about 15-20 cows and it had high running costs, Mr Almasi said.

Another method being assessed was the use of Sniffers - devices fitted in the dairy measuring the methane concentration in the air exhaled by each cow at each milking.

This method could be used with automatic dairies.

It had high correlation with the gold standard respiration chambers and was cheaper than other three methods.

Mr Almasi warned that Australia was falling behind other countries in testing different cows' methane emissions.

In 2022 Australia ranked third in the numbers of cows tested, behind Canada and Spain.

But since then the Netherlands had tested 7500 cows, Spain 6000 cows and Canada 3500 cows per year, while Australia had tested only 200.

Mr Almasi said these four methods were the only ways to directly measure methane but some indirect measurements that could also be used.

For example sensors measuring things such as rumination time could be used if a correlation between rumination time and methane emissions could be calculated.

Mid-infrared (MIR) and near-infrared (NIR) measurements of milk could also potentially be used to identify cows that were high or low methane emitters.

Reducing methane using rumen microbiome

Agriculture Victoria research scientist Boris Sepulveda is researching another indirect method.

He is analysing the DNA of ruminal microbiota from cows to identify low methane-emitting cows.

Methane was not produced by cows directly, but was produced by the microbiota in the cow's rumen, he said.

But these microbes were affected by the cow's genetics.

Different cows created different rumen environments that better suited different microbes.

"The genetics of the animals make it a more likely to be colonised by a given microorganism," Mr Sepulveda said.

His research has analysed methane emissions and rumen content of more than 800 cows in Australia and Spain.

It has analysed the DNA of both the cows and the microbes from their rumens.

This could allow high emitting animals to be identified simply by looking at their microbes.

It could also allow researchers to link lower-emitting cows genetically.

Mr Sepulveda said the 'green cow' project would put Australia in a strong position by identifying different ways to measure ethane emissions.

"Our goal is to find the best combination," he said.