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These sheep look like any others, but some burp a bit less methane

On a farm near Rotorua, breeding rams are having their methane-laced burps measured - so the next generation of lambs can be bred from climate-friendlier fathers. 

On a farm not far from Rotorua, a flock of sheep have started a journey to burping less climate-heating methane.

Like Harry Potter’s sorting hat, a methane-measuring machine has been sorting a selection of stud Romneys, not into magical houses such as Slytherin and Gryffindor, but according to how much methane they produce.

In future, a ram’s potential may be gauged not only by traditional measures such as fertility, but by his climate impact.

Within a matter of months, the results will be incorporated into the next breeding cycle, meaning lambs born in spring of 2020 on the Pāmu-owned farm in the Bay of Plenty will have the potential to be a little climate-friendlier than last year’s newborns.

While the improvement in each generation is small – potentially 1 or 2 percent less methane than the previous generation – the gains are cumulative and could be significant if they are spread around the country’s sheep farms.

It’s the first time commercial New Zealand farms have tried this kind of methane-sorting exercise in a bid to lessen the methane burping.

Sheep and cows together account for almost half of New Zealand’s greenhouse gas emissions, mostly because of methane from digestion in their rumens. Scientists all over the world have been trying different ways to reduce livestock’s impact.

Research by AgResearch on test-flocks at Woodlands near Invercargill has found that some sheep naturally make less methane than others. After a few generations of selective breeding, low emitting sheep can produce 10 percent less methane than their high-emitting counterparts. The climate gains can be achieved with seemingly no negative effects on the sheep’s ability to breed and make plentiful wool and meat.

Now, Government-owned farming company Pāmu is taking this research and piloting it on a commercial stud farm, before it goes live to the rest of the industry.

This month, 250 of the company’s best breeding rams at Goudies farm in Reporoa were placed, 12 at a time, in portable full-body respiration chambers, which captured and measured their exhalations for 50 minutes each.

A ram exiting the chamber trailer after methane measurements. The trailer has 12 measuring chambers. Photo: Supplied/Pamu

Two weeks later, the same rams were put in the chambers again, and their methane output recorded for a second time. Each ram has his methane production levels added to his personal file of genetic and other information, which farmers use to determine an animal’s breeding value. While a ram’s value as a potential father to lambs won’t be judged solely on his methane production, methane will now be part of the mix, with traditional factors such as fertility and weight gain.

While it’s not feasible to test every Romney in the breeding flock, Jim Inglis, Pamu’s senior business manager for its genetics programmes, says researchers will test a selection of rams from each of the company’s main breeding lines.

Inglis believes farmers can use this information to select lower-methane rams to breed from, without harming other valuable traits in the lambs – such as survival rates and growth rates. “It looks like we can make good gains in methane without compromising our existing breeding programme,” says Inglis.

The methane-shrinking effort involves several large players in New Zealand agriculture. The methane-breeding research was done by Agresearch using funding from farming organisations and the government. The farmer-supported Pastoral Greenhouse Gas Research Centre funded the bulk of the project and the taxpayer-funded NZ Agricultural Greenhouse Gas Research Centre also continues to fund the work. The genetic results are analysed using Beef & Lamb NZ’s genetics system, B&L Genetics nProve, which supplies breeding data to farmers.

To incorporate methane into their breeding decisions, the companies have had to make a few guesstimates about where carbon prices are heading.

Farmers make breeding decisions based on breeding values – financial quantifications of various inherited physical traits, for example fertility and weight gain. The future price of methane emissions isn’t clear in New Zealand yet. “To create an economic weighting for methane we have to have a guess at the value of carbon and how much of that we will be liable for in a farming system,” says Inglis.

Yet Inglis doesn’t see any financial risk from adding methane to the mix.

While he doesn’t want to share the exact cost of the methane-testing process, it is low enough to make the methane-sorting move a safe bet, economically, he says. “We know this is the right thing to do, and it’s cheap enough that we know that, no matter what is executed in law or what the price of carbon comes to, it’s going to be worth our while,” says Inglis.

There may be scientific gains from the process, too. Pāmu hopes the results will help AgResearch with its ongoing efforts to work out which genes, microbes and other attributes of sheep might explain why some produce more methane than others. Pāmu already holds the genomes of its breeding rams. It plans to make these available to AgResearch, alongside the rams’ methane readings, to help scientists pin-point which sheep have the less-gassy genomes. The rams also had fluid from their rumens – their grass-digesting stomachs – sampled before they went into the measuring chambers, enabling scientists to study whether their gut microbiomes are linked to lower methane levels.

Globally, scientists are trialling feeding cows and sheep different foods, seaweed extracts, medicines, and powdered feed additives to try to shrink their methane outputs. In Palmerston North, AgResearch scientists are pursuing a methane-lowering vaccine and feed methane inhibitor.

One day there may be potential for a similar methane-sorting process for cows.

Cows account for a bigger share of methane in New Zealand, on account of their bigger bodies, combined with a steep rise in cow numbers during recent decades, when sheep farms were converted to dairying.

However sheep are also an important part of the climate solution, and a potential precursor to shrinking cows’ belches. Not only do sheep contribute their own share of methane, they can serve as cheaper models for trying out gas-cutting methods that can later be translated to dairy cows. Since both animals are grass-eating ruminants, useful discoveries in sheep can often be transferred successfully to cattle.

If the methane-breeding plan goes well, Pāmu will roll it out across its other breeds around New Zealand, which Inglis says could make using lower-methane rams just a normal part of farming.

This is the fourth of five articles looking at innovations and new ways of farming being introduced by publicly owned farmer Pāmu, as part of a content partnership with Newsroom. The first, by Bernard Hickey, is here. The second, on producing milk from deer, is here . The third, on organic farming is here.

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