Moo! Will French cows burp less in the future to reduce methane emissions?

Cattle, the incorrigible ruminants of our countryside, have the fault of exhaling methane at length of burps, jaded by the boring spectacle of electrified railways. Each day, on average, a cow lets out between 400 and 500 g of this gas, which is starting to weigh heavily in the balance of global warming. Enteric methane emissions, as science coyly calls them, are responsible for 5% of greenhouse gas emissions in France. This is half of the total footprint of cattle farming, all factors combined.

Methane is a by-product of digestion, resulting from different fermentation processes in the rumen of these animals. All ruminants belch it. Much more than they fart, in fact, contrary to popular belief. But "some individuals emit a little less than their peers," explains Mickaël Brochard, an agronomist specializing in genetics. at the Livestock Institute. " It is both the result of their history – environment, health, consumption, etc. – but also of their own skills. This innate factor is the genetic factor." Breeders have been selecting the most productive and robust animals for decades, so why not also choose the least polluting ones?

This hypothesis has been driving research for several years. It is notably being explored as part of Methane 2030, a French project dedicated to the bovine sector. It is still necessary to be able to identify the animals that exhale the least methane. "There are different tools for measuring this gas, but they are adapted to cows in experimental farms, with breathing chambers or tracer gas," explains Solène Fresco, a doctoral student in genetics at the National Institute for Agricultural, Food and Environmental Research (INRAE) and the Eliance consultancy firm. These devices are precise, but they are also technical and expensive. And to "carry out genetic selection, you need a very large number of animals."

The researcher explored another avenue: she turned to data from milk quality controls. These are carried out throughout the year by specialized laboratories that "offer monitoring of the individual performance of each cow, depending on the subscription taken out by the farmer." These establishments publish mid-infrared spectra (MIR), which allow the molecules in milk to be visualized using wavelengths. These milk mirrors, which reflect a large amount of information and the physiological state of cows, are already used to predict their state of health. But a link with burping still remained to be found.

For two years, methane emissions from 240 cows of the Prim'Holstein, Montbéliarde and Abondance breeds were recorded using an automated system. In order to feed, the animals had to place their heads in a box. Sensors then recorded the exhaled gases and transmitted data in real time. Solène Fresco then compared this information with the MIR spectra of the milk of the animals concerned, in particular the concentration of fatty acids.

She developed a mathematical formula, published in the Journal of Dairy Science , that can predict theoretical methane emissions based on milk. It is then possible to assess the genetic potential of all cows associated with a MIR spectrum. The equation therefore opens up the field of possibilities, because millions of data are stored by laboratories that control milk quality. Enough to identify, "thanks to genetic kinship links, the fathers and sons of these cows." Once selected and integrated into the catalogs, these future parents will be able to transmit the genetic information coding a reduced methane footprint. And initiate a virtuous circle, generation after generation.

Milk production, morphology, health, reproduction... Between thirty and forty genetic selection criteria are currently evaluated. This new methane index could be added to this list, which guides breeders in mating and the constitution of their herd. Before that, its calculation must still be integrated into the tool of GenEval, a company that evaluates 1.8 million animals in France each year. "But it could technically be available this year," explains Mickaël Brochard, with the first values ​​available for animals.

However, breeders cannot be satisfied with cows that emit less methane. Their primary objective remains to produce milk. Everything will therefore depend on the decisions made by the selection bodies. These associations firmly hold the genetic rudder of each breed, for which they define the orientations. They produce a single synthesis index (ISU), which weights all the criteria of interest in breeding. That of the Prim'Holstein breed thus integrates 35% of characteristics linked to production, 22% linked to reproduction, 18% to udder health, 15% to morphology, 5% to longevity and as much to milking speed.

"There is a bit of alchemy to find the right weightings, and a lot of testing," explains Pierre-Alexandre Lévêque, head of the genetics department at the Prim'Holstein France association. Especially since the introduction of a new criterion can disadvantage or favor the expression of another. After infectious problems in the 1990s, an index on udder quality was introduced in 2001, replacing the milking speed index. Except that the first criterion has deleterious effects on the second. "As a result, at the end of the 2000s, cows had become too slow to milk," explains the engineer. Oops. Milking speed was reintroduced in 2012.

This time, according to initial feedback, the methane criterion does not contradict others. Which will not prevent marginal adjustments if necessary. Overall, all these calculations consist of making "averages between cabbages and carrots" , smiles Mickaël Brochard, who evokes "fairly sophisticated reasoning" but controlled. The integration of the methane criterion should be completed in the coming months or next year, according to the selection organizations.

"What's that again?" , complained the breeders of Prim'Holstein cows encountered at the Agricultural Show, who were already worried about future environmental obligations. "It's always the same. At first, it's optional and then, it's the kind of thing that will end up in the specifications of dairies or for CAP premiums." A little further on, on the contrary, a breeder of Normandy cows expressed his interest: "I'm waiting to see the correlations and the value sheet, but genetics, precisely, must allow breeders to be supported in the face of the challenges of our time."

There is still a catch. A cow that emits less methane does not guarantee more income. The difficulty will be to convince farmers to take this gamble, even if it means reducing the share of other more useful criteria a little. "Should this involve incentive criteria, and if so, with what level of premium? " asks Mickaël Brochard. "Should this involve a change in the specifications?" Questionnaires were sent to the various stakeholders to identify potential obstacles. The sector is also conducting economic simulations to study the financial viability of the various levers being studied to reduce greenhouse gas emissions.

Some environmental assessment tools, such as Cap'2ER, could integrate an additional criterion into matings, by refusing bulls with a methane index that is too high. But the breeders concerned by low-carbon labels most often work in short circuits, which reduces the scope of such a commitment at the national level. "Breeders are listening but they are waiting a little to see what happens next," summarizes Olivier Bulot, director of Brune Génétique Services, the selection organization for the brown dairy breed. "Everything will depend on how breeders are going to be remunerated for the reductions in carbon or methane emissions implemented in their breeding."

"Putting 5% or 20% of methane index in the single synthesis index will not have the same effect at all in reducing emissions. But to put a lot, it will be necessary to justify a real economic gain."

Olivier Bulot, director of Brune Genetics Services

to franceinfo

A call to the big dairy cooperatives, invited to make a financial effort to support the movement. "If we are simply talking about a few cents, I am not convinced that farmers will be encouraged to start." In Denmark, for example, the Arla cooperative grants "a significant bonus" to deserving farms. An incentive system, especially since it collects around 80% of the milk produced in the country. "At this stage, this subject of the methane index is not yet mature enough, but we will have to test all the options to lead the transition" , the Sodiaal group responds to franceinfo.

Furthermore, unlike the criterion of the quantity of milk produced, farmers will not even be able to observe the expected improvement, due to the lack of being able to measure the methane in their farm, Olivier Bulot also notes. "It's a bit like an athlete who trains without having a stopwatch to measure his progress." Selection on this criterion should be relatively low at the start, concedes Mickaël Brochard. But the latter mentions a "long-term process" and "continuous adaptation to the evolution of our environment" .

"We estimated that it would take two or three years of start-up before reaching a cruising speed of 1% reduction per year."

Mickaël Brochard, technical coordinator of Methane 2030

to franceinfo

"This should not start before 2029, and cows in their first lactation, within four or five years," says agricultural engineer Didier Boichard, research director at INRAE. On condition, however, that compromises are found that guarantee the financial balance of the farms. "If people are proactive, the decrease will be 1% per year from 2030 to 2040," he hopes. "By increasing methane production by 1% per year, we could reach -20% in 20 years, i.e. go from 500 to 400 grams of methane/day/cow," anticipates INRAE .

The Methane 2030 project aims to halve enteric methane emissions, "or 25% of the greenhouse gases of a herbivorous livestock farm" . The elementary methane index could be joined by other criteria, in order to take into account emissions over the animal's entire "career". The Alonge project seeks in particular to improve the longevity of animals, to reduce the share of unproductive young cattle in herds. Furthermore, "emissions could be reduced in the long term by 10% if all cows gave birth at two years old instead of three" , adds Didier Boichard. And by 5% by reducing the weight of cows by 100 kilos." There will be a lot of TGV trains before we can turn the page on howling methane.