Genetic makeup of an individual cow significantly controls the level and type of methane-producing microbes in its rumen
Cattle and other ruminants are known as significant producers of the greenhouse gas methane.
According to Agriculture Canada, a lactating dairy cow produces about 400 grams of methane each day. In one year, that adds up to the equivalent of greenhouse gas emissions from a mid-sized car driven 20,000 kilometres.
Given there are about 1.5 billion cattle worldwide, their methane production is considerable and adds to concern about greenhouse gases. It is a problem, despite recent findings that methane doesn’t persist in the atmosphere for as long as carbon dioxide.
Scientists at the University of Adelaide in Australia, in collaboration with universities in Europe, Israel and the United States, have conducted research that has shown it is possible to breed cattle to reduce their methane emissions. The genetic makeup of an individual cow significantly controls the level and type of methane-producing microbes in its rumen.
“Ruminants are unable to digest the plant material in their diets directly but the organisms in the rumen break down the plants into simpler molecules that the animals can digest. Reducing the number of organisms would reduce the efficiency of the fermentation process,” said professor John Williams, director of the Davies Research Centre at the University of Adelaide’s School of Animal and Veterinary Science.
“The fermentation produces hydrogen that the organisms use in creating methane. Therefore, it is controlling the community of organisms that is important. This is where the genetics comes in as the genetics of the animal seems to have an effect on the core communities with some animals favouring communities that produce lower amounts of methane.”
Williams said that the research project was developed in response to a call for proposals from the European Union. It allowed them to bring together an international team from the University of Aberdeen, Scotland, Parco Tecnologico Padano, Italy, and the Ben-Gurion University of the Negev in Israel.
The study focused on dairy cattle and specifically Holstein and Scandinavian Red cattle. The findings were confirmed in both breeds and across the different locations where diets varied slightly. While they did not include beef breeds, the consensus was that the core rumen microbiota would be under the same genetic influence inherent in beef cattle.
Other studies have shown a correlation between very early life experiences — whether or not an animal received colostrum, or dosing a neonate with (an) organism culture from the rumen of an older animal — and changes in rumen organisms. This is likely to occur by changing the response of the immune system.
“Therefore, one hypothesis is that the genetic effect is a result of genetically controlled differences in the immune system that affect the organisms,” Williams said.
The response to the new findings from farmers has been positive.
“One farmer in particular has installed GrowSafe feeders from Canada to breed and manage animals to increase efficiency of production,” he said.
“This farmer is also interested in reducing environmental impact of his operation. Methane contains a lot of energy (so) if the animal could capture that energy, rather than emitting it, the efficiency could be increased.
“Another very large producer in Queensland with many hundreds of thousands of beef cattle has also approached me to discuss how emissions could be reduced.”
The benefit of lowering methane emissions by selective breeding is that the genetics are permanent and passed on to the next generation. That investment will outweigh any dietary value.
The degree to which genetics can play a part will be set by the need to consider other characteristics such as meat quality, milk production and disease resistance. There also appears to be a possible correlation between the cows’ microbiomes and milk production efficiency. If it turns out in further research that low methane efficiency equates with high milk production, everybody wins.
“Selecting strongly for one trait means that other non-selected traits may be adversely affected,” he warned. “We have seen that when there was focused selection on milk production, fertility suffered. Including more than one trait in the selection usually means that genetic improvement in each is slower unless they are correlated.”