THE possibility of using selective breeding to produce cattle that are consistently low emitters of methane is being explored by an international team of scientists led by the University of Aberdeen in Scotland.
The investigation is part of the €7.7 million, European Union-funded RuminOmics project, which aims to increase the efficiency of ruminant animal production while decreasing the associated environmental footprint.
Ruminants emit methane — a greenhouse gas with a global warming potential 25 times greater than carbon dioxide — which is formed in the gut during the digestion of fibrous feeds and is mainly released into the atmosphere when the cow belches.
Preliminary findings of the four-year RuminOmics project — which comprises scientists from the U.K., France, Italy, Finland, the Netherlands, the Czech Republic and Sweden, along with international advisers from Canada and Australia — add further support to the existing idea that the genetics of an animal may influence the level of methane it produces.
Professor John Wallace, who researches microbial metabolism in the gut of humans and ruminants at the University of Aberdeen's Rowett Institute of Nutrition & Health, is leading the study.
"Methane production represents a waste of feed energy, varying between 2% and 10% of total energy consumed by an animal," Wallace said. "Methane production is important for cattle and sheep farmers because if the amount of methane produced can be lowered, then there are benefits for the environment, production and profitability."
The RuminOmics team has been investigating methane production and feed efficiency among individual animals and the effect of different feeds.
In dairy cattle, the researchers have shown that methane production is quite variable, particularly among individual animals. It is already known that diet can affect methane production.
"Currently, most diets that have been formulated to lower methane add costs or increase losses of other nutrients," Wallace said.
In one study from Sweden, increasing the dietary protein concentration lowered the methane emitted per kilogram of milk output, but at the expense of increasing nitrogen losses. Nitrogen is lost as ammonia in the urine, which builds up in the soil and is converted to the greenhouse gas nitrous oxide.
Pekka Huhtanen, a professor at the Swedish University of Agricultural Sciences who is also part of the RuminOmics consortium, believes that researchers need to take into account both global warming and nitrogen pollution impacts when any change is made to the diet of dairy cattle.
"The RuminOmics team is finding means to identify animals that are producing less methane and are more efficient across a range of diets," Wallace added. "Our work suggests that there is considerable variability between individuals, with some producing more than others. The finding has led the team to ask whether animals that are low emitters always emit low levels under all circumstances."
The team has started to explore this question, and so far, preliminary results from a group of 25 dairy cattle suggest that, irrespective of what the individual animals are fed, low-emitting animals are always low emitters; conversely, high-emitting cattle are always high emitters.
These 25 cows are just the start of the project, which will ultimately involve 1,400 head. The results will enable the genetic influence on methane emissions to be determined.
The RuminOmics team aims to use the data generated to develop new models and tools that will allow the livestock industry to select cattle with less environmental impact from methane and nitrogen emissions and with improved feed efficiency.