Researchers in Spain propose mitigating methane production by dairy cattle through breeding, according to an announcement from the publisher of the Journal of Dairy Science.

In an article appearing in the journal, scientists are targeting a reduction of enteric methane in the breeding objectives for dairy cattle to select for animals that use feed more efficiently and, thus, produce less methane.

Some estimates are that livestock farming contributes 13% of global greenhouse gas (GHG) emissions, and the researchers said selective breeding can reduce those emissions while increasing milk output.

Methane from enteric fermentation is considered a main contributor to GHGs coming from ruminants, the announcement said, noting that these emissions represent a loss of dietary energy in ruminants.

"Current selection pressure is increasing total methane production in the population of dairy cows but is reducing methane intensity (per kilogram of milk) due to higher productive levels of each cow. A reduction of methane in the breeding goals should also be included in the selection indices," said lead author Dr. Oscar González-Recio with the department of animal breeding at the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria in Madrid, Spain.

An evaluation of the genetic traits and economic response of the traits in the selection index was considered in this study, which used genetic parameters estimated with 4,540 records from 1,501 cows, the announcement said. The project was funded by the Spanish National Plan of Research, Development & Innovation 2013-2020.

While methane production is necessary to maintain rumen homeostasis, total methane emissions are expected to decrease 4-6% in 10 years due to increased milk production per cow, the researchers reported. If annual methane production per cow is included in breeding goals and ad hoc weights are placed on methane production, GHG emissions from cattle could be reduced 20% in 10 years, they added.

González-Recio noted that "increasing per-cow productivity may reduce the number of cows needed per billion kilograms of milk produced, contributing to mitigation of GHG emissions, but this is not enough. If no action is taken, the genetic potential for methane production is expected to increase."

While the biological limit of methane production remains unknown, this study shows the potential for including environmental traits in selection indices while retaining populations of cows that are profitable for producers, the announcement said.

The Journal of Dairy Science is published by the American Dairy Science Assn.