21 August 2023
By: Liana Mocke
Genetics are being used to breed cows that will do their part for the environment by emitting less methane.
Dairy farmers are facing increasing pressure from activists and the public in various countries to farm in a more environmentally friendly manner. In New Zealand, for example, the government aims to tax dairy farmers for methane emissions from their cows by 2025.
As a result, a Canadian farmer has inseminated cows and heifers with semen from bulls carrying the genetic trait for low methane production.
According to Reuters, Ben Loewith is eagerly anticipating the calves’ arrival in the Canadian spring. “Purposeful breeding that results in lower methane emissions from cattle sounds like a win-win situation to me, as long as other production traits aren’t compromised,” Loewith said in an interview.
The new product from Semex is based on seven years of research by two Canadian universities – Guelph and Alberta – where scientists measured dairy cows’ methane emissions.
The data collected was compared with genetic information from the cows and their milk to identify the animals whose breeding material was used for the product. These bull semen straws are already marketed in 80 countries, including Britain, the US and Slovakia.
Will it really make a difference?
Dr Carel Muller, a research fellow in veterinary science at Stellenbosch University, says using bulls that sire offspring producing less methane will undoubtedly make a difference over time.
“The only cow that doesn’t emit methane is a dead one. Cows produce methane simply because they are alive, not because they’re producing milk. If the methane is not released from their rumen, they will bloat and eventually die from suffocation.
“It’s the production of greenhouse gases like methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) by cows that’s the problem. It’s particularly CH4 that pollutes the atmosphere. Methane gas is the second-largest greenhouse gas after carbon dioxide and accounts for 14.5% of the world’s greenhouse gas emissions.”
Dairy cows alone produce about 4% of all greenhouse gases. “Cows eat for five to six hours a day. Because they are ruminants, they produce large amounts of CH4 in the rumen through the fermentation of feed. Methane gas is released into the atmosphere through belching,” says Muller.
“The more roughage the diet contains and the lower its digestibility, the more methane gas is produced in this process. That’s why a considerable amount of research abroad is focused on reducing the amount of greenhouse gases emitted by dairies. Improving the efficiency of a dairy also reduces methane production. Genetic changes indeed offer a more permanent solution.”
It can work!
Muller explains: “Genetic studies indicate that cows, regardless of their ration, vary in their ability to produce methane gas. This is linked to their milk-production capacity and feed-conversion efficiency. There is a positive correlation between the amount of methane gas and milk production levels.
“However, directly measuring the methane gas production of cows is a challenge. Nevertheless, it has been established that the heritability of methane gas production is 35%.”
How methane production is measured
“To include this trait in a selection index would require determining the methane gas production of a large number of cows in different production stages and feeding systems. It is difficult to directly determine the methane gas production of cows. Equipment needs to be attached to cows or they must be kept in airtight chambers to measure their emissions.
“Both methods are expensive and cumbersome. For the genetic evaluation of traits, a large number of cows are needed, which is why an indirect measurement method for cow methane production is more practical. One such method is the fatty acid composition of milk fat.
“Dutch researchers have proposed three formulas for estimating cow methane gas production. Therefore, the possibility exists that the analysis of the fatty acid composition of milk could become part of the milk recording scheme. This information could then be used to estimate the breeding values of bulls for the methane gas production of their daughters.”
