Using genetics to reduce methane output from cattle systems
Stuart Kirwan, David Kenny and Sinead Waters, Teagasc Grange, take us through the genetic selection of low methane emitting animals which has long been advocated as mitigation strategy for the ruminant livestock industry.
Recent data from Teagasc Grange and ICBF has highlighted a 30% difference in daily methane emissions between beef cattle of similar breed, age and diet. Therefore, there is significant potential to harness the genetic variation for methane emissions that exists within the national herd, to bring about permanent and cumulative reductions in the methane output of future generations of livestock, via implementation of a low methane emitting breeding programme. Indeed, the breeding of more feed efficient and faster growing animals has great potential to decrease the lifetime emissions of beef animals.
Sean Doorley, Teagasc Advisor caught up with Joe Patton, Head of Dairy KT, Teagasc at #Ploughing2022 to get an insight genetics and methane. The GreenFeed machine is used to measure methane on an individual animal basis. Methane varies between animals and we can measure it, and if we can measure it we can start making improvements through nutrition, breeding and genetics.
Lowering methane emissions
Until recently, the development of a national low methane emissions breeding programme had been limited due the lack of technology available to measure emissions from large cohorts of animals within a commercial setting. However, with the advent of the GreenFeed Emissions Monitoring System, as featured in the Teagasc display at Ploughing 2022, it is now practically feasible to estimate methanogenic output of individual animals, both at pasture and indoor feeding conditions. Each GreenFeed machine can measure approximately 25–30 animals daily in an indoor or pasture setting. The system relies on the animal to voluntarily visit the machine many times per day to ensure accurate results, which is achieved by offering a small amount of concentrate (30 grams) per visit. When the animal puts its head into the feed bin in the machine, an electronic identification tag is recognised and breath sampling commences. Readings for methane, carbon dioxide and hydrogen gas are taken via sensors and over time this builds a profile of emissions per animal.
The strong correlation between feed intake and daily methane emissions had traditionally limited the breeding of low methane emitting animals for fear of negatively impacting feed intake, which is a key driver of animal productivity, particularly in forage-based production systems. Nonetheless, the recent collaboration led by Teagasc in partnership with ICBF and UCD has identified the residual methane emissions (RME) index as the optimal metric for disentangling the relationship of daily methane emissions with feed intake. Methane emissions at the ICBF Progeny Performance Test Centre in Tully (Co. Kildare).
Residual methane emissions can be described as the difference between methane emissions predicted for an animal based on its body size and feed intake and that which it actually produces. At the ICBF National Progeny Performance Test Centre in Tully (Co. Kildare), individual RME values were calculated for 282 crossbred beef cattle (steers and heifers) undergoing a 90-day finishing period with detailed measurements of methane output, feed intake, growth rate and carcass output collected. Animals were ranked as high (undesirable) and low (desirable) in terms of RME. Low RME animals (efficient) produced, on average, 30% less methane, despite having the same feed intake, feed efficiency, growth and carcass output as their high (inefficient) ranking RME contemporaries.
Results highlight the potential to breed more environmentally sustainable animals, while at the same time not having a negative impact on the animals’ performance, and indeed profitability.
Further work is currently ongoing to study the underlying biology of the trait in an effort to potentially incorporate RME into the national breeding indices for Irish beef cattle.