Traditional animal breeding is credited globally with contributing half the gains in animal performance observed in the past century.

Despite this, it is clear that optimum performance can only be achieved through a co-evolution of breeding and management strategies.

On top of this, component research and deployment of specific tools (eg complementary feeds and breeding strategies) must remain cognisant of upstream and downstream ramifications along the highly integrated and interdependent agri-food chain. For example, what effect could feeding methane inhibitors to cows have on milk or meat quality?

The current breeding indexes in Irish dairy, beef and sheep are designed to improve environmental efficiency, even in the absence of direct measures of environmental traits.

Improvements

Improvements in the environmental efficiency of the animal should also produce economic efficiencies for the farmer.

For example, biological data from Teagasc’s next generation dairy herd was recently used to model the greenhouse gas emissions and nitrogen efficiency of two genetically divergent groups for the Irish dairy breeding index, the EBI. The two genetic groups consisted of either the top 5% of animals in Ireland on EBI (EBI = €181) or a group representative of the national average for EBI (EBI = €82).

Research on methane emissions in sheep is still in its infancy

Total greenhouse gas emissions were similar for both groups of animals, but when expressed relative to fat and protein corrected milk production (FPCM), the elite group produced 10% less greenhouse gas emissions compared to the national average. This was primarily due to their superior reproductive performance, which improves the parity structure and the productivity of the herd.

Analysis

A further analysis demonstrated that selection for increased EBI could lead to a reduction in Ireland’s greenhouse gas emissions intensity from its current value of 1.14kg of C02/kg of FPCM down to 1.03kg of C02/kg of FPCM over the coming decade. This would equate to a 10% improvement in the carbon emissions intensity of Irish milk.

Additionally, breeding for increased EBI can improve nitrogen efficiency as the elite group had a 5.3kg lower nitrogen surplus (kilos of nitrogen entering the system minus kilos of nitrogen leaving the system) compared to the national average group.

Beef and sheep research

In beef, preliminary results from measuring methane emissions at the ICBF Tully Performance test station, as part of the GreenBreed project, suggest that each €10 increase in the terminal index value of an animal corresponds to a reduced methane output of 2.9g. This benefit is compounded when the known younger age at slaughter in higher-index animals is factored in.

Research on methane emissions in sheep is still in its infancy and to date has focused on hoggets. The average daily methane output has been 8.62g.

Preliminary results reveal that five-star hoggets produced less methane emissions (7.87g per day) compared to one-star hoggets (8.47g per day).

While none of the dairy, beef or sheep breeding indexes explicitly include environmental traits, consideration of direct measures of environmental efficiency will improve the rate of genetic gain. How much these observed gains in environmental efficiency can be further accelerated by explicitly considering actual environmental traits must first be quantified.

To do this, actual animal-level environmental data will be required.

To this end, Teagasc, the ICBF and the VistaMilk SFI research centre (hosted by Teagasc) are strongly engaged in research to identify solutions to reduce the environmental hoofprint of dairy, beef and sheep. The approaches taken consider both breeding and feeding solutions. Breeding has the advantage that the benefit of improvement is cumulative over years.

As part of the GreenBreed project funded by the Department of Agriculture (DAFM), breeding solutions to further improve efficiency in dairy, beef and sheep are being explored. A dual strategy is being taken to evaluate how to reduce methane emissions per day, but also how to improve lifetime efficiency using readily accessible data.

Predictions of methane output and nitrogen use efficiency could be available on all milk-recorded cows for both management and breeding purposes in the years ahead

The latter includes improved lifetime productivity of the mature herd but also reducing age at slaughter in growing cattle and sheep.

The advantage of the latter approach is that the data is already available and breeding programmes can be implemented relatively quickly. The Science Foundation Ireland (SFI) research projects (VistaMilk SFI research centre and Starting Investigator Research Grant, or SIRG) focused on dairy cows are evaluating the potential to breed for reduced methane emissions and improved nitrogen use efficiency through the exploitation of information contained with milk.

If successful, predictions of methane output and nitrogen use efficiency could be available on all milk-recorded cows for both management and breeding purposes in the years ahead. The VistaMilk SFI centre is also evaluating complementary feeds for dairy cows as a means of further reducing methane emissions.

Measuring methane

Key to quantifying the potential reductions in methane emissions that can be achieved from breeding or feeding is a measurement of the actual methane produced per animal. While different approaches exist, Teagasc research is using GreenFeed measurement systems for cattle and portable accumulation chambers for sheep.

While most global studies in cattle focus on indoor feeding systems, Teagasc Moorepark has the only two GreenFeed machines in Ireland to enable the measurement of daily methane output in outdoor grazing animals.

The two GreenFeed machines used at Teagasc Moorepark to measure methane emissions from cows.

Each GreenFeed machine costs about €125,000 and can measure methane emissions on approximately 15 to 20 animals at a time.

Each outdoor GreenFeed machine is mounted on wheels, which enables it to be moved between paddocks along with the cows.

Pellets are dropped down into a hood every 20 seconds for three to four minutes. Animal visits are monitored and restrictions can be put in place to prevent excessive use.

A fan pulls air past the animal’s muzzle into ducts where airflow rates are captured and subsampled to measure methane and carbon dioxide concentration in the air.

Each measurement is only two to seven minutes in duration and cows usually visit one to three times daily. This can then be extrapolated to calculate daily methane output, although research at Teagasc is under way to evaluate alternative mathematical approaches to modelling this better.

Prof Donagh Berry, quantitative geneticist with Teagasc and director of VistaMilk research centre.

The first measurements of beef and dairy cattle, as part of the GreenBreed and VistaMilk projects, started in 2019. In Tully, on average, the steers and heifers belch out 248g of methane daily.

Greenfeed machine used to measure methane emissions from cattle at the ICBF progeny test centre in Tully, Co Kildare. \ Thomas Hubert

The first measurement of methane emissions in the Irish sheep population commenced in winter 2019 at Teagasc Athenry.

Portable accumulation chambers (PACs) were purchased from New Zealand, which enable the measurement of methane emissions of 12 sheep simultaneously.

The portable accumulation chambers (PAC) chambers for measuring methane emissions from sheep.

Individual sheep are placed into each of the 12 chambers for one hour where the methane emissions of the sheep are measured three times. The chambers are mounted on a trailer, enabling them to be transported to various sheep farms once validated in a research setting.

Validation of the chambers against gold standards is nearing completion.

Methane evaluation

The aim of the different projects in cattle and sheep is to collect methane data on several thousand animals over the next few years, which would be the minimum number required for national genetic evaluations.

The beauty of the strategy taken in these projects is that all cattle and sheep are also measured for an array of different characteristics such as performance (growth or milk yield), feed intake (indoors and grazing), liveweight, fertility and health, as well as product quality (milk and meat).

These rich datasets will facilitate the estimation of the relationships between performance and environmental traits, enabling the estimation of the potential to reduce daily methane emissions with minimal consequence on performance.

For example, based on beef steers and heifers fed indoors, there is a difference of more than 100g of methane per day between animals even with the same liveweight and growth rate.

Gross efficiencies

The strategy of reducing daily environmental footprint will be pursued in tandem with improvements in gross efficiencies. The impact of this will mean that dairy, beef and sheep breeding programmes in Ireland are breeding for a more environmentally benign animal, the benefit of which accumulates over time.