Reducing the environmental hoofprint in dairy, beef and sheep

What is the latest research on reducing livestock emissions? Researcher and director of the VistaMilk research centre gives us some information

Traditional animal breeding is credited globally with contributing half the gains in 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; moreover, component research and deployment of specific tools (e.g., complementary feeds, breeding strategies) must remain cognisant of upstream and downstream ramifications along the highly integrated and inter-dependant Agri-Food chain.

Current Breeding Indexes

The current breeding indexes in Irish dairy, beef and sheep are designed to improve environmental (concomitant with economic) efficiency even in the absence of direct measures of environmental traits. For example, biological data from Teagasc’s dairy Next Generation Herd was recently used to model the greenhouse gas emissions and nitrogen efficiency of two groups genetically divergent 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). Total greenhouse gas emissions were similar for both groups of animals, but, when expressed relative to fat and protein corrected milk production, 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 thus the productivity of the herd. A further analysis demonstrated that selection for the EBI could lead to a reduction in Ireland's greenhouse gas emissions intensity (kgs of greenhouse gas emissions expressed relative to kgs of fat and protein corrected milk production) from its current value of 1.14 to 1.03 over the coming decade. Additionally, breeding for increased EBI can improve nitrogen efficiency as the elite group had a 5.3 kg lower nitrogen surplus (kgs of nitrogen entering the system minus kgs of nitrogen leaving the system) compared to the national group.

What's happening in beef and sheep 

In beef, preliminary results from collected 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 2.9 grams lower daily methane output; 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 8.62 g. Preliminary results reveal that 5-star hoggets produced less methane emissions (7.87 g per day) compared to 1-star hoggets (8.47 per day).

Nonetheless, 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 but to do this actual animal-level environmental data are required.

Breeding and Feeding Options

To this end, Teagasc, the ICBF, and the VistaMilk SFI research Center (hosted by Teagasc) are strongly engaged in research to identify solutions to reducing 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, Food and the Marine, breeding solutions to further improve efficiency in dairy, beef and sheep are being explored; the dual strategy taken is considering the evaluation of how to reduce methane emissions per day, but also how to improve lifetime efficiency using readily accessible data; 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 are already readily available and thus breeding programs can be implemented relatively rapidly. The Science Foundation Ireland research projects (VistaMilk SFI Research Center and SIRG) focusing 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; thus, if successful, predictions of methane output and nitrogen use efficiency could be available on all milk recorded cows for both management and breeding purposes. The VistaMilk SFI center 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 achievable from breeding or feeding is a measurement of the actual methane produced per animal. While different approaches exist, Teagasc research is favouring the use of Greenfeeds for cattle and portable accumulation chambers for sheep (photos attached).

GreenFeed Machines

While most studies in cattle globally focus on indoor feeding systems, Teagasc Moorepark has the only two GreenFeed machines in Ireland to enable to measurement of daily methane output in grazing animals. Each GreenFeed machine costs approximately €125,000 and can measure methane emissions on approximately 15-20 animals at a time.

Beef and Dairy Cattle

Each outdoor GreenFeed is mounted on wheels which enable it to be moved between paddocks with the cows. Pellets are dropped down into a hood every 20 seconds for 3-4 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 ducting where airflow rates are measured and subsampled for determination of methane and carbon dioxide concentration. Each measurement is only 2-7 minutes in duration and cows usually visit 1-3 times daily. This can then be extrapolated to daily methane output although research at Teagasc is underway to evaluate alternative mathematical approaches to modelling this better. 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 248 grams of methane daily.

Sheep

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. These chambers enable the measurement of methane emissions of 12 sheep simultaneously. 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 thus 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.

Aim of the projects

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 numbers required for national genetic evaluations. The beauty of the strategy taken in these projects is that all cattle and sheep are also measured for a vary array of different characteristics such as performance (growth or milk yield), feed intake (indoors and grazing), live-weight, 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 thus 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 100 grams of methane per day between animals even with the same live-weight and growth rate.

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