Tommy Boland: Rational analysis proves sheep meat production will be an intrinsic element of sustainable farming
Following on from my article last month, where I challenged some of the rhetoric surrounding the debate of the credentials of red meat, I would like to examine this in more detail in the coming articles.
This is becoming ever more important considering the misrepresentation of the recent IPCC report on 'Climate Change and Land' in many media outlets suggesting the IPCC is recommending that individuals switch to plant-based diets.
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The exact wording, taken from the report's 'Summary for Policymakers', is as follows: "Balanced diets, featuring plant-based foods, such as those based on coarse grains, legumes, fruits and vegetables, nuts and seeds, and animal-sourced food produced in resilient, sustainable and low-GHG emission systems, present major opportunities for adaptation and mitigation while generating significant co-benefits in terms of human health (high confidence)''.
The 'high confidence' is a reference to how sure the authors are that their assertion is correct.
In Ireland our total national greenhouse gas (GHG) emissions are dominated by agriculture. Agriculture accounts for 33.3pc of our total GHG emissions in total, down from 36.7pc in 1990, and substantially below the peak achieved in 1998.
This reduction is driven by declining livestock populations, and fertiliser utilisation. It should be noted that agricultural emissions have increased year-on-year since 2012 as a result of an increase in the national dairy herd.
There are many reasons for the prevalence of agriculture in our GHG emissions and, except for New Zealand and perhaps Uruguay, this is unusual for a developed country.
Amongst these reasons are an absence of heavy industry, a relatively sparse population and the reliance on ruminants (cows and sheep) in our farming systems.
An argument often offered, is why not use the land currently supporting grazing livestock, to grow cereals, pulses and vegetables.
Globally, 12-14pc of the ice-free land surface, is used for cropping, and approximately 37pc of the ice-free land surface is used for grazing.
The 37pc figure breaks down into 2pc intensive grasslands, defined as 100 or more animals/square metre; 16pc savannahs and shrublands and 19pc extensive pastures.
Due to reasons of topography, climate, soil type, soil depth, growing season and many other factors it is not possible to use much of these lands to cultivate crops. Additionally, in some instances it may not be desirable to convert these lands to cropping as they are excellent stores of soil carbon, much of which is lost under cropping.
Therefore, the grazing of livestock offers an opportunity to utilise these lands for food production. Methane produced as a result of the digestion of feed in the digestive tract of cows and sheep accounts for approximately 61pc of all agricultural GHG emissions in Ireland.
This methane production is currently an inevitable consequence of the microbial fermentation taking places in the rumen - a process which converts nutrient sources (such as cellulose and non-protein nitrogen) which are unavailable to humans into high-quality protein and calories.
The current system to account for GHG emission converts each GHG to a carbon dioxide equivalent.
In such a system methane has an environmental impact approximately 27 times greater than carbon dioxide on a per kilogram basis, due to its ability to trap heat in the atmosphere.
More recently the way in which methane is treated in GHG inventories has come in for renewed focus.
A recent seminal paper from Dr Michelle Cain and colleagues from the Oxford Martin School promotes a rethinking of how the various greenhouse gases are treated.
Methane is a short-lived greenhouse gas, with its main warming effects occurring over a period of 12 years. Carbon dioxide, in contrast, continues to have a warming effect for centuries.
So, what does this mean for agriculture?
Basically, if we maintain current methane emissions from our national herd and flock, there will be no additional warming, due to enteric methane.
However, if there is a reduction in enteric methane emissions (as has been the case in Ireland compared to both 1990 and 1998), the warming impact of methane is reduced.
National sheep flock
If we look at the national sheep flock, which currently stands at approximately, 2.6m breeding ewes, this flock is now producing 43pc less methane per annum, compared to 1990.
This reduction is even more pronounced, when we compare it with the peak of the national sheep flock from the mid 1990s.
To put some further context on this, each kg of lamb produced in a flock producing 1.7 lambs per ewe with good grassland management, requires 22kg of grass DM, 4kg of silage DM and under 1kg of concentrate DM (much of which can be by-products).
In an Irish context at least, sheep meat production is not displacing human edible food.
Returning to the recent IPCC report, we can be confident that sheep meat production in Ireland fits within the definition of animal products that will play a part in future sustainable diets.
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