Managing Our Flocks and Herds in an Environmentally-Friendly Way
A Load of Hot Air?
Living in a technologically advanced country with a relatively benign climate, we’re largely sheltered from the more extreme effects of climate change. Those living in resource-poor countries are much more vulnerable to the impact of severe weather episodes. Their livestock graze marginal land that will barely support them in a normal year; when a catastrophic weather event hits, the results can be disastrous for both people and their animals. Add to this the global rise in human population (which has doubled since 1970, and now stands at around seven and a quarter billion), and the consequent increase in the demand for water, food and fuel; our global resources start to look quite hard-pressed, and our potential to damage the environment escalates dramatically.
From a global farming perspective, we need to create agricultural systems that will reduce our environmental impact, while at the same time increasing outputs to feed a growing world population. This means taking stock of the environmental cost of current methods of production, and micro-managing our diminishing natural resources in order to create systems that will not only feed a growing human population, but also be more resilient in the face of a changing climate.
Greenhouse Gases (GHGs)
Although these gases constitute just 1% of Earth’s atmosphere, they are largely responsible for regulating our climate. The three most important GHGs are:
- Carbon Dioxide (CO2), which is locked away as carbon (coal, oil and shale) when plants photosynthesise, and later released into the atmosphere by the burning of fossil fuels and deforestation; CO2 emissions are responsible for over 70% of the total ‘greenhouse effect’
- Methane (CH4), is the main component of ‘natural gas’ used domestically and by industry, Methane is created by bacterial decomposition of organic matter – which includes enteric fermentation – the process of ruminant digestion in cattle and small ruminants
- Nitrous Oxide (N2O), has a role in nitrogen fixation in the soil (for example, as an applied fertiliser), N2O is the most persistent of the GHGs, remaining in the atmosphere for as long as 150 years
Globally, agricultural production contributes a significant amount of GHGs, and some methods of production are more polluting than others – but the worst culprits are perhaps not always the most obvious ones!
Livestock: Part of the Problem, and Part of the solution
Rumination – the process by which ruminant animals, including cattle, sheep, goats and alpacas derive nutrients from vegetation – is not undertaken entirely by the animal itself, but also by microbial action in its rumen, which acts as a huge fermentation chamber. The main by-products of this digestion process are CH4 and manure. The CH4 part is belched directly into the atmosphere, while the manure decomposes gradually, releasing N2O into the atmosphere and depletes nitrogen (a valuable fertiliser) from the system. A figure of 39% of the sector’s GHG emissions is attributed to enteric fermentation, with a further 16% provided by the breakdown of manures.
Of course it isn’t just the flatulent habits of our farmyard animals that are creating the problem; we must also consider the environmental impact of their entire production cycle from breeding to dinner plate, via field, or feedlot. We simply cannot ignore the loss of nutrients (nitrogen), energy and valuable organic matter through inefficient production of animal protein. This includes land use, the manufacture of feedstuffs and pharmaceuticals, transportation, processing and marketing of the final product. It’s estimated that these operations represent approximately 45% of the livestock sector’s GHG emissions.
However, buried within this figure is the hidden cost of the worldwide expansion of farming into forest areas, both for grazing animals and to grow food, such as soya, for animal feed. These are the very forests that currently both protect our atmosphere by acting as a ‘carbon sink’ that stores CO2, as well as regulating water and weather through their shade and the process of transpiration.
So, is this an argument in favour of vegetarianism? Probably not, as much of the landmass (for example, approximately 40% in England) is only suitable for growing grass due to climate and topography, and a large proportion of that will support only native breeds that have been acclimatised over generations to survive on marginal land. Taking these aspects into account, small ruminants play a very important role by utilising upland areas for human food production, and providing local livelihoods. Equally, it can also be argued that livestock farming on highly productive, improved grassland in lowland areas creates additional carbon sequestration (known as ‘carbon sinks’). If these grassland areas were ploughed up for arable crops, this CO2 would be released into the atmosphere.
A recent report carried out by the Food & Agriculture Organisation of the United Nations (FAO) acknowledges that the livestock sector is a significant emitter of GHGs, and it also has large potential to reduce these emissions. This poses a considerable challenge to farmers worldwide to adopt new methods of production that will be both more productive and less polluting. Does this mean an inevitable increase in the industrialisation of livestock production, or can we manage existing agrarian systems more efficiently? The answer is, emphatically, the latter, with the emphasis on efficiency.
One of the most interesting, and encouraging aspects of the FAO report is its recognition of the scope for mitigation of GHGs that is attainable by all livestock farmers; from low-input subsistence smallholders, to high-input intensive corporate farms, and surprisingly, very similar principles apply regardless of the size of the operation. Moreover, the adoption of more efficient farming practices can hugely improve the lives of those who currently live on little more than a subsistence level of farming. We already have much of the knowledge and many of the tools that can enable us to both reduce emissions and lessen the worst effects of climate change globally, and many farmers around the world are already reaping the benefits of highly productive, low–emission livestock production.
Efficiencies, Opportunitiesand Challenges
By adopting new technologies and ‘best practice’, it’s estimated that emissions due to livestock farming could be reduced by 18-30%. To achieve this, every aspect of the flock or herd’s management needs to be objectively examined, starting with the fundamentals of how the ruminant derives its nourishment from grazing and browsing, often eating plant material that would not support other species. Ruminant digestion is very effective at doing this, but is fundamentally inefficient, meaning the animal has to spend a lot of time grazing. For a sheep this can be up to 9hours a day, followed by a further 8 hours cudding, to consume enough to maintain its biological functions and reproductive ability.
Grasses are the natural feedstuff for ruminants, but they contain a high proportion of indigestible cellulose. Ruminants have a well-developed digestive system to cope with this, but it is inherently inefficient. Modern grass varieties are more digestible, and have a higher feed value than most native grasses. A number of trials have been carried out with the aim of improving feed intake and efficiency of rumen fermentation, so that the animal can derive more nutrition, and produce less waste – including methane – from its feed.
Rumen efficiency trials in which calves are fed concentrates at a relatively high level have shown a significantly greater development of the papillae, which provide the absorptive surface of the rumen; this results in greater intake and less waste of nutrients, as well as reduced CH4 output, and gives the animal a feed conversion advantage throughout its life, enabling it to better utilise grazing and lessen or eliminate the need for cereal feeds.
Bioactive plant compounds have shown potential to enable ruminants to better utilise their feed; for example, the results of a trial to assess the use of Eucalyptus leaves in cattle feed demonstrated small but significant digestive efficiency benefits, without any detrimental effect on either milk or meat flavour.
Selective breeding in favour of animals that are genetically more efficient at converting feed to muscle and milk – rigorous record-keeping and a set of weigh scales is all that is needed to identify the youngstock that have a higher daily liveweight gain (DLG) than others reared under the same system. Similarly, selecting females that are milkier and so rear faster-growing youngstock will deliver significant production gains: these biological efficiencies are highly hereditable and are also reflected in reduced production of gas and manure, as the animals destined for slaughter will be ready sooner.
Selection for resistance to disease and parasites is an important criterion, as both challenges severely limit the productivity of the animal and increase utilisation of expensive resources such as antibiotics and anthelmintics, as well as reducing the growth and production potential of the animal.
Adjusting the lambing or kidding season to take advantage of highly nutritious new season grass growth for the ewes and nannies at turnout; this can reduce the need for supplementary feed, while outdoor lambing and kidding eliminates the need for lighting and bedding (and its decomposition, which releases yet more N2O into the atmosphere).
Alternative feedstuffs – there are classes of ruminant that need higher protein feed, for example pregnant and lactating ewes, and currently this is largely fulfilled by the use of imported soya, much of which is grown intensively in the Americas. While not a directly comparable protein source, homegrown field beans and rapeseed meal can provide good levels of Metabolisable Energy (ME), though females carrying twins may require an additional protein source.
Husbandry & health management – small flock improvements that promote better health, such as improved nutrition (which will in turn enhance fertility and longevity, while lowering premature mortality), vaccinating against disease, careful selection of sires, and ensuring access to shade and water.
Grassland improvement – by adjusting grazing intensities to match demand, forage production can be significantly increased; hard grazing followed by a fallow period can improve both quality and growth rates of the grass, as well as increasing the amount of carbon stored in the soil.
Benefits of Climate Mitigation
Easy to implement management techniques have also been shown to reduce polluting outputs, while at the same time transforming the lives of subsistence farmers who depend on the meat, milk and by-products derived from small ruminants. Obviously, the greater gains are to be made by the least-performing flocks & herds, but I’ll bet we can all find some room for improvement, and gain from both healthier and more productive livestock, as well as the knowledge that we are reducing our own personal ‘carbon footprint’.
The Future Challenge
The FAO report has predicted a growth in demand for livestock products of 70% between 2005 and 2050 driven by a growing population (to 9.6 billion by 2050) and increased urbanisation and consumption. If we are to fulfil this demand, the livestock industry, from smallholder to rancher, needs to address its environmental impact. Current indications are that we are falling well short of target!
This article was originally written by Carole Youngs for
Practical Sheep, Goats & Alpacas Magazine.