How livestock producers can cut their carbon footprint

Cutting the livestock sector’s carbon footprint has been high on the climate change agenda for years.

But farmers should thoroughly review their key performance indicators before taking any necessary steps, says Jude Capper, ABP chairwoman of sustainable beef and sheep production at Harper Adams University.

This should include age at first calving and growth rates.

Without knowing how the business performs, it is impossible to make informed decisions and chart progress, says Prof Capper.

See also: How a dairy is harvesting methane to save on diesel costs

Based on the findings, producers can then adopt a range of steps – some simple and some more strategic.

Areas where changes might be made are likely to include: optimising output, feed and grazing, slurry and manure, fuel and energy, genetics and breeding.

1. Optimising output

Achieving optimal production can significantly cut a farm’s greenhouse gas emissions.

Prof Capper explains that optimal means a balance of maximising output within the tightest management timeframe possible while still hitting quality targets.

Reduce days to slaughter

On a beef finishing unit, for example, cutting the days-to-slaughter figure will reduce the emissions from each animal by up to 25%.

But it does not simply mean sending stock to the abattoir earlier.

Instead, it means improving management procedures to hit target weight and carcass specifications at the earliest opportunity.

No stone should be left unturned in a bid to achieve this.

Work from the breeding stock upwards and select animals that work best within a particular system to meet the finishing or production goals.

The selection process should be imposed rigorously, always retaining the best animals and letting go of any underperformers.

For dairy farms, efficiency can often be improved by using sexed semen to produce beef-breed, bull calves and heifer replacements from the best cows, says Jonathan Foot, head of environment at the AHDB.

Beef from dairy farms generally has a lower carbon footprint. This is because the cows have a dual output meat and milk – to set against their emissions.

Maintain health and welfare

Excellent health and welfare go hand-in-hand with improved productivity. Good hygiene and carefully worked vaccination programmes will help to avoid any setbacks from disease challenges early in life.

This has a bearing on days-to-finish for meat animals and achieving the target age at first calving of 22-24 months for heifers.

Rearing a heifer to calving at 24 months emits about 3,700kg of greenhouse gas emissions, but this increases by almost 100% (7,290kg) if age at first caving extends to 40 months of age, says Prof Capper.

Better health and reduced stress also have a bearing on fertility with better in-calf rates.

This reduces the number of unproductive days when an animal is causing emissions that add to the carbon footprint calculation without having milk or meat output to offset it.

Finally, the 2020 Centre for Innovation Excellence in Livestock (Ciel) Net Zero Carbon and UK Livestock Report stated that ill health results in higher carbon footprints.

Bovine viral diarrhoea (BVD) can increase suckler beef’s carbon footprint by as much as 130%.

Prof Capper and Dr Foot both suggest calling in expert help to look at ways to improve efficiencies.

Working more closely with your farm vet, for example, can often improve the herd health plan.

2. Feed and grazing

Feed is a significant factor in a farm’s carbon footprint, says Dr Foot.

It is particularly high in the pig sector, where about 80% of a unit’s carbon footprint can be attributed to feed. Estimates for poultry units are similarly high.

On dairy units, the contribution of feed accounts for about 28% of the footprint, while for beef and lamb the figure is far lower, at about 6%.

The reason why feed incurs a heavy cost is often down to soya meal, which is mostly imported from the US, Canada and Argentina.

Carbon calculators are weighted heavily against the ingredient, particularly when associated with deforested land.

Consider alternatives

Switching to alternatives such as pea protein or co-products such as biscuit meal can dramatically cut carbon.

Products are often calculated as having a lower carbon cost because the majority of the emissions are already accounted for under previous processing, says Dr Foot.

The use of sustainably sourced soya meal is very attractive given its high levels of protein and relative cost.

However, farmers can seek to optimise the use of their own home-grown forage, which can have multiple benefits for profitability and emissions, providing it doesn’t have counterproductive outcomes on performance.

Alternatives may ultimately lead to longer finishing times and so a poorer carbon footprint overall. It is, therefore, vital to consult a nutritionist before making a move.

It is equally important to ensure that all ingredients have been analysed, especially forage.

Most bought-in feed will have been tested but forage is often fed by quantity rather than its nutrient contribution.

Analyse regularly

Having an accurate picture of forage quality allows a balanced ration formulation. It is possible that analysis will reveal bought-in feed could be reduced or different ingredients could be used to boost production performance and cut emissions overall.

With silage, analysis should be carried out regularly as progress through the clamp continues or when bales from different areas of the farm are opened up.

Cut waste

Good clamp and bale management will also help cut emissions.

Poorly compacted silage or loose clamp covers and damaged bale wraps will allow fermentation, causing waste, performance drops and higher emissions.

Across all feed types, allowing feed to deteriorate in clamps, bins, silos or bales will raise the carbon footprint.

Wasted feed adds huge pressure when carbon from the entire production cycle of the ingredient is accounted for.

Grazing management is another factor to consider.

Again, greater efficiency is the key, and tightly managed systems such as mob grazing can extract the maximum value from grassland.

Consider additives

There are also more direct actions that can be taken to curb emissions using in-feed additives for ruminants, Dr Foot says.

Methane-cutting additives are already commercially available – or about to reach the market. They include Royal DSMs 3-NOP and Harbro’s Rumitech.

Harbro’s product uses essential oils to alter the balance of rumen microbes away from those responsible for producing more methane.

Trials of the product have shown methane output for each litre of milk can be cut by 17.7%.

The improved microbiome enhances digestion and leads to further performance benefits.

3. Slurry and manure

In the past, farmers would have spread livestock slurry and manure according to the calendar or when storage capacities were reached, says Prof Capper.

But this approach leads to higher emissions and wastes a potentially valuable resource, she says.

Instead, slurry and manure management should be viewed as an opportunity to cut emissions at spreading and as a valuable resource.

This should be both in terms of reducing the amount of additional fertiliser needed and improving soil quality, says Prof Capper.

Analyse stocks and soil requirements

As with feed, it is important to analyse soil to ensure that any applications are carefully tailored to requirements, she says.

Dr Foot’s team at AHDB is responsible for updating and managing the nutrient management guidance document RB209. This should be used to devise a nutrient management plan that includes soil testing and analysis of the organic materials to be applied.

Dr Foot says farmers can use an agronomist to help them optimise management plans.

Switch to direct applications

The method of spreading is also key to cut the farm’s emissions, says Dr Foot. Trailing hose or direct injection equipment can cut emissions by more than 70% compared to splash plates.

In some parts of the UK, splash plates are already outlawed. But where they continue to be used, slurry must be worked into the soil within 24 hours to reduce emissions, he says.

Upgrade and cover stores

Having enough storage is key to optimising management of slurry applications and cutting emissions.

With storage capable of holding about six months’ worth of slurry, farmers have greater opportunities to select dates when plant uptakes are at their greatest and soil is in an ideal condition to cope with traffic, says Dr Foot.

Cover stores

• Ammonia, nitrous oxide and methane are produced by anaerobic actions in the slurry and pass into the atmosphere.
• Putting a lid over slurry stores will dramatically reduce these emissions.
• According to Defra figures, ammonia emissions can be reduced by 70-78% using a cover. For nitrous oxide the figure is higher still at 91%.

A range of covers exist to reduce losses according to the AHDB. Types of cover include relatively low-cost, permeable materials, such as:

• Chopped straw mulch
• Expanded clay aggregates
• Foam glass
• Floating plastic plates.

Alternatively, permeable plastic membranes that also keep out rainwater could be used, but costs for this method of containment can be high.

For tanks, options range from free-floating plastic covers with a lower cost, to PVC-reinforced fabric covers that can be fixed in place.

Fixed covers require support poles and attachments to the tank. Where additional work is required, these can incur the highest cost.

Consider additives

Like feed, there are direct solutions to reducing methane in slurry via additives. Research has shown that it may be possible to reduce total emissions from stored slurry by 90%.

The method alters the pH in tanks, making the slurry more acid and changing the microbacteria present. In trials, methane production was reduced by 67-87% and ammonia by up to 95%.

Inoculation with an antimicrobial that targets the anaerobic bacteria-producing methane has also been effective in trials. Methane output was cut by 72%.

Use multi-herbal leys

Drilling red clover and multi-herbal leys is an alternative method for reducing reliance on slurry and bought-in fertiliser, suggests Prof Capper.

Nitrogen-fixing plants can contribute significant quantities of nutrients to the soil – in some cases, halving the use of artificial fertiliser requirements.

Multi-herbal leys also yield more biomass in the ley and lead to better feed intakes. This boosts efficiency without resorting to buying extra concentrate.

4. Fuel and energy

Fuel is a major contributor to emissions from indoor pig and poultry units, accounting for about 10% of their greenhouse gas output. For most other livestock units, the contribution of fuel is far lower.

Undertake an energy audit

Dr Foot suggests using an energy audit. Identifying areas of high use will allow producers to adopt a strategic approach to fuel use, she says.

For example, it may be possible to alter routines so vehicles can combine tasks, or a smaller, more efficient mode of transport could be used.

Switching to contractors with more appropriate, more fuel-efficient machinery to carry out field work may also cut emissions.

Invest in renewables

Renewable energy sources can help offset the use of fossil fuel-derived power. In dairy parlours, water heating could be serviced by solar panels or heat pumps.

Swapping to LED lighting in housing and cattle sheds can reduce electricity use by 80%. The change in spectrum has also been shown to improve production performance in dairy cows and health and welfare in indoor pigs. 

Another alternative to cut emissions from slurry is to install an anaerobic digester (AD) plant.

This dramatically cuts emissions and produces renewable energy to heat buildings and so further cuts the farm’s carbon output. It is, therefore, well-suited to indoor pig or poultry units.

The AD plant also yields digestate, which can be used as fertiliser, reducing the need for bought-in nitrogen.

5. Genetics and breeding

Long-term solutions to cutting emissions at source – the animal itself – are developing fast. Launched in 2021, the AHDB’s EnviroCow venture is a genetic index that links lifespan, production, fertility and a feed conversion to reflect an animal’s likely carbon footprint.

The scale from -3 to +3 highlights the sire’s potential to pass on genes that govern its daughters’ environmental credentials.

The most efficient cows consume 400kg less food during a lactation to produce the same amount of milk. Selecting for this trait alone will significantly cut feed use and reduce the farm’s carbon footprint. 

Another development in the pipeline is the potential selection of ruminants on their methane output. Methane emissions are linked to the amount of saliva produced and this trait is heritable, researchers have found.

Early trial results suggest that selecting animals that produce less saliva leads to a 40% cut in methane output.

A more direct approach to cutting methane is a mask produced by the Zero Emissions Livestock Project (Zelp), says Dr Capper.

Although not yet commercially available, Zelp masks have proved to be a successful method of tackling ruminant methane output in trials. The masks attach to the animal via a head strap, and have flaps that extend over the nostrils.

A catalyst within the flaps then neutralises the methane as the animal breathes out. The venture has won significant financial backing, speeding up development. It is hoped they will come to market in the near future.

Transition Farmer Eddie Andrew

Transition farmer Eddie Andrew is weighing up two renewable energy options to cut emissions on his Yorkshire dairy farm.

© Our Cow Molly

The ice cream maker says the options of either solar panels or a slurry-fed anaerobic digester (AD) plant will help protect the business from volatile energy prices by meeting the farm’s total power needs.

Mr Andrew is researching the pros and cons and looking into potential funding schemes to offset the capital costs of purchase and installation.

Although the farm already has solar panels, possibly making it a simpler choice, Mr Andrew has concerns over the reliability of supply.

Most farms with solar panels need diesel generators as backup on darker, cloudier days. That would require purchase of fossil fuel prevent the farm going off-grid.

Bioelectric AD plants, on the other hand, are specifically designed to convert slurry into clean energy and create a constant supply of power.

A further benefit is the resulting digestate is a more potent fertiliser so could cut bought-in nitrogen, he explains.