Extending Grazing Season

Housing cattle too early raises costs and emissions.
Extending the grazing season boosts grass use and cuts emissions without hurting yields.

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The Climate Issue

Grazing is one of the most efficient ways to feed dairy cows. Fresh grass is high in energy, supports strong milk yields, and grows back quickly when well managed. It’s also lower in emissions than any other feed.

But in many systems, cows are housed for long periods, sometimes up to five months a year. During housing, more meal is fed, slurry builds up, and emissions rise from storage and feed imports. Each extra day indoors costs more and pollutes more.

The Solution: Extending Grazing Season

Extending the grazing season means turning cows out earlier in spring and keeping them at grass later into autumn. It builds on what nature already gives us: solar energy, homegrown feed, and strong root systems.

By grazing even 10 more days each year, farms can reduce greenhouse gases and feed bills. Grass replaces imported meal. Cows walk and spread manure naturally. Slurry is avoided. Trials show each extra 10 grazing days cuts GHG by up to 1.7 %.

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Key Benefits when Extending Grazing Season

Cut Emissions

Grazing longer reduces emissions from housing, feeding, and storage. It avoids methane from stored slurry and shrinks the carbon footprint of imported feeds.

Save Costs

Fresh grass is the cheapest feed. Grazing 10 extra days saves about €1.80 per cow – or €180 on a 100-cow farm. Those savings stack up across the season.

Yields from Grass

Longer grazing means more energy from grass and less from meal. Milk yields stay strong, while grassland management improves year-on-year.

Impact of Extending Grazing Season

Extending the grazing season is a cost-effective way to cut emissions, improve milk yield, and reduce slurry storage needs. Grazed grass offers higher energy content than silage and supports better animal performance.

When timed correctly, even modest extensions bring measurable environmental and financial gains without major infrastructure changes.

Studies from Teagasc and Farm Zero C show that longer grazing can:

Reduce GHGs by up to 10% with full-season extension
Increase milk returns by €1,400–€2,900 for 100 cows
Reduce indoor slurry by 15–25%
Lower housing energy use and feed demand

See the table below for expected impacts under Irish dairy conditions.

Scenario	Days at Grass	Extra Milk Revenue	GHG Emissions	% GHG Reduction
Baseline	241	-	0.960 kg CO₂-eq/kg milk	0% kg CO₂-eq/kg milk
Add 7 Days	248	€1,465	0.936 kg CO₂-eq/kg milk	1.04% kg CO₂-eq/kg milk
Add 21 Days	262	€2,930	0.936 kg CO₂-eq/kg milk	2.71% kg CO₂-eq/kg milk

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Considerations

Weather & Soil

Grazing longer depends on mild weather and well-drained soils. Heavy rain or poor pasture can damage swards. It’s essential to avoid poaching and protect paddocks during shoulder seasons.

Infrastructure & Planning

Good access lanes, shelter, and paddock rotation help support spring turnout and autumn grazing. Reseeding, liming, and fertiliser timing can also improve resilience.

Grazing Management

Mob grazing and block rotation work best. Planning ahead – including closing paddocks early, ensures enough grass is available when cows go out.

Implementation

Extending grazing takes planning, but the gains are significant. With good soil, rotation, and infrastructure, many farms can hit +30 or even +60 days per year. Here’s how to get started.

1. Target early turnout. Begin planning in autumn by closing paddocks early to build spring grass cover. Aim for 30–40 % of grazing days to occur by early March for best results.

2. Improve access points. Maintain or upgrade farm infrastructure such as laneways, back-fences, and gates. Good access reduces the risk of poaching and supports turnout in variable weather.

3. Plan your rotation. Use a rotation planner to align grass growth with herd demand. Combine paddock walks and feed budgeting tools to avoid overgrazing and improve pasture use year-round.

Behind the Research

ODOS Tech was founded by Cian White and Alejandro Vergara, two sustainability specialists with deep expertise in agricultural climate action.

Alejandro (left), a PhD in environmental engineering from University College Dublin, helps farmers measure their carbon footprint and implement mitigation strategies to reduce their impact. Cian (right), a researcher at Trinity College Dublin with a PhD in ecology, works on restoring nature to increase biodiversity on farms using satellite imagery to monitor habitats.

Together, they helped lead the carbon and nature-based work for the Farm Zero C project at Shinagh Farm, one of Europe’s first net-zero dairy pilots. In 2020, they launched ODOS, a platform that built smart, science-based tools to help agri-food businesses protect the environment and restore nature.

Research

Teagasc Pasture Trials

Teagasc has trialled extended grazing across dairy systems and found each 10-day gain cuts emissions by ~1.7 % and improves grass utilisation, milk solids, and fertiliser efficiency across the board.

Tirlán Grazing Reports

Industry data shows that farms reaching 270+ grazing days per year report better margins, lower feed bills, and more consistent pasture growth over time.

IPCC and EU Policy

Longer grazing aligns with climate-smart practices recommended by the IPCC and EU. It supports biodiversity, improves nutrient cycling, and reduces emissions without sacrificing productivity.