Grass remains the cheapest and most environmentally friendly feed for livestock. Optimising the grazing season ensures cows are fed with highly nutritious herbage and reduces the amount of manure to be stored. This reduces greenhouse gases and costs associated with the purchase of silage and concentrates.
In Ireland, dairy cows are out grazing on pasture for an average of 235 days per year though there is a different variation across regions. Extending the grazing season involves maintaining the quality of forage so that animals can have access to fresh herbage for a long time in the year.
Why should I consider extending the grazing season?
- The extra days at grass reduce the volume of manure generated during the housing and therefore reduce ammonia emissions and other greenhouse gases.
- According to Teagasc, for every 10 days increase in the grazing season, there is a 1.7% reduction in GHG emissions.
- Every extra day grazing in spring is worth on average €2.70/cow/day(Teagasc media)
The following video provides information on the importance of extending the grazing season and how this could be achieved on dairy farms.
How to extend the grazing season?
- The autumn rotation planner is a tool to help extend the grazing season into late autumn and if followed, will ensure that paddocks are set up correctly for grazing the following spring.
- Build average farm covers by increasing rotation length to more than 35 days from mid-September.
- Options for building grass covers include increasing supply (nitrogen supply, more growing area) and reducing demand (reducing stocking rate, introducing silage).
- In spring ground and weather conditions can prove difficult and thereby reduce grazing opportunities.
- Grazing management is crucial, for instance by using the on/off techniques, cows can be retained at pasture during periods of heavy rainfall without any poaching damage.
Economic and Environmental Benefits
Increasing days at grass represents a saving by either reducing the costs of concentrates or increasing milk production. Extending the grazing season reduces the volume of manure generated during the housing period and therefore reduces ammonia emissions and other greenhouse gases.
To quantify the economic and environmental benefits of increasing days at grass for a herd of 84 cows, two scenarios were presented in Table 4 below.
|Scenario 1||Scenario 2||Scenario 3|
|Extra 2 days||Extra 7 days|
|Days at grass||233||235||237|
|Extra milk revenue(€)||–||538||1883|
|Emissions(kg CO2-eq / kg FPCM)||0.95||0.949||0.945|
|Reduction in emissions (%)||0.11||0.53|
Stocking rate is 2.05 LU, 41ha, 84 cow herd total farm area soil drainange is average
Net savings/ cost are the savings or cost per year for the farm
Research at Farm Zero C
Research within FZC goes on to model the likely emission reductions of increasing the days at grass without compromising productivity. Preliminary findings have found a 2.4% reduction in greenhouse gas emissions when grazing season has been extended by 5 days due to reduced use of concentrates.
The key findings from previous research show that:
- Grazed grass offers Irish livestock farmers an economic advantage over their European counterparts as the grass is cheaper and locally grown (ifac.ie, 2018).
- On average each additional tonne of dry pasture matter used increased gross profit by €278 and net profit by €173 on dairy farms in Ireland (Hanrahan et al., 2018).
- The average number of grazing days in Irish grass-based systems is 235 and it differs across regions.
- Grazing days could be increased from 213 to 273/ year resulting in increased grass utilisation, milk and milk solids production, and reduced annual supplementary feed requirements (Cahill et al., n.d.).
- Significant cost reduction could be realised by increasing days at grass (Läpple et al., 2012).
Links to more research
Strategies to extend the grazing season
Factors associated with profitability in pasture-based systems of milk production
Grass – The key competitive advantage in Irish farming
Extending the grazing season as a strategy help farmers meet the following climate change targets and regulations.
The Nitrates and water directive
Ag Climatize roadmap 2021– Extending days at grass indirectly contributes to the reduction in supplementary protein concentrates fed to dairy cows in sync with the following action plans of the roadmap to climate-neutral agriculture.
- “Action 6: Reduce the crude protein content of livestock feeding stuff to 15% to minimise ammonia loss.”
- “Action 8: Increase the proportion of home-grown protein in livestock rations to reduce over-reliance on imported feed ingredients.”
This is a management strategy which does not require suppliers’ information.