Optimising the grazing season ensures cows are fed with highly nutritious herbage and reduces the amount of manure stored. This reduces greenhouse gases and costs associated with the purchase of silage and concentrates.
Overview
In Ireland, dairy cows are out grazing on pasture for an average of 241 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?
Extend the grazing season in early spring and late autumn using the following tips.
- Close paddocks from 5-10 October
- Close the farm in rotation
- Target 60% of paddocks closed by 1-7 November
- Don’t regraze closed paddocks
- Target a closing farm cover of 550kg DM/ha
- In spring gradually increase the proportion of grazed grass in the diet of the cow while at the same time budgeting so that there is enough grass until the start of the second grazing rotation
- Target an opening average farm cover of 900 kg DM/ha in early February to ensure that supplementation is kept to a minimum
- Monitor grass covers to ensure that good quality grass is available at all times
- Use on/off grazing during periods of challenging weather
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 93 cows, two scenarios were presented in the Table below.
Reduction of emissions by extending the grazing season
| Scenario 1 | Scenario 2 | Scenario 3 | |
| Extra 2 days | Extra 7 days | ||
| Days at grass | 241 | 248 | 262 |
| Extra milk revenue(€) | – | 1465 | 2930 |
| Environmental Impact | |||
| Emissions(kg CO2-eq / kg FPCM) | 0.960 | 0.950 | 0.934 |
| Reduction in emissions (%) | 1.04 | 2.71 |
The increase in days at grass is 50:50 for Spring and Autumn
Extra day at grass gives an extra €2.70 in Spring and €1.80 in Autumn Savings (Teagasc, 2020)
Research
Research at Farm Zero C
Researchers at FZC modeled the environmental impact of increasing days at grass for Shinagh farm and found that a 7-day extension of grazing days on average reduces the emissions by 1%. This was due to a combination of the following factors. Grazed grass in the early and late seasons is a higher quality more digestible feed than grass silage leading to improvements in animal productivity and a reduction in the proportion of dietary energy lost as methane. The shorter housing season leads to reduced CH4 and N2O emissions from slurry storage.
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 (Läpple et al., 2012).
- 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).
- Extending grazing season results in increased grass utilisation, milk, and milk solids production, and reduced annual supplementary feed requirements (Cahill et al., n.d.).
Links to more research
Sustainable grassland management
Strategies to extend the grazing season
Factors associated with profitability in pasture-based systems of milk production
The effects of extending the grazing season
Regulations
Extending the grazing season as a strategy helps 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.”
Suppliers
This is a management strategy that does not require suppliers’ information.