- Average Pasture Cover (APC) is an estimate of pasture quantity on the farm.
- Maintaining APC above 1800kg DM/ha in early spring and between 2000-2400kg DM/ha throughout the season will help maximise growth rates.
- When average pasture cover is low (and the rotation length is not slowed) this may result in pastures being grazed before the 2 leaf stage. Grazing at (or before) the 2-leaf stage reduces growth rates and compromises total pasture DM production.
- By observing changes in pasture cover on a week by week basis, the grazing manager is in a good position to respond to changes in APC before they become critical.
Average Pasture Cover and Pasture Growth Rates in Spring
How to calculate APC
The APC is measured in kg DM/ha and is determined by calculating the cover on each paddock (for pasture measurement and recording see Pasture assessment), multiplying the area of each paddock, adding all these together and then dividing by the total area.
- Estimate pre-grazing cover on each paddock including the one just grazed (grazing residuals figure)
- When all paddocks have been assessed, multiply the area (ha) by pre-grazing cover (kg DM/ha), for each paddock
- Sum all these together, and divide by total area
APC is found by dividing the ‘pasture cover x area’ by the ‘total area’.
Pasture Cover (kg DM/ha)
Pasture cover x Area (kg DM)
(APC: 17,250 kg DM ÷ 8.5ha = 2,030 kg DM/ha)
Rapidly estimating average pasture cover: If you have a large number of paddocks, estimating the average pasture cover can take several hours. It can be estimated roughly by taking the average of the five longest paddocks (with the most feed) and the five shortest paddocks (with the least feed). This is usually quite close to the mark.
The Easy-as APC Assessment Form allows you to group paddocks to calculate APC.
Assessing your average pasture cover
You can create a target average pasture cover range when you are in a steady state situation.
- Minimum pasture cover = (target pre-grazing cover + optimum grazing residual) ÷ 2
- Maximum pasture cover = (maximum pre-grazing cover + grazing residual) ÷ 2
Using a maximum and minimum average pasture cover for the farm helps ensure plans are feasible while ensuring pasture quality remains within an acceptable limit and cows continue to consume target intake. It is a great tool to have on a board in the dairy shed to monitor grazing events with the rest of the team.
Pasture growth rate does not remain constant, nor do rotation length and cow feed requirements. So your minimum average pasture cover will change during the year to reflect changes in target pre- and post-grazing yields.
Similarly, maximum average pasture cover will reflect the maximum pre-grazing cover desired at a time of year. When considering maximum pasture cover, your concern is to maintain pasture quality rather than cow intake.
Managing maximum cover is important as pasture quality deteriorates under high pasture covers.
Average Pasture Cover (APC) targets are important for managing pasture supply. Working to achieve key APC targets will either help ensure there is enough quality feed ahead of the cows or to ensure pasture supply in the following season.
- Achieving your APC target at balance date is important to ensure that the cows have sufficient high quality pasture in peak production months. For more information, see APC at balance date.
- Achieving your target average APC at calving is important for meeting feed demand, and for pasture growth rate and quality. APC at calving will determine how cows are fed for the first two months after calving, see APC targets for calving.
- Having an APC target at dry off is important for transferring autumn grown pasture into early spring. The average pasture cover target is achieved during autumn by increasing rotation length and reducing herd demand (culling, drying off), see Pasture Road map.