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Regular pasture assessment on your dairy farm helps you manage your herd's feed, plan grazing, and detect surplus or deficit in pasture. Using tools like feed wedges and rotation planners, you can measure pasture availability and use the data for feeding decisions. Measurement can be done visually, or using devices like the Rising Plate Meter or the C-Dax Pasture Meter. Record your assessments to monitor growth rates and set cover targets. Software solutions also exist for pasture data analysis. Managing grazing effectively improves pasture quality and cow performance. Your end goal should be optimising pasture consumption and maintaining desirable grazing residuals.
You can only manage what you measure. Regular pasture assessment such as a weekly or fortnightly farm walk is important for pasture utilisation. A pasture assessment will help answer the following:
Assessing your farm's pasture regularly, using tools like feed wedges, spring rotation planners, or autumn planners depending on the season, gives you important information to make feeding decisions.
Having accurate and timely information about your pastures helps you align the available pasture with what your herd needs. It also helps you identify if you have too much or too little pasture. Properly allocating pasture is crucial during the peak growing season to reach desired leftover amounts and avoid long-term consequences throughout the season.
There are several ways that pastures can be assessed and measured. Some of the common methods are calibrated eye assessment and manual measurement using the Rising Plate Meter (RPM) or an electronic meter or probe. Another approach is a sensor attached to a quad or ATV bike such as the C-Dax Pasture Meter (also known as the Rapid Pasture Meter).
This approximates pasture mass and puts hard numbers on the grazing management plan. They are designed to measure ryegrass and clover pastures and provide a point of reference when several people are making pasture decisions.
This can be as good as any current tool, but requires practice and calibration. Calibration can be achieved through DairyNZ discussion groups, regular farm walks with a farm consultant or the farm team, or through occasional comparison with a tool like the RPM.
Pasture condition score tool
The pasture condition score tool is a visual assessment guide which provides an alternative way to compare paddocks for renewal or maintenance such as fertiliser, under or oversowing. Many pastures have less than desired density of ryegrass and clover because of treading damage in winter, or insect and drought during the previous summers.
Assessing the damage in each paddock by ranking them one to five based on visual scores, can help establish a plan for each paddock.
See the Pasture condition score tool.
Regular pasture assessment, which is well recorded (notebook, spreadsheet or in a suitable computer program) can provide valuable information not only for short term decision making but also for future management decisions.
Regular pasture data can provide:
This information can be used to build a feed wedge, increase accuracy in feed budgeting and to assess paddocks for renewal or development.
The feed wedge and the Spring Rotation Planner are the most important tools for pasture management
There are a range of computer programs and software available through commercial suppliers aimed at helping make decisions from pasture data.
View programs and suppliers here:
|AgHub pasture management tools and P-Plus software||GPS-it|
|Agrinet||Irish Farm Computers Ltd|
|Feed wedge ready reckoner||DairyNZ|
|FeedFlo||Agricultural Software Limited|
|Land and Feed||LIC|
|Pasture Coach||Pasture Coach|
|Pasture Management software||Jenquip|
|Rotation (your grazing rotation planner)||Farm-Market Media Ltd|
|Smart Maps||Ravensdown/ CDax|
All programs offer a feed wedge and some products provide additional reporting tools. Examples of other functionality that may be included is below.
◦ Farm mapping
◦ Pasture cover reports
◦ Feed budgets
◦ Feed wedge
◦ Fertiliser usage
◦ Rotation planner
◦ Pasture growth rates
◦ Daily planners
◦ Predicted/ forecasted growth rates
◦ Rotation length
◦ Mobile access
◦ Ability to import/export data
Over 12 months most paddocks will have 9 to 10 grazings. It only takes one poor grazing event to adversely impact the next 2 or 3 grazing events.
Pasture allocation affects the quality and quantity of pasture at future grazings. The purpose of allocating pasture accurately is to optimise both pasture eaten per ha and animal performance. This requires having targets pre and post-grazing, measuring regularly, and planning the grazing event.
Managing grazing yield and leaf stage will enable the correct decisions around grazing order, ensure the right targets are chosen, and pre-grazing and post-grazing targets are achieved.
To achieve intakes of 16-18 kg DM/cow/day pre-grazing yield must be managed at between 2800-3200 kg DM/ha to maintain high quality pasture in front of the cows and make it easier for the cows to reach a 1500 -1600 kgDM/ha (3.5 - 4cm) grazing residuals.
Where lower dry matter intake (DMI) is sufficient (14 kg DMI), such as in late lactation, pre-grazing yields up to 3800 kg DM/ha may be grazed to a 1500-1600kg DM grazing residuals.
Achieving post grazing residuals and good animal performance requires accurate pasture allocation. This allows you to calculate pre-grazing cover. (Stocking rate x pasture intake x rotation length) + optimum residual = pre-grazing cover.
Achieving post-grazing residuals and good animal performance requires:
For a ryegrass clover pasture a consistent, even grazing height (few or no clumps) will be 7-8 clicks on the rising plate meter, 3.5 to 4 cm compressed height or 1500 - 1600 kg DM per ha in spring.
The plate meter will over estimate residuals where there are weeds or there is pugging damage. Grazing residuals
It is important to have pasture growth information for your farm for strategic planning (e.g. annual feed budgeting, identify underperforming paddocks) but also for tactical management (e.g. predicting a surplus situation)
Pasture growth is measured in kg DM/ha/day. Working out the growth rates for your farm requires good record keeping. In most cases, software available for feed wedges and pasture data can calculate growth rates at a farm level. The method below will allow you to calculate pasture growth rates at a paddock level.
What you need: a board or spreadsheet to record each grazing date for each paddock and to record the corresponding pre-grazing and post-grazing cover.
This information can then be used as a guide for the next grazing round (and following seasons). Saving this information will allow you to build up a file of data that can be used for feed budgeting purposes.
Average Pasture Cover is the measure of the quantity of pasture on the farm. Having APC targets for the farm at key times of the year is important for managing pasture supply and demand.
APC is a key indicator of feed on hand and is the most reliable way of feed budgeting in the short-term. The amount of pasture on hand can be estimated enabling short-term tactical decisions to be made with relative confidence.
The APC is measured in kg DM/ha and is determined by calculating the cover on each paddock, multiplying the area of each paddock, adding all these together and then dividing by the total area.
APC is found by dividing the ‘pasture cover x area’ by the ‘total area’.
|Paddock No.||Area (ha)||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.
You can create a target APC range when you are in a steady state situation.
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-grazing 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 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.
The level of pasture cover at calving is very important. Too much feed will mean that pasture is wasted and growth may be reduced. If there is insufficient pasture, the cows will be underfed and pasture growth reduced.
If there is insufficient pasture the inter-grazing interval is reduced, resulting in pastures being grazed before the 2½ leaf stage. Pasture growth will be reduced and pasture cover will stay low until the summer.
Therefore average pasture cover (APC) at calving (and supplements available) determine how well cows are fed for the first two months after calving.
This page covers what you can do if APC is below target at the start of calving.
Achieving the target average pasture cover (APC) at balance date is important to ensure that the cows have sufficient high quality pasture in peak production months and during mating.
Target average pasture cover is dependent on the stocking rate and the pasture demand per cow (influenced by days since calving, production, breed and supplement fed). This should be the lowest that APC will reach all year and most farmers will set it within the range of 1900 – 2100 kgDM/ha.
Pasture cover targets and rotation length targets outside this range should be managed carefully.
Balance date is when pasture growth rate increases to meet feed demand.
APC at balance date is required to set up the Spring Rotation Planner (SRP). The SRP is then used to monitor actual pasture cover against target pasture cover, allowing rotation length to be sped up or slowed down to bring the farm’s average pasture cover back on target.
Is your balance date APC number sensible for your farm?
Take care interpreting this figure, as the calculation can signal pasture cover targets and rotation length targets that are not appropriate for good management (i.e fast rotations for low covers, and slow rotations for high covers are not appropriate management at balance date).
Other considerations for your balance date cover include:
Ensure your fastest rotation length, used in this balance date APC calculation, is appropriate for optimum pasture growth and suits your farm system. The rotation length at balance date is usually 20-25 days. Lower stocked farms or farms using high amounts of supplements may go to an 18 day round. Farms that are subject to very volatile growth rates (one week 80 kg DM/ha the next week 20 kg DM/ha) tend to have a slower rotation (23-25 days) at balance date, as do high stocked farms.
For a discussion on rotation lengths in relation to ryegrass leaf stage click here.
|Stocking rate/feed demand||Predictability of pasture growth after balance date||Rotation length||Controlling surplus feed after balance date|
|1900 kg DM/ha at BD||Suits lower stocked farms||Suits farms with more predictable pasture growth in the months immediately after balance date||Suits farms that a longer rotation (say 25days +) at balance date||Suits farms that are forced to harvest surplus feed to control pasture quality|
|2100 kg DM/ha at BD||Suits higher stocked farms||Suits farms with less predictable pasture growth in the months immediately after balance date||Suits farms that prefer a shorter rotation (say 21 days) at balance date||Suits farms that need to have surplus feed harvested to transfer from one season to another.|
High Stocking rate= feed demand of 50kg DM/ha or more at balance date (3.1 cows/ha x16 kg DM/cow = 50 kg DM/ha /day. Rotation length 23 days= 2075 kg DM/ha average pasture cover)
Low stocking rate= feed demand of 42 kg DM/ha/day or less at balance date=(2.6 cows/ha x16 kg DM/cow=42 kg DM/ha. Rotation length 21 days= 1937 kg DM/ha average pasture cover)
If you would like assistance determining your APC at balance date, contact your local DairyNZ regional team