Pasture assessment - DairyNZ | DairyNZ (2024)

Improving grazing through regular assessment

You can only determine what you measure. Regular pasture assessment, such as a weekly or fortnightly farm walk, is important for pasture use. A grazing assessment helps answer the following questions:

• How much grass do I have today?
• How much should I have next week?
• What is the profit or loss?
• How much grass was left when the cows left the pasture?

Regularly assessing your farm's pastures using tools such as forage wedges, spring rotation planners or fall planners, depending on the season, will provide you with important information to make feeding decisions.

Having accurate and timely information about your pastures allows you to tailor the available pastures to what your herd needs. It also helps you determine if you have too much or too little grass. Correct allocation of grassland is essential in the high season to achieve the desired residual quantities and avoid long-term consequences during the season.

Measurement of grassland

There are several ways in which pastures can be assessed and measured. Some commonly used methods include calibrated eye assessment and manual measurement using the Rising Plate Meter (RPM) or an electronic meter or probe. Another approach is a sensor mounted on a quad or ATV, such as the C-Dax Pature Meter (also known as the Rapid Pature Meter).

De Rising Plate Meter en C-Dax Grasmeter

This approximates the grazing mass and puts hard numbers on the grazing plan. They are designed to measure ryegrass and clover pastures and provide a point of reference when more people need to make decisions about pastures.

Calibrated eye or visual grazing assessment

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 advisor or farm team or through occasional comparisons with a tool such as RPM.

Scoring tool for grassland conditions

The Grassland Condition Score Tool is a visual assessment guide that provides an alternative way to compare paddocks for renewal or maintenance, such as fertilization, underseeding or overseeding. Many pastures have less than desirable ryegrass and clover densities due to trampling damage in winter or insects and drought in previous summers.

By assessing the damage in each fold by ranking them from one to five based on visual results, you can create a plan for each fold.

See denScoring tool for grassland conditions.

Admissions and decision support

Regular grassland assessments that are properly recorded (notebook, spreadsheet or in a suitable computer program) can provide valuable information not only for short-term decisions, but also for future management decisions.

Regular grazing data can provide the following:

• Annual growth rates for companies
• Individual fold growth rates
• Seasonal average measures for grassland.

This information can be used to build a feed wedge, increase the accuracy of feed budgeting, and assess pastures for renewal or development.

The feeding wedge and the Spring Rotation Planner are the most important tools for grass management

• UseSpring rotation plannerfrom calving to balance sheet date
• Usefeed wedgeafter the balance sheet date until the autumn.

There are a number of computer programs and software available from commercial suppliers whose purpose is to make decisions based on grazing data.

View programs and providers here:

Effective grazing management

Managing grazing yield and leaf stage allows the right decisions to be made about the grazing sequence, ensuring the right targets are chosen and the targets are achieved before and after grazing.

• Understand your target caps to set the correct rotation length. The rotation length should be set based on your company's leaf stage assessment (seeLeaf stagefor more information on how to set the rotation length), while ensuring that the paddocks are grazed within the desired pre-grazing interval.
• Monitor cow intake and residues. Accurate pasture allocation is driven by grazing assessment (e.g. weekly farm walks).). Skip folding if necessary.
• Consider leaf phase management. Nitrogen-fertilized ryegrass pastures will have higher yields (N increases leaf size) at the lower leaf stages, which may require grazing before the 2½ leaf stage. Consider the feed needs of the farm compared to the amount of pasture being farmed. On farms with higher stocks, a more advanced leaf stage (longer grazing interval) may be more favorable.
• Changes in yield before grazing and unfavorable weather conditions will make it difficult to obtain residual products. During extended periods of high rainfall, target residues may not be achieved, but it is wise to correct these residues where possible (lower pregrazing yield in the next rotation, removal to silage, top).

High meadow shot

To achieve an intake of 16-18 kg DM/cow/day, pre-grazing yields should be limited to between 2800-3200 kg DM/ha to maintain high quality grass for the cows and make it easier for the cows to achieve 1500-1600 kg DM/ha (3.5 - 4 cm) of grazing residues.

Location pasture opname

Where a lower dry matter intake (DMI) is sufficient (14 kg DMI), such as in late lactation, a pasture yield of up to 3800 kg DM/ha can be grazed to 1500-1600 kg DM of pasture residue.

Calculation of grazing coverage

To achieve post-grazing residue and good animal performance, accurate grass allocation is required. This makes it possible to calculate the grazing coverage. (Stock density x grass intake x rotation length) + optimal residue = grazing coverage.

Achieving residual flows after grazing and good animal performance requires:

• Accurate grass distribution
• Calculation of grazing coverage and evaluation of chicken coop roof and rotation length.
• Use of corrective action when goals are not achieved.

Grazing remains

• Grazing residues are the most important indicator of pasture use after grazing. Poor grass utilization results in high residues after grazing, i.e. grazing waste.
• High residues after grazing will suppress the average growth rate of the pasture and reduce the digestibility of the pasture at the next grazing, thus affecting animal performance.
• In late spring, planing perennial ryegrass transitions from vegetative to reproductive growth. This leads to stem elongation, which increases the amount of stem in the pasture that is eaten. If not managed properly, this can lead to a slight increase in residual height after grazing. If this continues when roughage is scarce (e.g. in summer), the cows will be forced to eat lower quality stalks.
• Achieving target residues in the spring will reduce reproductive tillering, minimizing the increase in grazing residues that would otherwise occur.
• Winter provides an opportunity to reset residue levels for the coming season and ensure leaf growth is promoted at the base of the grazing area.

Ccontinuous, even grazing height

For a clovergrass ryegrass, a uniform, even grazing height (little or no clumps) will be 7-8 clicks on the rising plate gauge, 3.5 to 4 cm compacted height or 1500 - 1600 kg DM per have in the spring.

The plate meter will overestimate residues if there are weeds or if there is excavation damage. Grazing remains

Calculation of the growth rate of grassland

It is important to have pasture growth information for your business for strategic planning (e.g. annual feed budgeting, identifying underperforming pastures) but also for tactical management (e.g. predicting a surplus situation)

Grass growth is measured in kg DM/ha/day. Calculating growth rates for your business requires good record keeping. In most cases, software available for forage wedges and grazing data can calculate growth rates at the farm level. The method below allows you to calculate the pasture growth rate at paddock level.

How to calculate growth rates

• Measure the grazing residues per pasture, e.g. 1,500 kg DM/ha
• Measure again before grazing, e.g. 2,800 kg DM to 1,300 kg DM grassland cultivated since the last grazing
• Divide this by the number of days between measurements, e.g. 24 days
• The average growth rate is 54 kg DM/ha/day

You will need: A whiteboard or spreadsheet to record each grazing date per paddock and record the associated coverage before and after grazing.

This information can then be used as guidance for the next grazing round (and subsequent seasons). Storing this information can help you build a database that can be used for feed budgeting purposes.

Average Grass Coverage (APC)

The average grazing coverage is a measure of the amount of grassland on the farm. Having APC targets for the farm at key times of the year is important for managing pasture supply and demand.

Understanding APC

APC is an important indicator of available feed and the most reliable way to budget feed in the short term. The amount of grassland available can be estimated, allowing short-term tactical decisions to be made with relative confidence.

• The Average Grass Cover (APC) is an estimate of the amount of grazing on the farm.
• Maintaining an APC above 1800kg DM/ha in early spring and between 2000-2400kg DM/ha throughout the season will help maximize growth.
• When average grazing coverage is low (and rotation length is not slowed) this can result in pastures being grazed before the 2-leaf stage. Grazing at (or before) the 2-leaf stage reduces growth rate and compromises total DM production from grazing.
• By observing changes in grazing coverage week by week, the grazing manager is well positioned to respond to changes in APC before they become critical.

Average growth rates for pastures and pastures in spring

How to calculate APC

APC is measured in kg DM/ha and is determined by calculating the cover on each paddock, multiplying the area of ​​each paddock, adding them all together and then dividing by the total area.

1. Estimate the pre-grazing coverage on each paddock, including the pasture just grazed (number of grazing residues)
2. When all paddocks have been assessed, multiply the area (ha) by the grazing coverage (kg DM/ha) for each paddock
3. Add these all together and divide by the total area

Example:

APC is found by dividing the 'grass area x area' by the 'total area'.

(APC: 17.250 kg DM ÷ 8,5ha = 2.030 kg DM/ha)

Quick estimate of the average grass area:If you have a large number of pastures, it may take several hours to estimate the average pasture. This can be roughly estimated by taking the average of the five longest folds (with the most feeding) and the five shortest folds (with the least feeding). This is usually quite close to the mark.

Assessment of your APC

You can create a target APC area when you are in a steady state.

• Minimum grazing cover=(target grazing coverage + optimal grazing residue) ÷ 2
• Maximum grazing coverage = (maximum pre-grazing coverage + grazing residue) ÷ 2

Using maximum and minimum average grazing coverage for the farm ensures plans are achievable while ensuring grass quality remains within an acceptable range and that cows continue to consume the target intake. It's a great tool to have on a board in the parlor so you can monitor grazing with the rest of the team.

The growth rate of the pasture does not remain constant, nor do the rotation length and the cow's feed requirements. So your minimum average grazing coverage will change throughout the year to reflect changes in target yield before and after grazing.

Likewise, the maximum average grazing coverage will reflect the maximum grazing coverage desired at any time of the year. When you consider maximum grass cover, you are concerned with maintaining grass quality and not with cow intake.

Managing maximum cover is important as grazing quality deteriorates under tall grass mats.

APC target

Average grazing coverage targets are important for grazing supply management. By working to achieve the most important APC objectives, sufficient quality feed for the cows can be ensured, or the pasture supply can be guaranteed in the following season.

• Achieving your APC target by the balance sheet date is important to ensure that cows have sufficient, high-quality grazing during the peak months.
• Achieving your target APC at calving is important to meet feed demand and for pasture growth rate and quality. APC at calving determines how cows are fed during the first two months after calving.
• Having an APC target during drought is important for transitioning fall grass into early spring. The average grazing cover target is achieved in autumn by increasing rotation length and reducing herd demand (culling, drying).

APC at Afkalven

The degree of grass cover at calving is of great importance. Too much feed means grazing is wasted and growth is reduced. If there is not enough pasture, the cows will become malnourished and pasture growth will decrease.

If there is insufficient pasture, the inter-grazing interval is shortened, resulting in pastures being grazed before the 2½ leaf stage. Grass growth will decline and grazing cover will remain low until summer.

Therefore, the average grazing coverage (APC) at calving (and the amount available) determines how well cows are fed in the first two months after calving.

On this page you can read what you can do if the APC is below the standard at the start of calving.

Calculation of the required APC at calving

• The APC is determined by the calving frequency, coverage on the balance day and strategic decisions about the use of nutritional supplements. For most companies this APC target is between 2200 and 2400 kg DM/ha.
• A formal feed budget is often not necessary if there is sufficient knowledge from previous years to determine the APC on the calving and balance date.
• If you are on a new farm, a feed budget helps determine the amount of feed required (cover, grazing, supplements) and predict the APC at calving.
• Feed budgeting is a prediction based on the best available knowledge. Therefore, gather as much information as possible about the farm's growth rate, soil temperature, nitrogen supply, conditions that can cause feed waste and estimates of feed intake.

If APC is below target

• Face your situation - go to the farm, confirm the extent of any shortfall and make a plan on how to make up for the shortfall over the next two weeks
• Get out of the plan
• Seek advice
• Continue to monitor actual grazing coverage weekly and adjust the plan weekly or biweekly as necessary.

Make a plan

Think about if you can grow more grass?

• Apply nitrogen
• Minimize pugging
• Reduce rotation (feed supplement) to increase APC as quickly as possible.

Can you increase the feed supply?

• Reduce waste to make reserves last longer
• Buy extra food

Or reduce feed requirements and slow down rotation?

• Lower stocking rate (if possible, remove later calves or dry herd from the farm)
• Prioritize the herd and monitor intake, co-intake at calving is significantly lower than peak intake.

APC on balance sheet date

It is important to achieve the average pasture (APC) target at the balance sheet date to ensure that cows have sufficient high quality pasture during peak production months and during mating.

• The balance date is the point at which the pasture growth rate increases to meet the demand for forage.
• The balance date must have the lowest average grass cover (APC) of the season.
• Setting the target balance date APC to a range of 1900-2100 kg DM/ha should ensure that cows are adequately fed while maintaining good quality over the following months.
• Balance sheet date APC can be calculated, after which the number is tested against these factors:
  • Inventory quantity/feed demand – high versus low
  • Predictability of pasture growth as at balance sheet date – reliable versus unreliable
  • Length of rotation - faster or slower
  • Management of surplus feed by the balance date – focus on maintaining quality v. change feed to another period to fill a gap

The importance of average grazing coverage on the balance sheet date

• If the average pasture coverage is too low, the cows will become malnourished and grass growth will decrease.
• If average grazing coverage is too high, pasture quality will decline later in the spring and production will suffer by forcing cows to graze on a lower residual amount than with previous grazing.

The target for the average pasture depends on stocking density and grazing needs per cow (influenced by days since calving, production, breeding and supplementary feeding). This should be the lowest APC will reach all year and most farmers will estimate this to be between 1900 and 2100 kgDM/ha.

Measurements of grass cover and rotation lengths outside this range should be made carefully.

The balance date is the point at which the pasture growth rate increases to meet the demand for forage.

The APC on the balance sheet date is required to prepare the Spring Rotation Planner (SRP). The SRP is then used to compare actual grazing coverage with target grazing coverage, allowing the rotation length to be accelerated or slowed down to bring the farm's average grazing coverage back to target levels.

Does your APC number on the balance sheet date make sense for your company?

Use caution in interpreting this figure as the calculation may indicate grazing cover targets and rotation length targets that are not appropriate for good management (i.e. fast rotations for low cover and slow rotations for high cover are not appropriate management at the balance sheet date).

Other considerations for your balance sheet coverage include:

• If your stocking rate and/or grass growth pattern means that supply will far exceed demand during peak growth in spring, set your APC to the lower end of the 1,900-2,100 kgDM/ha range; And
• If your spring growth is unreliable after the balance date, set your APC at the higher end of the 1,900-2,100 kgDM/ha range.

Please ensure that the fastest rotation length used in this balance date APC calculation is suitable for optimal grass growth and suits your farming system. The rotation period on the balance day is usually 20-25 days. Companies with lower livestock production or companies that use large amounts of supplements can go to a round of 18 days. Companies exposed to very unstable growth rates (80 kg DM/ha one week, 20 kg DM/ha the next week) tend to have lower turnover at the balance sheet date (23-25 ​​​​days), as do companies with high stock. .

For a discussion of rotation lengths in relation to the leaf stage of ryegrassclick here.

Detailed examples of APC measures at the balance sheet date for two situations

High stocking density = feed requirement of 50 kg DM/ha or more on the balance date (3.1 cows/ha x16 kg DM/cow = 50 kg DM/ha/day. Rotation length 23 days = 2075 kg DM/ha average grass cover)

Low stocking density= feed requirement of 42 kg DM/ha/day or less on balance date=(2.6 cows/ha x16 kg DM/cow=42 kg DM/ha. Rotation length 21 days= 1937 kg DM/ha average grass cover)