The Feed Budget Cycle

Effective feed budgeting is the key to meeting the feed requirements of grazing livestock whilst at the same time optimising pasture use efficiency and maintaining pasture quality.

Whether grazing dairy cows, beef cattle, young stock or sheep, having an accurate feed budget shows how much feed is available, how and when to use it, and whether there’s a surplus or deficit coming up in the near future. It also allows action to be taken before a critical situation arises.

The feed budget cycle for pasture management

The basic feed budget cycle is shown below. The feed budget is the plan around which every decision revolves.

How to create a feed budget

The starting point for a feed budget is an assessment of how much grass is in each paddock. This is calculated by multiplying the area of each paddock by the pasture cover (measured in kg of grass dry matter per hectare, kg DM/ha).

  1. Methods for measuring pasture cover

Cutting, drying and weighing pasture samples is the most scientific and accurate method to measure pasture cover, but is slow, time-consuming and destructive to the pasture. To overcome this, rising plate pasture meters were developed as an easy-to-use practical tool for measuring pasture cover in all weather conditions. In terms of accuracy, a good quality Rising Plate Pasture Meter is second only to cutting, drying and weighing pasture samples.

Other methods of pasture cover measurement include sward sticks, pasture probes and quadbike-mounted Rapid platemeters, some of which use GPS (global satellite positioning) technology. However, each can have limitations in accuracy under different weather conditions.

  1. Using a rising plate pasture meter to measure pasture cover

A rising plate pasture meter makes it easy to measure the amount of grass in a paddock, taking into account both grass height and density. During manufacture, the meter’s plate is calibrated for weight and area, so that it is supported a set distance above the ground for a certain grass volume.

In use, the meter is lowered vertically onto the grass, with the shaft dropping through to rest on the ground. The taller and denser the grass, the further off the ground the meter’s plate rests.

Usually, 30 to 50 samples are taken in each paddock to generate an average reading that’s then used to calculate pasture cover.

  1. Calculating total pasture cover

Once the volume of grass in each paddock has been measured, the readings, such as those from the Jenquip Folding Pasture Meters, need to be converted into a total pasture cover value. This requires the use of a formula or equation (see below), and can be worked out simply with a calculator or by using the quick reference charts included in many feed budgeting books.

Nowadays, the electronic counter on meters like the Jenquip Electronic Plate Meter EC-09, or Jenquip Pasture Management Software, can do the hard work for you.

The result is a total pasture cover figure in kg DM/ha.

  1. Calculating total and available pasture dry matter

Multiplying the total pasture cover by the area of the paddock will give the total pasture dry matter in each paddock (kg DM).

Total pasture cover (kg DM/ha) x Paddock area (ha) = Total pasture dry matter (kg DM)

But for a feed budget, it’s the available pasture dry matter which livestock can graze which is needed. Available pasture cover is calculated by subtracting the target residual pasture cover (after livestock have finished grazing a paddock, in kg DM/ha) from the total pasture cover to produce an available pasture cover (kg DM/ha).

Total pasture cover (kg DM/ha) – Residual pasture cover (kg DM/ha) = Available pasture cover (kg DM/ha)

Multiply this by the area of the paddock to get available pasture dry matter.

Available pasture cover (kg DM/ha) x Paddock area (ha) = Available pasture dry matter (kg DM)

The typical recommendation for residual pasture cover for cattle pasture is 1,500kg DM/ha, but this can be reduced to 1,300kg DM/ha, or even lower, for weedy paddocks or where they are required to be grazed out.

  1. Matching livestock feed requirements to available pasture dry matter

Herd or flock daily feed requirements can now be compared to the available pasture dry matter in each paddock, and paddocks split, break-fed or stock shifted accordingly.

This repeated process of pasture measurement, feed budget recalculation and adjustment of grazing pressure is the feed budgeting cycle. It’s a continuous process, with livestock observation used to override and adjust the feed budget if there are any signs of under- or over-feeding, for example.

The result, if carried out correctly, will be livestock that are well fed, minimal feed wastage (optimal use of the grass available) and pastures that are maintained in good condition and producing good quality grazing.

More comprehensive instructions on feed budgeting can be found within the Jenquip Pasture Management Software, and are available from several organisations that run training courses.

Equations and formulas

Standard pasture cover equations / formulas

Dairy pasture:

  • Manawatu and surrounding districts (moderate rainless periods)

Rising Plate Pasture Meter reading x 158 + 200 = pasture cover (kg DM/ha)

  • Taranaki district (reasonably consistent rainfall)

Rising Plate Pasture Meter reading x 158 + 1000 = pasture cover (kg DM/ha)

Sheep pasture:

  • Nationwide

Rising Plate Pasture Meter reading x 200 = pasture cover (kg DM/ha)

Seasonal variation pasture cover equations / formulas

Depending on the time of year, the following equations can be used instead of the standard equations:

  • Winter and early spring (before stem growth)

Rising Plate Pasture Meter reading x 125 + 640 = pasture cover (kg DM/ha)

  • Late spring and early summer (during stem growth)

Rising Plate Pasture Meter reading x 130 + 990 = pasture cover (kg DM/ha)

  • Mid-summer

Rising Plate Pasture Meter reading x 165 + 1480 = pasture cover (kg DM/ha)

  • Early autumn (before autumn rain)

Rising Plate Pasture Meter reading x 159 + 1180 = pasture cover (kg DM/ha)

  • Late autumn (after autumn rain)

Rising Plate Pasture Meter reading x 157 + 970 = pasture cover (kg DM/ha)

LIC seasonal (standardised) pasture cover equations / formulas

Dairy pasture:

  • Winter (April to September)

Rising Plate Pasture Meter reading x 140 + 500 = pasture cover (kg DM/ha)

  • October

Rising Plate Pasture Meter reading x 115 + 850 = pasture cover (kg DM/ha)

  • November

Rising Plate Pasture Meter reading x 120 + 1000 = pasture cover (kg DM/ha)

  • December

Rising Plate Pasture Meter reading x 140 + 1200 = pasture cover (kg DM/ha)

  • January

Rising Plate Pasture Meter reading x 165 + 1250 = pasture cover (kg DM/ha)

  • February

Rising Plate Pasture Meter reading x 185 + 1200 = pasture cover (kg DM/ha)

  • March

Rising Plate Pasture Meter reading x 170 + 1100 = pasture cover (kg DM/ha)

Feed budgeting

For each paddock measured, enter the start and finish readings from the bottom counter on the Jenquip Manual Plate Meter, along with the number of measurements taken shown on the top sample counter. For electronic Rising Plate Pasture Meters or if assessing by eye, simply enter the pasture cover (kg DM/ha).

The Jenquip Pasture Management Software will automatically calculate the total pasture cover (kg DM/ha) and total pasture dry matter (kg DM) for that paddock, along with average and total values for the entire farm.

Target levels can be assigned to each paddock, usually set to match target residual levels of pasture cover after grazing. This allows some paddocks (e.g. young grass) to be grazed lighter than others.

Available pasture cover and available pasture dry matter values are automatically calculated as the difference between measured totals and assigned target residuals.

Results can be viewed and printed off in four different reports. Reports are permanently stored in the program against the appropriate calendar date for later review.

The feed wedge calculation and report is a valuable tool that shows any deficits or surpluses arising in the future. The feed wedge line can be adjusted to assess and evaluate the impact of different feeding strategies.