2-Determine the grazing duration

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Select a paddock and determine grazing duration to achieve best utilisation and animal performance targets

Guidelines to achieving best utilisation and animal performance

Select grazing paddocks to meet production targets

Select a paddock using pasture objectives (growth phase, mass and quality) that meet animal production targets. Complete the following tasks to determine predicted production levels and expected daily pasture intake by cattle:

  1. Define the class of cattle (sex, weight, stage in reproductive cycle for females) and daily growth target (to gain or lose weight at a specified rate).
  2. Use the MLA Pasture Ruler (see Tool 3.1) to look up the pasture performance criteria (minimum quantity and quality) required to achieve production targets.
  3. Refer to Tool 3.5 to determine the average daily gain of steers for a range of liveweights, and pasture quantity and quality options.
  4. Use the partial budget spreadsheet in MLA's Stocking Rate Calculator to calculate appropriate stocking rate and length of paddock rotation – available from www.mla.com.au.

Best production is achieved when paddocks are grazed no longer than three days

In most grass and legume-based pastures, the best utilisation and animal productivity are achieved when grazing is completed between a minimum of one day and a maximum of three days in each paddock of the planned grazing sequence. In some paddocks, tactical grazing may be applied to achieve seasonal objectives, for example, to encourage desirable species (eg clover) to set seed and to discourage undesirable species.

Tool 3.4 recommends information that provides the knowledge and skills to lift the efficiency of pasture utilisation, as do 'Chapter 5: Managing pasture weeds' and 'Chapter 8: Grazing Management' of MLA's Towards Sustainable Grazing: The Professional Producer's Guide.

In practice

Where the graze duration is more than three days:

  • pasture regrowth will be re-grazed before leaf area has recovered, reducing stores of soluble carbohydrate in roots and slowing the regrowing process (repeated re-grazing can cause plant death and loss of productive pasture species)
  • animal performance is lowered through wastage (fouling and trampling) of pasture.

Where the graze duration is less than one day:

  • labour and capital (fencing and water) costs are high to accommodate more frequent movements of herds.

If stock numbers are insufficient and grazing pressure is too light:

  • useable pasture is not fully utilised and pasture energy is wasted due to an increasing rate of leaf senescence (death) before the next grazing
  • patch grazing can occur and lead to under- and overgrazing of pasture areas within the grazing unit.

Tactical grazing ensures best pasture use and animal productivity

A combination of tactical grazing and adjusting the cattle class or herd size is the most practical method of ensuring that the grazing duration will achieve best pasture use and animal performance targets. If pasture mass exceeds the desired maximum and a larger herd is not available, consider maintaining pasture quality through fodder conservation (if cost-effective) or pasture topping by mowing, slashing or spray-topping (late herbicide application to prevent weed seed-set). Generally, spray-topping or leaving the standing dry matter to be eaten later is your best option if this is a feed surplus heading into summer or a period of limited growth.

What to measure and when

Calculations are based on:

  • available pasture for cattle to graze (see Tool 3.1)
  • an estimate of short-term stocking rate (see Tool 3.5)
  • pasture allowance, including wastage, required for growth or maintenance of various classes of cattle (see Step 2 of Tool 3.5 for a guide)
  • stocking rate over short grazing periods (one day) (see Tool 3.5)
  • stocking rate over longer grazing periods (three days or more) (see Tool 3.5).

The more frequently these calculations are made in the lead up to grazing a paddock in the planned sequence, the greater the precision in determining the grazing duration to achieve best utilisation and animal performance targets.