National Feed Base

Understanding “Green” and “Dead” in the National Feedbase Monitor

Alastair Rayner, 12/10/2023

The release of the National Feedbase Summaries (see examples above) marks the first-time grazing managers have been able to objectively view the levels of feed available at a national, state, regional and local level.

This objective view can be further refined to property scale, 1Ha resolution through the Australian Feedbase Monitor, and to paddock level through subscription to PastureKey.

Beef Central has started publishing fortnightly broad summaries of the trends. Click here to view yesterday’s second fortnightly summary in the series.

Total Standing Dry Matter is reported in Kilograms of Dry Matter per Hectare.  This is important for users of the Cibo Labs imagery to understand.  ‘Dry Matter’ refers to the weight of plant material available without water.

Dry Matter provides a consistent measure to compare feeds and pasture types across grazing environments or when developing livestock rations.  All pastures, crops and feeds contain some degree of moisture. However water offers no nutritional value to livestock.  And, due to the variation in water content depending on stage of growth and even time of day.

Grazing managers are primarily interested in what animals can physically consume and utilise to meet their daily energy requirements.  In order to understand this, the water component of feeds is excluded, and assessments are focussed only on the Dry Matter that is available.

Aside from offering an assessment of the Total Dry Standing Matter, the Cibo Labs Feedbase Summaries also provide updates on the amount of Green and Dead Standing Dry Matter on a per hectare basis.  It is important to understand the difference between ‘Green’ and ‘Dead’, and where these differences can be useful for livestock and grazing management decisions.

The Green component of the Feedbase Summaries use the images captured by Fractional Cover.  Fractional Cover refers to areas which can be observed as being Photosynthetically Active (growing), Non-Photosynthetically Active (Dead) or the image records Bare Ground.

The models used by Cibo Labs calculate how much contribution to the Total Amount of Dry Standing Matter is made up of Green or Dead plant material or areas of bare ground in order to determine the amount reported in the summaries.

Using Green or Dead Summaries

For livestock managers, the key focus is to ensure that the day energy requirements for all livestock classes can be met.  Livestock production is driven by daily energy intake.  In a grazing environment the intake of energy is driven by the amount of feed on offer (described as Kilograms of Dry Matter) and the quality of the feed that is available.

There is a direct relationship between the amount of energy within a feed and its level of digestibility.  Highly digestible feeds, which are often short, green, and actively growing are the most easily digested by livestock and offer the greatest level of energy per kilogram of dry matter.

As plants grow and mature, the level of digestibility along with the energy content available starts to decline.  In pastures dominated by tropical and native species, the levels of digestibility and energy at the same stage of growth are generally lower than temperate species.

Once pasture species enter a phase of late flowering digestibility has often fallen below 60% and once the amount of dead leaf and stem dominates the feed on offer, pasture digestibility is only capable of maintaining liveweight for dry stock and may actually be insufficient to meet the needs of stock that are growing or lactating.

Withing the Feedbase Summaries, pastures that are excessively dominated by Dead Material – that is – dead leaf and stem, users should not be expecting to achieve weight gain in dry stock and may expect weight loss to occur.  However, depending on the amount of material that is reported, producers may be able to improve livestock intake through the use of appropriate protein supplementation in order to promote and stimulate rumen function and digestion of this lower quality material.

Eyes on the Ground still important

While the Feedbase Summaries will accurately describe the Total amount of Standing Dry matter, and the amounts of Green and Dead Standing Dry Matter that are present in the landscape, grazing managers should still look at the actual pastures they have.  This visual assessment will determine at what phase of growth pastures have reached.  This ground truthing will help determine if the green material is sufficient to meet livestock needs or if there is a requirement to grazing practices or introduce supplements to assist in driving intake.

It is important to remember that in Describing the amount of dead material, the Feedbase Summaries are reporting only on the amount of dead leaf and stem that is available for grazing.  It may well be that the parent plant has entered a period of dormancy.  However even though dormant, there are still parts of leaves and stems attached to the plant which could be consumed by livestock.

These attached plant components are technically dead and are reported as such.  This may be useful for producers planning to use dead standing feed to meet specific outcomes that require lower levels of feed digestibility in order to meet a production target, or to know which the most appropriate supplement is to use for that feed quality and for the amount of feed on offer.

 

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Comments

  1. Dionne Walsh Range IQ, 12/10/2023

    Great summary, thank you for clearing up this potentially confusing terminology relating to the Feedbase Monitor. Cheers, Dionne

    • Greg Campbell, 12/10/2023

      Totally agreed with Dionne. A well written summary Alastair.

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