Utilisation and carrying capacity
Pasture utilisation is one of the key profit drivers for a grazing enterprise and is also important in managing land condition.
Pasture utilisation requires balancing how much pasture is grown with how much is eaten by livestock.
Using more of the green pasture grown throughout the year is the most cost effective way to lift the productivity of a grazing enterprise. Grazing managers should aim to convert the largest amount of pasture energy and nutrients into saleable product while leaving pasture residue in the best condition for rapid regrowth.
Optimal utilisation is achieved by identifying the stocking rate and stocking density (the number of stock per unit area) that an enterprise can sustain to maximise green pasture utilisation. The number of animals will depend on the nature of the enterprise (breeding and/or trading), but should be sufficient to ensure high utilisation of the pasture grown while maintaining the long-term sustainability of the pasture and the grazing system.
To achieve an increase in pasture use, a plant-based grazing management approach that considers seasonal plant growth patterns should be adopted. This approach should be underpinned by a grazing plan which determines the stocking densities and grazing durations for the pastures within an enterprise.
In developing such a plan, a producer will need to consider:
- Feed supply and demand.
- Stocking rates required to achieve increased utilisation.
- Pasture monitoring (quality, quantity and ground cover) to help determine grazing start and finish times.
- Feed budgeting to determine grazing duration.
- Livestock categorisation to help match animal requirements to pasture type.
Long-term carrying capacity
Long-term carrying capacity refers to the average number of animals that a paddock can support over a planning period (5-10 years) and depends on the:
- Mix of land types.
- Condition of these land types.
- Evenness of use by livestock.
- Feed accessibility due to water availability and geography.
- Grazing strategy or method.
- Goals for animal production and land condition.
Calculating the long-term carrying capacity provides an indication of the safe stocking rate under a set stocking regime and provides a benchmark for projections, forecasting and ongoing management. It is important to remember that the long-term carrying capacity may not always correspond with the short-term carrying capacity, and seasonal adjustments may be required to optimise pasture utilisation and land condition.
Short-term carrying capacity
Short-term carrying capacity is the number of livestock a paddock can support in the short-term and differs from long-term carrying capacity due to variations in rainfall.
The three broad approaches to managing variation in short-term carrying capacity are:
- Conservative approach, which plans for little variation in livestock numbers over time (set stocking).
- Opportunistic approach, where the base number of animals changes little over time, but uses temporary stocking-up to take advantage of runs of wetter years and stocking-down when conditions are poor.
- Trading approach, where livestock numbers are frequently adjusted in line with short-term carrying capacity.
All three approaches require careful monitoring of land condition, animal condition, forage supply and markets to avoid a decline in land condition that can affect profitability.
Feed budgeting is the practice of balancing the amount of feed on offer against the feed demand to maintain land condition and meet production targets. Feed budgeting answers two key questions:
- How long will a paddock last when grazed by a defined number of livestock?
- How many livestock can I put into a paddock while still maintaining a desirable level of residual pasture cover?
When stocking paddocks from year-to-year based on the long-term carrying capacity, feed budgeting is recommended to anticipate and avoid periods of either over-grazing or under-grazing. Feed budgeting can also be used to support short-term carrying capacity stocking strategies.
Achieving a balance between stocking according to the long-term carrying capacity and the short-term carrying capacity based on feed budgeting is the key to optimal pasture utilisation.
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