1-Determine the stocking rate
Determine stocking rate, plan paddock sequences and use tactical grazing to maximise conversion of pasture into beef
Guidelines for tactical grazing by planning paddock sequences
This procedure is the essential link between planning stock numbers for the cattle enterprise and achieving the highest efficiency of green pasture utilisation.
Use pasture assessment techniques to plan and set targets for each paddock to be grazed, and to set the minimum and maximum limits for pasture mass and quality (see Tool 3.1).
Use assessment techniques to calculate pasture mass (kg green DM/ha)
- Ensure the pasture quality (MJ ME/kg DM) of all grazing units within a paddock grazing sequence is within the limits for energy criteria set for the herd (see Tool 3.2).
- Maintain the pasture mass (kg green DM/ha) of all grazing units above the minimum threshold that supports the intake set for the herd (see Tool 3.2). To assist you, Tool 3.3 provides a guide to estimating daily pasture growth rates (kg DM/ha/day) in various regions across southern Australia. MLA’s Stocking Rate Calculator and Feed Demand Calculator can also assist with this task – available on the MLA website: www.mla.com.au.
- Set a residual post-grazing pasture target to manage pasture mass over time.
The highest level of conversion of green pasture into beef can only be achieved when the paddock grazing sequences ensure that:
Balance grazing pressure by matching pasture availability with animal demand
- the most appropriate animals are allocated for grazing so that animal energy demand matches pasture energy supply
- pasture mass is maintained between 1,500 and 2,500kg green DM/ha for as long as possible
- the number of animals allocated for grazing enables the predicted grazing period to be achieved, while maintaining pasture mass above 1,000kg green DM/ha to prevent regrazing of new growth (ideally, animals should be removed when post-grazing pasture target reaches 1,500kg DM/ha).
The number of animals an enterprise can carry will be influenced primarily by pasture growth rate and growth patterns, preparedness to use supplementary feed, and the nutrient requirements of each class of animal. Critical information for decision-making about carrying capacity includes:
- annual pasture growth rate curve and variation across the farm
- likely variability in pasture growth curves over time based on historical weather data
- metabolisable energy value of the pasture when plant growth stage changes
- energy requirements for each class of livestock at each physiological state
- minimum energy content of grass that will meet the energy requirement for each class of livestock
- management strategies applied to the breeding herd (timing of calving and weaning, culling strategies, selling ages)
- fodder conservation and supplementation strategy.
This information can be used to establish the number of stock (stocking density or head/ha) the beef enterprise can sustain when maximising the efficiency of green pasture utilisation.
Maintaining pasture at the desired growth phase is necessary to keep the growth rate of cattle on track to meet production targets. Plan the grazing sequence of your paddocks to ensure pasture remains within the limits you set for pasture mass and quality. The growth curve of pastures can be simplified into three phases.
- Phase I – below 1,000kg green DM/ha (for a moderately dense pasture): pasture growth is slow because of insufficient leaf area; prolonged grazing depletes root reserves of perennials so plant survival is at risk and the development of bare areas leads to run-off, erosion and weed invasion; cattle growth rate and weight gain is low at best.
- Phase II – between about 1,000 and 3,000kg green DM/ha (for a moderately dense pasture): the most rapid pasture growth occurs when sunlight is caught by increased leaf area and converted efficiently into pasture growth; cattle productivity is highest; pastures are sustainable.
- Phase III – above about 3,000kg green DM/ha (for a moderately dense pasture): plants are mature, pasture growth is slowing and quality is lower; death and decay of plant material can be greater than the regrowth; root reserves are replenished and seed allowed to set; cattle growth rate is slower as pasture quality declines.
Note: these pasture availability guidelines are indicative only. Very dense, closely grazed pastures will have a higher (up to + 25%) pasture mass at the same height. Conversely, more open, lightly grazed pastures have a lower pasture mass at the same height. The differences due to density are greater at pasture heights above 6cm. On-farm experience will help you determine what is appropriate for your pastures. Using your own data in the Feed Demand Calculator makes the output more valuable.
Manage the grazing system carefully to maintain optimum pasture levels. Use tactical grazing to meet different animal and pasture objectives.
Using tactical grazing prevents under- and overgrazing of individual paddocks. Check the pasture growth, and add or remove paddocks from the grazing sequence to slow down or speed up the rotation. (Supplementary feed can be provided if suitable pasture is not available and feeding is economically viable; a reduction in livestock growth rates may be more economical.) The use of a nitrogen based fertiliser, such as urea, is sometimes a very economical way to increase dry matter availability. Another option is to use gibberellic acid on suitable perennial grass-based pastures to promote winter pasture growth.
- Under-grazing of all or some areas of pasture will waste pasture, reduce the pasture growth rate as a result of senescence and shading, and lower pasture quality.
- Overgrazing of all or some areas of pasture will reduce animal intake and the growth rate of pasture regrowth.
Tactical grazing is easy to implement when a rotational system is already in place
Any failure to detect a change in pasture quantity and quality or animal demand will increase the risk of missing pasture and animal production targets. Overall productivity will be reduced by:
- an increase in predicted pasture growth leading to higher pasture mass and total pasture energy supply (additional pasture will be wasted if not used)
- a decrease in predicted pasture growth, or unplanned events that decrease pasture availability, which will lead to reduced pasture mass and animal intake, and eventually overgrazing
- repeated overgrazing without adequate rest, which leads to reduced pasture composition and groundcover, and soil and environmental degradation.
The loss of a perennial-based pasture is a large economic loss. For example, it costs more than $400/ha to re-sow a perennial pasture when taking into account agistment, seed and lime, if required (refer to the Pasture Improvement Calculator on the EverGraze website: www.evergraze.com.au/tools.htm).
Use tactical grazing to meet different animal and pasture objectives
Successful beef producers find that strict adherence to either set stocking or rotational grazing is not the best way to achieve herd or enterprise targets. Tactical grazing is the preferred grazing technique.
Tactical grazing uses many grazing methods, including set stocking and rotational grazing, throughout a single year or series of years, to meet different animal and pasture objectives at various times. A tactical approach to grazing must be flexible to adapt to different animal and pasture objectives. This enables a balance to be struck between the demands of various classes of stock for growth rate, reproduction and maintenance, and balances pasture supply with animal demand.
Tactical grazing is a relatively easy concept to implement on farms that already have some form of rotational or deferred grazing system. Such farms will already have the infrastructure (ie fencing and water supplies) to use any grazing method and to switch between methods to meet production targets. For example, management changes are simpler to implement if moving from a rotational grazing system to set stocking during calving.
Further information on successful grazing management practices and tactical grazing is provided in 'Chapter 8: Grazing management' of MLA's Towards Sustainable Grazing: The Professional Producer’s Guide.
What to measure and when
- Regularly check pasture growth and livestock performance and assess against targets set in the grazing plan. Tool 3.3 provides a guide to estimates of daily pasture growth rates across southern Australia.
- Use a range of pasture assessment techniques (Tool 3.1) to plan and set appropriate targets for each paddock to be grazed.
- Aim to balance the level of animal intake (ie head/ha x intake/head should be equivalent to pasture growth/ha) in relation to predicted pasture growth rate to give the best pasture utilisation in targeted and longer grazing events.
- Review and revise fortnightly or weekly, according to the needs of the stock class and pasture management.
The longer the grazing period, the more critical monitoring becomes as other controls, such as grazing duration and manipulation of grazed areas with temporary fencing, decline in effectiveness.
- area to be grazed (ha)
- target graze period for the paddock/s (days)
- daily pasture growth estimates (see Tool 3.3 or pasture curves from the Feed Demand Calculator)
- initial pasture herbage mass (kg DM/ha)
- initial pasture quality (MJ ME/kg DM, or simply M/D)
- predicted pasture growth for the graze period (kg DM/ha/day)
- predicted animal intake for each class of allocated animals (kg DM/day).
- pasture assessment assessed pasture mass in paddock/s (kg green DM/ha)
- estimated pasture energy content (MJ ME/kg DM, or simply M/D)
- animal assessment
- individual and average initial body condition (fat) score
- current (field) estimate of range in condition score
- weight of animals at last weighing
- current (field) estimate of weight range
- current liveweight.
- Towards Sustainable Grazing: The Professional Producer’s Guide available from MLA at www.mla.com.au or by phoning 1800 023 100.