Guidelines for tactical grazing by planning paddock sequences
These are 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.
• Ensure 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.
• Maintain the pasture mass (kg green DM/ha) of all units above the minimum that supports the intake set for the herd.
• 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:
• The most appropriate animals are allocated for grazing so that animal energy demand matches pasture energy supply;
• Pasture mass is maintained between 1,500kg 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 re-grazing of new growth. Ideally animals are removed when the 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 on which to base decisions about the number of stock to be carried includes:
• Annual pasture growth rate curve and the variation across the farm;
• Likely variability in pasture growth curves over years based on historical weather data;
• Metabolisable energy (ME) value of the pasture when plant phenology changes;
• Energy requirements for each class of livestock at each physiological state;
• Minimum energy content of grass that will allow the energy requirement for each class of livestock to be met;
• Management strategies applied to the breeding herd include timing of calving and weaning, culling strategies and selling ages; and
• 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 of water, erosion and weed invasion; cattle growth rate and weight gain is low.
Phase II
Between about 1,000kg 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 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%) kg green DM/ha at the same height. Conversely, more open, lightly grazed pastures have a lower kg green DM/ha at the same height. The differences due to density are greater at pasture heights above 6cm.
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 no suitable pasture is available.) Using tactical grazing prevents under- and overgrazing of individual paddocks.
• Undergrazing of all or some areas of pasture will waste pasture energy, reduce the rate of pasture growth by shading, and affect quality.
• Overgrazing of all or some areas of pasture will decrease animal intake and reduce the rate of pasture regrowth.
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. This additional pasture will be wasted if not utilised.
• A decrease in predicted pasture growth, or unplanned events that decrease pasture availability. This will lead to declining pasture mass, lowered intake by animals and eventually overgrazing.
• Repeated overgrazing without adequate rest. This leads to a decline in pasture composition, reduced ground cover and soil and environmental degradation.
Tactical grazing
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. There is increasing recognition that ‘tactical grazing’ is the best grazing technique. Tactical grazing uses a range of grazing methods, including strategies such as 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 and able 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 (fencing and water supplies) to allow any grazing method to be used and to enable the switch between methods during the year to meet production targets. Under a rotational grazing system, the changes in management needed to set stock during calving, for example, are simple to implement.
What to measure and when
• Continually check on pasture growth and livestock performance against targets set in the grazing plan.
• Use a range of appropriate pasture assessment techniques to plan and set appropriate targets for each paddock to be grazed.
• Aim to balance the level of animal intake (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.
• Continually monitor pasture and livestock performance and assess against targets.
• Review and re-plan 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 area with temporary fencing, decline in effectiveness.
Planning data
Includes:
• Area to be grazed – hectares
• Target graze period for the paddock(s) – days
• Daily pasture growth estimates
• Initial pasture herbage mass – kg DM/ha
• Initial pasture quality – MJ ME/kg DM (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
Monitoring data
Includes:
Pasture assessment
• Assessed pasture mass in paddock(s) – kg green DM/ha
• Estimated pasture energy content – MJ ME/kg DM
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
