Grazing management systems

By Regional Agricultural Landcare Facilitator Rohan Leach, May 2020

With welcome rains and groundcover re-established over much of the Central West region, growers should be assessing their grazing systems to ensure they are getting the most out of their pastures. Farmers should aim to have a flexible grazing system that suits their management style and enterprise mix.

Grazing systems can be categorised broadly into continuous grazing, also called “set stocking”, and rotational grazing.

Continuous or “Set Stock” Grazing

Continuous grazing refers to systems that allow constant grazing pressure on a paddock from livestock with no breaks between grazing events. These systems are generally stocked at levels calculated to enable grazing year round. However, some supplementary feeding may be necessary to fill feed gaps during low growth periods.

Continuous grazing allows livestock to selectively graze more freely which puts pressure on the more palatable pasture species. While individual animal performance will be higher, pastures tend to degrade over years with grazing tolerant plants (usually unpalatable weeds) coming to dominate the pasture stand (Michalk et al, 2003).

Another feature of this system is the ease of animal husbandry and management. Minimal stock movements requires less direct labour inputs and allows animals at parturition (birth) to be managed more suitably. Small mobs sizes which are a feature of continual grazing mean that mismothering is minimised (AWI & MLA).

Table 1: Suggested mob sizes in sheep

Source: Making More from Sheep, Module 10: Wean More Lambs

Rotational Grazing

Rotational grazing is used to describe systems where stock are constantly moved from one paddock or pasture to the next. It allows the pasture to be rested between grazing events with grazing focused on the stage that pasture is most nutritious in its growth cycle. Rotational grazing typically employs higher stocking densities then continual grazing. There are many different styles or schools of thought with rotational grazing with the basic difference being periods between grazing and stocking density.

Graziers that rotationally graze are generally looking at a balance between two major factors; dry matter (DM) levels and pasture growth stage. It is difficult to decide when to initiate grazing as increasing DM levels typically lead to lower pasture digestibility as plants move from a highly digestible vegetative phase to a low digestibility reproductive phase. Maintaining pasture levels of at least 1,200 kg DM/ha is suggested for maximum pasture utilisation with grazing to commence when levels reach 2,500 kg DM/ha (MLA). To roughly estimate DM:

• Dense, high rainfall, high fertility, 100% green pasture 1 cm = 300 kg/ha
• Lower density, lower fertility pasture 1 cm = 200 kg/ha
• Open, low density pastures 1 cm = 150 kg/ha

Figure 1: The MLA Pasture Ruler. It gives an estimate on pasture dry matter based on pasture height.

Time control, herd, cell, crash and Management-intensive Grazing (MiG) are but a few of the terms used to describe different systems of rotational grazing. While they all have slightly different philosophies and methods, they share the central principles of high stocking rates on confined areas, limiting the amount of time that animals are grazing an area.

As stock have less time to graze an area, selectivity of grazing is reduced. Livestock are then forced to eat less palatable species as well which means that graziers can manage their pastures with species selection in mind (Popay & Field, 1996). Less desirable plants can be reduced while more palatable species are given breaks to replenish and persist in the pasture (Dowling et al, 2004). However this does come at a cost to animal production as animals are eating less nutritious pasture.

Initial infrastructure costs can be also be a hindrance in adoption of this practise. Subdivision of existing pastures with permanent fencing can be time consuming and expensive with ongoing maintenance of electric fences increased compared to that of conventional fencing. Additional water infrastructure should also be factored in, with transportable watering points a cheap, but labour intensive option.

Each system has its positives and negatives with some producers deciding a balanced approach combining aspects of both continual and rotational grazing, better suits their grazing objectives. Often this will be termed tactical grazing. Research has been variable on which system has been the most profitable for landholders (Heidschmit et al, 1990, McKosker 2000, Michalk et al, 2003), however it fundamentally comes down to individual management. A well run continuous grazing system will be more profitable than a poorly managed rotational grazing system and vice versa.

If you would like to know more about grazing systems and how you can apply them to your business get in contact with our Ag Advisory Team. Alternatively, see the references section and use Tool 7.5, ‘Grazing management guidelines for individual species’ found here.

References

Australian Wool Innovation and Meat & Livestock Australia. Making More from Sheep, “Module 10: Wean More Lambs, Procedure 10.3, Keep maximum number of lambs alive to weaning”. Retrieved from: http://www.makingmorefromsheep.com.au/wean-more-lambs/procedure_10.3.htm

Australian Wool Innovation and Meat & Livestock Australia, Making More from Sheep, “Module 7: Grow More Pasture, Tool 7.5, Grazing management guidelines for individual species”. Retrieved from: http://www.makingmorefromsheep.com.au/grow-more-pasture/tool_7.5.htm

Dowling, P., Leys, A., Verbeek, B., Millar, G., Lemerle, D. and Nicol, H. (2004) ‘Effect of annual pasture composition, plant density, soil fertility and drought on vulpia (Vulpia bromoides), Australian Journal of Agricultural Research, Vol. 55, pp 1097-1107

Heitschmidt, R., Conner, J., Canon, S., Pinchak, W., Walker, J., and Dowhower, S. (1990) ‘Cow/Calf Production and Economic Returns from Yearlong Continuous, Deferred Rotation and Rotational Grazing Treatments’, J. Agr. Prod., Vol. 3 pp. 92–99.

Meat & Livestock Australia (MLA), EverGraze Project, Future Farm Industries CRC. Retrieved from: https://www.evergraze.com.au/library-content/estimating-pasture-growth-on-your-farm/

McCosker, T. (2000) ‘Cell Grazing – the first 10 years in Australia’, Tropical Grasslands, Vol. 34, pp. 2017-218

Michalk, D., Dowling, P., Kemp, D., King, W., Packer, I., Holst, P., Jones, R., Priest, S., Millar, G., Brisbane, S. and Stanley, D. (2003) ‘Sustainable grazing systems for the Central Tablelands, New South Wales’, Australian Journal of Experimental Agriculture, Vol. 43, pp 861-874

Popay, I. & Field, R. (1996) ‘Grazing Animals as Weed Control Agents’, Weed Technology, Vol. 10, No.1, pp. 217-231