A four-year Meat and Livestock Australia-led research project has reinforced earlier findings that stocking rate management is the major driver of pasture and animal productivity in northern grazing operations, as opposed to the type of grazing system.
The project used nine grazing sites throughout Queensland to compare the effect of cell grazing, rotational grazing and continuous stocking on key attributes such as pasture and soil-surface condition, grazing days generated and diet quality.
The work was based on the premise that many beef producers are considering more intensive grazing systems to remain productive and viable, but are unsure of the costs and benefits of alternative systems.
Part of the attraction of more intensive systems is their perceived potential to increase stocking rates, improve land condition, and enhance animal performance due to factors such as improved spatial distribution of grazing, long spell periods, and maintaining pasture in a vegetative state.
While interest in more intensive grazing systems has grown, there are mixed views, and a lack of positive experimental evidence over their benefits and their suitability for different environments, levels of property infrastructure, management capacities and lifestyle preferences.
Nine properties were selected, with each operating paddocks under at least two of the broad system types of interest – continuous, rotational and cell grazing.
Properties were located in both north and south Queensland and on either brigalow or eucalypt country.
The intensive systems on each property had been in place for up to 10 years prior to the project starting.
During the four-years of measurement from 2006 to 2009, there were initially two or more years at each site of well below average rainfall followed by up to two average rainfall years.
A total of 74 paddocks (54 cell, 13 rotation and seven continuous), across 21 grazing systems (eight cells, six rotational and seven continuous), were monitored for the four year period.
The different grazing systems within a property were not managed independently of each other but tended to be operated as an integrated management system.
This meant cattle could spend time within different systems within the one 12-month period, especially during dry years.
In combination with differences in animal classes between systems at some sites, this precluded attempts to directly assess the impact of grazing system on individual animal productivity.
The researchers noted that the integrated management of paddocks across systems on each property suggested that key management principles, such as matching stocking rate to carrying capacity, were applied to all paddocks on a property to a similar extent.
This helped to explain lack of impact of grazing system per se, and supported extensive evidence that stocking rate management, and not grazing system, was the major driver of pasture and animal productivity.
The final report, completed last month, showed little or no impact of grazing system on pasture attributes or soil surface condition.
Trends in pasture condition and growth were dominated by seasonal conditions, with pastures in all systems responding well to the better rainfall conditions towards the end of the project.
Diet quality (measured by NIRS) was generally lower in the more intensive systems, especially during the growing season.
There was no consistent difference in grazing days per hectare due to grazing system.
There were small but consistent impacts of grazing system on pasture species diversity, with least diversity in cell paddocks and the spatial variability of defoliation, with least variability under cell grazing.
There was a trend, significant in one year, for cell paddocks to have more spatially uniform groundcover.
All paddocks improved in condition during the latter two years of average to above-average rainfall, but the degree of improvement was not affected by grazing system.
Historical analysis (previous 20 years) of trends in annual groundcover (Landsat data using VegMachine software) was done for each monitored paddock at each site. Groundcover levels and trends followed trends in annual rainfall with no influence of grazing system.
Grazing system had no affect on the grazing days per ha per year imposed on paddocks, except for some instances of lower grazing days from rotational systems due, in part, to extraneous factors.
Overall, there were similar numbers of stock days per hectare per year for paddocks within the cell (119) and continuous systems (115). On average, cell and continuous paddocks were grazed somewhat above the objectively assessed values for long-term carrying capacity.
Grazing system affected diet quality as estimated via faecal NIRS. More intensive systems generally had lower diet quality. Over all sites and seasons, the continuous system had 1-2pc higher crude protein and digestibility than the cells, with diet estimates for the rotation system consistently between those for continuous and cell systems.
These differences were largest from samples collected during the growing season and least with samples collected during the dry season.
A grazing system intensity index (GSI) with a scale from 0 to 100 was calculated from three factors: capital costs, operating costs and management inputs. The values for the different systems at the nine sites ranged from 21 to 96. The average GSI for the systems was: cells 79 (range 63-96), rotations 61 (range 45-84) and continuous 26 (range 21-31). However, following on from the results above, GSI was generally unrelated to pasture and animal performance.
While the research found that grazing system or method was "relatively unimportant", researchers stressed that this did not diminish the importance of improved grazing management for the beef cattle industry in northern Australia.
Other grazing research had shown that major opportunities for improved land condition and productivity are based around:
- better spatial distribution of grazing pressure (through location and number of water points, sub-divisional fencing);
- better matching of stocking rate with carrying capacity; and
- targeted use of wet season spelling.
“Producers seeking improved grazing management to achieve improved land condition and/or increased carrying capacity should therefore objectively assess the current long-term carrying capacity for each paddock and systematically identify the most cost-effective opportunities for improvement.
“Most of these opportunities will be based around better spatial distribution of grazing pressure, better matching of stocking rate with variation in short-term carrying capacity, and use of wet season spelling.
“Implementing a more intensive grazing system is one way of addressing these issues, but results from this project strongly suggest that simpler and less expensive management systems will achieve similar outcomes.”
The results were anticipated to have a significant impact on future plans of beef producers across northern Australia in developing their grazing strategies.
“Simply stocking paddocks based on past expectations or subjective criteria, without objective assessment of carrying capacities (both long-term and short-term) is not sufficient to ensure optimal productivity and acceptable land condition," the report said.
“However, intensive grazing systems are not required to achieve such improvements.
“Increased awareness and appreciation of the soil and pasture resource as the basis of a beef business, and the motivation to better manage grazing, arise from association with the training in livestock business management typically associated with promotion of intensive grazing systems.
“It is therefore very likely that implementation of an intensive grazing system is associated with a whole raft of changes in management philosophy and practices across the enterprise that provide producers with greater control and direction.
“The associated benefits for enterprise management could well be significant. Be that as it may, implementation of an intensive grazing system per se is not a pre-requisite for improved grazing management.
“Results from the project have the potential to save the beef industry significant investment in intensification to levels beyond which the owners cease to gain production and land condition benefits.
“There are multiple examples across the northern beef industry of over-intensification causing a waste of resources as the systems are subsequently simplified to management levels that are more acceptable to the owners' abilities, resources and lifestyle choices.”
The research was conducted by MLA in conjuction with Queensland's Department of Employment,Economic Development and Innovation and the Commonwealth Scientific and Industrial Research Organisation.