Managing grazing by alternating water points- determining the effect on grazing patterns, Rockhampton Downs

Summary

Installing multiple water points in large (>120 km2) paddocks requires additional labour and capital, but can influence grazing distribution and improve pasture utilisation. Managing water supply between a number of sources could also be an effective tool for manipulating cattle distribution across extensive paddocks typical of Australia's rangelands. Grazing animal distribution and pasture utilisation are valuable measures of how well rangelands are managed. With the availability of GPS devices for tracking livestock there is a relatively reliable and easy method to quantify the utilisation of different landscape units and distances travelled by cattle based on managing water availability. 
The current use of GPS tracking devices for livestock provides a direct measure of cattle distribution across different landscapes. These devices have been used to measure landscape preferences of Brahman cattle in the subtropical savannas (Tomkins and OReagain 2007) and provide an invaluable tool in measuring livestock distribution patterns relative to property infrastructure and changes in management. This report describes the spatial distribution of 13 breeder cows from two herds of approximately 1000 animals for 8 weeks in 253 km2 and 280 km2 paddocks when water was available from one or three water points, respectively. The study used archival GPS units and was conducted on Rockhampton Downs Station (1856'S, 13511'E) 160 km north-east of Tennant Creek, on the Barkly Tableland Northern Territory, during April - November 2007 (dry season). 
The three initial objectives of this project were to: 
1. Quantify the effect of two rotations in water point access, in a paddock where only one of several watering points operates for a six week period only, on grazing patterns and compare animal distribution across commercial sized paddocks to those in a control paddock, where water is available from a number of sources, over the same time. ​
2. Relate the effect of managing water availability to measured patterns of biomass availability and pasture utilisation. 
3. Speculate on the effects of the grazing system as a whole on grazing distribution through-out the year relative to the control paddock. 


This study was among the first of its kind (see also Hunt et al. 2007) to be applied in an extensive commercial situation in northern Australia. Objectives outlined in the initial proposal relied entirely on functionality of property infrastructure and replication of previous activities where water was managed in a control manner to effect the movement of cattle across the landscape. The project was not able to meet its objectives in terms of quantifying animal distribution as a result of two six week rotations of water point access at different sites. 
Cattle management was affected by the collapse of bores and inability to supply water to nominated tanks. Cattle generally returned to water points they had been accessing prior to the study period and intermittent storms were also reported to scatter cattle across one of the paddocks. The planned second rotation and deployment of GPS units was not conducted due to below average seasonal rainfall and a management decision to destock Rockhampton Downs. Nevertheless, positional data collected during the 8 week period indicated a pronounced bimodality in movement by all collared animals. Cattle travelled between 1.0 and 1.4 km/h when moving between water and grazing areas at dawn and dusk and moved considerably less (0.2 to 0.4 km/h) at other times. Cattle given access to three water points travelled significantly further over 24 h than animals in a similar sized paddock where there was only one water source. 
​While this study has demonstrated that providing additional water points in large paddocks can increase the distance animals travel from water (4.6 v. 4.0 km) and their home range (19% v. 16% of area), the difference was not significant (P > 0.05). Pasture availability (TSDM) in both paddocks increased from