Methods
A map of my rotational grazing system. The red lines represent physical fences and the yellow shapes are the virtual fence lines. I used virtual fencing to essentially cut each physical pasture in half.
Experimental design
This trial included 51 animals, composed of 49 female cattle randomly selected from a larger herd and 2 bulls selected to breed them. Each animal was equipped with one NoFence virtual fencing collar. There were 8 grazing rotations, each 7 days long, over 6 virtual pastures. Each rotation has been split into three phases: early grazing (the first two days), late grazing (the last two days), and mid grazing (approximately three days in the middle).
Access to grass and water were controlled through virtual fencing. Virtual fencing was also used to rotate the animals from one pasture to another, without physical intervention.
Cattle were weighed before and after the trial (day -11 and 56), and every two weeks during (days 6, 21, 35, and 48). On weighing days the virtual fence was turned off and cattle were manually herded a short distance to the processing facilities. The virtual fence was reactivated with the new pasture when the weighing was complete.
My predictor variables are time, grazing phase, and forage supply (grazing pressure). My response variables are the audio warnings and electrical shocks that the cattle experience.
Data collection
The NoFence virtual fence collars automatically send warning, shock, positional, activity, environmental, and technical data to a cloud storage system, where the data is immediately available.
Forage biomass samples were obtained for each grazing phase (early, mid, and late) of every rotation. 6 samples were taken from the active pasture for each rotation - samples were chosen using stratified random sampling. Areas that represent very little of the total pasture environment, such as vehicle trails and the tops of hills, were excluded. The samples were randomly chosen by tossing a 50cm by 50cm quadrat into an area that is representative of the entire pasture. Litter was discarded and forbs (non-grass plants) were plucked out first and stored separately. Grass that was rooted within the quadrat was clipped to a length of 2cm. All samples were dried and weighed.
Cattle weights were taken every two weeks to monitor forage demand and animal wellness. They were also weighed before and after the trial, as within subject controls.
