Justin Sexten: Grazing Tech
With summer in full swing the chores turn to checking cattle, fences, water and grass. Optimistically as you read this your pastures are lush and rain is plentiful. Optimal pasture conditions tend to reduce the need for fence checking. Abundant forage reduces the primary reason most cattle have to wander.
Historically the technology used to manage and monitor pastures was a keen eye on the pasture to see that adequate grass was available, coupled with cattle monitoring to know when it is time to move. In my case, there have been a number of instances where my evaluation of supply and demand was at least a day off and the cattle moved themselves.
This month we highlight a couple articles that evaluate pasture tech to understand grazing behavior and optimal forage use. In her 2017 Agriculture article Jaime Manning and her co-workers at The University of Sydney reported how cattle behavior changes relative to forage availability.
Forage availability was measured before turning cattle out into a paddock and common cattle behaviors: grazing, walking, standing, resting, and ruminating, were tracked during the 15 day grazing period. This longer grazing period in a fixed pasture is similar to a continuous pasture management approach where cattle graze existing and regrowth forage.
As one might expect, forage availability declined. Across the paddock the average forage on offer dropped from 1,962 to 446 lbs per acre. While forage was not limiting on average, the distribution of grazing pressure was not uniform. Longer grazing periods allow cattle selective grazing near water, shade and other resting areas resulting in overgrazed areas.
The variable forage cover contributed to the observed behavior changes. Cattle increased grazing time from 31% to 69% of the day. In the middle of the experiment cow collar data showed the distance covered while grazing and walking each day also increased, from about 2.5 miles to 3.1 miles. The work associated with foraging is clearly linked to the amount of forage offered
This experiment was too short to measure performance differences but increased walking, reduced forage availability and greater grazing activity are not likely to increase gain. These data support the managed grazing systems model where small paddocks and short grazing periods provide more uniform grazing pressure and limit the need for cattle to change behavior to support pasture intake.
Small paddocks or pasture sizes are relative to demand, matching forage supply and demand to a 3 to 5 day grazing period is a compromise of fence, labor and grazing efficiency. THe demand side of the equation is reasonably simple if you have accurate weights. The technology to estimate forage supply is more variable.
Adrien Michez and coworkers' recent article in Remote Sensing highlighted inexpensive technology to monitor pasture growth and supply. This Belgium-based research group used commonly available drones to monitor pasture growth.
Drones offer the opportunity to sample large pasture areas quickly under a variety of weather conditions without damaging forage. The drones were outfitted with cameras and sensors to collect data for evaluation by prediction models. While the final package was far from an off-the-shelf product, the test drones were able to generate results comparable to more common research methods.
The experimental drones were more accurate at predicting forage availability than forage quality. These results are consistent with producer expectations as most suggest they run out of quantity before quality becomes limiting.
The technology to assess and monitor forage will continue to advance. The idea of precision grazing seems extreme to most. The number of pasture acres for rent, lease or purchase continues to decline, suggesting the need for improved pasture use will only increase. Acres that are available today are often cost prohibitive to the average beef enterprise.
Simple solutions are available to enhance productivity for most continuously grazed pasture acres. Current temporary fencing options offer the opportunity to nearly double pasture productively using simple pasture divisions. While this technology may not be as exciting as drones, sensors and GPS collars, the off-the-shelf options available today offer increased carrying capacity without additional land investments.
Justin Sexten if vice president of strategy for Performance Livestock Analytics.
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