Cell grazing involves the very intensive ‘cleaning out’ of small areas within a field or paddock by animals, which are moved on to new pasture in 24 or 48 hours.
Relative to set stocking, it has been identified as a way of potentially improving the performance levels within the cattle sector.
A recent research project completed by scientists at Rothamsted Research in the UK is confirming that cell grazing has positive effects on soil carbon sequestration, pasture growth, and live weight production/ha compared to set-stocking.
The four-year study compared cell grazing (CG), using TechnoGrazing infrastructure, where animals were moved every one to two days to new and set stocking (SS), where animals remained in the same area for the grazing season.
With TechnoGrazing, a block of pasture is divided into a grid of grazing cells, each usually less than 0.1ha, by permanent and temporary fences with fibreglass posts.
Permanent fences are used to form long narrow lanes, and temporary fences are placed across these lanes to form the cells.
Research
According to the Rothamsted study, the cell grazing method achieved substantially higher pasture growth, with dry matter (DM) production nearly 40% higher than SS.
By the third year, CG areas supported double the livestock/ha compared to SS – and produced 140% more liveweight/ha.
Despite more intensive grazing and higher stocking densities, soil carbon content increased in cell grazing enclosures, while it decreased in set stocking, indicating higher levels of carbon sequestration.
In a perfect system, livestock would graze all parts of a field equally. In reality, the animals tend to cluster around features like water troughs, leading to uneven grazing and bare patches.
Cell grazing reduces these problems; animals are evenly rotated around the paddock, grazing more intensively.
The pasture then has the possibility to rest and recover from being eaten and generate new growth.
In contrast, SS approaches may lead to overgrazing of certain areas, affecting pasture productivity.
“These results give the best evidence yet that it’s not the cow, it’s the how,” said Rothamsted’s Dr. Jordana Rivero, who led the CG study.
“In other words, the way you manage your grazing system is important and can deliver beneficial outcomes.
“Cell grazing benefits both the farm productivity and some aspects of the environment. Negative environmental impacts like increased nutrient runoff potential or soil compaction were similar between the two methods,” he added.
The Rothamsted study team found a range of other effects including changes in the botanical composition of the two systems.
Cell grazing
Cell grazing increased the abundance of perennial ryegrass within the sward and maintained levels of white clover, while set stocking led to an increasing abundance of weed species.
“This study is the first time that the two systems have been systematically compared taking into account both productivity and environmental impacts in lowlands in the long-term.
“We found no added environmental costs in cell grazing systems despite its greater stocking densities.
“Moreover, animals in cell grazing plots also had a grazing season three weeks longer, on average, than those in set stocking, potentially reducing cost of winter housing and feeding.”
The Rothamsted study started in 2018 and is still ongoing.
The most recent interim report includes the results collated over the first four years. It involves six enclosures, with three replicates of each method (CG and SS).
Autumn born dairy x beef steer calves arriving at around six-months-old were randomly allocated to groups.
They were grazed for two consecutive seasons with the aim of finishing off grass by 24-months-of-age.
“Long-term trials are critical to assess any intervention applied to productive systems.
“If we are interested in understanding how the components of the system such as soil, plants and animals evolve over time, and how the system adapts to the new management, we need to run extended studies,” said Dr. Rivero.
“The work is ongoing: a couple of week ago, the fourth cohort of calves were turned out to the experimental paddocks to launch the seventh grazing season,” he added.