Thomas Lyons 
A recent study conducted by the United States Agricultural Research Service (ARS) has shown that rotational grazing may not be as effective as previously thought when it comes to beef cattle on range-based systems. This is in stark contrast to the results found on Irish livestock farms, where rotational grazing has been proven to be a successful method. The study compared rotational grazing with continuous grazing options to determine which system allows for more sustainable and profitable free-range livestock production.
Rotational grazing involves rotating cattle seasonally among different pastures on a farm, while many farmers also allow cattle to graze season-long in a single pasture. Implementing a more intensive rotational system within the growing season had been thought to offer a greater chance for more sustainable grazing management. The ARS team completed a 10-year study on how grazing practices used in these two systems affect cattle foraging behaviour, diet quality, and yearly weight gain in semi-arid, extensive rangelands.
The team used GPS tracking collars combined with activity sensors to monitor the animals’ grazing activities. This allowed the researchers to measure the steers’ foraging behaviour and relate it to how they were gaining weight. “The collars collected precise data based on the animals’ feeding habits per day,” said David Augustine, a research ecologist with the ARS Rangeland Resources and Systems Research in Colorado. The use of this technology informed ranch managers about animal distribution and foraging behaviours of free-ranging cattle in extensive rangelands.
In a range-scale experiment, the ARS researchers divided steers into smaller herds in the paddocks of a non-rotational grazing system or managed them as a single large herd in a multi-paddock rotational system. The first five years of data showed that the rotationally managed cattle gained, on average, 14% less weight than cattle in the season-long management system. “Cattle did not have as much freedom to roam and be more selective on what to eat, so they ended up eating what was available in front of them, which was lower quality forages with less protein, and they gained less weight as a result,” Augustine explained. The study showed herds in the multi-paddock rotating system feeding in more linear pathways instead of moving around looking for greener grass and selecting bites of more digestible vegetation. They also fed slower, spent more time on the same patch of grass, and didn’t turn their heads around much while feeding, compared with steers in the continuous grazing system. These behaviours of less selective foraging resulted in a lower diet quality, which led to reduced weight gain during the growing season.
While the results of the study are surprising, it is important to note that they are based on a specific set of conditions in the US. Irish livestock farms have seen success with rotational grazing, and it remains a popular method for managing cattle. However, the study does highlight the importance of considering the specific conditions of a farm or ranch when choosing a grazing method. It also emphasizes the value of technology in monitoring and managing livestock in free-range systems.
Overall, the study conducted by the ARS provides valuable insights into the effectiveness of rotational grazing for beef cattle on range-based systems. While the results may not be applicable to all farms and ranches, they do indicate the need for careful consideration of grazing methods based on the specific conditions of each operation.
