New Research Reveals How Grazing Management Practices Affect Cattle Weight Gain by Altering Foraging Behavior

By Maribel Alonso

Ranchers often rotate cattle seasonally among different pastures on their operations but may allow cattle to graze season-long in a single pasture. Implementing a more intensive rotational system within the growing season—dividing the pasture into smaller areas, or paddocks, and shifting a herd of animals throughout the season—has been suggested to offer a greater chance for more sustainable grazing management. However, there have been very few experimental studies testing these ideas in extensive grazing systems.

A team of researchers at the USDA's Agricultural Research Service is completing a 10-year study on how grazing practices used in these two systems affect cattle foraging behavior, diet quality, and yearly weight gain in semi-arid, extensive rangelands.

The team started by exploring the efficiency of using cattle global positioning system (GPS) tracking collars, combined with activity sensors, to monitor the animals' grazing activities.

"The primary objective of the study was using the sensors to measure the steers' foraging behavior, and relate this to how they are gaining weight," said David Augustine, a research ecologist with the ARS Rangeland Resources & Systems Research in Colorado.

The collars collected precise data based on the animals' feeding habits per day, such as how much time was spent grazing every day, how many steps were taken (grazing speed), the shape of the foraging pathways, and how long each animal lowered their head as a sign of eating (representing the length of meals).

Even though the accuracy of the application is still being refined, results showed that the technology can inform livestock managers about animal distribution and foraging behaviors of free-ranging cattle in extensive rangelands. Being able to monitor foraging behavior continuously in turn allows managers to make more timely decisions on how, when, and where to move cattle within their operation, or to sell cattle at optimal times.