The quality of forage on dormant rangeland isn’t sufficient to meet nutrient requirements for cattle, resulting in lost profitability for producers. Researchers with the University of Idaho (UI) Extension are exploring how protein supplements and rotational grazing can assist in maintaining cow body condition.
In 2016 and 2017, UI Extension beef specialist Jim Sprinkle monitored 292 cows from the UI Nancy M. Cummings Research, Extension and Education Center grazing at the U.S. Sheep Experiment Station in Dubois, ID. Cattle grazed dormant rangeland pastures from mid-October to mid-December and were split into four treatment groups.
The first group included cows managed in a continuous grazing system—meaning they stayed in the same pasture—with no supplement; the second group was managed in a continuous grazing system with 7 pounds of a 28 percent crude protein supplement fed once a week at midday; the third group was managed in a rotational grazing system—rotated through at least two pastures—with no protein supplement; and the final group was managed in a rotational grazing system with 7 lbs. of a 28 percent crude protein supplement fed once a week at midday.
A small group of 2-year-old cows (24 cows/year) was fit with collars containing both a GPS logger and an accelerometer. An accelerometer is used on rockets to measure velocity in three directions. It’s also the technology that switches the screen orientation when a smart phone is rotated. Accelerometers were used to determine daily grazing, resting and walking activity.
Results from the study show that the first group—cows that received no supplement and stayed in the same pasture—lost weight. Both groups that received supplements gained weight, and the cattle that received no supplement but had the opportunity to rotate pastures also gained weight. This suggests that providing cattle with a new, previously ungrazed pasture during late-season grazing can be a quasi-form of supplementation.
The study also found that cows receiving protein supplements grazed forage more efficiently than nonsupplemented cows. They spent more time resting and less time futilely searching for better quality forage—expending less energy to graze.
Results from the study will help Idaho producers increase forage harvesting efficiency while minimizing weight loss and reducing subsequent winter feed costs. — UI Extension
