August 17, 2020

Interpretive Summary: Supplement Intake of Grazing Beef Cattle

Interpretive Summary: The influence of age and environmental conditions on supplement intake by beef cattle winter grazing northern mixed-grass rangelands

By: Anne Wallace

Energy needs of cattle increase in cold environments as they must maintain metabolic homeothermy (a consistent core body temperature despite temperature extremes). During winter months, grazing cattle in northern latitudes require feed supplementation to prevent significant productivity losses. However, supplementation is costly, so a better understanding of how to provide extra feed in the most efficient way possible is needed.

In this July 2020 Journal of Animal Science study, researchers studied how age and environmental conditions impacted the supplement intake of grazing cattle. They hypothesized that both these factors would affect grazing behavior and supplementation needs.

Cattle grazing on rangeland pasture were categorized based on age, from year 1 through 6, and a seventh category with cattle greater than 7 years of age. Salt-limited canola meal-based supplements were delivered in a Smart Feed Pro self-feeder system. This feeder enabled an accurate determination of how much supplemental feed was consumed. A HOBO weather station collected information on environmental temperature adjusted for windchill. Cattle were studied over two consecutive winter grazing seasons (December through January each season).

Both age and environmental conditions affected supplemental intake. As age increased, less supplements were consumed by older cows on days with below average temperature (adjusted for windchill) compared to younger cows. Feed intake was adjusted for body weight.

The results of this study found that “in general, younger cows ate more supplement and displayed less intake variation during periods of cold stress than older animals.” The authors also note that their study’s results were contrary to the findings of a previous study (that could only estimate supplemental intake) where older cows were found to consume more feed. Overall, more studies into how to best measure and optimize supplemental feed intake