New research shows how cattle are coping with searing summertime heat while grazing on rangeland, which could help prairie ranchers better understand how to manage their herds in a warming climate.
A University of Alberta study of free-ranging beef cattle looked at their activity during the unusually warm summer of 2021, when temperatures repeatedly rose to as high as 35 C in the province. The researchers found that during heat waves, cattle changed how much they walked and when they were active, focusing their movement during specific times of the day.
The discovery points to "marked behavioural shifts in grazing cattle when there is heat stress," says Edward Bork, a professor of rangeland ecology and management in the Faculty of Agricultural, Life & Environmental Sciences (ALES), and a co-author on the study.
"That's important to understand as extreme temperatures in Western Canada become more common under global warming."
Heat stress can alter a cow's physiology so they burn more energy trying to keep cool, and they may stop eating, lose weight, and produce less milk for their calves.
To measure how extreme weather conditions could affect animals in a northern rangeland like Alberta, the study monitored heifers and young cows with their calves as they grazed on the U of A Roy Berg Kinsella Research Ranch. Cattle were fitted with leg-mounted pedometers, and their movements, including their steps and time spent lying down, were monitored 24 hours a day while they were on pasture from June to August, and again from August to November.
