Sixty years with the cattle industry has created many stories for me — good, bad and funny. Veterinarians don’t get called to many good ones, but there are a few funny stories mixed in with the many tales chronicling sickness and dying. Fortunately, more animals respond to treatment and recover than not. Bills get paid. Everyone is temporarily happy.
Climate change and the fragility that comes with living in an environment that shifts between hot and cold, floods and drought unpredictably, is one of the few things that brings with it some of the saddest stories, the ones that linger and torment.
This past year turned out to be one of the warmest in memory. Range in North America suffered in the hot, dry weather. Water supply in many areas reached critically low levels. Thousands of cattle died from heat and humidity in parts of the U.S. I’ve seen serious bouts of salt poisoning when cattle are deprived of water through periods of heat, then gain free access to fresh water and end up dying.
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Production in feedlots across North America suffered through cycles of heat. Signs of heat stress include:
- Panting
- Increased respiration rate
- Increased water intake
- Loss of appetite
- Listlessness or lethargy
- Increased salivation
- In severe cases, unconsciousness
Hundreds of cattle died from extreme heat and humidity in the mid-U.S. through July as the world recorded its hottest month ever. Climatologists predict cattle production to lose up to $40 billion yearly due to heat stress or nearly 10 percent of the value of production of meat and milk from cattle in 2005 — the scientists’ baseline year.
Canadians recently enjoyed one of the warmest Decembers on record, then faced a polar vortex that dropped temperatures to -45 C in places.
Ranchers found themselves having herds graze fescue under a chinook arch in a manner reminiscent of the first-generation ranches of the early 1900s, then opening bale yards to double or triple feed intake just so cows could cope with the bitter cold. A stark reminder of why early ranches failed without feed reserves.
Over the years cold snaps on the Prairies always spawned cases of “straw bellies” (abomasal impaction) for producers reluctant to provide better-quality feed. Cows can’t eat enough straw to survive. Cold stress or hypothermia occurs when the body’s temperature drops below average (38 C). Beef cattle in Alberta can usually handle -20 C in winter without difficulty. The cold tolerance of cattle amazes me. Enough heat is generated by digestion to sustain them through periods of harsh cold as long as quality feed is provided.
I witnessed late-spring blizzards kill hundreds of head by forcing cows and calves into sheltered areas, then smothering them in banks of wet snow. Calves can be fooled when water bodies are covered with a blanket of wet snow resembling ice. But the snow can’t support the weight of calves. They break through and drown.
There were several instances when ranchers watered cattle from a deep slough in winter. Herds gathered to drink. The ice collapsed, drowning several animals unable to climb out of the ice because of poor footing. Survivors were roped from shore and pulled out of danger by a good saddle horse.
During years of drought, our practice saw multiple cases of green algae poisoning in cattle consuming water from sloughs and lakes when algae blooms were blown against the shores. Or cattle dying when dry sloughs in the spring revealed water hemlock plants, which the cattle subsequently uprooted and ate. The tubers contain cyanide, which kills within a few feet of the slough’s shore.
The death toll from severe weather trimmed the North American cattle herd, already the smallest in decades. Drought in many areas drove ranchers to slaughter cows due to a lack of pasture. The seismic effects of heat were linked to hundreds of human deaths (700 to 800 in B.C. alone). The ecological toll continues to unravel. Canada awaits another season of wildfires. In 2023, 6,500 wildfires consumed 18.5 million hectares of forest or five per cent of the nation’s forest cover, over 10 times 2022’s losses. Smoke choked all provinces from time to time and smothered the northeastern U.S., including New York, for much of the summer. Some doubt Canada will ever be the same again.
We tend to concentrate on the Prairies but heat affects sea creatures as well. Chris Harley, a marine biologist at the University of B.C., walked onto Vancouver’s Kitsilano Beach in late June and smelled death. He estimates a billion seashore animals may have cooked to death. According to Harley, “Carpeting the sea rocks were tens of thousands of mussels, clams, sea stars and snails, emitting a putrid odour that hung thick in the heat.” More than one billion seashore animals living along the Salish Sea coastline may have died as temperatures reached 40 C in Vancouver. Temperatures reached 50 C on the rocky shorelines when tides were low.
An interesting twist to heat tolerance is a project at Thompson Rivers University examining the genetic component of heat resistance in Senepol hybrids, a specially created breed from St. Croix, one of the U.S. Virgin Islands. Dr. John Church and participating producers are examining the heat tolerance of the short-haired breed.
While we can’t control the heat, there are some things we can control to help cattle through it. The following points on handling heat are from the University of Nebraska:
- Water – Make sure cattle have access to plenty of clean water, and that there is enough access space for all cattle, including calves, to get to water.
- Shade – If you have the option, move cattle to a pasture that offers shade, or use portable windbreak panels to provide some shade.
- Air movement – Allow cattle to get into the breeze, if there is one.
- Surface – Access to surfaces covered with vegetation will help cattle keep their temperatures lower.
- Additional stress – Consider rescheduling anything that will add stress to cattle, like gathering, weaning, preconditioning, etc., if that’s an option.
Manitoba producers apply these principles to keep livestock safe amid spring heat domes that frequently hover over the province.
