Jaclyn De Candio
Beef circles widely discuss the effects of heat, but cold has an equally serious effect on cattle health and ranch economics. A study funded by the Beef Cattle Research Council indicates that cold stress increases maintenance energy requirements by approximately two per cent for every degree below the lower critical temperature. The physiological challenges that accompany this are many, leading to significant losses in both weight gain and the upcoming calf crop carried by pregnant cows.
The Cost of Cold Stress
To best understand the impact of cold stress, one must first understand an animal’s thermal neutral zone (TNZ). The TNZ isn’t a solid temperature; rather it is the range of “ambient temperatures” where mammals stabilize internal temperatures without expending extra metabolic energy. In this range of external temperatures, an animal’s basal metabolic rate provides ample heat. There is no need to shiver or sweat because the core is naturally consistent.
The TNZ, though, depends on several variables unique to each animal, including age, body condition, breed and productive stage. The typical range for cattle is 0°C to 25°C. Beyond this is the lower critical temperature (LCT) which is the point where animals must increase their metabolic heat production.
“When animals reach their lower critical temperature, they increase metabolic activity to maintain body temperature,” explains Melissa Atchison, research and extension specialist at Manitoba Beef Producers. “This raises feed requirements significantly.”
Therefore, one of the most cost-effective ways to prepare for winter is to keep cattle in good condition with sufficient fat cover.
Kristen Bouchard-Teasdale, livestock and forage extension specialist at Manitoba Agriculture, goes into detail. “In Canada, a body condition score (BCS) of 3.0 (out of 5.0) is considered ideal,” she says. “If cows are thin when they come home from pasture in the fall, it’s important to start improving their condition right away.”
The more weight they lose, the more vulnerable they become to cold stress. Cows that calve in poor condition during winter are harder to breed back in the spring and are more likely to produce lower-quality colostrum and less milk.
A rule of thumb is to provide an extra pound of grain per head per day for every five degrees the temperature is below -20°C at midday.
Cold Weather Feeding Strategies
Every degree below the LCT increases the energy required for maintenance, as animals must burn more calories to maintain body heat. This is particularly crucial for vulnerable animals like calves, heifers and second-calf cows.
According to a provincial spokesperson from Manitoba, “During prolonged cold snaps, cattle are diverting energy to maintaining their body temperature, so less energy can go toward growing a fetus, gaining weight or even maintaining weight. In extreme cold, cattle may not be able to consume enough of their current ration to meet their energy needs, and adding higher energy feedstuffs like concentrates may be necessary.”
In addition to increasing energy density, overwinter forages should be very high quality for the provision of both energy and digestibility. This keeps the rumen generating warmth sufficiently. It is essential to monitor body condition to ensure animals aren’t losing weight, as adding condition during winter can be difficult and expensive.
“Keep feed fresh and snow-free,” says Atchison. “Timing feed deliveries to coincide with colder parts of the day can stimulate metabolic heat production, helping animals maintain body temperature naturally.”
Adequate water is essential; frozen troughs or inconsistent access can reduce intake, compromising energy balance and animal health. The provincial spokesperson emphasizes that while some producers assume cattle can lick snow, that isn’t actually an option for certain stages of production, according to the Beef Codes of Practice, which are industry standards.
Regular monitoring of body condition is vital to adjust rations appropriately for winter stress. Animals with insufficient energy or protein intake will lose condition rapidly during cold snaps. The spokesperson adds that while concentrates may be an added expense, the economic fallout of weight loss, including abortions, low birth weight calves and poor immune function, can be far more costly down the road.
“Assess cows before winter feeding begins, during pregnancy checks or weaning,” Atchison notes. “Group animals by condition and production stage to ensure they receive appropriate nutrition.”
Bouchard-Teasdale adds. “Knowing the nutritional value of the feeds you have on hand makes it much easier to ensure your herd’s needs are being met, especially in severe weather. Tools like CowBytes can then be used to build rations that are both practical and cost-effective. And don’t hesitate to reach out to your nutritionist, veterinarian or local extension specialist.”
Shelter and Environmental Management
Providing protection from wind can make a significant difference in how well animals tolerate low temperatures.
Atchison notes that cattle can handle very cold conditions as long as they have adequate energy, but wind exposure dramatically increases the effective cold they experience. She recommends using natural windbreaks, like hollows or tree lines, whenever possible, and supplementing with man-made options such as portable windbreaks.
For man-made structures, a porosity of about 25 to 33 per cent is ideal, allowing some airflow while reducing wind chill. Proper placement to block prevailing winds also increases effectiveness.
Regional factors also play a role. The provincial spokesperson notes that “wind chill is a huge factor into the actual effective temperature. Providing wind protection can dramatically increase comfort and decrease the temperature that the animal is experiencing,” which is especially critical on the open prairie compared to more sheltered, wooded pastures.
Bedding is another essential. Wet or matted hair coats significantly reduce insulation, so providing dry, fluffy bedding allows animals to fluff their hair and trap heat, similar to a down jacket.
“Cattle acclimate to colder weather by growing a longer, thicker hair coat,” explains Bouchard-Teasdale. “This coat provides the animal with insulation by trapping air next to the skin, which helps retain body heat and reduce the impact of cold temperatures. However, the coat must be clean and dry to maximize its effectiveness.”
Bedding creates a layer of insulation between the animal and the cold ground. This is helpful in preventing frostbite of extremities such as teats and testicles, as well as hypothermia. Bedding also helps to keep animals clean and dry so long as it is refreshed frequently.
Low-stress handling is particularly important during extreme weather. Minimizing movement, and thus energy expenditure, during cold snaps helps reduce these risks. When procedures such as vaccinations, weaning or treatments are necessary, schedule them on milder days to limit the combined effects of cold stress and handling.
Transport also requires careful planning. Loading and unloading cattle in freezing conditions can exacerbate stress and heat loss, so it is important to provide extra bedding and consider wind protection in trailers.
Observation and Monitoring
Continuous observation and early intervention are critical. Signs of cold stress include lethargy, reduced feed and water intake, and visible shivering. A provincial spokesperson explains that beyond weight loss or discomfort, producers should also watch for respiratory symptoms such as coughing, nasal discharge or laboured breathing, since pneumonia often appears when cattle are stressed.
Atchison advises producers to pay attention to behaviour and use it to guide management decisions, including timing of feed delivery, handling and shelter use. Early detection and intervention help prevent setbacks and bolster the bottom line even through winter.
