Cattle producers across the U.S. are dealing with winter weather. Cattle are naturally adapted to cold weather, but their ability to stay warm depends on factors such as their winter coat, body condition score (BCS), nutrition and staying dry.
Justin Waggoner, a beef cattle specialist with Kansas State University Extension, says the combination of cold, wind and snow can significantly increase stress on cattle, particularly if producers are not proactive. How cattle respond to cold stress depends largely on their environment.
Waggoner explains during a recent Agriculture Today interview there are key differences between cattle in confined settings, such as feedlots, and those in more extensive environments such as pastures or corn stalks.
What is Cold to Beef Cattle?
According to K-State Extension leaders, cattle are most comfortable and perform optimally when effective temperatures are neither too warm nor too cold. This is referred to as thermoneutral. Effective ambient temperatures are what the temperature feels like.
“Beef cows begin to experience cold stress when effective ambient temperatures drop below the lower critical temperature,” says Jason Warner, K-State assistant professor and Extension cow-calf specialist.
Effective ambient temperature accounts for wind chill, humidity and solar radiation. Lower critical temperatures are influenced by environmental and animal factors.
Beef cows begin to experience cold stress when effective ambient temperatures drop below the lower critical temperature (Table 1). Once effective temperatures are below this point, the cow must generate additional heat to maintain her body temperature.
Thin cattle, younger calves and animals with lower body condition are at higher risk, Waggoner adds. While snow on a dry winter hair coat can provide insulation, wet coats dramatically increase energy needs.
According to K-State, here are 10 points to consider when managing cow herds through cold stress:
- Body condition is key; cows in a body condition score of 5 or greater are better able to withstand cold stress
- It is difficult to add body condition after calving, even more so during cold weather
- Thin cows (body condition score ≤ 4.0), cows without wind protection, and with wet hair coats are at greatest risk
- The lower critical temperatures are simply a guide for when cold stress can occur
- When dry, energy requirements increase 1% for each degree Fahrenheit below the lower critical temperature
- When wet, energy requirements increase 2% for each degree Fahrenheit below the lower critical temperature
- Start with conservative amounts of grains (0.2% of body weight) and gradually increase
- Feed low-starch feedstuffs, such as distiller’s grains or wheat middlings as first choices
- Provide bedding to help insulate cold, frozen ground surfaces
- Ensure cows have sufficient access to clean, fresh water
What Nutrients Should be Increased and by How Much?
Cold stress increases the energy required for a cow to maintain her body temperature. As energy demands increase, K-State Extension leaders say there is no clear effect on protein, mineral or vitamin requirements.
The energy needs of a cow in a body condition score 5 or greater with a dry hair coat increase by 1% for each degree Fahrenheit below the lower critical temperature. For example, if the lower critical temperature were 32°F and she requires 12 lb. of TDN (total digestible nutrients) every day, then her needs would increase to 13.2 lb. if the effective temperature were 22°F.
The following steps show this calculation:
- 32°F (lower critical temperature) – 22°F (effective temperature) = 10-degree difference.
- A 10-degree difference is a 10% increase in TDN, which equals 1.2 lb. (12 lb. × 0.10.)
- 1.2 lb. + 12.0 lb. = 13.2 lb. TDN needed per day, accounting for cold stress when dry.
If the cow has a wet coat, regardless of hair length, then energy requirements increase by 2% for each degree below the lower critical temperature. For a cow requiring 12 lb. of TDN, her energy needs increase by 74% with a wet hair coat (lower critical temperature of 59°F ) and a 22°F effective temperature (59 – 22 = 37 × 2 = 74).
How Should the Feeding Program be Adjusted?
Feeding additional pounds of an average-quality hay typically offsets increased energy needs during periods of moderate cold stress. In cases of severe or prolonged cold stress, hay alone is usually not sufficient.
“When we get a winter weather event, that common behavioral response is for cattle to huddle up,” he says. “Where we start to see differences is really how they react in terms of intake patterns.”
In feedlot environments, cattle often increase their feed intake ahead of an approaching storm. While that response can help them prepare for colder conditions, it can also create challenges.
“It’s not uncommon to see cattle become a little more aggressive at the bunk and increase intake,” Waggoner says. “That can set up scenarios with acidosis or other digestive upsets.”
Once the storm arrives, cattle might reduce trips to the feed bunk, and feed delivery can be delayed. To offset those disruptions in intake and feeding patterns, Waggoner recommends increasing roughage in the diet.
“Some operations will cover with hay, others will feed a storm ration,” he says. “That usually means adding more roughage, maybe 2% to 4% on a dry-matter basis, to help cattle avoid digestive issues.”
Those rations are typically fed starting about 12 hours before a storm and continued for up to 36 hours afterward as cattle recover normal eating patterns.
Cattle on pasture face a different set of challenges, especially when snow covers grazing areas.
“As we get snow cover, it becomes more challenging for cattle to graze,” Waggoner adds. “That means we have to replace some of that forage intake with supplemental feeding.”
Water access is another critical concern that is often overlooked. In feedlots, Waggoner says producers should ensure tanks remain open by increasing overflow or checking electric heaters.
“If we see snowfall, clearing a path to water tanks is important,” he says. “That’s true in both confined and extensive environments.”
While cattle can consume snow to meet some water needs, Waggoner cautions that heavy snowfall can still limit access to water tanks.
Don’t Forget Bedding, Wind Protection to Prevent Cold Stress
Providing bedding is another effective strategy. Producers should roll out enough bedding so all animals have a dry place to lie down, especially in muddy or wet areas.
“Giving cattle a dry place to lay down can really help them weather the impacts of a winter storm,” Waggoner stresses.
Wind protection can also greatly reduce cold stress. Temporary windbreaks using portable windbreak panels, hay bales or even stock trailers can be effective if placed with prevailing winds in mind.
“If we can block the wind, that can greatly reduce the impact of cold stress,” Waggoner says.
Prioritize Producer Safety, Too
Waggoner also emphasizes safety for producers and workers.
“Humans experience cold stress, too,” he says. “Dress in layers, stay hydrated, take breaks and be cautious with portable heaters and heat lamps, which are a common source of barn fires.”
He encourages producers to use the buddy system and check in regularly when traveling to distant pastures.
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