Managing Beef Cows During Cold Stress
Tips for assessing what’s cold to a cow, how nutrient needs increase and what ration changes need to occur.
January 8, 2025
by Jason Warner & Justin Waggoner, Kansas State University
Cow-calf producers generally recognize that severe winter weather is a stressor that increases cow nutrient requirements. The practical questions that must be asked when managing cow herds through cold stress events are: “What is cold to a beef cow?” “What nutrients increase, and by how much?” And, “How should the feeding program be adjusted to offset the increase?”
What is cold to a beef cow?
Cattle are most comfortable, and perform optimally, when effective temperatures are neither too warm nor too cold. This is also referred to as thermoneutral, and beef cows begin to experience cold stress when effective ambient temperatures drop below the lower critical temperature (LCT; see Table 1).
Essentially, once effective temperatures are below this point, the cow must generate additional heat just to maintain her body temperature.
Effective ambient temperatures account for factors such as wind chill, humidity and solar radiation. LCTs are influenced by both environmental (wind speed, precipitation, humidity) and animal [hair depth or thickness, hide thickness, the amount of mud present on the hair, body condition score (BCS)] factors. Windchill factors for varying combinations of wind speeds and temperatures for beef cows in a BCS 5 with a dry, winter hair coat are provided in Table 2.
Table 1: Estimated lower critical temperatures (LCT) for beef cows in a 5.0 body condition score
Table 2: Windchill factors for beef cows with a dry, winter coat and BCS 5.0
The Kansas Mesonet is also an excellent resource for both current and forecast cattle cold stress conditions across the state. It takes into account humidity and solar radiation factors. In wet conditions, cows can begin experiencing cold stress around 60° F, which would be a relatively mild winter day. However, for cows with a heavy winter coat, the estimated LCT under dry conditions is about 18°. So, cold to a beef cow is when the effective ambient temperature is something less than the established LCT.
What nutrients increase, and by how much?
Cold stress increases maintenance energy requirements of the cow to offset her need to produce extra body heat. Energy demands increase, but there is no clear effect on protein, mineral or vitamin requirements. A good, practical rule of thumb to follow for a cow in a BCS 5 or greater with a dry hair coat is that her energy needs increase by 1% for each point (° F) below the LCT. For example, if the LCT were 32° and she requires 12.0 pounds (lb.) of TDN (total digestible nutrients) daily, her needs would increase to 13.2 lb. if the effective temperature were 22°. This would be determined by the following:
- 32° (LCT) – 22° (effective temperature) = 10° difference.
- A 10° 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 would be needed per day accounting for cold stress when dry.
If she has a wet (regardless of hair length) coat, energy requirements increase by 2% for each point below the LCT. So, for a cow requiring 12.0 lb. of TDN, her energy needs would now increase by 74% with a wet hair coat (LCT of 59° and a 22° effective temperature (59 – 22 = 37 × 2 = 74), putting her requirement at 12.0 + (12.0 x 0.74) = 20.9 lb. TDN.
How should the feeding program be adjusted to offset the increase?
Feeding additional pounds of an average-quality hay can typically offset increased energy needs during periods of moderate cold stress (see Table 3). In cases of severe or prolonged cold stress, hay alone is usually not sufficient, and providing additional energy by feeding higher-quality, more energy-dense feedstuffs may be required. When supplementing grains such as corn, wheat or sorghum, avoid feeding more than 0.5% of body weight to reduce negatively affecting forage digestion and risks with founder unless cows are slowly and gradually introduced to higher amounts.
Table 3: Example feeding scenarios for precalving and postcalving beef cows for offsetting additional energy needs due to cold stress*
Consider using feedstuffs with highly digestible fiber and lower starch content, such as distillers’ grains, wheat middlings, soybean hulls, or corn gluten feed if available. It is typical that beef cows in a confinement or pen-fed setting respond to cold stress by increasing voluntary forage intake. However, beef cows on pasture may spend less time grazing during cold-stress events, which reduces forage intake and makes it challenging to meet the cows’ additional energy requirement solely through voluntary forage intake.
It is critical that cows have access to sufficient water during cold-stress events because water restriction will further reduce forage intake and subsequent body heat production.
Important points to consider when managing cow herds through cold stress include:
- Body condition is key — cows in a BCS ≥ 5.0 are better able to withstand cold stress.
- It is very difficult to add body condition after calving, even more so during cold weather.
- Thin cows (BCS ≤ 4.0), cows without wind protection and with wet hides are at greatest risk.
- The lower critical temperatures are simply a guide for when cold stress may occur.
- When the hair coat is dry, energy needs increase 1% for each ° F below the LCT.
- When the hair coat is wet, energy needs increase 2% for each ° F below the LCT.
- Start with conservative amounts of grains (0.2% of body weight) and gradually increase.
- Feed low-starch feedstuffs (distillers’ grains, wheat middlings, etc.) if available.
- Provide bedding to help insulate from cold, frozen ground surfaces.
- Ensure cows have sufficient access to clean, fresh water.
Editor’s note: Justin Warner is assistant professor and extension cow-calf specialist for K-State; Justin Waggoner is professor and beef systems extension specialist, Garden City, K-State. Reprinted with permission from the K-State Beef Tips newsletter. [Lead photo by Shauna Hermel.]
Angus Beef Bulletin EXTRA, Vol. 17, No. 1-A
Topics: Nutrition , Management
Publication: Angus Beef Bulletin
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