Cold Stress Management: Navigating Winter Challenges for Optimal Herd Health.

 By Jaclyn Krymowski.

 Just as heat can adversely affect animal productivity, so can winter’s unforgiving chill pose significant challenges for beef cattle. Fluctuations in temperature, particularly during cold snaps, impose stress on livestock, leading to immunosuppression, reduced feed intake, and overall lethargy.

As the animal responds to the cold by shivering, the heart rate increases and breathing deepens. As well, energy requirements increase, which may lead to a downward spiral, not just for the cows themselves, but the calves they may be carrying. Thus next year’s fall calf crop is also at risk.

Cold Stress and Environment
While many cattle breeds in the U.S. possess a degree of cold tolerance, even these hardy breeds can become susceptible to cold stress due to environmental or physiological predispositions. These factors include inadequate body condition, insufficient feed, poor winter coat growth, and exposure to extreme windy or wet conditions. Cattle grappling with these challenges experience cold stress at higher temperatures than their better-prepared counterparts.

It is important to note that the overall herd can be impacted by the environment and shelter conditions. For instance, when rain penetrates a thick winter coat, it compromises its insulating properties.

David Hartman, a Penn State livestock educator, underscores this in his bulletin Cold Stress and Beef Cattle, explaining that a dry coat will go from withstanding a critical temperature of 32° F to about 59-60° F when exposed to rain.

Managing the Long-term Effects
One of the most profound long-term consequences of cold stress is the deterioration of body condition. For pregnant cows, this deterioration can lead to weaker calves, dystocia issues during calving, and challenges in rebreeding.

Mary Drewnoski, Nebraska Extension Beef Systems Specialist, and Karla H. (Jenkins) Wilke, UNL Cow/Calf Systems and Stocker Management, delve further into the concept of the lower critical temperature (LCT) and its implications in their bulletin Helping Cows Cope with Cold Stress.

Understanding the concept of LCT  is critical for managing energy balance and stress during cold snaps. LCT is the threshold temperature at which cattle start expending energy to maintain their body temperature. Cows in good condition with dry, heavy winter coats, for instance, do not need to expend energy for temperature regulation until the wind chill index drops below 19°F.
 
Buffering Against Energy Drain
Wind shelters, both natural windbreaks and purpose-built structures, play a vital role in reducing energy expenditure. They also minimize the need for additional hay or mineral supplementation. However, maintaining optimal body condition remains a cornerstone of effective winter weather management.

Drewnoski and Wilke suggest a practical approach is to group thin cows with first-calf heifers, given their elevated energy requirements. This grouping allows for strategic feeding of higher-quality forage or supplementation while grazing.
 
Nutritional Considerations
In the face of unpredictable winter weather, altering rations daily is neither beneficial nor advisable. Instead, providing higher-energy sources or supplementing low-quality forage becomes paramount. The aim is to prepare cattle for extreme conditions, factoring in the impact of wind chill.

Cattle naturally increase their feed intake to meet the escalating energy demands of plummeting temperatures, particularly when temperatures drop below the LCT.

Extension agent William Halfman highlights the correlation between temperature decrease and increased energy requirements in his article Manage Feeding to Help Cattle Handle Cold Stress. For every degree Fahrenheit below the LCT, cattle’s feed requirements surge by approximately 1%. Understanding feed quality is crucial for informed supplementation decisions, especially as requirements escalate with decreasing temperatures.
 
Shielding Cattle from the Elements
Preserving cow health during the transition from winter requires a multi-faceted approach. Beyond maintaining body condition and overall well-being, environmental control emerges as a key defense against cold stress. Avoiding muddy conditions becomes pivotal, as it safeguards the cow’s inherent insulation mechanisms.

Appropriate bedding, such as fluffy straw or cornstalks, preserves insulation when cattle are indoors. Additionally, supplementing cattle with grain or by-products during cold snaps, especially when forage quality is compromised, can prove invaluable.
 
Transportation Considerations
Transporting animals in cold conditions demands special attention. While livestock trailers are designed to mitigate heat stress by providing continuous airflow, this setup can inadvertently create chilling conditions during winter, particularly in windy weather.

Minimize airflow by using panel covers or strategically positioned straw bales to reduce excessive wind exposure during transport.
 
Embracing a Comprehensive Approach
To effectively cope with cold stress, adopt a holistic strategy that considers nutrition, environment, and management elements. Prioritize cow well-being, protect against the elements, and maintain optimal feed quality pivotal components to prepare for the challenges of winter weather. Your most valuable weapons in the war with winter are nutrition and environment. Consider both to advance the resilience of your herd.