Don’t Stress About Cold Stress
By Jaclyn Krymowski
The science is clear – cattle suffering from cold stress are less productive and don’t reach their potential, much like heat stress. But because the symptoms of animals suffering in cold weather aren’t always immediate, it can be an easy one to pass us by. After all, many of our major beef breeds are relatively hardy to cooler climates.
Taking care of your cows and their replacements is important for longevity and the impact on the cows and replacements can be a ripple effect in the years to come.
Cold stress is essentially defined as when the cattle’s body temperature drops due to a combination of metabolic processes and natural insulation not enough to protect against the low temperatures.
By and large, cattle have great resilience to cold weather for a decent length of time, especially if they can stay dry and out of harsh wind.
Exploring Cold Stress
Protecting against the cold is challenging, especially when winter weather can be all over the board.
In a University of Nebraska-Lincoln bulletin, Pasture and Forage Minute: Cold Stress Preparation, Feeding Brown Hay and Silage Safely, educators Samantha Daniel and Ben Beckman note the threshold points which cattle have to use energy to maintain or generate body heat against the cold. Providing additional protection in the form of a shelter can help keep their coats dry and limit the wind chill effects.
“Shelter can also help in other ways. Calving success can increase by 2% behind a windbreak, according to a Kansas study,” they write. “In Montana feedlots during severe winters, cattle behind windbreaks gained 10.6 lbs. more than cattle that did not have windbreaks.”
In the grand scheme of things, we are doing more than just protecting against the cold. It’s also helping set the animal up for success in other parts of its herd life—calving, breeding, lactation, weight gain, etc.
Likewise, there is a reason that body condition scores are stressed going into winter and out of winter with the proper body weight. Maintaining cattle through these peak cold stress periods can be a key to keeping that body condition score where it needs to be.
“Cold stress increases a cow’s energy requirement which, if not met, can pull down body condition,” note Daniel and Beckman. “A general rule of thumb we can use is that for every degree of cold stress a cow faces, they increase their energy requirements by 1%.”
High-quality hay (while very important in heat generation) during extreme cold can’t meet the increased energy demands, however corn is a great high energy option.
How Cold Stress Impacts Animals
The big pillars that keep cattle warm in cold weather are simple enough: good body condition, dry coat, shelter, and adequate nutrition. But a multitude of factors, including windchill, snow, and freezing rain, and the availability (in some cases logistical hurdles like transportation) of quality feedstuffs can quickly cause one or more of these pillars to collapse.
Nutritional needs are arguably the most important as they can impact not only the health of your cows and youngstock, but also the calves they may be pregnant with.
In Lingering Effects of Cold Stress, a West Virginia State University Extension bulletin by livestock specialist Kevin Shaffer discusses this in detail.
“The effects of cold stress on cows are hard to quantify, but can include abortions, weak calves and retained placentas. These impacts are primarily the result of inadequate nutrition during late gestation; however, the most significant impact of cold stress on cows is fertility during the subsequent breeding season. Cows that experienced cold stress and/or were lacking in available nutrition at, or around, the time of calving will often have a longer postpartum interval. Because calving causes significant damage to the uterine tissue, it has to be repaired before the cow successfully conceives again. Protein, energy and other nutrients are necessary for the cow to heal effectively. Furthermore, fertility is known to be lower in the first cycles after calving, so it is necessary for the cow to cycle two to three times to achieve maximum fertility before being exposed to a bull.”
As Shaffer alludes, requirements for an animal’s maintenance and reproduction vary and can compound cold stress if unmet.
Having a Preventative Mindset
If you raise cattle in a region with notorious winters, you are well acquainted with the importance of windbreaks. While a powerful asset, there are many times when windbreaks alone are not enough.
While they can keep out the wind, they may not be as successful in keeping animals (or their laying areas) dry, especially during freezing rain events. Wet coats are unable to provide the natural insulation effect that dry hairs standing on end provide. Not only does this initially make the animal cold, but it will also allow the animal to rapidly lose body heat generated by the rumen even with adequate feeding.
A bedded pack with straw or cornstalks can be a useful accompaniment to a windbreak that may help reduce excessive wet coats. But to be effective, the pack must be kept thick with a dry layer on top at all times.
Nutrition that matches the dropping temps can also be a strategy to help battle against cold stress.
According to the University of Wisconsin-Madison, when cattle are below their bodies’ critical temperature (this is 32 degrees F with a dry coat and 18 degrees F with a thick, heavy winter coat, without factoring in windchill), feed intake will increase from 2% to 25%. And that can even go up in extreme conditions.
It is best to test your forages before the season, so you know your cattle also meet their nutritional needs as they consume more. Remember, they are less likely to graze when there is snow and have lower energy due to the cold.
Making strategic herd management decisions that can weather the harshest winter conditions doesn’t happen by accident. And often, the most brutal losses are those you don’t prepare for – winters can be unexpectedly harsh or long. If you don’t have the measures to meet your herd’s needs in advance, it will be too late when you find yourself in the midst of a deep freeze.