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Feeding the Cow Herd During Extreme Temperatures

by Wyoming Livestock Roundup

It seems as though this winter has seen its share of extreme temperature fluctuations. As I sit here and write this article, it is once again well below zero outside. It has reminded me of the importance of meeting the nutrient requirements of the cowherd. This is especially important as we near the calving season.  

Numerous articles have been written about the importance of maintaining the optimal body condition score during the winter and through calving. These reasons include the ability of the cow to calve, milk and rebreed in a timely manner.  

Additionally, the immediate health of the soon-to-be newborn calf, as well as the lifetime productivity of that calf, can be negatively impacted if the cow is not fed to her requirements during this last stage of pregnancy. 

Wind chill

It is important to remember that wind chill factor can play a significant role in the requirements of the cow.  

Cows that are in good condition with a dry hair coat will have a one percent increase in requirements for every degree below 30 degrees.  

For example, if the outside air temperature, also taking into account wind chill to determine relative temperature, is zero degrees Fahrenheit, a cow has an increased requirement of 30 percent.  

Similarly, if the outside air temperature is 20 degrees Fahrenheit and the wind chill drops the temperature to zero degrees, there is a 30 percent increase in requirements.  

Example scenario

A 1,200 pound cow during late gestation has an energy and protein requirement of 11.8 pounds total digestible nutrients (TDN) and 1.7 pounds crude protein (CP). Therefore, if the hay is moderate quality grass hay, testing at 55 percent TDN and seven percent CP, cows would need to be fed approximately 22 pounds of hay per cow to meet their energy requirements. That same amount of hay would provide approximately 1.5 pounds of CP, almost 0.25 pound deficient, meaning a protein supplement is needed.  

However, if an additional 30 percent were required for temperature, those cows would need to consume 15.4 pounds TDN and 2.21 pounds CP, or an additional six pounds of hay to meet the additional energy requirements, with a protein supplement still needed.  

Condition of the cow is extremely important.  

The example above assumes a cow in good condition.  If cows are thin or wet in extreme conditions, the requirements could increase by 40 to 50 percent. In that scenario, a cow likely will not be able to consume enough hay to meet her requirements, and an additional supplement will likely be required.  

In reality, a quick storm that blows through in a day or two likely won’t affect the condition of a cow. However, cows could drop a significant amount of weight and future performance during these artic blasts that are lasting a week to 10 days.  

Supplements during these periods of time may be the best way to meet additional requirements. There are all types of supplements, including mixing your own with raw ingredients.  

Here are a few thoughts on each.

Commercial supplements

Commercial supplements are an option to add needed nutrients and/or to stretch limited forage supplies.  

In most cases, these commercial supplements will contain a combination of energy, protein, vitamins and minerals. The challenge for producers who are buying commercial supplements is to first find the correct supplement that will meet, without significantly exceeding the nutrient requirements of the animals they are feeding and, second, to make sure it is cost effective compared to other alternatives.  

Many commercial supplements have been created to reduce labor, such as tubs, tanks, etc., and the value assigned to convenience must be evaluated by each producer.

High protein supplemental feeds 

Probably the best source of supplemental protein is in the form of dried distiller’s grains (DDGS).  

Since the price of DDGS has been very closely tied to the price of other traditional feeds, such as corn and soybean meal, their use in rations has not always reduced the cost of production.  

When DDGS are used in cow rations, producers need to be aware that there are limitations in how much can be safely fed. The levels of protein, or nitrogen, fat, sulfur and phosphorus in distiller’s grains need to be considered when balancing rations to minimize their effects on reproduction, animal health and carcass quality.  

In general, the recommendation for distiller’s grains has been to include them in diets at levels that meet the animal’s protein requirement and make sure the calcium to phosphorus ratio is at least 1.5 to one.  

Feeding high levels of distiller’s grains, or using it as a primary energy source, is where nutrient excesses become a problem. 

High energy supplemental feeds

Historically, corn has been one of the cheapest sources of energy and the energy source of choice for cattle.  

When corn prices exceeded six dollars per bushel, many producers began searching for a cheaper energy source.  Corn is not only expensive, but in Wyoming, it is difficult to find.  

However, a more readily available product, beet pulp, a highly digestible fiber resource, contains about 10 to 12 percent protein but no starch.  This lack of starch makes it an excellent energy source to balance high forage diets.  

General pulp requirements

In general, beet pulp can substitute pound for pound with corn as an energy supplement on high forage, maintenance or grower-type diets.  

Although, beet pulp can be used in most rations as an energy source, it does have inclusion limitations. Pelleted beet pulp can expand six to eight times in size when they come in contact with the rumen liquid and can cause bloat when fed at higher levels. Cattle should not be fed at levels that exceed one percent of body weight. For example, a 1,300-pound cow should be fed a maximum of 13 pounds per day.  

In growing diets, such as creep feed, early wean rations, heifer and bull development rations, etc., forage quality, level of beet pulp and amount of other feed ingredients in the diet will interact to affect animal performance.  

Some starch, such as corn, oats or wheat will be needed to maintain the desired level of performance in young calf rations and in feedlot rations.

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