VALLEY — Feed is the major cost associated with owning or managing livestock.  Most of this cost occurs during the winter months when animals are fed hay and supplements.  Feed is also the major factor influencing reproductive performance.  Shorting needed nutrients in the winter can have long lasting implications on herd performance. 

The primary nutrients needed by animals are grouped into five categories; protein, energy, vitamins, minerals and water. Adequate nutrition will help animals meet their needs in each stage of production. Energy is the primary nutrient that needs to be increased in cold weather. This increase in energy is used primarily for increased maintenance needs. Weather does not change protein, vitamin, mineral or water needs.

Animals use nutrition for four stages of production.  Each stage has a priority status.

Biological Priority of Nutrients

Priority Function

1 Maintenance

2 Growth

3 Milk Production

4 Reproduction

Just like you and I, animals have a comfort zone where they are more comfortable than at other temperatures. This comfort zone is called the “Thermoneutral Zone” where animals are neither too hot nor too cold. The thermoneutral zone changes when the animal is wet or dry and as the ambient temperature outside changes. 

The effective ambient temperature considers wind, humidity, and solar radiation in addition to the actual air temperature. In addition to actual weather conditions, the amount of insulation on the animal influences the lower critical temperature (the temperature where the animal’s performance is adversely influenced by their environment). 

When the temperature is below the lower critical temperature, increased energy feed should be provided. 

Estimated Lower Critical

Temperature for Beef Cattle

Coat Description Critical Temp.

Wet or Summer Coat 59ºF

Dry fall coat 45ºF

Dry winter coat 32ºF

Dry heavy winter coat 18ºF

The general rule of thumb is that for every degree the temperature drops below the lower critical temperature, the energy in the ration should be increased 1 percent.

All feeds have some energy in them. Dormant grass has the lowest amount of energy for feeds animals in our environment would be eating. Hay such as grass or alfalfa will have higher energy contents. Small grains such as barley, wheat, oats, corn, etc. will have the highest amount of energy per pound of feed.

When looking for an energy feed, cost, including shipping, must be considered.  Some of our alfalfa will have a high enough energy content that using a small grain isn’t necessary. 

There are other factors to consider when determining an animal’s nutritional needs.  Animal weight, age, body condition, milk production or physical activity all have an impact on overall nutritional needs. These factors often have a smaller impact than cold weather, but they can be significant. 

For more information on feeding needs of animals in cold weather, contact the San Luis Valley Area Extension Office a call at 719-852-7381.

Extension programs are available to all without discrimination, Colorado State University Extension, U.S. Department of Agriculture and Colorado counties cooperating.