Winter grazing can be an inexpensive forage resource, but it also requires careful management. Meeting a cows nutritional needs ensures successful calving and rebreeding. Supplementation for winter grazing becomes a necessity to make up for nutritional deficiencies in plants cows will be grazing.

Vitamin A and phosphorus are particularly low in dormant grasses. But most likely to limit performance of beef cows on native range is protein. Proteins vary in their ability to supply nitrogen and amino acids to the cow. In order to provide your cows with the proper protein, the supplement formulation should be considered. Choosing the right supplement program depends on management style and what is economical to use on your ranch. Proteins can be broken into three broad categories:

* Degradable protein is readily available for use in the rumen. Because it is degraded fairly rapidly in the rumen, protein supplements that contain high levels of degradable protein should be provided at least three times a week. Good sources include field pea and sunflower, canola, crambe and safflower oil meals.

* Bypass or undegraded protein moves further into the digestive tract where it can be used directly by the cow. Commercially available forms tend to be more expensive than others, but offer some benefit in terms of nitrogen recycling. This gives producers an option to provide supplement twice a week or even less frequently.

* Non-protein nitrogen is almost immediately available to rumen microbes. These include urea and biuret which need to be consumed daily to avoid excessive nitrogen losses in the rumen.