Winter grazing can be a great way to reduce feeding costs by allowing animals to harvest their own forage and forgo the expense of harvesting or purchasing and storing large quantities of hay. No matter what the livestock species, their specific nutritional needs should be taken into consideration during this period.

Rebecca Kern-Lunbery

Animal Scientist / Ward Laboratories Inc.

Email Rebecca Kern-Lunbery

For most animals to achieve optimal production will require a reasonable level of protein and energy in their forage along with supplementation for a complete diet that meets their needs. Ensuring a heterogeneous plant species makeup on pasture is key to meeting these requirements. For these animals to successfully maintain their body condition and achieve reproductive performance, they will need more than just dormant grass. A good mix of grasses to provide fiber and bulk with legumes and forbs to provide protein, and other essential nutrients key to health, will support pregnancy and production performance.

Pasture considerations

Most pastures will have two productive seasons. First, in the spring when most animals are turned out to start grazing. Then, as plants mature and head out, there is a slump in the heat of the summer months. Then in the fall, pastures can become productive once again. Typically, this means forage quality is at its highest during the spring, then it can peak again in the fall under the right environmental circumstances, including sun and precipitation. This year in central Nebraska, we have had lots of late-summer/early-fall rain, making fall pastures much greener and productive than they have been in previous drought years. I have had many producers asking not only about grazing pastures this winter but also regrowth on their hayfields.

However, once the first hard killing frost comes, forages stop growing and go dormant. The quality of these dormant forages is variable and depends on their species and what growth stage they were at when the killing frost came. More mature forages typically have higher fiber content, lower protein and lower mineral concentrations.

Native pastures and rangeland

Native pastures can be variable in nutritional quality. We have a lot less control over what forage species are present on native range pastures. Furthermore, Rocky Mountain region pastures are especially unpredictable, with plant species makeup and forage quality depending on so many factors. Some of these factors include elevation, precipitation, weather patterns, soil type and health status as well as other management practices. In addition to these factors, we have seen invasive species such as cheatgrass become an issue on Rocky Mountain grazing lands. Cheatgrass crowds out native species and provides little nutritional value as well as being high in fiber and therefore unpalatable.

Managed pastures

Managed pastures can be highly variable in nutritional quality as well. Research in the Sandhills of Nebraska found that dormant warm-season grasses contained 5% to 7% crude protein (CP), with cool-season grasses having only slightly more protein. Meanwhile, research in Wisconsin shows cool-season grasses could have up to 18% CP during winter months. Some of these differences can be explained by the very different soil types, as well as management practices. In the Sandhills, fertilizer application is uncommon on sandy soils because the risk of it percolating through the soils and into our water is high. In Wisconsin, however, they specifically applied nitrogen (N) to increase the protein content of those pasture forages.

A young cow stands on winter pasture near Valentine, Nebraska. Image by Elane Wright-Johnson.

Weeds

While species diversity often adds nutritional value, another consideration on both native or rangeland pastures and managed pastures is to know what weeds are out there. Toxic plants will still be present and pose a threat to animal health during winter months. Walking pastures and keeping an eye on both plant species for nutritional values and potentially toxic threats is a key to successful winter grazing. This year, I have received several calls about nightshade specifically. This weed seems to be more prevalent during wet years.

Nutrient decline

Beyond weed risks, nutrient decline is another key consideration on both native and managed pastures; stockpiled forages do typically lose protein content and increase in fiber content, leading to lower-quality forages from fall to winter months due to the seasonal weather, wind, snow, etc. So unless the pasture has been very carefully fertilized and managed, protein and energy supplementation will be key. In managed pastures or hayfields, windrowing has shown success in protecting underlying forage from nutrient decline from the elements. Furthermore, mineral and vitamin supplementation would be advisable, as forages at this time would typically have very little mineral content.

Snow cover

Converse to what you might think, snow-covered forages are protected from the elements. Therefore, snow-covered forages in a winter pasture typically hold better nutritional value. Additionally, well-timed snow cover can help with soil moisture and allow the pasture a quicker recovery and more productive spring season. However, snow cover can impact the success of grazing these forages.

It's believed that most livestock species can graze up to 8 inches of snow. Yet, livestock should be observed during winter grazing, and when it appears that they are struggling with the snow cover, quality hay should be provided to ensure their nutritional needs are met.

Conclusion

Winter grazing can reduce feeding costs and provide quality nutrition under the right conditions, but success depends on more than just turning animals out. Pasture species diversity, forage maturity, weed presence and snow cover all play major roles in the nutrients available. Since forage quality often declines as a result of fall-to-winter transitioning weather elements, protein, energy and mineral supplementation are necessary to maintain animal condition and reproductive performance. Regularly monitoring both pastures and animal body condition ensures timely adjustments. With proactive management, winter grazing can be a cost-effective, healthy option for grazing livestock.

References omitted but available upon request by sending an email to an editor.