Leopold Center - Stockpiling shows potential

Using stockpiled forage for winter grazing is a proven practice in many operations to reduce the amount of stored feed for maintaining mature cows over winter. However, less is known about how the system works for young pregnant cows, which have higher nutrient requirements, lower feed intake, and less winter grazing experience.

To learn more about heifers and grazing, the Leopold Center funded a two-year study by Iowa State University animal scientist Jim Russell. The larger project looked at the sustainability and productivity of forage-based production systems for developing heifers.

Winter grazing of grass and/or legume forages that have been allowed to grow during late summer and fall has become an effective management strategy, especially in southern Iowa. This approach eliminates harvesting and storage overhead, as well as allowing producers time to focus on other areas of the operation.

Research has shown that extending grazing into fall and winter months, rather than feeding cattle harvested forages, can lower winter production costs even during years of above-average snowfall. Livestock in these systems become accustomed to winter conditions and graze through comparatively deep snow to get access to the high-quality forage.

Properly managed stockpiled forage alone has sufficient nutritive value to be fed as the sole energy and protein source in rations for mature cows. However, nutritional supplements may be necessary if excessive snow or ice limits forage availability or quality relative to the nutritional requirements of the cattle. This grazing and supplemental feeding strategy focuses on reducing input costs associated with winter feeding by allowing cattle to harvest most of their own feed. Nutritional quality of the diet is maintained by using supplemental rations as needed, or when weather conditions prevent grazing.

Two-year comparison
In the ISU study, Russell compared second-calf heifers under two winter production systems at the ISU Beef Nutrition Farm near Ames. One group grazed stockpiled forages in pastures, and the other group was confined to dry lots and fed tall fescue-red clover with a corn gluten feed supplement. For the cattle on pasture, Russell used two stocking rates and two levels of corn gluten feed supplementation.

The study included 24 Angus-Simmental two-year-old heifers, each pregnant with their second calf, divided by weight and body condition score (BCS). Beginning in October, this group was allowed to strip-graze for 147 days at two different stocking rates: 0.48 or 0.34 cows per acre. Eight similar second-calf heifers were placed in two dry lots and fed tall fescue-red clover hay. The grazed animals were fed corn gluten supplement to maintain a mean BCS of either 5.0 (on a 9-point scale) for the high supplementation level, or 4.33 for the low supplementation level, and when weather prevented grazing.

The bottom line
The first year of the grazing trial (2003-04) had above-normal snowfall. The pregnant two-year-old cows consumed on average 16 pounds (low supplementation) or 279 pounds (high supplementation) of corn gluten feed per cow with no additional hay. Depending on stocking rates, this equaled $0.12 to $0.45 savings per cow per day when compared to cows in the dry lots that were fed hay (5,642 total pounds dry matter per cow) and a corn gluten feed supplement (5 total pounds dry matter per cow).

Snowfall was below normal the second year of the trial (2004-05). Over the same grazing period, the pregnant two-year-old cows consumed on average 20 pounds (low supplementation) or 286 pounds (high supplementation) of corn gluten feed per cow with no additional hay. Depending on stocking rates, this equaled $0.13 to $0.49 savings per cow per day when compared to cows kept in dry lots and fed hay (4,747 total pounds dry matter per cow) and a corn gluten feed supplement (134 total pounds dry matter per cow).

Forage for thought
Increased productivity of grazing livestock systems has the potential to encourage farmers to view their resources, especially their land, in a different light. A land’s productivity can be measured by more than its use for row crops; land can be productive by creating a sustainable livestock production system. One of the goals of this project was to improve the economic sustainability of Iowa’s livestock sector. This can be achieved by increasing the use of in-field forages during winter months, improving the productivity of pregnant two-year old cows, reducing input costs and improving land utilization.

Russell’s results are tangible evidence that winter grazing of stockpiled forage is an effective management strategy to reduce winter maintenance costs for pregnant two-year old cows while maintaining adequate body condition, even in winters with above-average snowfall. He also has indicated that there may be other ways to trim costs further by increasing stocking rates and compensate with more supplemental corn gluten feed.

Here’s another way to look at it: Winter grazing of stockpiled forage is one way that Iowa beef producers can add value to previously “idle” land during winter months.

Why consider stockpiled forage?

More than three-fourths of all beef operations in the United States have less than 50 animals. To remain viable, these small operations must consider all of their costs and maintain a minimal capital investment.

Feed accounts for more than half of the total costs of a cow-calf operation, with winter feed costs being the single largest expense. Although some costs may be reduced, none has as great an impact on herd profitability as feed costs.

The use of hay as a feed source during winter is associated not only with high machinery and storage costs, but also requires time and labor for harvesting and feeding. Therefore, using stockpiled forage for winter grazing makes an ideal focal point for producers to become more efficient and potentially reduce production costs.

More about stockpiled forage

Management strategies for using stockpiled forage vary by region, type of stock and available technology. In Iowa, considerable information exists on use of stockpiled forage in the summer, but less is known for its use over the winter season.

Any grass or legume species can be used for stockpiling. Tall fescue is useful because of its fall growth; it also maintains quality when exposed to adverse weather. Other choices include smooth bromegrass and orchardgrass with legumes such as red clover (which can be established by frost-seeding in late winter) and berseem clover (for its late summer growth).

For maximum yield and nutritive value, forage must be stockpiled approximately 70 days before grazing. Research at the McNay Farm showed that longer periods of stockpiling result in increased forage yields but much lower nutritional quality. The research suggests an early August forage harvest by grazing or mowing before initiating stockpiling.

The effect of snow on grazing of stockpiled forages is not as great as might be expected. Cows can graze through up to 16 inches of snow but even a little ice can effectively halt this activity. Winter precipitation can physically limit grazing as well as reduce the nutritional value of the forage.

For more information about winter feed management, check the ISU Extension publication on Stockpiled forages, SP-42.