An overwintering, cow-calf beef herd produces manure — quite a lot of it. In one day, the average 1,250-pound beef cow produces 75 pounds of manure and urine. This manure has about 0.31 pound of nitrogen (not all of this is retained), 0.19 pound of phosphate and 0.26 pound of potassium. The feeding method beef farmers use to deal with this nutrient resource can have a positive impact on their forage and other crop production systems. Care should be taken to not overfeed in an area. Too great of an accumulation of wasted hay and manure can have a negative impact on forage yield next year.

There are four basic approaches to feeding the cow-calf herd over the Michigan winter:
Drylot feedyard. Confining and feeding cattle in a drylot pen from October through April, or later. Cows are fed daily, and nutrients accumulate in manure and straw pack over the winter.
In-field bale feeders. Bale feeders are placed in a field with frequent relocation of the feeders to better distribute manure and waste feed nutrients, and avoid sod damage.
Bale processing. Unrolling or grinding and spreading one large round bale at a time in a windrow on the ground, or packed snow, out in a field. The feeding site is moved each time to allow waste feed and manure to be evenly distributed across an area.
Bale grazing. Bales are set in place in a field in the fall. They can be pre-arranged by forage quality. Cattle are allowed gradual access to the bales on a planned schedule by moving temporary electric fencing.

What becomes of the nutrients from cattle manure and wasted feed under each of these systems? According to University of Wisconsin Extension’s publication, “Guidelines for Applying Manure to Cropland and Pasture in Wisconsin,” as much as 50% of the total nitrogen and phosphorus and 40% of the potassium may be lost from manure on an open lot through volatilization, runoff or leaching. Up to 40% of the nitrogen and from 5% to 15% of the phosphorus and potassium may be lost during daily hauling and spreading. Much less of the nutrients are lost when cattle are winter-fed in the field.

Research from up north
Bart Lardner from the Canadian Western Beef Development Center conducted research on this issue in 2003-05. His paper, “Winter Feeding Beef Cows — Managing Manure Nutrients,” states a definite difference was in the capture and utilization of manure nutrients between beef winter feeding systems. His conclusions include:

“Significant benefits can result from winter-feeding beef cows on preselected sites due to increased capture and utilization of manure nutrients. Deposition of nutrients with cows versus machinery indicates more efficient cycling of nitrogen for subsequent pasture growth. In this study, economic calculations favored in-field feeding. Cow cost per day was lower for field feeding than wintering cows in drylot pens. Feed costs were similar between the systems, but field feeding had savings in machinery use and manure handling costs. Results also indicate that benefits from wintering cows on feeding sites can be managed to reduce daily costs with minimal impacts on cow performance.”

In effect, the most desirable winter feeding systems with regard to manure nutrient retention and recycling (in order of efficiency):
• bale grazing
• bale processing
• drylot feeding

IN-FIELD NUTRIENTS: Manure has been deposited throughout a field where bales were unrolled for winter feeding. (Photo: Jim Isleib, MSU)

In-field bale feeders were not included in Lardner’s study as a separate feeding system type. It is reasonable to assume the effect on manure nutrient retention would be better than the drylot feeding system if the bale feeder was moved frequently over a large field area.

For those cow-calf farmers who feed their herds over winter in drylot settings and do not scrape, haul and spread the accumulated manure in spring, this practice results in wasting manure nutrient resources and may present a situation posing risk to nearby surface and groundwater resources. Investment in machinery (e.g., manure spreader, bucket loader) to facilitate scraping, hauling and spreading drylot manure should be considered.

Isleib and Wardynski write for Michigan State University Extension.