Windrow Grazing Trial - Fall 1998 and Winter 1999

by Robbie Baird LeValley, Area Extension Agent (Livestock & Range)


  • The swath grazing trial was funded by a grant from the Grazing Lands Conservation Initiative (GLCI).
  • Thanks to the GLCI, Campbell Ranches and the Delta Soil and Shavano Soil Conservation Districts.

Windrow Grazing on the Central West Slope of Colorado

Windrow Photo
Image 1 - Test area site picture

Windrow grazing has been used successfully in Canada, Wyoming, the San Luis valley and Gunnison, Colorado. Windrow grazing involves cutting the forage when it is at the optimal nutrition level and raking it into windrows. Animals are allowed to graze the windrows at a later point. It has proven successful in climates where there is consistent snow cover (Brummer and Haugen, 1997). It has significantly reduced the cost of harvesting and feeding hay. Windrow grazing had not been tried in the Tri River Area (Montrose, Delta, Ouray and Mesa counties) where snow cover is less consistent and fall rains more prevalent.

A trial was set up in the fall of 1998 near Hotchkiss, CO on the Campbell ranch. The test area is a tall fescue grass hay field that had traditionally been harvested in June and August with an additional fall grazing. Elevation is listed at 6500 feet. The weather in the fall and winter of 1998 was above average for temperature and rainfall (Colorado Climate Center, 1998). Due to the significant amount of rainfall, the hay was not windrowed until December 1, 1998. Ten acres were windrowed with a 12-foot conditioner. Two days later, three windrows were raked into one windrow. The windrows were approximately 3 feet in diameter.

Forage samples were taken from the windrow and from adjacent standing pasture. The standing forage had been harvested twice. The stubble height on the standing forage was approximately 10 inches. Forage samples were taken every two weeks until harvested by the cows. Samples measured crude protein, digestible protein, Acid Detergent Fiber, Neutral Detergent Fiber, energy, and macronutrients.

The cows were turned in on the windrows on December 31, 1998. 112 cows were used in this trial. The cows were in the last trimester of pregnancy. The cows were a frame score 5.5 and body condition score (BCS) of 6.5. At the start of the trial, the cows were given access to two windrows at a time. The remaining windrows were restricted using electric fence. When it was time to move the fence, the cows would be moved to an adjoining field. Once the fence was moved, the cows were let back in. During the time the cows were on the windrows, they also had access to standing pasture.

A heavy wet snow fell two days after the cows were put on the trial. The cows did break through the ice and snow that was on top of the windrows however they were not efficiently using the feed. The cow's saliva produced additional ice on the windrows. To alleviate this problem, the cows were restricted to one windrow every other day. Once this adjustment was made, the cows increased their utilization of the windrowed feed. Similar results have been observed in Gunnison .

The grass underneath the windrows stayed green until harvested by the cows. The cows utilized the windrows efficiently. BCS did not change during the trial. The 112 cows stayed on the 10 acres from December 31, 1998 to January 19, 1999. This equates to 2128 animal days.

Traditionally, these cows would have been fed harvested round bales every day. The producer estimates that this type of feeding is $25 per day including time and equipment.

Table 1. Comparison between traditional versus windrow inputs. Based on a 10-acre trial site. Feeding 112 cows for 20 days.
Electric fence
Moving the cows

Traditionally these 10 acres has yielded 35 tons of hay per year. This would feed the same 112 cows for 9.5 days.

The cows were on a higher level of protein when utilizing the windrows versus the standing forage or harvested forage. The following table shows the nutritional values of the windrows, standing and harvested forages.

Table 2. Nutritional comparison of windrows, standing and harvested forage at the time the cows was harvesting the windrows.
Moisture, %
Dry Matter, %
Crude Protein, %
Acid Det. Fiber, %
Neutral Det. Fiber, %
Total Dig. Nut., %
NE Main. (Mcal/lb)
NE Gain (Mcal/lb)
NE Lact (Mcal/lb)
Calcium, %
Phosphorus, %

Forage samples indicated that protein supplementation was not needed when the cows were grazing the windrowed forage. Traditionally, the cows were supplemented with protein at a cost of .26/head/day. This equates to cost savings of $582.40 for the 20 days of grazing.

The protein in the windrows did not change significantly from the time of harvest till the cows were turned in. The protein tested at 8.0% at the time of cutting and 7.8% at the time of grazing. Neutral Detergent Fiber and Acid Detergent Fiber stayed at constant levels throughout the trials. There was no mold detected in the windrows at any time during the trial.

Total cost savings for windrow grazing includes:

Harvesting costs $430.00
Protein supplementation $582.40
Feeding costs $500.00

This equates to cost savings of $13.50 per head.

Initial findings indicated that swath grazing would work in the Tri River Area. Additional trials need to continue to experiment with cutting the hay earlier, grazing the spring forage to delay maturity of the grass and further defining forage quality.

Literature Cited

Brummer, J

Colorado Climate Center, web page, 1999.

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