Cows prefer clean grass. Even over weedy clover.   
GPS collars help Missouri researcher track grazing preferences.

Kevin Bradley has walked a lot of pastures with cattlemen where he thought weeds severely limited grazing value. But producers often balked at losing the clover growing in the grass if they initiated a spray program. Using GPS technology to track fix points and let the cattle vote on which forage they prefer, the University of Missouri Extension weed scientist has learned that weed control improves pasture productivity and creates a grazing space preferred by most cows.

• Conducted across three Missouri locations — each infested with a mix of broadleaf weeds and/or broadleaf weeds and brush.
• Cows fitted with GPS collars to track fix points and monitor grazing habits.
• Collars recorded the cows’ grazing activity at one-hour intervals throughout the grazing season.
• After one month, Bradley treated half of each pasture with ForeFront^® R&P/GrazonNext^® herbicide or Grazon^® P+D plus Remedy^® Ultra herbicide.
• Monthly forage sampling measured desirable versus undesirable forage yields.

Highlights

• Prior to weed control, cows grazed the pasture relatively uniformly and continued to do so during the first month after treatment.
• Two months after the herbicide application, grazing patterns shifted. Cows grazed 77 percent of the time on the treated half and only 23 percent of the time on the untreated area. Those results remained constant throughout the duration of the grazing season.
• In untreated areas, weeds comprised as much as half the total forage — including clover — yield.

This is a satellite view of the pasture with all grazing points marked during the four months after spraying. Yellow dots mark grazing in the treated area; blue in the untreated area. Cattle grazed the treated part of the pasture 74 percent of the time.

• The cows’ grazing preference was the treated half of the pasture where there was far less weed pressure — and no clover.
  Cows apparently prefer weed-free grass more than they do a weedy pasture that contains clover.
• When weed density reaches light to moderate levels, spraying presents a real opportunity to improve productivity. o Nearly 2 pounds of grass replaced every pound of broadleaf weeds and woody plants controlled.
  o Pasture utilization improved. Cattle more uniformly grazed the entire treated area, while they avoided weeds and brush on the untreated portion.
  o Grass volume remained relatively constant and was greater in the treated area at the end of the season, even though it received most of the grazing pressure.
  
• Solve a weed problem first, then work to bring back the clover if it fits your long-term management objectives.
• Proper grazing management that maintains a grass stand to compete with the weed seedlings can slow reinfestation in the long term.

More information (PDF format):

Surprise! Cows prefer clean grass! Even over weedy clover.  (241KB PDF)