Turning cattle out too early can damage pastures and reduce productivity, but so can waiting too long. That’s the message from Iowa State University specialists who note that an unusually mild fall and winter in many areas allowed producers to leave their cattle on pasture later than usual. Now they are entering spring with abundant supplies of hay, and might be tempted to wait a little longer for turnout.

Iowa State University Extension grazing specialist Dan Morrical says "Keeping cows on hay late this spring may not be the best decision for forage management." Good pasture management matches forage growth rate with early season cow consumption. "Excessively early turn-out can be detrimental to forage growth later in the year because the plants have not established adequate root reserves to combat defoliation; damage to both plants and soil may result from hoof traffic on muddy soils," Dr. Morrical says. "On the other hand, waiting too long reduces forage productivity and nutritional value because plants become overly mature. Plants allowed to reach maturity produce less during the summer slump than forages managed appropriately." Utilization rates are also lower when the herd is grazing mature standing forage.

The type of grazing system also influences the ideal turnout date. According to ISU research, producers using rotational grazing systems can turn cattle out nearly two weeks earlier than in traditional grazing programs. Rotation staggers forage available and allows forages time to recuperate, and in the ISU study, initiating grazing 14 days earlier increased seasonal forage production by 8 percent and forage crude protein concentration by 5 percent.

Continuously grazed pastures, on the other hand, have little or no recovery time and benefit from additional growth before turnout, Dr. Morrical says. "Producers should use growing conditions and forage availability as factors to determine when to turn cows out, rather than a specific calendar date."

For more information, visit the Iowa Beef Center Web site at www.iowabeefcenter.org