As spring approaches, most producers are anxious to get cows out of the lot and make use of early-spring grazing. Even with the advantages of sending pairs out into fresh air and wide-open spaces, producers need to evaluate forage availability and diet quality.

A lot of rangeland in Nebraska is warm-season dominate and is considered to provide on average 0.6 animal unit month (AUM) of grazing per acre. This estimate, however, is developed from season-long growing, which is typically June through October. Therefore, that amount of forage is not actually available early in the spring, such as early May, in this example.

A light stocking rate in May on typical Sandhills range would be about 0.20 to 0.22 AUM per acre, while a heavy stocking rate during that time would be 0.30 to 0.33 AUM per acre. This basically means that stocking at half the normal stocking rate in early spring is still too heavy, which could have negative impacts on the future range condition and the expected performance of the cattle.

A study conducted at the Gudmundsen Sandhills Laboratory near Whitman, Neb., used esophageally fistulated cows at stocking rates of 0.22 and 0.33 AUM per acre. Within one week of May grazing, the cows began to select less-digestible forage with lower protein than when initially turned out. Data from clipped forage samples from grazed pastures compared to ungrazed pastures indicated this was due to the cows eating more dormant, previous-year growth as the month progressed.

First-calf heifers present a unique challenge to producers, as these heifers have increased nutrient demands for both their own continued growth, the onset of lactation and the return of estrus. If this growing, lactating heifer can eat ad libitum of this green forage, she can meet her nutrient demands. However, if the heifer is only able to get about half of her daily intake from this early forage and must get the rest from hay or dormant range, she will not be able to meet her nutrient demands.

Providing 2 pounds of supplemental dried distillers grain would provide the energy and protein the grazing did not. However, most producers find cattle first turned out to green grass often will not eat supplement, making it less effective.

If producers are concerned about the nutrients available to meet the needs of the young lactating heifer grazing warm-season-dominated pastures this spring, managers could consider stocking at a lighter rate (around 0.20 AUM per acre), or retaining heifers in a drylot where nutrient intake can be more controlled for two to three weeks, giving the grass time to accumulate substantial growth and to adequately meet the needs of the young cow.

Jenkins is a cow-calf specialist at the University of Nebraska-Lincoln. This report comes from UNL BeefWatch.