Producers should let the condition of their cattle and forage dictate when to wean calves, two North Dakota State University Extension Service specialists say.
"Cow herd management is oftentimes a great art of matching a cow's changing requirements to an ever-changing forage resource base," says beef cattle specialist Carl Dahlen. "A recurring theme through the years is the variability in moisture accumulation and the coincident variability in forage growth. In cases of limited forage availability and declining forage quality, cow body condition and calf growth can be impacted."
But only 17 percent of producers use forage availability and the physical condition of cows as the most important factors in determining when to wean.
"For the health of pastures and the long-term productivity of breeding females, producers should consider the condition of forages and the cattle when making decisions about when to wean," Dahlen says.
The 2013 growing season was unusual for pasture production and quality across North Dakota. Much of the western region received above-average moisture throughout the summer, while the central and eastern portions received excessive moisture early, then limited rain in July and August. These moisture patterns create two different scenarios that result in differing forage quality issues, according to rangeland management specialist Kevin Sedivec.
On average, forage production on North Dakota's rangeland was at or above normal throughout much of the state. Eighty percent of the state's forage grows from late May through early July. Most of the state received sufficient moisture in May and June to grow grass.
"However, if you were the unfortunate livestock producer who did not receive much rain in July and August, you will have quantity and quality issues," Sedivec says.
The May and June moisture created ample standing growth. However, as the moisture became deficient, green regrowth was limited, and what is left is mature growth that is low in quality. These producers also will lack the 20 percent growth that occurs from late August through late September (regrowth that occurs with late-summer moisture and cooler weather).
In the end, cattle grazing low-quality, mature plant material that lacks regrowth will suffer from protein, vitamin and mineral deficiency, the specialists say. In addition, overgrazing pastures in the fall may reduce pasture yields during the next growing season.
"For those ranchers who received moisture throughout the summer, quantity and quality will be adequate until a killing freeze," Sedivec says. "Once we receive a killing freeze, quantity still will be fine, but quality will deteriorate within two weeks following the event."