Hereford cow and calf at the
Fort Keogh Livestock and Range Research Laboratory, Miles City, Mont. Click
the image for more information about it.
Season of Birth Affects Calf Growth on Great
Plains By Erin
Peabody April 18, 2006
To everything, there is a seasoneven for ranchers raising herds
of cattle out on America's Great Plains.
According to scientists with the Agricultural Research Service (ARS), calving seasonthe time of year
when a cow gives birth to a calfis an important factor in determining how
healthy a cow and calf will be, how much weight they'll gain, and how much
high-quality nutrition will be available to them.
ARS animal scientist
Grings, along with colleagues at the agency's
Keogh Livestock and Range Research Laboratory in Miles City, Mont.,
recently completed a three-year study investigating differently timed
calving-season and weaning strategies and how they affect mother cows and their
The researchers also wanted to see how certain calving timeslate
winter, early spring or late springaffect the economics of livestock
In the northern Great Plains, which includes Montana, Wyoming and
North Dakota, the primary inputs for raising cattle are the costs associated
with providing ample nutrition to the animals. This feed comes in the form of
supplements, winter hay, and the grasses that the animals graze.
In this semiarid region characterized by rolling hills and broken
badlands, ranchers are accustomed to a narrow growing period that typically
peaks in May and June, when temperatures and precipitation encourage new,
cool-season grasses to sprout. According to Grings, this forage can be a vital
source of food for lactating cows, which pass important nutrients on to their
calves through their milk.
In choosing a calving season, a rancher changes the priority of how
the most nutritious forage is used. The rancher can time the cows' reproduction
so that the highest quality forage goes to boosting cows' weight gain during
pregnancy, encouraging milk production for their nursing calvesor to
nourishing the calves themselves, which need hardy forage to properly grow and
Grings' calving study was published in the Journal of Animal Science.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.