Super-sized
Cows Require
Appropriate
Management
by Donald Stotts,
OSU ag communications specialist
It is a truth hiding in plain sight: Mature weight and milk production of many commercial beef cows are both greater than they were 30 years to 40 years ago, and that means management considerations must change as well.
Oklahoma State University (OSU) animal scientists Bob Kropp and Glenn Selk explain that many commercial ranchers underestimate the mature size of their cows simply because they have not weighed the adult cows to know what average mature weight to expect.
"Today's cows are not the type your grandfather was used to raising," said Selk, OSU Cooperative Extension livestock reproduction specialist. "To expect large, heavy-milking cows to be in moderate body condition at calving and maintain condition through breeding, they must receive more feed than smaller, lighter-milking cows."
According to the 1996 National Research Council's guidelines for beef cows calving in February and March and weaning in October, heavier-milking cows weighing about 1,250 pounds (lb.) require 34% more energy on average for an entire year, compared to 1,100-lb. moderately milking cows.
Consequently, an operation that was carrying 100 head of the smaller cows need carry only 66 head of the larger cows to use the same quantity of forage available on a specific farm or ranch.
The larger cows also will require 34% more winter hay and supplement to maintain body condition.
Kropp, an OSU professor of animal science, said feed and fertilizer prices highlight the need for producers to consider reducing herd size to better fit required stocking rates.
"Reduced stocking rates will definitely be necessary on improved pastures if lower amounts of fertilizer are applied," he said. "Proper use of pasture forages is the foundation of any cattle ranch."
A larger mature cow size also affects the principle of percent of body weight needed for heifers to reach puberty. For a cow that eventually will weigh 1,000 lb., the target weight for the heifer would be 650 lb. For a cow that eventually will weigh 1,250 lb., the target weight would be 812 lb. going into the heifer's first breeding season, if the producer is to promote a high cycling and pregnancy rate.
"Many ranchers underestimate the target weight for replacement heifers," Kropp said.
"Successful and long-lasting cattle operations are those that maintain efficiency during periods of volatile input costs and roller-coaster cattle markets," he said.
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