During the last 20 years, cow size has increased over 200 lbs. As cow size increases, producers need to be more aware of their cow's nutritional requirements. During his presentation at the recent Range Beef Cow Symposium in Mitchell, NE, Ken Olson, South Dakota State University (SDSU) beef specialist, asked producers if they knew what their cows weigh.

“If everyone had a scale at their ranch, this would be known,” he says.

Instead, producers must rely on other alternatives such as the scale weights of their cull cows, adjusted for any differences between the culls and the cows that remain in the herd. Another alternative is estimating mature cow size based on the live weight of their finished offspring.

“The general rule of thumb is that mature cow weight and live weight of their progeny at slaughter should be similar,” Olson explains.

Data from the USDA Germplasm Evaluation Program showed a head-to-head comparison of several sire breeds. The average cow weight across all breeds was 1,390 lbs. in 2009. The data also indicated British breeds have surpassed continental breeds in mature cow size. In the data, the mature cow weight of a Hereford was 1,419 lbs.; Angus, 1,410; Red Angus, 1,409; Simmental, 1,404; Gelbvieh, 1,323; Limousin, 1,391; and Charolais, 1,371.

“This may be a function of genetic trends that are changing the size of cows in each breed at different rates,” Olson explains of the data. “The breeds that produce the bigger cattle may still be changing."

With mature cow size averaging 1,300 to 1,400 lbs., producers need to manage the size of their cows so they don't get any larger.

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