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Today, compared to 30 years ago, the industry has many more tools available to manage and manipulate mature cow size in a beef herd. Consequently, a cattle breeder can target a mature cow size goal and gradually work toward that goal through sire selection decisions and culling.

of mature cow weights to calf weaning weights in commercial cow-calf opera- tions. They discovered that for each 100 pounds of additional cow weight, calf weaning weight increased by an average of 6.7 pounds. Arkansas data published in 2006 indicated that this relationship was 15 pounds of added weaning weight for each 100 pounds of additional cow weight. “Climate may be important in this relationship,” Lalman said. “Without solid evidence, in challenging environ- ments larger cows will wean calves weighing about six pounds more per each 100 pounds of additional cow. In less restrictive environments, larger cows would be expected to wean calves weighing 15 or more pounds per each 100 pounds of additional cow weight.” “Less restrictive” can be interpreted as higher quality, more abundant forage, lower stocking rate (allowing the cattle to select a better quality diet),

more harvested forage feeding, more supplementation, more winter annual grazing, less heat or cold stress, less parasite exposure and so on. Lalman added that, based on the evidence available, it appears that each additional 100 pounds of cow weight generates about $6-$30 of added calf income, depending on the calf market. However, in a 2011 study, the addition of each 100 pounds of cow weight cost an additional $42 due to increased feed costs and grazing land required. “Larger mature cow size generates more cull cow income,” Lalman said. “One factor often overlooked when crediting larger cows with increased cull income is that additional cow weight is not free to begin with.” He further explained that for exam- ple, comparing 1,000-pound cows to 1,400-pound cows and a $70 per hun- dredweight cull cow price, 1,400-pound cows generate an additional $280 at

culling time. However, the additional 400 pounds of growth required addi- tional nutrients through the develop- ment stages and about six to seven years of age when they finally reach their mature weight. While forage is generally the cheapest feed resource on a ranch, the conversion of forage (even CONTINUED ON PAGE 23 

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