Cow-calf producers calculating likely winter feed costs need to take into account the importance of estimating forage usage by cows.

Glenn Selk, Oklahoma State University Cooperative Extension emeritus livestock specialist, said hay or standing forage intake must be estimated to make the calculations, and forage quality will be a determining factor in the amount of forage consumed.

"Higher-quality forages contain larger concentrations of important nutrients, so animals consuming these forages should be more likely to meet their nutrient needs from the forages," he said. "Just remember, cows can consume a larger quantity of higher-quality forages."

Higher-quality forages are fermented more rapidly in the rumen, leaving a void that the animal can refill with additional forage. Consequently, forage intake increases.

For example, low-quality forages — those below approximately 6% crude protein — will be consumed at about 1.5% of body weight on a dry-matter basis per day. Higher-quality grass hays — those with more than approximately 8% crude protein — may be consumed at about 2% of body weight on a dry matter basis per day.

"Excellent forages — good alfalfa, silages or green pasture — may be consumed at the rate of 2.5% of body weight on a dry matter basis per day," Selk said. "The combination of improved nutrient content and increased forage intake makes high-quality forage very valuable to the animal and the producer."

With these intake estimates, producers can calculate the amount of hay that needs to be available.

For example, take 1,200-pound pregnant spring-calving cows with good-quality grass hay, tested at 8% crude protein. The cows will voluntarily consume 2% of their body weight, or 24 pounds per day. However, the 24 pounds is based on 100% dry matter. Grass hays are often 7% to 10% moisture.

"If we assume the hay is 92% dry matter or 8% moisture, the cows will consume about 26 pounds per day on an as-fed basis," Selk said.

Plus, a curve is thrown into the decision-making process. A producer also must consider hay waste when feeding big round bales. Waste is difficult to estimate, but studies have generally shown it to be between 6% and 20%, though it can be higher.

In the example above, assume 15% hay waste. Selk said this means approximately 30 pounds of grass hay must be hauled to the pasture for each cow each day, with hay expected to be the primary ingredient in the animals' diet.

Cattle and calves are the top agricultural commodity produced in Oklahoma, accounting for 53% of total agricultural cash receipts, according to National Agricultural Statistics Service data.