Evaluations guide supplementing decisions

Nov 11, 2011

On a scale of 1 to 10, 10 is usually a good thing. But when it comes to body condition scores (BCS) for cattle, somewhere around a 5 is ideal.

BCS is one of the things to evaluate when planning for feed requirements heading into winter, said Jack Whittier, beef extension specialist at Colorado State University. The other thing to evaluate is the nutrition content of hay or forage.

The BCS is a method of evaluating a cow’s condition in the interest of estimating her feed requirements. The system uses a series of guidelines from 1 to 9, with 1 being emaciated and 9 being obese. Heading into winter, it’s best to have cows at somewhere around a 5 to 7, Whittier said. “It’s easier to keep a cow at a constant level of condition, or have a little ground to lose, than try to make up for poor condition during the winter and when it gets close to calving.”

BCS can be evaluated without working the cattle and causing stress. It’s estimated by just looking at the cows and noting which category they fall into.

Once the BCS is established, that information can be used in a variety of ways, depending on a producer’s setup and goals.

“If a producer has the ability, we recommend sorting cows by body condition,” Whittier said. “Cows that are adequate or at 7 or above can get by with less supplementation than cows that are a 3 or 4. It allows the producer to target the cows that need it the most, without overfeeding the cows that don’t need it.”

Young, thin cows are the first priority for supplementation, Whittier said, followed by more mature cows with lower scores. Young cows, especially first-calf heifers, have more nutritional needs because they are still growing.

The other element to consider when planning for winter feed needs is the quality of the forage or hay. “In the northern Great Plains, protein is usually the most limiting nutrient,” said Julie Walker, beef extension specialist with South Dakota State University. “Producers need to balance the rations and compare the quality of hay or forage to what the cows need for their nutrient content to determine if they need additional supplementation.”

The best way to determine if cows are going to need additional protein is to have the hay tested, Whittier said. “Generally, you can assume that winter forages on dormant western ranges are going to be in the 6 to 7 percent protein range. A cow’s requirement averages close to 8 or 9 percent. Making up the 2 percent of the diet difference with some kind of supplementation is almost always required and cost-effective.”

“The cow’s protein needs vary from 6.5 to 10.1, depending on the stage of production,” Walker said.

While there isn’t an efficient method of measuring the nutrient content of most pastures when they’re dormant, history tells most producers whether the forage is going to provide adequate protein for cattle to get through the winter in good shape, Walker said.

Hay is easier to sample and get a good evaluation of the nutrition content. “Hay quality may be higher than native range,” Whittier said. “Producers may not have to supplement as much if they are feeding hay, especially if there is an alfalfa or legume component, as if they are grazing standing forage. Hay usually comes from better ground and is harvested when the nutrient content is higher.”

For producers who are feeding hay through the winter, it pays to have the hay tested for nutrient content, Whittier said. The test costs about $20 in most labs and can help producers decide how best to manage their feed resources.

“It’s definitely worth the producer’s while and the investment to get that done,” Whittier said. Most universities offer this service and cooperative extension staff can help producers find labs to test their hay.

Walker said she’s heard from several producers who have had good luck maximizing their forage quality by rotating pastures. “Cattle graze the forage with the highest nutrition content first, so as the winter goes on, they’re left with the lower quality forage. Later in winter is when the cows’ nutrition requirements are the highest. By continuing to give them fresh pasture through the winter, you would potentially be maintaining a higher range quality. It may require cross-fencing large pastures, but some producers were able to eliminate winter supplementation completely by implementing pasture rotation through the winter.”

Once the nutrition requirements for the cows and the nutrition content of the available feed have been determined, it’s time for producers to do the math and figure out the best solution for their situation,” Walker said.

“If they’re short on protein for their forage base, they have several options,” she said. “Some ways of making up a protein shortfall could be a high quality alfalfa hay, range cake, protein blocks, cubes or lick tubs. They’re all different structural forms of protein, but all could meet a cow’s protein requirements. Some of the decision of what to supplement with has to be based on what the producer has the ability to feed. If he has to buy a new cake feeder, it might not be as economical. One option is to blend a higher and a lower quality feed.”

The best way to figure out the most economical method of supplementing is figuring out the cost per pound of protein from each potential protein source, including any investment in a delivery method, Whittier said.

Producers also need to plan for a cow’s changing nutrition requirements over the winter, Walker said. “They need to figure out how many days they plan to feed and how much hay they have. If they have multiple hay types, they should keep the hay with the highest protein content for early lactation, when a cow has the highest nutrition requirements. The next highest requirement is during the last third of pregnancy.”

Producers should keep in mind that cold stress does not increase a cow’s protein demands, only energy demands. “Cold weather stress increases the energy requirements; however, cold does not increase crude protein requirements. The rule of thumb is for each 10 degrees F drop below a wind chill of 30 degrees F, the energy requirements increase 13 percent for cows in good body condition with a dry, winter hair coat; thin cows or cows with a wet or summer hair coat is 30 percent,” Walker said. It’s not practical or necessary to increase the amount of protein fed during cold weather, but making sure they have plenty of hay or forage is necessary.

Both Walker and Whittier emphasized the importance of a supplemental mineral program in addition to the protein supplement. “A standard program mineral program is important. Most producers are supplying that on a self-fed basis so the mineral is available at all times,” Whittier said.

Supplementing with starch—grain products like corn—isn’t usually necessary or economical through the winter for bred cows, Whittier said.

“Planning should already be well underway for where the cattle are going to be and what sources they’re going to use. Early winter storms may speed the process up a little bit, but producers should have a pretty good idea of what they’re planning to do to make sure the nutrition needs are being met,” Whittier said. — Maria Tussing, WLJ Correspondent