In a recent webinar sponsored by the National Corn Growers Association, Karla Wilke discussed importance of building a nutrition program for cow-calf operations. Wilke is a cow-calf/stocker management specialist for the University of Nebraska whose research includes maintaining production in cow-calf pairs in confinement to provide grazing deferment for range or as part of a system’s reduced dependency on perennial pasture.  She also evaluates alternatives such as field peas or crops like sugar beets in beef cattle diets.

Most cow herds are spring calving. In winter they are usually on dormant winter range or crop residues. “If they don’t need to gain weight before calving and just need to maintain body condition, they need about 11 pounds of TDN (total digestible nutrients) and about 1.6 pounds of crude protein. If the low-quality forage they consume is about 6% crude protein and about 52% TDN, if a cow could eat 22 to 23 pounds of dry matter (calculating moisture out of it), it would supply enough TDN and fairly close to enough crude protein to meet her needs—and no supplementation would be necessary if she has enough to eat,” said Wilke.

During late gestation, however, she needs more than 22 pounds of dry matter, but she may have limited access and/or it may have limited digestibility. “Winter forages may be inadequate. You might move cows to a field you haven’t grazed, but there’s only a certain amount of residue and no regrowth.” As cattle graze and pick through it, less nutrients are available.

“Her requirements have also increased in late gestation so she’s short on what she needs and will likely lose weight,” said Wilke. “If we feed two pounds of dried distiller’s grains (on dry matter basis) and assume 20 pounds from forage, cows would be getting a little over 10 pounds of TDN from forage and 1.2 pounds of crude protein.  If we assume distillers grain is 108% TDN and 30% crude protein, the two pounds would have enough TDN and crude protein, and nitrogen in the protein might help increase intake a little, due to better digestibility.”

A 5-year study with March-calving cows grazed on cornstalk residue from October to February showed those cows started out in body condition score 5.4 on a 1 to 9 scale.  “One group was supplemented and one group was not. There was some change in body weight because the fetus is growing, but for body condition score, the cows that were not supplement still came in holding their own at 5.4. Cows that were supplemented bumped up to 5.6 score,” she said.

Cow measurements

That study followed cows through calving and rebreeding, looking at birth weight, pregnancy rate, calving interval, weaning weight, etc. “We didn’t see any difference in measurements that actually counted. Supplementation in that 5-year study didn’t pay, since those cows didn’t perform any differently. This can depend on several factors, however.”

Assuming the feed is still there and cows can to root down through snow to get to the forage—if it is not crusted over—corn stalk residue and dormant range grazing works without supplementation, until it doesn’t. “This past winter, many regions had deep snow.  Some cows became too thin to do a good job raising the calf they were carrying and didn’t rebreed because they couldn’t recover in time.  Every year is different and we need to be watching for changes we might need to make,” said Wilke.

The 5-year study assumed that producers have time to get cows ready to calve. “They brought cows in from grazing in February and they didn’t calve until March so they had a month to do something different. Sometimes, however, spring on the calendar doesn’t mean green grass.  How long is it from onset of lactation to green grass? That’s a critical question for winter feeding programs. We need to know if cows are in moderate condition holding their own, and whether they have opportunity to make some of it up if they lose weight.”

Another question is how much lactation changes the cow’s needs. “Sometimes we don’t realize the magnitude of that change and this can get us in trouble. During late gestation and early lactation producers generally increase the nutrients—maybe saving the best quality hay for that time, plus adding a supplement. This still may not meet her needs for lactation,” said Wilke.

How much time will elapse between the hay and three pounds of distillers that won’t quite meet her lactation needs and when she can actually go to grass? What is her body condition when she starts early lactation? We need to know if she has enough condition to give up a little during that interval before she goes to grass. 

“Does she have it to give, and how long are we talking about? Things that can trip us up include weather. Maybe it’s been dry or cold and we have to delay turnout, so those cows are starting to lose weight. Maybe they are in a confinement situation and not going to grass, and we have to make that adjustment,” Wilke said.

“If we are going to grass fairly soon and she’s lost some condition but now has an increasing plane of nutrition on grass, things may be fine for rebreeding. If there are delays or hitches in our system, however, we need to be aware of what’s going on and make an adjustment. Evaluating body condition during winter can be challenging. In winter, cows may have a lot of hair, which may make it harder. Also deceptive is that when cows are on low-quality forage with a slow passage rate, they may have a big, full gut.  You might think they are in good condition, but it’s just gut fill. If we are not looking at where the fat cover should be (hips, pin bones, ribs, etc.) we might misjudge her condition.”

Checking for fat cover

If the cow doesn’t have much gut fill and looks slab-sided you might think she is thin and needs more feed, when in fact she does have some fat cover. “A good place to look is the brisket, as well as over the bones. If you put the cow in a chute and put your hands along her back, check for spacing along her spinal column,” said Wilke.

Pregnancy rate is impacted by body condition. Most people use a 45 or a 60 day breeding season which makes it all the more important that cows be in a condition score 5 or 6.  “Immunoglobulin production in colostrum (to enhance immunity in the calf) also depends on body condition. A blood sample taken from the calf at 24 hours of age can show how much immunoglobulin is in its system after it nurses the cow.” The thin cow generally does not produce high-quality colostrum, and may also give birth to a smaller, weaker calf that may not get up and suckle as quickly. 

“We talk about the importance of vitamins, minerals, energy and protein for reproduction. In my part of the world, 2022 was our third year of drought and we had to pull cows off grass early. They went onto crop residues and byproducts, which don’t have many vitamins and minerals. It is important to supplement those cows, but often they are shorter on protein and energy than vitamins and minerals. If they are short on protein and energy, it doesn’t matter how good the vitamin/mineral program is,” she said.

“Providing a vitamin/mineral package when you have a protein and energy shortage is like putting a Bandaid on a cut that needs stitches. It won’t do much good. It might help a little, but doesn’t solve the problem.”