February is when a lot of things come together in a beef herd, and when small nutritional deficiencies start showing up in big ways. Most spring-calving cows in the Midwest are now in their third trimester of gestation, and this is when winter weather, fetal growth and cow body condition converge.

This is not the month for cows to “get by.” What happens nutritionally in February shows up at calving, rebreeding, and on the scale when calves are weaned.

Roughly 70 percent of fetal growth occurs in the last trimester. At the same time, the cow is trying to maintain herself in cold conditions and prepare for lactation. Energy and protein requirements increase sharply – often faster than we sometimes realize.

A mature cow in late gestation needs more energy, especially during cold stress. She needs adequate protein to support fetal growth and colostrum production, and enough intake capacity to meet both, which can be a challenge with low-quality forages.

Cows that enter February at a body condition score of 5.5 to 6 are set up well. Cows below that are already borrowing from the future.

The cold stretch many of us are experiencing right now changes nutrient requirements immediately. Wind, snow, mud, and wet hair coats push energy needs up, sometimes dramatically.

The lower critical ambient temperature for a beef cow is 32° F. If the temperature drops to 0° F, a cow would need about 2# DDGs or 2# cracked corn per day in addition to her normal ration so she does not lose weight during the cold snap. Wet or muddy cows can see energy needs increase well above this figure. Wind can also zap their energy, so having a wind break – stacking big round corn stalk bales across the fence can work – is critical. Thin cows feel cold stress sooner than fleshy cows.

During extreme cold, maintaining body condition becomes the priority. Losing condition now almost guarantees problems at calving and delays return to estrus. Short-term increases in energy – through higher-quality hay, additional grain or energy-dense supplements – are often the most economical choice, even if they feel expensive in the moment.

Windbreaks, bedding, and dry lying areas are not “nice extras” in February. They are nutritional tools.

Late gestation rations often fall short on protein, especially when cows are fed corn stalks or average-quality hay. A cow can consume enough dry matter and still come up short if protein is limiting rumen function. An easy test to see if protein is adequate is to look at the manure. Cow manure should form a patty with fresh manure having the consistency of pancake batter. If the manure stacks up or has folds in it, this is an almost sure sign that protein is deficient.

Inadequate protein in late gestation affects fetal growth, calf vigor, and colostrum quantity and quality. Cows on protein-deficient diets will not be able to consume enough hay (the rumen bugs are not functioning properly), and they have reduced feed efficiency.

If cows look full but are still losing condition, test your hay for nutrient content.

February is when thin cows stop being a theory and start being obvious. These are often older cows, first-calf heifers, or cows that struggled early in winter.

Thin cows at calving produce less colostrum, have weaker calves, and take longer to breed back.

Sorting thin cows now and feeding them with your bred heifers or open replacement heifers is one of the highest-return management decisions you can make this month. Feeding the whole herd more to accommodate a few thin cows is almost always the wrong answer.

Mineral intake is often inconsistent in winter, and antagonists from corn-based co-products can reduce copper and zinc availability right when immune function matters most.

Poor mineral status in late gestation can show up as weak or slow calves, and increased scours risk.

This is the time to make sure cows are consuming – not just offered – a balanced mineral at appropriate intake levels. If you are feeding anything in a bunk, add the salt-mineral mix to the feed so that every cow consumes an adequate amount of mineral. We know that about 15 percent of cows offered free-choice salt-mineral mix eat almost none.

By the time calves are on the ground, it’s too late to fix most nutritional problems. Third-trimester nutrition in February determines whether calving season is calm or chaotic.

A central Indiana producer I worked with last winter thought his cows were “holding their own” through February. They were on decent grass hay, and nothing looked alarming from the road. But when we body condition scored them in early February, over a third of the mature cows were below BCS 5, and nearly all the coming 3-year-olds were thinner than he realized.

We sorted the thin cows and heifers, added DDGS, and improved bedding and wind protection.

That April, calving was noticeably smoother. Fewer weak calves. Better colostrum. And when breeding season rolled around, conception rates were up compared to the previous year. In his words, “It was the first time February feeding showed up as a check instead of a bill.”

Walk through your cows. Body condition score them honestly (or have a neighbor do it). Add feed during extreme cold. Sort cows that need extra attention. These are not complicated steps, but they matter more now than any other time of year.

The most important work now is keeping late-gestation cows in the right shape so that calving and rebreeding seasons are successful.