Beef Cow Ration Formulation: Balancing Energy, Protein, and Fiber

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

Forage testing is paramount: Guessing hay quality is the most common and costly error; a representative sample analyzed by a certified lab provides critical data on dry matter, crude protein, ADF, NDF, and TDN, enabling accurate ration formulation.
Nutrient requirements vary by production stage: A mature beef cow's needs for crude protein (11-14%) and TDN (52-65%) increase significantly from mid-gestation through early lactation, with cold weather further elevating energy demands by approximately 1% per degree below the lower critical temperature.
Fiber is crucial for rumen health: Adequate effective fiber stimulates chewing and saliva production, buffering rumen pH between 6.0-6.8; ADF should be 19-24% and NDF 25-35% of the total ration dry matter to prevent acidosis.
Body Condition Score (BCS) is a primary monitoring tool: Cows should calve at a BCS of 5-6 (on a 1-9 scale); a BCS below 4 indicates critical nutritional deficiency requiring immediate intervention, while BCS loss exceeding one point between trimesters signals inadequate energy intake.
Gradual ration changes are essential: Introduce new feeds over 7-14 days to allow rumen microbes to adapt, preventing digestive upset such as acidosis, off-feed, or founder.
Water is the most critical nutrient: Lactating cows can consume 15-20 gallons daily in hot weather, and water quality (e.g., sulfate, nitrate levels) directly impacts intake and health.

Balancing a beef cow ration is one of the most important management decisions you make each year. Feed costs represent the largest single expense in most cow-calf operations, and getting the energy, protein, and fiber balance wrong can cost you money through poor conception rates, weak calves, lost body condition, and higher veterinary bills. This guide covers the fundamentals of beef cow ration formulation, including how to determine nutrient requirements, how to sample and test your feed, how to build a balanced ration using common feedstuffs, and how to monitor your cows to confirm the ration is working. It is written for cow-calf producers, stocker operators, and anyone who feeds beef cattle and wants to make better informed decisions about nutrition.

At a Glance

Test your forage before you balance any ration. Guessing at hay quality is the most common and most expensive mistake in beef cattle nutrition.
Beef cows need six classes of nutrients: water, energy, protein, fiber, minerals, and vitamins. Energy and protein get the most attention, but fiber keeps the rumen functioning properly.
A mature beef cow in mid-gestation needs roughly 11 to 12 percent crude protein and 52 to 55 percent TDN in her total diet on a dry matter basis. Late-gestation needs rise to about 12 to 13 percent protein and 55 to 60 percent TDN.
Body condition score is your best monitoring tool. Cows should calve at a body condition score of 5 to 6 on a 1 to 9 scale.
The protein to energy ratio matters as much as the absolute levels. Too much protein with too little energy wastes nitrogen and can reduce performance.
Introduce any ration change gradually over 7 to 14 days to give the rumen microbes time to adapt.
Water is the most essential nutrient. A lactating beef cow can drink 15 to 20 gallons per day in hot weather.
When in doubt, have your ration checked by a qualified nutritionist or your local extension agent before making major changes.

Understanding Beef Cattle Nutrition Requirements

Before you can balance a ration, you need to understand what the cow actually needs. Beef cattle nutrition requirements are typically expressed on a dry matter basis, which means the nutrient content of the feed after all water is removed. This is important because feeds vary widely in moisture content. A bale of hay at 15 percent moisture and a bale of silage at 65 percent moisture look very different in the bunk, but the dry matter basis allows you to compare them fairly.

The beef cow's digestive system is designed to process forage. The rumen, which is the first and largest stomach compartment, houses billions of bacteria, protozoa, and fungi that break down fiber through fermentation. These microbes produce volatile fatty acids, which are the cow's primary energy source, and they also synthesize microbial protein that the cow can digest. This means the cow is really feeding two mouths: her own and the microbes in her rumen. A ration that does not support the microbes will not support the cow, no matter what the lab analysis says.

Energy Requirements

Energy is the nutrient required in the largest amount and is often the most limiting nutrient in beef cow rations. Energy requirements are expressed in several ways, but the most common systems use Total Digestible Nutrients (TDN), Net Energy (NE), or the newer systems like NEm and NEg which separate energy needs for maintenance from energy needs for gain.

For practical purposes, most producers and extension services use TDN or NEm values. A mature beef cow in mid-gestation needs about 52 to 55 percent TDN in her diet on a dry matter basis. This increases to 55 to 60 percent TDN in late gestation when the fetus is growing rapidly, and to 60 to 65 percent TDN during early lactation when she is producing milk.

Energy needs also increase in cold weather. The cow's lower critical temperature, the temperature below which she must burn extra energy to stay warm, is around 30 to 32 degrees Fahrenheit for a cow with a dry, heavy winter coat. For every degree below this threshold, her energy requirement increases by roughly 1 percent. A wet coat raises the lower critical temperature to about 60 degrees Fahrenheit because wet hair loses its insulating properties. This is why a cold rain in the fall can be harder on cows than a dry snow in January.

Protein Requirements

Protein provides the building blocks for muscle, fetal development, milk production, and the microbes in the rumen. Crude protein is the standard measure, and it is calculated by measuring the nitrogen content of the feed and multiplying by 6.25. This works because protein is approximately 16 percent nitrogen.

But not all protein is equal. Rumen degradable protein (RDP) is the portion that the rumen microbes can break down and use to build their own protein. Rumen undegradable protein (RUP), also called bypass protein, escapes rumen fermentation and is digested directly in the abomasum and small intestine. Most forages provide mostly RDP, while some supplements like distillers grains and fish meal provide significant RUP.

A mature beef cow in mid-gestation needs about 11 to 12 percent crude protein in her total diet. Late-gestation needs rise to 12 to 13 percent, and early lactation needs climb to 13 to 14 percent or higher depending on milk production level. Growing replacement heifers have higher protein needs relative to their energy needs than mature cows do.

Fiber Requirements

Fiber is often overlooked in ration formulation, but it is essential for rumen health. The cow needs adequate effective fiber, which means fiber that is long enough and coarse enough to stimulate chewing, saliva production, and rumen contraction. Saliva contains bicarbonate, which buffers the rumen and keeps the pH in the range of 6.0 to 6.8 where the fiber-digesting microbes thrive.

When fiber levels drop too low, rumen pH falls, acidosis can develop, and the cow may go off feed, founder, or develop liver abscesses. When fiber levels are too high, the ration becomes bulky and the cow cannot consume enough dry matter to meet her energy needs.

For most beef cow rations, the forage portion should provide at least 50 to 70 percent of the total dry matter. The acid detergent fiber (ADF) level of the total ration should be in the range of 19 to 24 percent, and the neutral detergent fiber (NDF) level should be 25 to 35 percent. These values are measured in a forage lab and are standard outputs on a feed test report.

Mineral and Vitamin Requirements

Minerals and vitamins are needed in smaller amounts, but they are no less important. The macrominerals, calcium, phosphorus, magnesium, potassium, sodium, and sulfur, are needed in larger quantities. The trace minerals, copper, zinc, manganese, selenium, iodine, cobalt, and iron, are needed in much smaller amounts but are critical for immune function, reproduction, and growth.

Vitamin A is the most commonly deficient vitamin in beef cow rations, especially in winter when cows are eating stored forages that have lost their vitamin A content. Vitamin D is synthesized by the cow's skin in response to sunlight, and vitamin E acts as an antioxidant. Most mineral supplements include these vitamins, but the amounts and forms vary widely between products.

A free-choice mineral program is the standard approach for most cow-calf operations, but the mineral must be formulated for your specific region and your specific forage base. For example, areas with high molybdenum or sulfur in the water and forage need higher copper supplementation because these elements bind copper and make it unavailable. Selenium is deficient in many parts of the United States and Canada, and the selenium level in your mineral should be matched to your region. Your local extension agent can tell you which mineral deficiencies are common in your area.

Water Requirements

Water is the most essential nutrient and the one most often taken for granted. A beef cow needs 5 to 15 gallons of water per day depending on her size, stage of production, ambient temperature, and the moisture content of her feed. Lactating cows have the highest demand, needing 15 to 20 gallons per day in hot weather. Cows eating lush pasture or silage get some water from the feed itself, but cows eating dry hay need almost all of their water from drinking.

Water quality matters too. High sulfate levels, high nitrates, high salinity, or contamination with manure can reduce intake and cause health problems. If your cows are drinking less than expected or you suspect water quality issues, have the water tested by a certified laboratory.

How to Determine Your Cows' Requirements

The first step in ration formulation is knowing what your cows need. This requires knowing three things: the stage of production, the expected mature weight, and the expected milk production level.

Stage of Production

The beef cow's nutrient requirements change dramatically through the production cycle. The typical cycle includes:

Mid-gestation (second trimester): This is the lowest nutrient demand period. The fetus is small and the cow is not lactating. Many producers can maintain cows on good quality forage alone during this period.
Late gestation (last 60 to 90 days before calving): The fetus grows rapidly during this period, and the cow's energy and protein needs increase by about 20 to 30 percent. This is also the time when she needs to gain or maintain body condition in preparation for lactation.
Early lactation (first 60 to 90 days after calving): This is the highest nutrient demand period. The cow is producing milk and trying to rebreed at the same time. Her energy needs may be 50 to 80 percent higher than in mid-gestation.
Late lactation (after the calf is 3 to 4 months old): Milk production declines as the calf starts eating more forage and creep feed. The cow's nutrient needs gradually decrease.
Weaning: After the calf is weaned, the cow's nutrient needs drop sharply. This is a good time to evaluate body condition and make plans for the winter feeding period.

Mature Weight and Body Condition

A 1,200-pound cow needs more total nutrients than a 1,000-pound cow, but the nutrient concentration in the diet can be similar if both cows are eating proportionally to their size. The cow's body condition score tells you whether she is storing or using body fat, which affects her nutrient requirements.

Body condition scoring uses a 1 to 9 scale where 1 is emaciated and 9 is extremely fat. A body condition score of 5 means the cow is in moderate condition with a smooth appearance and no visible ribs but palpable fat cover. A body condition score of 6 means she has a slightly fleshy appearance with fat cover over the ribs and tailhead.

For most cow-calf operations, the target is a body condition score of 5 to 6 at calving. Cows that calve at a body condition score of 4 or lower have longer postpartum intervals, lower conception rates, and produce less colostrum and milk. Cows that calve at a body condition score of 7 or higher are carrying excess fat, which increases calving difficulty and feed costs without improving performance.

Milk Production Level

Milk production is the most variable factor in beef cow nutrient requirements. A high-milking cow needs substantially more energy and protein than a low-milking cow of the same weight. If you do not know your cows' milk production level, use breed averages as a starting point. Continental breeds like Simmental and Charolais tend to milk more heavily than British breeds like Angus and Hereford, but there is wide variation within breeds.

The practical way to estimate milk production is to look at calf weaning weights. If your calves are weaning at 600 pounds or more at 205 days, your cows are producing more milk than a herd weaning at 500 pounds. Adjust your ration to match.

Sampling and Testing Your Feed

You cannot balance a ration if you do not know what is in your feed. Forage testing is the single most cost-effective step you can take in your feeding program. A forage test costs between 15 and 40 dollars per sample, and the information it provides can save you hundreds of dollars per ton of supplement that you may not need or prevent a nutritional deficiency that costs you a calf.

How to Take a Hay Sample

The goal of hay sampling is to get a representative sample of the entire lot. A core sampler is the standard tool. It is a hollow metal tube, usually attached to a drill, that you push into the end of a bale to remove a core sample.

Follow these steps for a representative sample:

Sample at least 10 to 20 bales from each lot of hay. A lot is hay that came from the same field, was cut at the same time, and was stored under the same conditions.
Core each bale from the round side, not the flat end. Insert the probe 12 to 18 inches deep.
Combine the cores from all bales into one clean plastic bucket.
Mix the cores thoroughly and place about one pound of the mixed sample in a clean plastic bag.
Label the bag clearly with your name, the field, the cutting date, and the lot number.
Send the sample to a certified forage testing laboratory within 24 to 48 hours. Do not let the sample sit in a hot truck or in direct sunlight.

For square bales, core from the end of the bale. For silage or baleage, sample from the face of the pile or the middle of the bale after it is opened, and be aware that silage samples are more variable than dry hay samples.

What the Lab Report Tells You

A standard forage test report includes:

Dry matter percentage
Crude protein percentage
Acid detergent fiber (ADF) percentage
Neutral detergent fiber (NDF) percentage
Total Digestible Nutrients (TDN) percentage
Relative Feed Value (RFV) or Relative Forage Quality (RFQ)
Mineral concentrations including calcium, phosphorus, potassium, magnesium, and sulfur

Some labs offer near-infrared reflectance spectroscopy (NIRS) analysis, which is faster and cheaper than wet chemistry analysis. NIRS is accurate for most routine parameters, but wet chemistry is preferred when you need precise mineral values or when you are testing feeds that are unusual or that may contain anti-quality factors.

Understanding the Numbers

Crude protein tells you the nitrogen content of the feed. Good grass hay typically runs 8 to 12 percent crude protein, while legume hay like alfalfa runs 15 to 20 percent. ADF is the least digestible fiber fraction, and it correlates negatively with digestibility. As ADF increases, energy content decreases. NDF represents the total fiber content and correlates with intake potential. As NDF increases, the cow can eat less of the feed because it fills the rumen faster.

TDN is a measure of the energy content. You can estimate TDN from ADF using a simple equation: TDN equals 88.9 minus 0.779 times ADF. For example, hay with 35 percent ADF has an estimated TDN of about 61.6 percent. Many labs provide this calculation on the report.

RFV and RFQ are indexing systems that combine digestibility and intake potential into a single number. RFV is calculated from ADF and NDF, while RFQ uses more sophisticated digestibility estimates. Both are useful for comparing hays, but they are not the same as TDN and should not be used directly in ration formulation.

Balancing the Ration Step by Step

Once you know your cows' requirements and your feed's nutrient content, you can build a ration. The process is straightforward, but it requires attention to detail and a willingness to adjust based on what the cows tell you.

Step 1: Determine the Target Intake

The first question is how much dry matter the cow will eat. Dry matter intake is driven by the cow's weight, stage of production, and the quality of the feed. A good starting estimate is:

Dry cow in mid-gestation: 2.0 to 2.5 percent of body weight in dry matter
Dry cow in late gestation: 2.0 to 2.5 percent of body weight
Lactating cow: 2.5 to 3.0 percent of body weight
Growing replacement heifer: 2.5 to 3.0 percent of body weight

A 1,300-pound cow in mid-gestation eating 2.2 percent of her body weight will consume about 28.6 pounds of dry matter per day. This is the amount of feed she needs on a dry matter basis, not as fed. If you are feeding hay at 90 percent dry matter, she needs about 31.8 pounds of hay as fed to get 28.6 pounds of dry matter.

Step 2: Match Forage to Requirements

Start with your base forage. Determine whether it meets the cow's needs for energy, protein, and fiber at her current stage of production. Use the following worksheet:

Dry matter intake (pounds per day) multiplied by the forage's crude protein percentage equals the pounds of crude protein provided.
Dry matter intake multiplied by the forage's TDN percentage equals the pounds of TDN provided.
Compare these values to the cow's daily requirements.

For example, a 1,300-pound cow in mid-gestation needs about 2.0 pounds of crude protein and 14.9 pounds of TDN per day. If she eats 28.6 pounds of dry matter from hay that tests 10 percent crude protein and 55 percent TDN, she gets 2.86 pounds of protein and 15.7 pounds of TDN. This ration meets her needs with no supplement.

Now consider the same cow in early lactation. Her requirements jump to about 3.4 pounds of crude protein and 19.5 pounds of TDN per day. If her dry matter intake increases to 35.8 pounds per day, the same hay provides 3.58 pounds of protein and 19.7 pounds of TDN. She is still meeting her needs, but just barely. If the hay tested 8 percent protein instead of 10 percent, she would be short on protein.

Step 3: Add Supplements to Correct Deficiencies

When the forage does not meet the cow's needs, you must add supplements. The supplement choice depends on which nutrient is deficient.

If energy is deficient, you can add grain, byproduct feeds like corn gluten feed or wheat middlings, or high-energy forages like corn silage. Corn is high in energy but very low in protein, so it is best used when the forage is adequate in protein but short on energy.

If protein is deficient, you can add oilseed meals like soybean meal or cottonseed meal, or you can use non-protein nitrogen like urea. Non-protein nitrogen is only effective when the rumen has adequate energy to convert it into microbial protein, and it should never be used in rations that are also deficient in energy.

If both energy and protein are deficient, which is common with low-quality hay, you may need a combination supplement. Distillers grains, corn gluten feed, and whole cottonseed are examples of feeds that provide both energy and protein. These byproduct feeds are often cost-effective compared to mixing separate energy and protein sources.

The key is to calculate exactly how much supplement is needed. Do not guess. Use the same worksheet approach as in Step 2, but now add the supplement to the forage and check the totals.

For example, a 1,300-pound cow in late gestation eats 28.6 pounds of dry matter from hay that tests 8 percent crude protein and 50 percent TDN. She gets 2.29 pounds of protein and 14.3 pounds of TDN. Her requirement is about 3.4 pounds of protein and 16.5 pounds of TDN. She is short 1.1 pounds of protein and 2.2 pounds of TDN.

If you supplement with soybean meal, which is about 48 percent crude protein and 90 percent TDN on a dry matter basis, you need about 2.3 pounds of soybean meal to meet the protein deficit. This also provides about 2.1 pounds of TDN, which nearly meets the energy deficit. The final ration is 28.6 pounds of hay plus 2.3 pounds of soybean meal, totaling 30.9 pounds of dry matter. The cow may eat slightly more than her target intake when supplemented, so you should recalculate using the actual expected intake.

Step 4: Check the Protein to Energy Ratio

The ratio of protein to energy in the total ration matters as much as the absolute levels. The rumen microbes need a balanced supply of nitrogen and energy to grow efficiently. If protein is too high relative to energy, the excess nitrogen is absorbed as ammonia and converted to urea in the liver, which costs energy and can reduce performance. If protein is too low relative to energy, the microbes cannot use all the available energy, and feed efficiency drops.

A simple way to check the ratio is to divide the crude protein percentage by the TDN percentage. A ratio of 0.18 to 0.22 is generally appropriate for most beef cow rations. For example, a ration with 12 percent crude protein and 58 percent TDN has a ratio of 0.207, which is in the target range. A ration with 15 percent protein and 50 percent TDN has a ratio of 0.30, which indicates excess protein relative to energy.

Step 5: Convert to As-Fed Weights

Once you have the ration balanced on a dry matter basis, convert to as-fed weights so you know how much to feed. The formula is:

As-fed weight equals dry matter weight divided by the dry matter percentage of the feed.

For example, if the ration calls for 25 pounds of dry matter from hay that is 88 percent dry matter, the as-fed weight is 25 divided by 0.88, which equals 28.4 pounds. If the ration calls for 5 pounds of dry matter from a supplement that is 90 percent dry matter, the as-fed weight is 5.6 pounds.

Step 6: Adjust for Weather and Other Stressors

The balanced ration is a starting point, not a fixed prescription. You must adjust for conditions that change the cow's requirements or intake.

Cold weather increases energy requirements. For every degree below the lower critical temperature, add about 1 percent more energy. You can do this by feeding more of the same ration, or by adding a high-energy supplement. A practical approach is to increase the feeding rate by 5 to 10 percent when a cold snap is forecast and return to normal when it passes.

Mud is another energy drain. Cows walking through mud use significantly more energy than cows on firm ground, and mud also reduces feed intake because cows are reluctant to walk to the feeders. Provide a firm feeding area and be prepared to increase energy intake during prolonged wet periods.

Common Mistakes in Ration Formulation

Many feeding problems trace back to a handful of recurring mistakes. Recognizing these can save you time, money, and animal health.

Guessing Instead of Testing

The most common mistake is feeding hay without testing it. Producers often assume that all grass hay is similar or that a hay that looks good must be good. Visual assessment is not reliable for predicting nutrient content. Two bales of hay that look identical can differ by 3 to 5 percentage points in crude protein and 5 to 10 percentage points in TDN. These differences are enough to make the difference between a balanced ration and a deficient one.

Ignoring the Protein to Energy Balance

Some producers add a high-protein supplement to low-quality hay without considering energy. The result is a ration with adequate protein but insufficient energy. The cow uses the protein for energy instead of for tissue building, and the excess nitrogen is excreted in urine. This is wasteful and can cause the cow to lose condition even though she appears to be getting a good ration.

Overfeeding or Underfeeding Supplements

Supplement feeding errors are common. Some producers feed a fixed amount of supplement all winter without adjusting for forage quality or cow condition. Others feed too little because they are trying to save money, which results in thin cows and poor conception rates. The right approach is to test the forage, calculate the deficit, and feed the amount that actually corrects the deficiency.

Sudden Ration Changes

The rumen microbes need time to adapt to a new feed. A sudden switch from hay to grain or from one hay to a very different hay can cause acidosis, off-feed, and even death. Introduce any new feed gradually over 7 to 14 days, increasing the new feed and decreasing the old feed in small steps.

Forgetting About Minerals and Vitamins

A ration can be perfectly balanced for energy and protein but still fail if minerals and vitamins are deficient. Free-choice minerals are essential, but you must ensure the mineral is appropriate for your region and your feed base. Also remember that mineral intake varies between animals and over time. If some cows are not consuming mineral, provide additional feeders or mix the mineral into the ration.

Not Adjusting for Body Condition

Body condition score is the best tool you have for evaluating the ration. A cow that is losing condition is telling you the ration is short on energy, regardless of what the lab says. A cow that is gaining excessive condition is telling you the ration is too generous. Check body condition scores monthly and adjust the ration accordingly.

Decision Thresholds for Ration Adjustments

Knowing when to adjust the ration is as important as knowing how to adjust it. Use these decision thresholds as a guide.

Body Condition Score Below 4 at Any Time

If a cow drops to a body condition score of 4 or lower, she is in serious trouble. Her immune function is compromised, she is at higher risk for calving difficulty, and her ability to rebreed is severely reduced. Take immediate action to increase her energy intake. This may mean separating thin cows from the main herd and feeding them a higher-energy ration.

Body Condition Score Below 5 at Calving

Cows should calve at a body condition score of 5 or 6. If cows are calving at 4 or lower, your late-gestation feeding program is inadequate. Review your forage test results and supplement program, and make changes for the next season.

Cows Losing More Than One Body Condition Score Between Trimesters

A modest loss of condition from mid-gestation to late gestation is normal, but a loss of more than one full body condition score indicates the ration is not meeting energy needs. Increase the energy density of the ration or the total amount fed.

Cows Going Off Feed

If cows go off feed, check for problems with feed quality, mold, spoilage, or a sudden change in the ration. Also check water availability and quality. Off-feed is an early warning sign that should be investigated immediately.

Calves Weaning Below Expected Weight

Calf weaning weight is a direct reflection of milk production, which is a direct reflection of the cow's nutrition during lactation. If weaning weights are below breed or herd averages, review the lactation ration and consider increasing energy and protein during early lactation.

Monitoring and Recordkeeping

A good feeding program is a cycle of planning, feeding, monitoring, and adjusting. Keep records that allow you to evaluate your program and make improvements over time.

What to Record

Forage test results for every lot of hay and silage
The amount of each feed fed per day and the number of animals fed
Body condition scores for the cow herd at key times: weaning, mid-gestation, pre-calving, and breeding
Calving dates and calf birth weights
Weaning weights and weaning dates
Weather conditions, especially temperature, wind, and precipitation
Feed costs per ton and per pound of nutrient
Health events including any cases of metabolic disease, pneumonia, or digestive upset

How to Use the Records

Review your records at least twice per year, once after weaning and once after calving. Look for patterns. Are cows losing too much condition in late winter? Are first-calf heifers lighter than the rest of the herd at weaning? Is the cost per pound of gain going up?

Use the records to make decisions about next year's feed purchases. If your hay consistently tests low in protein, plan to buy a higher-protein supplement. If your cows maintain condition well on a certain type of hay, try to source that hay again.

Body Condition Scoring Protocol

Body condition scoring is subjective, so be consistent. Score the same side of the cow each time, and use the same person to do the scoring. Score cows at the same time of day, preferably in the morning before feeding. Use the following landmarks:

The back and loin area: Feel for the spinous processes (the backbone) and the transverse processes (the ribs that extend sideways from the spine).
The tailhead: Feel for the fat cover around the tailhead.
The ribs: Look for visible ribs. At a body condition score of 5, the ribs are not visible but can be felt with light pressure.

Practice on cows of known condition to calibrate your eye and your hand. Your local extension agent or veterinarian can help you learn the technique.

When to Call a Veterinarian or Extension Agent

Most ration formulation problems can be solved with careful observation and adjustment, but some situations require professional help.

Call Your Veterinarian If

Cows are going off feed and you suspect acidosis, bloat, or another digestive emergency.
Multiple cows show the same signs of illness, which could indicate a toxic feed problem such as nitrate poisoning, prussic acid poisoning, or mold toxicity.
Cows are showing signs of mineral deficiency such as rough hair coats, poor hoof quality, or reproductive failure.
You suspect a disease outbreak that is affecting feed intake or nutrient utilization.
Calves are being born weak or with congenital defects that could be related to nutrition.

Call Your Extension Agent If

You need help interpreting forage test results.
You want to compare the cost of different supplement options.
You are considering a major change in your feeding program, such as switching from dry hay to silage or adding a new byproduct feed.
You need help calculating a ration for a specific group of animals, such as first-calf heifers or mature bulls.
You want to learn more about body condition scoring or other monitoring techniques.

Extension agents have access to ration balancing software and can help you build a ration that is both nutritionally adequate and cost-effective. This service is typically free or low cost.

Frequently Asked Questions

How often should I test my hay?

Test every lot of hay that you plan to feed. A lot is defined as hay from the same field, cut at the same time, and stored under the same conditions. If you buy hay, test each load before you feed it. If you grow your own hay, test each cutting from each field. Hay that has been stored for a year or more should be retested because nutrient content can decline during storage, especially if the hay was stored outside.

Can I balance a ration without a forage test?

You can make a rough estimate, but you cannot balance a ration accurately without knowing the nutrient content of your feed. The difference between a good year and a poor year for hay can be 3 to 5 percentage points in crude protein and 5 to 10 percentage points in TDN. These differences are large enough to require different supplement strategies. The cost of a forage test is small compared to the cost of overfeeding or underfeeding supplement for an entire winter.

What is the best way to supplement protein to cows on low-quality hay?

The best supplement depends on the specific deficiency and the available feedstuffs. Soybean meal, cottonseed meal, and canola meal are all good sources of rumen degradable protein. Distillers grains and corn gluten feed provide both protein and energy. Non-protein nitrogen like urea can be used in some situations, but it is risky with low-quality forage because the rumen may not have enough energy to convert the nitrogen into microbial protein. Work with your extension agent to choose the most cost-effective option for your area.

How much grain can I feed a beef cow?

Beef cows are not designed to eat large amounts of grain. The rumen microbes that digest fiber are sensitive to low pH, and high grain diets can cause acidosis. As a general rule, keep grain in the total ration below 30 percent of the dry matter. If you need more energy than that, consider using a byproduct feed like corn gluten feed or distillers grains, which are less likely to cause acidosis than straight grain.

Should I feed first-calf heifers a different ration than mature cows?

Yes. First-calf heifers are still growing themselves while they are also gestating and lactating. They need higher protein and energy concentrations than mature cows, and they also need more mineral, especially calcium and phosphorus. Many producers feed first-calf heifers separately from the mature cow herd for the first 60 to 90 days after calving. This allows you to give them a higher-quality ration without overconditioning the mature cows.

How do I know if my cows are getting enough energy?

Body condition score is the most practical indicator. If cows are maintaining or gaining condition through the winter, they are getting enough energy. If they are losing condition, they are not. You can also look at behavior. Cows that are chronically short on energy will be more aggressive at the feed bunk, will bawl more, and may chew on wood or eat dirt. These are signs that the ration is not meeting their needs.

What is the ideal body condition score for beef cows at calving?

The ideal body condition score at calving is 5 to 6 on the 1 to 9 scale. Cows at a body condition score of 5 have a smooth appearance, no visible ribs, and fat cover over the tailhead that can be felt but not seen. Cows at a body condition score of 6 are slightly fleshy with obvious fat cover. Cows below 5 at calving have reduced colostrum quality, lower milk production, and longer intervals to first heat. Cows above 6 are carrying excess fat, which increases calving difficulty and feed costs.

Can I use distillers grains as the main supplement in a beef cow ration?

Distillers grains are an excellent supplement for beef cows because they provide both protein and energy, and the protein is relatively high in rumen undegradable protein. However, distillers grains are also high in phosphorus and sulfur, so you need to watch total phosphorus and sulfur intake. High sulfur can interfere with copper absorption and can cause polioencephalomalacia in extreme cases. Limit distillers grains to no more than 30 percent of the total dry matter, and make sure your mineral program accounts for the extra phosphorus.

Related Farming Guides

This section will be populated with links to other farming guides on this site that cover related topics such as beef cattle health, pasture management, and calf nutrition.

Related Clinical & Scientific Guides

References

Beef Cattle Research Council: https://www.beefresearch.ca/
USDA APHIS Cattle Health: https://www.aphis.usda.gov/livestock-poultry-disease/cattle
WOAH Terrestrial Animal Health Code: https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/
FAO Animal Production and Health: https://www.fao.org/animal-production/en/
WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.