Preg Checking Cows: Methods, Timing, Cost and Open Cows

By the XES Netting team — bale net-wrap manufacturer · Updated October 10, 2026 · ~18 min read

Preg checking cows in the fall is the cheapest way to keep winter hay out of cows that will not calve. Ohio State University Extension educator Dean Kreager put the math simply in Pregnancy Testing Pays Off (September 2025): at $60 a round bale and five bales a cow, an open cow eats $300 of hay over winter, and “This number could easily go up to $500.” Yet a USDA survey found that fewer than a third of cow-calf operations test at all. Every fall AgTalk argues the details: palpation or ultrasound, a blood test you draw yourself, how soon after the bulls come out, and whether an open cow should go to town, to the feed bunk or to a fall-calving herd.

This guide is for beef cow-calf producers deciding how and when to pregnancy-test a herd and what to do with the cows that come up open. It is not veterinary advice: diagnosis, herd health and any drug use belong with your veterinarian, and who may perform pregnancy checks is set by state law. XES manufactures bale net wrap, and most cow herds winter on round bales, so we put the decision in bales of hay. We read 29 archived AgTalk discussions about preg checking, open cows and late-bred cows (603 posts, August 2022 to March 2026) and checked them against Extension guidance from Ohio State, Nebraska, Florida, North Dakota State and Oklahoma State.

Why preg checking pays: the hay math

An open cow costs you twice. She eats a full winter’s hay, and she produces no calf to sell next year. The second cost depends on calf prices; the first one you can measure in bales. The table below uses one 1,300-lb dry cow, two intake rates and a common round bale, so you can swap in your own numbers.

Assumptions: dry-matter intake of 2.0% to 2.5% of body weight, 1,200-lb bales at 85% dry matter, and 15% added for storage and feeding loss. North Dakota State University’s Janna Block uses 2.5% of body weight as a planning estimate and a 15% loss allowance in Now is the time to estimate winter hay needs; our guide to how much hay a cow eats explains why that figure is an estimate and how to replace it with your own. The result lines up with Ohio State’s five-bale example.

Scale it to a herd. In a 100-cow herd with 10 opens, which is about what Ohio State says surveys find in many herds, the open cows would eat roughly 44 to 55 bales over a 150-day winter. Checking all 100 cows at $10 a head costs $1,000. A southwest Minnesota producer did the same arithmetic on AgTalk in October 2025:

"100 head, 6 opens. $6 to preg check. That’s $100 to find each open. Do your own math after that. How long can you feed an open for 100?"

— Hick, Sw mn · AgTalk thread 1217606

That thread started with a Saskatchewan family that had never preg checked, mostly because of the labor and their chute, asking how to show the rest of the family it would pay. A Michigan producer listed the unknowns to fill in: “What's your cost per cow, per day (some folks it might be $3 a day)?” and what you charge for your own time. A central South Dakota rancher added that “those of us that borrowed money to own cows had to preg test to show the banker what we had.” Hay is only part of the bill, but it is the part you can see stacked in the yard.

Testing is still the exception. In the USDA National Animal Health Monitoring System’s Beef 2017 survey, analyzed in the University of Florida IFAS publication AN379, 31.6% of cow-calf operations used any pregnancy test. Palpation, the most common method, was used by 14.2% of operations with fewer than 50 cows, 29.3% with 50 to 199 and 53.6% with 200 or more.

Palpation, ultrasound or blood test

All three methods need one trip through the chute. They differ in how early they work, what else they tell you, who can do them and how fast you get an answer.

The timing and limits come from Nebraska Extension’s Aaron Berger in Pregnancy diagnosis in heifers and cows provides management options (2024), Ohio State’s 2025 article and the manufacturer’s IDEXX Bovine Pregnancy Test sheet. Ohio State notes that ultrasound can work as early as 20 days in some situations and sexes fetuses from about 60 days.

Palpation and ultrasound

Palpation is the old standby and needs no equipment, only a skilled arm. An Idaho producer gave the field version of the early window: “45 days the embryo should be about the size of a grape. 55 days a walnut.” Ultrasound adds a picture, which lets an operator confirm a live fetus, find twins, age the pregnancy closely in the first trimester and sex calves in the right window. Several producers said accuracy depends more on the person than the tool; one west-central Illinois producer wrote down his palpating vet’s staging calls and found “about 1/3 of what he predicts is way off.”

Some ranches now own a scanner. A Canadian producer who bought one, learned from online tutorials and checks his own herd described the catch:

"Finding breds is generally a piece of cake. … Confirming an open is the hard part."

— Alberta Cowman · AgTalk thread 1184552

Blood tests you can draw yourself

Blood tests measure pregnancy-associated glycoproteins, proteins the placenta releases into the cow’s blood. Ohio State says the tail-vein draw is something “Most producers can do” with minimal practice, samples ship at room temperature, and results come back in a few days. The trade-off is information: a blood test says pregnant or open, with no fetal age or sex.

"We do prob 75 percent of our pregging with blood test. I like the idexx kits because you don’t have to mail the tubes off. We pull the bulls early so staging cows isn’t a big deal for us. Accuracy has been very good as well."

— 7210jd, Nw mo · AgTalk thread 1209697

The same producer said “70 cows at a time is about my limit” for chute-side kits, about as many tests as he can keep straight on a tailgate. First-timers mostly struggle with the draw. In a 2022 thread on mail-in tests, a north Florida producer advised beginners “Don't try to learn with the vacuumtainer. Learn with a 1" needle and 3mL syringe,” and a southeast Texas producer said holding the tail too high makes it harder.

Accuracy is uneven by direction. IDEXX reports 99.3% sensitivity and up to 95.1% specificity at 28 days, and says an open result means the cow is open with “over 99% certainty.” Most errors are false “pregnant” readings in cows that lost a pregnancy recently or calved too recently, because the proteins linger. That is why some ranches retest before shipping:

"any question pregs get tested again in thirty days, this is no big deal as they are caught and going down the road if open anyway. We just feed them, test again and ship with confirmed opens, the second test has always been conclusive. We can't afford to cull bred cows and even two arm mistakes per hundred is to many."

— rock, Tablerock Ranch eastern Wa · AgTalk thread 1090784

Milk pregnancy tests run on the same proteins and suit dairies or beef cows sampled at weaning while they still milk. Watching for cows that are ridden late in the season is a rough screen, not a test: a southeast Wisconsin producer said several cows he remembered being jumped “turned out to be bred.”

When to preg check cows

The Florida analysis puts the herd check at least 30 days after the end of the breeding season, usually the day the bulls come out, or at weaning; from about 30 days after conception all the methods are highly accurate. Herds that use artificial insemination followed by bulls often check twice: about 30 days after AI to measure AI conception, and 30 days after bull removal for the season. A northeast Missouri producer put the simple rule in five words, “Pull the bull, ultrasound 30 days later.”

Many herds instead check later, around weaning, so the veterinarian can stage each cow by cycle and the late ones can be sorted:

"Number 1, does your vet ultrasound and call true days. If he doesn't, find one that does. We usually preg 90 or so days after AI or bull turnout. Vet can call 1st cycle, 2nd cycle and 3rd. Won't be many 3rd's. Keep the 1st and 2nd's, get rid of the rest. … Late calves never catch up."

— oldtiger, NEMO · AgTalk thread 1232230

If the bulls stay in all year, a southwest Minnesota producer’s rule sets the date: “preg check with an ultrasound on the date that corresponds to the day you want your last calf.” Three timing details matter:

• Calving date limits blood tests. A spring-calving cow checked at weaning is far enough from calving; a fall-calving cow checked early may not be. Ohio State uses 73 days after calving and Nebraska 75.
• Early pregnancies are fragile. Nebraska Extension cites research showing pregnancy loss of 1% to 3.5% when palpation or ultrasound is used at 40 to 75 days of gestation, and stress early in pregnancy can cause losses. Producers argue whether the exam itself causes any; checking a little later, or by blood, sidesteps the question.
• Checking early catches a bull problem in time. Cows that are not cycling, a bull that quits, or a lazy bull in a timbered pasture often show up only on preg day.

"Quite a few cows just weren’t cycling so we didn’t notice until we checked them. … At my place, we reBSE bulls we buy before turnout. … We have caught 3-4 bulls in 18 years this way that passed before the sale but were shooting blanks by the time we wanted to use them."

— HL, Nebraska · AgTalk thread 1080414

Fall calvers flip the calendar. A west-central Iowa producer pulls bulls around March 1 and has the vet check about 50 days later, and an eastern Kansas producer hauls his small fall group to the clinic for a check around April 1.

What preg checking costs

Ohio State puts pregnancy tests at about $5 to $20 a cow. A mailed blood sample runs about $5 including tube and needle, plus shipping; a chute-side kit about $10 a cow with results in 20 minutes; palpation or ultrasound a per-head fee plus, usually, a farm call. Producer reports in the threads fit that range:

• Veterinary checks: $6 a head (southwest Minnesota, 2025). At a September 2026 Wyoming legislative hearing, a rancher testified that her veterinarian charges $5.25 a head.
• Trip charges: a west-central Illinois producer pointed to the “$75 trip charge no matter how long he's there” that makes vet calls for two or three cows hard to justify (2022).
• Mail-in blood: $4 a head plus shipping for a first-time user in 2022, and “about $1.50 per head at 30-head or more” through a university vet-school lab in 2025.
• Labor and setup: a working chute, a dry place to work and pre-sorted pens. Ohio State notes the farm-call fee is a bigger share per head when you only have a few cows.

A New York dairyman summed up the trade-off in 2024: “Yes your vet is expensive but so is feeding an open cow.”

Who can preg check your cows

Checking your own cattle and selling pregnancy checks to other people are different things in the law. In most states, diagnosing pregnancy for pay falls under the veterinary practice act. Wyoming is a current example: it is a crime there for a non-veterinarian to practice veterinary medicine, punishable by up to six months in jail and a $750 fine, while ranchers may check their own livestock. On September 22, 2026, Cowboy State Daily reported that the legislature’s Joint Agriculture Committee killed, 8 to 5, a bill that would have let non-veterinarians sell pregnancy checks. Supporters pointed to the shortage of rural veterinarians; veterinarians said losing preg-check work would drive large-animal practices out of the state.

AgTalk argued the same question in April 2024, after two Pennsylvania men who ran a dairy reproductive-ultrasound service were jailed following earlier fines and cease-and-desist orders for practicing veterinary medicine without a license (AGDAILY). One reply drew the line most producers accepted:

"These folks were providing services for hire. Your hypothetical(s) seems to always worry about owners doing for their own. I believe a sharp a practiced 'layman' could learn to skillfully and accurately preg check cattle. Probably at a lower price point than a licensed vet but should we go that direction? We already are short large animal vets."

— Doug61, Eastern NE KS · AgTalk thread 1156780

Rules differ by state, and some allow trained lay technicians under conditions or veterinary supervision. Before you hire anyone other than a licensed veterinarian, ask your veterinarian or your state’s veterinary board. Drawing blood from your own cows and mailing it to a lab, as many producers in the threads do, keeps a professional laboratory in the loop.

What open rate is normal, and what causes opens

Nationally, the Florida analysis of the 2017 survey found that 93.5% of cows and 83% of heifers produced a calf. Producers’ own benchmarks run in the same range: a central Iowa producer wrote that “My vet that does my preg checking says the average opens is 10%,” with some years above 16% and some below 5%. A Manitoba rancher who checked a May-June calving herd at 11% open said about 5% was decent for a well-managed herd in his area. And a North Dakota producer with three decades of records was blunt:

"I’ve never been to a breed up better than 8-10%. Switched to 50 days after being 60 day breeding. I think we were at 14% this year. 2nd and 3rd calves being the biggest culprit."

— bacon, SC North Dakota · AgTalk thread 1187751

Young cows recur in the numbers. A Manitoba producer’s second calvers came up 25% open two years running, and a Montana rancher wrote “Nothing more expensive than an open 3 year old.” Bad years are usually regional: after the 2023 heat waves, a northeast Iowa producer’s veterinarians found “abnormal CL's” in several open cows, a sign of heat-affected cycles they were seeing in many herds.

When the open rate jumps, the threads point to a short list of suspects. Work through it with your veterinarian rather than guessing:

1. Bulls. Test them close to turnout, not only at the sale. A South Dakota producer’s advice was “Test right before turnout,” especially yearlings moving to grass and heat. Single-bull pastures hide a bull that quits.
2. Body condition. Thin cows at calving struggle to rebreed, but fat ones can too (see below).
3. Water and feed access. Groups too large for the tank or the bunk leave timid cows short.
4. Disease and venereal infections. Trich, BVD and lepto belong in a vaccination and testing plan set with your veterinarian.
5. Heat, toxic forage and poor hay. Endophyte-infected tall fescue lowers conception, and moldy hay and high-nitrate forage can cause abortions; see our guides to moldy hay and nitrates and prussic acid.
6. Mineral program. Low or changed intake came up in several bad years; our winter mineral guide covers cows on hay.

"body condition at calving and 90 days following probably has the most impact. … I don't know if the mineral switch was a big deal but I'm certain the water was."

— HL, Nebraska · AgTalk thread 1133912

HL’s herd had its highest open rate after running larger groups on undersized tanks; after adding and upgrading tanks, opens dropped back to average or below. Too much condition can cost conception as well. An Idaho rancher described his father’s herd, fed plenty of hay every winter:

"Dad's herd always ran 10% open. He checked for BVD you name it, he did it. … It solved the 10% open deal. Those cows where just too fat."

— Russ In Idaho · AgTalk thread 1187751

What fixed it was wintering those cows on desert graze-out instead of generous hay. Hay quality matters in the other direction too, which is why the hay a bred cow eats in late pregnancy should be tested; our hay test guide and winter supplement comparison cover the numbers.

What to do with open and late-bred cows

Most producers in the threads ship opens at preg check. The strongest case came in the October 2025 thread:

"Check and dump the opens asap. Keeping them is a trap, unless they are incredibly shelly and will gain weight to make a salable animal. The whole white fat market only works when the market is in an upswing."

— oldskool · AgTalk thread 1217606

Timing the sale matters. Nebraska Extension notes that cows are traditionally pregnancy tested in the fall, which “is also when cull cow prices are typically at their lowest.” Oklahoma State University livestock marketing specialist Derrell Peel has put the average seasonal decline in Oklahoma boning-cow prices from August to November at about 15 percent (Cow-Calf Corner). Checking 30 days after the bulls come out, by blood or ultrasound, can move culls ahead of the November run. Ohio State’s September 2025 example valued a 1,400-lb cull cow at $1.60 a pound, $2,240, and with the hay savings counted, “over $2,500 income by culling now.”

The alternatives each need a plan:

• Feed them out. Some producers put opens on corn and sell them fat; a Nebraska producer wrote “feed corn hard for 60-75 days and sell.” It pays only with cheap feed and a rising cull market.
• Move them to a fall herd. Several producers give a good spring open one more chance in a fall-calving group. An eastern Kansas producer runs it as two strikes: “If a fall fails, that is strike 2 and she's out.”
• Trade opens for bred females. Sometimes cheaper than a year of feed on an empty cow, but bought cattle carry their own risk.

"I traded my 29 opens plus a couple of open 3 year olds for 25 nice simangus bred heifers out of Sk. I might have half of those cows left now. … In the long run I would probably have been more profitable to feed my opens over winter and breed them as 2 year-olds."

— northerngrazer, MB, Canada · AgTalk thread 1080414

Buying other people’s open cows to rebreed drew the most warnings. A Montana rancher said “I’d say to expect 8-12% open if normal is 5%,” and another producer cautioned that an open cow can carry trichomoniasis: “You are playing with fire buying open cows to try and rebreed.” Some states restrict how open cows can be sold; check your state veterinarian’s trich rules first.

Late-bred cows in a high market

With bred cows bringing record money, a cow bred late is no longer a cull. In July 2025 a northeast Iowa producer argued for leaving bulls in:

"It used to be P1 cows in November would be sold for cull price. Now they bring several hundred dollars more then cull value no matter how late they are bred."

— 17821x, NE Iowa · AgTalk thread 1209143

Others warned that sorting late-breds by fetal age “isn’t perfect” and that a long season lets less fertile cows stay. Hay supply often decides it:

"We get a dry year it seems every 5-7 years, late cows are first to go to make feed match number of cows, now it looks like I will have hay coming out of my ears so late cows will stay as they weill make more money then giving hay away."

— WCWI · AgTalk thread 1209143

In a short year, the late and open cows are the first place to cut demand; our guide to stretching a short hay supply ranks the other options.

Preg-check day checklist

1. Set the date from the bull calendar. At least 30 days after bulls come out; for blood tests, 60 to 75 days or more after calving.
2. Book early. Fall is the busy season for large-animal veterinarians. If you use blood kits, check reagent expiry dates before the day.
3. Sort before the vet arrives. Pens full and the alley ready keep a per-hour or per-head bill down. A roof over the chute keeps the work dry and shaded.
4. Record more than open or bred. Write down ear tag, the call, fetal age or cycle, body condition, teeth, udder and feet. Those notes set calving groups and next year’s culls.
5. Confirm before you ship. Retest doubtful blood results and recheck any good young cow called open.
6. Re-sort winter feeding groups. Group bred cows by expected calving date and condition, and save your best hay for late pregnancy and young cows. Our weaning guide covers the calves that come off at the same time.
7. Decide the opens the same week. Sale date, feed-out or fall herd, before they start eating winter hay.
8. Recheck purchased bred cows after a long haul. An eastern Kansas producer described a neighbor’s sale of 74 cows hauled about 460 miles: two were called open on recheck, and the seller paid the difference between purchase price and cull value. Spell out terms like that before the cattle ship.

Frequently asked questions

How soon can you preg check a cow?

Ultrasound can confirm pregnancy from about 28 days after breeding and blood tests from 28 days (25 in heifers, per Nebraska Extension), while palpation by an experienced veterinarian usually starts around 35 to 50 days. For a whole herd, check 30 days or more after the bulls come out, often at weaning.

How much does it cost to preg check cows?

Ohio State Extension puts pregnancy tests at about $5 to $20 a cow: around $5 for a mailed blood sample plus shipping, about $10 for a chute-side kit, and a per-head fee plus farm call for palpation or ultrasound. Producers on AgTalk reported paying $6 a head for veterinary checks in 2025.

Can I preg check my own cows?

Many producers draw tail-vein blood themselves and mail it to a lab or run a chute-side kit, and Ohio State says most can learn the draw with minimal practice. Palpation and ultrasound take training. Selling pregnancy checks to other people without a veterinary license is illegal in many states, including Wyoming.

How accurate are blood pregnancy tests for cattle?

The maker of the IDEXX blood test reports 99.3% sensitivity and up to 95.1% specificity 28 days after breeding and says an open result is over 99% certain. Most errors are false pregnant readings in cows that recently lost a pregnancy or calved, so test at least 60 to 75 days after calving and retest doubtful cows.

Should you sell open cows in the fall?

Usually yes, because a 1,300-lb open cow eats roughly 4 to 6 round bales over a 150-day winter and raises no calf. Cull prices are typically lowest in November, so checking earlier helps. Feeding opens out or moving them to a fall-calving herd can pay with cheap feed and a plan.

The bottom line on preg checking cows

Preg checking cows turns a winter of guessing into a list: which cows get the hay, which cows calve when, and which cows should leave before they eat another bale. Pick the method that fits your vet, your chute and your schedule; check 30 days or more after the bulls come out; confirm the doubtful calls; and decide on the opens the same week. The hay you stack for winter is the biggest bill a cow herd pays, and much of it goes up as round bales, so make it count: XES bale net wrap keeps bales tight from the field to the feeder, so the hay you feed reaches the cows that will pay you back with a calf. If you keep your own replacements, our guide to replacement heifers covers raising, buying and developing them on hay.

Research note: We read 29 archived AgTalk discussions about preg checking, open cows and late-bred cows (603 posts, August 2022 to March 2026; three of them about dairy cows or horses, used only for testing logistics), then checked the linked Extension, survey, manufacturer and news sources on October 10, 2026. Post counts include questions and replies, not counts of farms, and producer numbers are what they reported at the time. The hay table is an XES calculation from the stated assumptions. XES sells bale net wrap and does not endorse any test, kit, laboratory or equipment brand; nothing here is veterinary or legal advice.

Featured photograph: Feeding time for the cows 01, Indy beetle, dedicated to the public domain under CC0, via Wikimedia Commons. A farmer brings out round hay bales to feed beef cattle in Shiloh, Rockingham County, North Carolina, December 30, 2022. Image unchanged apart from display resizing.