How accurate should I expect ultrasound to be?

[Ozhorse]

I have been getting the same person to ultrasound my cows for the past 3 years. They do a few other big farms around here as well. I have found a consistent pattern that the cows calve usually at least 3 weeks, and often a month to 6 weeks, earlier than estimated. Either that or I am calculating wrong. They will say 8, 10, 12, weeks or whatever, and I work back to the service date and calculate from there based on a 283 day gestation. I suppose that gives me +/- 2 weeks, which is a month, for accuracy of date as they only guess in even fortnight multiples. Perhaps I am calculating wrong. I think they did about 160 head for me last March.


Also this year they missed a first calving heifer that was twinning. If I had known in advance I would have avoided a wreck (ended up with one live cow with one live calf at foot in the end, after a lot of work). But then I did not ask for twins to be looked for.

One of my big old registered cows was called in as open. I know they fished around in her for a fair time. She is a really big cow and has had a calf every year. Perhaps she hid it somewhere in there, low down. I remember them saying she looked like she was ovulating at the time of ultrasound. She was AI on 31st Oct 2013 and ultrasound on 6th March 2014. I had her in the yard to ship her to the the meatworks with other old cows, but got soft and threw her out is a really tough back paddock.

I was having a look around the other day, and she looked like she was going to calve. And she did, to the AI on the 5th August, a nice bull. She is in a lot worse condition for being out in that paddock as I would not have put a calving cow there.

Usually I get rid of empty cows so I dont know if empties really were not in previous years.

Is this an acceptable level of accuracy? Do you think I should give feedback? (politely with figures and let them show me if I have calculated wrong) I am not particularly unhappy or anything, just wondering from those who have had more experience than me what level of accuracy I can reasonably expect.

 

[Jessica06]

Are they using their arm, or a probe? I have found that you can ocassionally miss a late 2nd or 3rd trimester pregnancy in a really big, deep bodied cow. Uncommon, but it does happen. Because of this, I took a class to learn palpation and palpate every open that looks questionable to me on the screen. Open uteruses are easy to find and it only takes a second. I don't know how much time your tech spends on an open, but I usually take a minute, maybe two, figuring that the time lost will be made up on the breds that can be found almost instantly.

As far as accuracy goes, I think that it depends mainly on how long they spend on the opens. About 20% of the time, if I don't see a pregnancy right away, I eventually find it if I keep searching for a while longer. In the last group I did, I had a 50 day fetus sitting right under the spine...I had to turn my probe completely upside down to find it.

You figure blood testing is supposed to be 95-99% accurate, with the average palpator in the 70-90% range. I figure ultrasound should be 90%+, to be competitive with the other methods. Any decent tech should be way above that consistently, impo.

 

[Ozhorse]

A long probe is used for the ultrasound. They spend more time on the open cows.

If accuracy of only 90% is to be expected that would mean 10 cows wrong out of 100, which is a lot. Only one wrong out of 140 - 160 cows is over 99% accurate. I also get sheep ultrasound. It was only something like 50c for wet/dry and 75c for twin/single/dry. So half again more money to take the time to look for twins or triplets. I didnt pay for twins to be looked for in the cattle so I should not expect them to be found. What you say indicates that the accuracy for dry/in calf seems reasonable.

Interesting that a really big bodied cow can hide that calf in there. The calf she missed would have been 4 1/2 months along.

The next question is how accurate is it reasonable I expect the dating to be. I find that the cows are calving up to 6 weeks, and often 3 weeks, earlier than expected from ultrasound estimates.

Is that also within tolerance limits of the technique?

 

[wbvs58]

I have been buying a couple of stud cows a year from a New England Angus stud and now have about 14 of them I think. They have been scanned I am given a due date calculated from the scan and they always calve within 2 or 3 days of that date. Half will be to the AI the rest would be paddock served and they would have no idea of the date of service.
I have spoken to the owner and he says they put them in management groups for calving together from the scans and they seldom calve outside of a couple of days from the due date.
I did buy a donor cow a couple of years ago that had scanned open and she calved right on the AI date for me, a bit of a bonus. Even the best of them get an occaisional one wrong. Probably similar circumstances to your old cow, it got lost down in that deep old belly.
I think your operators pregnancy diagnosis is OK but they need to improve a lot on gestation length.
Ken

 

[Ozhorse]

Just for interest I calculated the average between the estimated vs the actual date of the 30 that have calved so far. The average number of days earlier than estimated came in at about 26 days with only 4 on time or early and the majority of the rest about 3 weeks early, but 8 of them 40 to 56 days earlier.

So fairly consistent on my gut feel, which was I can expect the calves three weeks earlier than calculated.

I think I might just give the estimated vs actuals in a spreadsheet next time they are here. I think I might ask for the heifers or other poorer condition young cattle to be checked for twinning also as the big old ladies can handle it, but the young ones can come a wreck.

 

[Jessica06]

The tricky part about using the probe is that you have to be really careful not to rupture the rectal wall when you are looking for the really deep ones. If I had one that I couldn't tell on, I would take the probe out and palpate. On the really late bred ones, sometimes the calf's head will be so tight against the uterus and take up so much room, that it almost looks like an open because you can't see any fluid. However, you can usually tell that something doesn't look quite right, which is the signal to palpate her instead.

To me, 90% on ultrasound is the absolute minimum. If I find out that I miss even one, I feel pretty rotten. If I were hiring someone to do it, I would expect 95% or better, though most should be closer to 100% if they are pretty experienced. We haven't done a whole lot, but are pretty close to 100%. If I had a pretty important cow show open, I would definitely take more time on her, and even blood test if I had to, to be absolutely certain.

As far as aging, if the cows are 120 days or less I would expect the aging to be off by no more than 10-15 days. 30 days is too much. Now if they are over 120, it gets difficult because a lot of the time the head has dropped too far, or grown too large to measure and it's hard to find any other reliable landmarks.

We are starting to calve out our first big group to age, and so far both of the cows are within a week of their due date, all natural service. The rest look about like they should!

On a side note, we played around with ultrasounding in my sheep and goat class in college, and as far as management tools go I don't think you could find a more useful one.

 

[Ozhorse]

As far as aging, if the cows are 120 days or less I would expect the aging to be off by no more than 10-15 days. 30 days is too much. Now if they are over 120, it gets difficult because a lot of the time the head has dropped too far, or grown too large to measure and it's hard to find any other reliable landmarks.

That is going to have been the problem then. The first bulls were out on the 1st October 2013 and the cattle were ultrasounded on three dates, starting the 6th March 2014. The earliest in calf cows were already 5 to 6 months pregnant, which is 150 to 180 days.

Fortunately for me I rotate bulls as a new bull I got last spring has turned not to have sired a single calf for the entire month of November. So I have about 30 cows that got in calf from December on. I will see how accurate the dating of calving is with the later cattle. They would only have been in calf 120 days at most or less.

I really appreciate being able to ask these questions here. Rural communities are small and everyone is related or knows each other and whatever one asks gets spread about. I do not want to be heard to criticise someones livelihood and professional practice or put doubts in the minds of this operators other clients. It is easy for people to take things the wrong way. If it was not for this forum I dont think I could question like this, on the other hand I need educating.

I really appreciate the level of deep expertise here.

If the estimated calving date gets close the later and closer to the ultrasound date then the fault has been mine. Come to think of it I knew that was not the ideal time for preg-testing as I timed it to fit in with my program, not best time for the job.

When I am having the sheep done I have always been careful to work in with the operator (different one for sheep) to make sure the date is within a close range so that the twin/single/triplet can be worked out. Also we are often doing 1100-1200 animals so we need conditions to be optimal.

With the sheep, ultrasound was a great way to work out fertility issues. After the first round we culled out about 8o dry from 1000, the next year 60 from 1100 and the year after only about 40 so I quit doing them after that as it was obvious that getting in lamb was not the restrainer. All the ones that were not getting in lamb had been removed. I worked out that while separating the twinners from the singles and running them separate sounds like a great idea in principle, in practice it just led to a concentration of problems in one paddock, a lot more work and money spent, and in the end probably no more, and possibly less, sheep at the end of the exercise. If one had a different environment and management options then drafting off the twinners would be good practice.

 

[Craig]

Try ultra sounding earlier. I try to do mine at 30-35 days post AI. Anybody comes up open they get a shot of lute. The vet says things are typically more out in the open earlier. Easier to spot a heartbeat, or two. If you use a bull try 90 days after turning him out.

 

[Fire Sweep Ranch]

We have a cow that twinned as a 3 year old and raised them both. We AI'd her back, and ultrasounded her at 70 days. I asked our vet to double check for twins, because I did not want her to have to go though that again, or at least so we could be prepared. He assured me there was just one calf in there, and it was a bull. Well, 2 weeks early, she calved... twin bulls calves, both dead because the first was breech and she went into labor in the night sometime and we did not find her till morning.
So yes, they can be wrong.
But our gestation days are right on, but of course we know right when they are due because we AI, no bull exposure.

 

[regolith]

Try ultra sounding earlier. I try to do mine at 30-35 days post AI. Anybody comes up open they get a shot of lute. The vet says things are typically more out in the open earlier. Easier to spot a heartbeat, or two. If you use a bull try 90 days after turning him out.

The vets we use for dairy won't confirm anything as bred that is less than six weeks - about 42 days. A couple years ago my vet got to play with some short bred cows of mine and he was seeing them with the scanner at 28 days, I had one about 14 or 17 days pregnant that he couldn't detect (she did calve to that mating).

What I've been doing to get accurate dates is getting the vet out twice, once four weeks after the bull comes out (about sixteen weeks after the start of mating) then again four weeks later to confirm the late calvers that caught on the last cycle. If I only did the second visit I'd have my early calvers confirmed in calf, but they won't call a date past twelve weeks so they couldn't distinguish between a cow that is due in the first week of calving and one due five or six weeks later.
I don't think I've ever found one called wrong, except for the times when short bred cows later turn up open. I have seen them called wrong when working with other herds where the whole herd is scanned.

Scanning should be 95%plus accuracy. Opens I don't just trust the scanner, usually I'll observe them in heat & also have them confirmed open by palpation before culling.

 

[dun]

Our vet has a window of about a week that he likes to scan. It's earlier then I would have thought. He says that sexing the embryo at that stage is easiest. Before it is too small and after it's harder to see it clearly, not sure if he looks for the testicles or the penis, but he was 100% right when we had him do it. We had some AIed cows that before we decided which ones we would sell we wanted to know the calf's gender. All other years we just have him palpate and he's usually within a week of right for the pasture bred cows. Last year we had a cow we planned on selling since I knew she had bred late, just didn;t know how late. He said he couldn;t tell for sure but thought she felt bred. A couple of mnths later we hauled her to the ale barn and they palpated her bred, she would have been about 2 1/2 weeks bred when he palped her. He is a fairly experienced vet. Worked at MARC in the reproduction unit for a couple of years and taught reproducition at kansas state for a bit.