Ultrasound Due Dates

[randiliana]

For the last few years we have had our cows ultrasounded for pregnancy. I really like having them ultrasounded rather than palpated. This year the vet who did it dated all the cows and heifers. Within 5 days. In the past, other than to call the odd one "early" or "late", the rest were either bred or open. Now, I've always written down any info that the vet has given us, and ALL the "early" or "late" ones were actually what they vet called. Sooo, how accurate should I expect the vet to be? I realize that there is about a 2 week window on either side of any due date of course....

 

[diana55]

I have used the same ultrasound technician for last 3 years and he is very accurate. Maybe a week or two each way but often depends on how early they are tested. He has said 4 weeks in calf and they are usually spot on. At about 14 weeks it has more variation. Over 20 weeks he just says heavy bred. In addition to natural mating, I also AI and implant embryos throughout year so I have cows calving most months and I can match up mating dates with what the techie says. I am happier with u/sound as palpation may cause abortion- maybe only a small chance but could be expensive. We don't test recips until 3 months after implantation.

 

[randiliana]

Yes, those are the same time frames he gave us. Actually, he dated till about 110 days then just called them bred, but that was fine for us, as they could only go about another 10 days earlier anyways.

We did have a cow abort, but he said when pregnancy testing them that early, there is about a 1% chance of that, and we've experienced that in the past. I guess if we want to do them earlier than 90-100 days bred there is a possibility of having a couple abort. But then, they likely would do it anyways, they would just be called open later.

The cow that aborted just happened to be in the corral and we saw the foetus.

 

[Jessica06]

Up to about 60 days, it's pretty easy to tell a 5 day difference. From there to about 120 a 10 day difference is still very noticeable. From 120-150 you can still get pretty close by the size of the cotyledons and amount of fluid. If you wait longer than that you might have problems since the calf is starting to drop and you might not see anything that's easy to measure. You can still get a pretty good idea on months bred all the way up to the end by judging cotyledon size, or finding an eyeball to measure. In general, the earlier you can check with ultrasound the more accurate it will be. We try to hold off until 45 days on our commercial cows to allow for any early abortions, but we check our AI's at about 35 days. The earliest pregnancy I've seen is 27 days.

Since we've started aging our pregnancies and calling due dates, I don't think we've had any more than 2 weeks off. The vast majority were within a week. Might be a few more surprises this year since we weren't able to get to them until about 150 days. More early calves would be great!

 

[randiliana]

Thanks, the heifers were done at about 80 days from bull turn out and the cows around 120 days. I will be keeping track, so it will be interesting to see.

 

[randiliana]

I'm glad to know that it is quite accurate. It will be very useful for us as we sort our heavies off about every week during calving season, and this should be much more reliable than just looking at them. Hoping for no more calves born in the pasture on a cold night!