Pregnancy testing cattle
- Allows you to cull non-pregnant cows earlier
- Allows better feed management control, including lead feeding
- Allows better reproductive records, and more accurate dry off/ weaning dates
- By rectal palpation we can diagnose pregnancy from 6-7 weeks after conception until calving
- Diagnosis by rectal palpation is by size of the uterus, embryo vesicle, uterine arteries and the size of the cotyledons which attach the placenta to the uterus.
- The most accurate age of diagnosis is from 7-10 weeks giving +/- 1 week of the conception date
- Between 10-15 weeks variation of pregnancy increases allowing an accuracy of +/- 2weeks, as the uterus has dropped over the pelvic rim.
- After 16 weeks staging pregnancy becomes less accurate, as the accessibility of the uterus and fetus is limited and there is an increase in the natural variation of the pregnancy.
- How far in calf is very different to when will she calve? Naturally cows calve +/- 2 weeks and sometimes up to 3 weeks from their expected calving date. Therefore late stage pregnancy testing accompanied by individual variation can result in very inaccurate results.
Using the above information you can determine when pregnancy testing would best suit your management system. If you require dates (i.e. dairy cattle) testing between 6 to 12 weeks is the best. Having AI or heat dates also helps improve the accuracy, as we can determine the conception date to help with your reproduction records.
In beef enterprises it maybe that you just need to know if they are pregnant or not. In this case it maybe that testing at weaning time will be suited for cows, and 7 weeks after taking the bull out for heifers. This will allow you to cull heifers and cows which are not being productive in your herd.
Facilities play a large role in how long it will take to do the pregnancy testing. In a good set up it is usually 1-1.5 minutes per cow. This is much longer if the set up is poor, especially if the vets’ safety is at risk.
Ultrasound can be used. There are 2 types of ultrasound, one is by a hand held probe via the rectum, this still requires the vet to rectal examine the cow. The second is via long probe inserted into the rectum which has the ultrasound camera at the end of it. Recently we have purchased the second type of sector ultrasound scanner. This has allowed pregnancy testing to be just as accurate as before, if not more accurate but is much safer on the cow and the vet. It is recommended cows are pregnancy tested between 8 and 16 weeks of pregnancy but it can be used from 5 weeks through to 25 weeks. Beyond 25 weeks it becomes difficult to detect pregnancy and give accurate readings.
For further information contact Clare Valley Vet Services, 08 88422822