New Technology to Detect Pregnancy Still Needs to Improve on Accuracy

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When Bossy starts demanding pickles and ice cream with her forage you know it may be time to pullout the pregnancy detection tests.

Getting and keeping cows pregnant is one of the most critical management control points on your dairy farm. Knowing which cows are pregnant gives you some definite management options for cows that are still open.

New science, using a protein present in the early stages of pregnancy, has lead to development of an on- farm product called the early conception factor (ECF) Dip Stick test. This test allows pregnancy detection from day six to day 20 of a cow's pregnancy. What you really want to know is which animals aren't pregnant so you can reprogram the cows to re-inseminate them or, if necessary, cull them. The test is supposed to detect the ECF protein in serum and milk as soon as 24 hours after breeding.

Several studies have evaluated the product based on predicting both pregnancy and non-pregnancy. Results so far suggest it doesn't yet offer an acceptable accuracy rate.

One field study to determine the test's reliability used three dairy herds that are part of the Faculty of Veterinary Medicine clinic at Montreal. One hundred and thirty- nine cows were artificially inseminated and blood was taken from them between day 11 and day 15. Researchers examined the cows by ultrasound on days 25 to 40 and palpated them rectally as well.

The conception rate based on rectal palpation was 38 per cent. In this study the ECF falsely predicted 64 out of 139 cows to be pregnant. So, 46 per cent of the cows that the test indicated as pregnant were actually still open at a later date when they were ultrasounded or palpated.

Some of the pregnancies may have experienced early embryonic death. However, most research shows early embryonic death ranges from five to 20 per cent.

But the test is primarily for identifying open cows and, in this test, the ECF dip stick falsely interpreted 19 per cent of the cows to be non-pregnant. California research found that 49 per cent of the tests falsely showed cows to be open when they were actually pregnant.

An Ohio State study, conducted on 436 animals, showed more promising results. Tests there correctly diag- nosed non-conception in 95.5 per cent of the cows 24 to 48 hours after breeding. Of the pregnant cows, 5.5 per cent were determined open.

To eliminate the question of early embryonic death, a study in Wisconsin looked at collecting embryos from cows on day six after insemination to verify pregnancy. Knowing the pregnancy status of the cows at that point eliminated the influence of early embryonic death.

In this study, researchers found the test had a 14 per cent false negative pregnancy prediction. As well, predictions for open cows were correct only four per cent of the time. They concluded that using this test to predict non-pregnant cows would be no better than a guess.

Knowing as soon as possible if a cow IS open means you can re-program her using prostaglandins and rebreed, saving about 10 days of reproductive time. With the ECF and prostaglandins costing about $20, you'd have to make up more than that in reducing revenue lost from decreased days open.

An accurate ECF could easily achieve such a return on investment. Research we've seen so far, however, shows you could be aborting a significant number of cows by using this test to ascertain a cow's pregnancy status and act on the results by administering prostaglandin. When 10 to 20 per cent of cows rebred are aborted first, due to inaccuracy of the test, the cost of lost pregnancies outweighs the benefit of rebreeding open cows early.

Current research shows the available test has no practical value. Nevertheless, pregnancy detection technology will continue to evolve and, no doubt, an accurate ECF eventually will be developed.

Ballotment, the earliest practical pregnancy detection method, sped up the process from simply waiting for the cow to calve. Rectal palpation and then ultrasound decreased the time you spend waiting to know your cows' pregnancy status. New tests such as ECF will continue to be refined and developed to allow earlier detection. Also, such technologies as infrared thermography may be used in future to reduce calving intervals further.

By identifying open animals, we can keep the pickles and ice cream for the pregnant cows. Then we can focus on getting open cows to develop those pregnancy cravings faster. .

References

Adams, C.S., Jardon, P.W. Evaluation of the Early Conception Factor (ECF) Test in cows 3-7 days post breeding. Proc Am. Assoc Bovine Practitioners 32: 240- 24L 1999.

Cordoba, M.C., Sartori, R and P.M. Fricke, J.Dairy Sci: 84:1884-1889;

DesCoteaux, L, Carriere, P.D. & Bigras- Poulin, M; Evaluation of the early conception Factor (ECF) Dip Stick Test in Dairy Cows between Days 11 and 15 Post-Breeding. Bov. Practitioners 34:87- 91

Threfall W.R., Immunosuppressive early pregnancy factor determination for preg nancy diagnosis in dairy cows. Theriogenology 41:317

This article appeared in the "The Milk Producer" magazine in April 2004 .

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