Milk Progesterone and PAG Tests for Early Pregnancy Checks

Two lab tests help check pregnancy in cows and buffaloes. A progesterone test, on milk or blood, follows the hormone that rises after an egg is released. A PAG test looks for proteins made by the placenta. Each has limits, so a vet reads them together with the service record and an examination of the animal.

Why use a lab test for pregnancy at all?

A vet can usually tell if an animal is pregnant by feeling the womb or by an ultrasound scan, and those methods stay the main ones. A lab test is useful when the vet is not available, when the animal is hard to examine, when a farm wants to screen many animals, or when heat signs are weak, as they often are in buffaloes. Finding out early that an animal is not pregnant saves weeks of waiting and lets the vet plan the next step.

What does the progesterone test show?

Progesterone is made by a structure on the ovary after an egg is released, and it stays high if the animal becomes pregnant. If she does not, it falls before the next heat. The Milk Progesterone ELISA measures the hormone in a small milk sample, so no blood needs to be drawn, and the Progesterone, Serum measures it in blood.

The test is most trustworthy as a negative check. A very low level at the time when it should be high points toward an animal that is not pregnant. A high level is less certain, because an animal that is simply in the middle of her cycle, or one with a structure on the ovary that lingers, can also have a high level. A vet therefore reads the result against the date of service.

What does the PAG test show?

PAG stands for pregnancy-associated glycoproteins. These are proteins made by the placenta, so they appear in the mother's blood once a pregnancy is established. The Pregnancy-Associated Glycoprotein (PAG) ELISA looks for them in a blood sample. Because they come from the pregnancy itself, a positive result is stronger evidence than progesterone alone. The proteins can stay in the blood for a while after calving, so the test is not used too soon after an animal has given birth. A test done too early can miss a very young pregnancy.

What should you note before sampling?

Write down the date of the service, which bull or semen was used, the date of the last heat and the date of calving. The vet needs this to pick the right time and to interpret the result. The lab confirms the sample needs and the reporting time when you book.

How is the sample taken?

For milk, wash your hands, clean the teat, discard the first streams and collect a little into a clean, dry, lidded container. Label it with the animal's number, the date and the time, and keep it cool. For blood, the vet draws it from a vein into the tube the lab names. Fresh samples give the most reliable readings.

What happens next?

If the test suggests a pregnancy, your vet may confirm it later by examination. If it suggests that she is not pregnant, the vet can plan the next service or look for a reason why the animal has not conceived. A registered veterinarian always reads the lab result together with the animal's history. A lab test is a help and not a replacement for a vet's examination.

Read next

If an animal keeps failing to conceive, see Repeat Breeder Cows and Buffaloes: Lab Tests That Help. For a young female before her first service, read Growing Heifer Checks Before First Breeding.

Testing in Bhopal

The lab at C-200, C Sector, Shahpura, Bhopal accepts milk and blood samples, and collection is free anywhere in Bhopal. Call or WhatsApp +91 88175 01118; the lab confirms the method, sample needs and reporting time when you book. Farms in other districts can send chilled samples by courier, bus parcel or through their vet.