Top 10 uses of rapid progesterone measurement in milk

Progesterone (P4) is a hormone well known for its uses in fertility management and heat detection in cattle. Today we are showing you 10 ways you can use progesterone measurement in milk to aid in improving your herds fertility.


  1. You can use rapid progesterone detection tests to confirm heat when you have observed bulling or have a cow that does not demonstrate signs – a low P4 result confirms heat, allowing you to time your AI correctly.
  2. Progesterone levels can provide a clear distinction of heat from false bulling. If a cow is showing signs of heat but has high progesterone levels, the bulling behaviour is a false indicator of heat.
  3. Cows can exhibit silent heat – they will cycle in and out of heat as normal but do not present any of the traditional behavioural signs observed. To detect when she comes into heat, you can test once a week for three consecutive weeks. AI at the first low or more closely monitor her levels 3 weeks later for more precise timing.
  4. You can identify the return to cycling of post callers using progesterone measurements. If you sample weekly from day 25 post calving, or from the end of the voluntary waiting period. When you begin to see her progesterone levels fluctating to two high results and one low results in a 3 week period, you know that she is back to her usual cycle.
  5. Progesterone levels can be used to check if the AI has taken and be used to prevent the insemination of an already pregnant cow. AI of a pregnant cow can sometimes cause spontaneous abortions.
  6. The ideal time to AI your cow can be determined using progesterone measurements. We advise testing daily from day 18 of her cycle, and then to AI on the second day of low P4 for the best conception rates.
  7. Identify cows that are not cycling properly – measure the progesterone levels once a week for 3 consecutive weeks. If get you 3 high or 3 low results, she is not cycling properly and you should consult your vet as she likely has fertility issues. 3 High results could also infer that she is not cycling because she is in calf.
  8. To determine a anoestrous cow, test her milk at weekly intervals for 3 weeks. If they are all low progesterone she is not cycling.
  9. Check to see if your AI has taken – confirm non-pregnancy by testing her 21-24 days post AI. If the progesterone levels are low she has returned to cycling and is not pregnant. She is safe to AI again.
  10. If you have a herd of synchronised cows, it may be a good idea to test the progesterone levels of one or a few cows prior to AI, to ensure your timing is correct.

We hope you found these uses of progesterone measurement useful. Who knew one hormone could have so many uses and tell us so much about fertility!