Cow-side milk progesterone tests are effective in determining the presence
of an active corpus luteum (CL) on the ovary. The test is best used as an adjunct
to the Preventive Herd Health Program (PHHP) as a means of identifying cows that
have not yet been detected in heat and are candidates for synchronization with
prostaglandin (PGF). Several test kits are on the market, and all involve similar
chemical principles. However, each test has its own protocol, so read and follow
directions EXACTLY. A “control” or “sample” must be run with each test
for comparison.