A new management tool available to dairy producers and veterinarians is simple and rapid progesterone testing of milk. Accurate and easy to use, milk progesterone tests are an important technological advance. Milk progesterone measurements can provide diagnostic information regarding the status of the ovary, making it possible to accurately monitor the reproductive status of the cow. This information will be useful in daily reproductive management as well as in diagnosis of herd reproductive problems. To interpret results from milk progesterone testing one must have a working knowledge of progesterone concentrations and how they change with reproductive status.
Progesterone is secreted into the blood and subsequently into the milk.
Since milk samples are easier to obtain than blood, the progesterone levels in milk can be used, more conveniently, for the same diagnostic purposes as blood. Progesterone is at its lowest level at the time of estrus, and reaches its highest level with maturation of the CL during mid- cycle. The RIA tests have been performed solely in central labs, resulting in turn-around times of 3 to 7 days for sample analysis and return of results. This demonstrates the need for rapid, easy, inexpensive tests which could provide for timely action by dairy producers or veterinarians. Recently, a new procedure for measuring milk progesterone has been developed.