Development of an ELISA-based kit for the on-farm determination of progesterone in milk

Effective reproductive management is a crucial concern in the dairy industry and missed oestrus and late recognition of unsuccessful insemination can lead to substantial financial loss. Progesterone levels change in a predictable manner with progress of the oestrus cycle and with the onset of pregnancy. We report here the development of a simple ELISA test for the measurement of progesterone levels in bovine milk. The method is based on the use of polyclonal antibodies raised against 11α-hydroxyprogesterone-hemisuccinate and competition for antibody binding sites between free progesterone and horseradish peroxidase-labelled progesterone. Binding is quantified by means of the colour reaction between horseradish peroxidase and 3,3’,5,5’-tetramethylbenzidine. The method has proved to be a cost effective, sensitive and easy to perform alternative to currently available methods of oestrus and pregnancy detection. The practical feasibility of the method has been proven under dairy farm conditions.