Lack of correlation between the electrical conductivity of milk and the blood progesterone levels in cows.

A study was conducted to investigate the possibility of measuring the electrical conductivity (EC) of cow's milk as a practical and cost-effective means of determining oestrus in cows. Prostaglandin injections were used to synchronise the oestrous cycle of 15 cows. From the onset of oestrus, milk and blood samples were collected from each cow every 2nd day over a period of 22 days. A portable, commercially available instrument was used to measure the EC of the milk. The blood progesterone levels were determined by means of an enzyme immuno-assay method. No correlation was found between the EC of milk and the blood progesterone levels of the cows tested. Electrical conductivity measurements of milk are of no value in determining the onset of oestrus in cows.