<title>Fluorescence photon migration techniques for the on-farm measurement of somatic cell count in fresh cow's milk</title>

Abstract

Currently, the state of the art of mastitis detection in dairy cows is the laboratory-based measurement of somatic cell count (SCC), which is time consuming and expensive. Alternative, rapid, and reliable on-farm measurement methods are required for effective farm management. We have investigated whether fluorescence lifetime measurements can determine SCC in fresh, unprocessed milk. The method is based on the change in fluorescence lifetime of ethidium bromide when it binds to DNA from the somatic cells. Milk samples were obtained from a Fullwood Merlin Automated Milking System and analysed within a twenty-four hour period, over which the SCC does not change appreciably. For reference, the milk samples were also sent to a testing laboratory where the SCC was determined by traditional methods. The results show that we can quantify SCC using the fluorescence photon migration method from a lower bound of 4x10⁵ cells mL^-1 to an upper bound of 1 x 10⁷ cells mL^-1. The upper bound is due to the reference method used while the cause of the lower boundary is unknown, yet.