Intensification of milk somatic cell response to intramammary device

Treatments consisting of copper-impregnated polyethylene intramammary device (PIMD-Cu), PIMD-Cu which had been abraded to ensure exposure of surface copper (APIMD-Cu), PIMD which had been abraded in an identical manner (APIMD), and an untreated control were established in mammary quarters of 2 cows. Quarters selected were bacteria free and had milk somatic cell counts (MSCC) in strippings of less than 240 X 10(3) ml. Milk somatic cell counts were determined from strippings immediately after milking and 6 hours later. Cows were monitored for 4 weeks after devices were inserted. Milk samples (250 ml) were collected and analyzed for free fatty acids, a measure of hydrolytic rancidity, at 14 days. The devices were removed from mammary quarters after 4 weeks and examined with a scanning electron microscope. Surfaces of the devices were assessed for plaque buildup and presence of leukocytes. Immediately after and 6 hours later, geometric mean MSCC for APIMD, APIMD-Cu, PIMD-Cu, and control quarters average 946/1,556, 1,479/2,882, 512/1,148, and 161/190 X 10(3) ml, respectively. There was no difference in free fatty acid values of samples from treated and control quarters. Plaque formation was observed over the entire surface of APIMD. Numerous leukocytes were found associated with plaque and appeared to initiate development of plaque. Smaller amounts of plaque were found on APIMD-Cu, and minimal amounts were found on PIMD-Cu. Results indicate that modification of PIMD by abrading or addition of copper will increase MSCC to concentrations (greater than 900 X 10(3) ml) that should be protective against establishment of infection by mastitis pathogens.