Effects of conventional and no pulsation milking systems on bovine teats and on immunological components of different milk fractions

Physical forces induced by machine milking may cause changes in teat tissue, blood circulation and cell population, so that reactions of the local immune system occur. To assess the influence of machine milking on the teat tissue immune status a cross-over study was conducted, in which the effects of a no-pulsation milking system (NOP) were compared to those of a conventional unit (CON). The results of the measurement at the teat end indicated significantly larger teat diameters and significantly higher teat thickness, values after milking with NOP compared to CON. Overall, the PMN fraction in foremilk and in teat secretion was not influenced by the milking system applied, while a significant increase of the resident population of the lymphocytes was observed for NOP. An increase in levels of NAGase and immunoglobulins was also seen after NOP milking. The observed changes most probably are a consequence of the increased amount of fluid in the teat tissue after milking without pulsation (NOP). The comparison of all values indicated that, compared to foremilk samples, the analysis of teat secretion samples was more effective in evaluating machine-induced local immunological changes.