Somatic cells and electrical conductivity in relation to milking frequency

Somatic cells and electrical conductivity were measured in quarter milk fra ctions of 16 healthy quarters (4 cows) throughout 12 days during which 4 mi lkings were applied (at: 6 a.m.; 10 a.m.; 2 p.m.; 6 p.m.) to evaluate the i nfluence of varying milking intervals on both inflammatory parameters. The milking intervals were 4 h during the day and 12 h overnight. The mean dail y yield per cow was stable throughout the study. The following milk fractio ns were used: the first milk jets (FIM), the following 15 ml of milk (FOM), residual milk (MSM) and quarter composite samples (QCM). The general trend of changes was identical in all types of milk fractions. Milking intervals of 4 h resulted in a significant increase of SCC and electrical conductivi ty. The values of both parameters were identical at all 3 milkings after an interval of 4 h. After the 12 h interval at morning milking during the tre atment period the SCC was significantly reduced while the electrical conduc tivity was significantly increased compared to the values after the identic al interval during the control periods with twice daily milking at 12 h int ervals. The milking regime applied caused an increase in cell influx to the milk of approximately 16% over 24 h compared to the control periods despit e the fact that the milk yields were unchanged during the study. Obviously, mechanisms not related to the volume of milk yield secreted over 24 h are involved in the regulation of milk composition.