TEAT TISSUE-REACTIONS TO MILKING - CHANGES IN BLOOD-FLOW AND THICKNESS IN THE BOVINE TEAT

Machine-induced changes in teat skin blood flow and teat thickness wer e measured after milking at four different milking conditions (C: conv entional milking, liner bore 24.6 mm; CB: conventional milking, liner bore 21.0 mm; CP: liner C with cyclic application of 35 kPa positive p ressure to the pulsation chamber; CWP: liner C without pulsation). Blo od flow was measured using two laser Doppler instruments (Diodopp and Periflux). Using the Diodopp instrument, the mean percentage changes i n blood flow, relative to the premilking values, throughout the first min after milking were -24 % for system C and 46 % for system CB. The corresponding values measured by the Periflux instrument were -5 %, 10 6 %, 116 % and -64 % for system C, CB, CP and CWP, respectively. The m ean percentage changes in teat barrel thickness (measured by an electr onic caliper instrument) rel-ative to the pre-milking values, were 12 %, 1 %, 2 % and 36 % for system C, CB, CP and CWP, respectively. In co nclusion, when only minor changes in teat thickness were observed, the blood flow was increased immediately after milking (system CB and CP) . In contrast, when the teat barrel thickness was increased, the blood flow was reduced (system C and CWP). The increase in teat skin blood flow can probably be regarded as active hyperaemia, while the decrease in blood flow was, most likely, caused by machine-induced teat tissue oedema.