Using infrared termography to monitor the effect of different milking vacuum levels on teat tissue in dairy ewes

This study was carried out to monitor via infrared termography the thermal profile of the ovine teat tissue exposed to the action of different vacuum levels during machine milking. Two groups of six Sardinian lactating ewes were milked at 28 kPa and 42 kPa and digital thermographic images of the teats were taken before and after milking, till the complete recovery of the initial udder temperature. All animals were milked with a medium weight milking unit (490.3 g) and the same pulsation parameters (120 pulse/min an 60:40 pulsator ratio). Thermographic analysis of teat areas (teat base -TB, mid teat - MT and teat tip - TT) showed that during milking the skin temperature had a general drop of about 2.2 and 1.9 °C, respectively at low and high vacuum level. There was a temperature gap among teat locations depending on monitoring period. Before milking only the difference between TT and the other locations was significant while after milking the MT and the TB have assumed a specific temperature pattern. Differences between low and high vacuum levels are reported also in terms of frequencies distribution of temperature ranges (0.2 °C). The temperature recovery time was shorter at the teat base for the group milked at 28 kPa, and this may be attributable to a faster return to a normal blood flow, as result of a lighter mechanical action exerted by the machine during milking at a low vacuum. Besides, a classification of the teat phenotype (1-3 classes), in terms of teat cistern volume and sphincter protrusion, could be used to optimize the mechanical milking procedure