Teat reactions in cows associated with machine milking.

In the present investigations, referring to conventional milking machines and conventional milking technique, teat ends were transversally compressed for a short moment by means of a cutimeter before, during and after milking (main series), or before and after milking (additional series). The thickness of the teat ends between the jaw plates of the instrument decreased during the high flow-rate phase, increased during the low flow-rate and overmilking phases, and started decreasing as soon as milking was finished. The decreased values in the beginning of the milking process reflect the thinning of the teat wall following the vacuum-induced teat elongation that occurs when the teat cups are attached. The subsequent increased values are due to active, i.e., functionally significant hyperaemia in the teat wall, especially in the specific teat venous system, and locally elevated vascular pressure. Both the thinning and the thickening seem to occur within physiologically tolerable limits. The diagnosis, proposed in the literature, of teat congestion (passive hyperaemia) and/or oedema involving risks of impaired teat and udder health has no support in our investigations.