Understanding the influence of machine milking on teat defense mechanisms

Three related experiments were conducted to gain a better understanding of the physiological responses of teat tissue to machine milking. In the first experiment changes in peak milk flow rate were used as an indicator of congestion of teat end tissues that occur during the milking phase of each pulsation cycle. Teat end congestion was increased by increasing both the b-phase of pulsation and the milking vacuum level and was reduced by the application of increasing liner compression. Ultrasound measurements were used to measure changes in teat wall thickness and indicated that increasing vacuum level increased teat wall thickness and that at some critical level of liner compression the recovery rate of teat wall congestion may be reduced. The development of teat end hyperkeratosis was studied for liners with differing compression levels. This experiment confirmed that increasing liner compression increased the development of teat end hyperkeratosis.