Abstract
Friesian-type dairy cows were milked with different machine settings to determine the effect of these settings on teat tissue reaction and on milking characteristics. Three teat-cup liner designs were used with varying upper barrel dimensions (wide-bore WB = 31.6 mm; narrow-bore NB = 21.0 mm; narrow-bore NB1 = 25.0 mm). These liners were tested with alternate and simultaneous pulsation patterns, pulsator ratios (60:40 and 67:33) and three system vacuum levels (40, 44 and 50 kPa). Teat tissue was measured using ultrasonography, before milking and directly after milking. The measurements recorded were teat canal length (TCL), teat diameter (TD), cistern diameter (CD) and teat wall thickness (TWT).Teat tissue changes were similar with a system vacuum level of either 50 kPa (mid-level) or 40 kPa (low-level). Widening the liner upper barrel bore dimension from 21.0 mm (P < 0.01) or 25.0 mm (P < 0.001) to 31.6 mm increased the magnitude of changes in TD and TWT after machine milking. Milk yield per cow was significantly (P < 0.05) higher and cluster-on time was reduced (P < 0.01) with the WB cluster as compared to the NB1 cluster. Minimum changes in teat tissue parameters were achieved with system vacuum level of 40 kPa and 50 kPa using NB and WB clusters, respectively. Similar changes in teat tissue and milk yield per cow were observed with alternate and simultaneous pulsation patterns. Widening pulsator ratio from 60:40 to 67:33 did not have negative effects on changes in teat tissue and had a positive effect on milk yield and milking time. Milk liner design had a bigger effect on teat tissue changes and milking characteristics than pulsation settings.
Highlights
Changes in teat thickness are minimal when milk is removed via a catheter inserted in the teat canal (Hamann and Mein, 1990) or by hand (Gleeson et al, 2002)
In this paper we report the effects of liner design, pulsator settings, and pulsation characteristics with different system vacuum levels on machineinduced changes in teat tissue as measured using the ultrasonic technique
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Summary
Changes in teat thickness are minimal when milk is removed via a catheter inserted in the teat canal (Hamann and Mein, 1990) or by hand (Gleeson et al, 2002). An increase in thickness values after machine milking can be interpreted as a response of the teat tissue to the machine milking action. Correspondence: Physiological and pathological changes in the circulatory system associated with milking may decrease the efficacy of the defense systems. Zecconi (1992) observed higher infection rates of quarters and more ducts colonised in teats, where teat end thickness changed by >5% than with teats showing less congestion. This decreased efficiency may be prolonged after In this paper we report the effects of liner design, pulsator settings, and pulsation characteristics with different system vacuum levels on machineinduced changes in teat tissue as measured using the ultrasonic technique
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