Effect of milking on bovine teat tissue as measured by ultrasonography

The objective of this study was to establish, using an ultrasonography technique, the effect on bovine teat tissue of hand milking, catheter milking and machine milking, pre-milking teat stimulation, over-milking and cow milk yield. The periods required for teat tissue recovery after machine milking were also investigated. The following teat tissue parameters were measured directly before and after milking in a series of six experiments: canal Length (CL), teat diameter thickness (TDT), cistern diameter (CD), and teat wall thickness (TWT). Teat Length (TL) was measured manually using a calibrated transparent tube into which the teats were placed. Ultrasound scan measurements (mm) are presented as the mean tissue changes (increases or decreases) from the pre-milking values. Machine milking resulted in significant (P<0.001) changes in all teat tissue parameters measured. Hand milking (P<0.001) and milk withdrawal using a catheter (P<0.05) resulted in Lower TDT values than machine milking. Pre-milking teat stimulation for 30s increased (P<0.001) CD and reduced TWT and CL values as compared to non-stimulated teats. Milk yield (6.4 kg vs. 17.8 kg per milking) had a significant effect (P<0.01) on changes in CL, CD and TWT, but did not affect TDT. Over-milking by five and eight minutes did not affect TDT, TWT or CL values, but reduced (P<0.01) CD values. The TDT and TL values returned to pre-milking values within 1h of milking. The CD and CL values had not returned to pre-milking values at 5h after milking. Machine milking induced changes in TDT, but teat stimulation, cow milk yield or over-milking did not increase-thickness values.