Differences between Jersey and Holstein cows in milking-induced teat prolongation during lactation

Factors consequential to milking-induced teat prolongation (MITP) were identified. Effects of breed, teat position, lactation number, lactation stage and their interactions were evaluated. The length of each teat before and after milking was measured seven times during lactation in 59 Holstein cows and 45 Jersey cows. Rear teats seemed to prolong more with the exception of rear left teats of Holstein cows. MITP of Holsteins was more balanced among quarters compared to Jerseys, where we observed significantly higher MITP of their rear teats. The pairs mostly had similar reactions even for different teat lengths, therefore for future studies evaluating one of each pair should be sufficient and more effective. Development of MITP during lactation showed more variability at the onset of lactation, followed by more uniform response at later stages. Lower MITP for higher parity cows was observed only in Holsteins. Overall, Jerseys achieved a significantly higher level of MITP, which suggests breed differences in reaction to milking. Effects identified in this study should be taken into consideration while designing future experiments in this area. In addition, our results suggest the future necessity to improve milking technology to allow group or even individual settings optimization based on breed, lactation stage, lactation number, and teat position.