Effects of flow-responsive vacuum and pulsation with early attachment of the milking unit on teat tissue condition and milking performance in Holstein dairy cows.

The objectives of this study were to assess the effects of flow-responsive vacuum and pulsation, in conjunction with early attachment of the milking unit (TRT), on teat tissue conditions and milking characteristics in dairy cows. In a switchback trial, 5,235 Holstein cows milked 3 times daily in a rotary parlor were assigned to the TRT or control (CON) group. The trial lasted 84 d and comprised 4 alternating 3-wk periods of TRT and CON. For both groups, premilking udder preparation consisted of teat brushing, forestripping and predipping, and wiping of teats, resulting in a stimulation time of 4 s. In the TRT group, the preparation lag time was 58 s, and in the CON group, it was 91 s for early- and mid-lactation cows and 105 s for late-lactation animals. Upon milking unit attachment, the TRT cows were milked at a lower vacuum (37.6 kPa) and reduced liner-open phase (pulsation rate of 50 cycles/min, pulsation ratio of 30:70). The vacuum and pulsation settings were changed to milking mode when the milk flow reached 0.5 kg/min (pulsation switchpoint) and 1.6 kg/min (vacuum switchpoint). For the milking mode, the vacuum setting was 47.7 kPa, and the pulsation rate was 60 cycles/min at a ratio of 65:35. The CON cows were milked with a flow-responsive vacuum, using the same vacuum settings as the TRT group. We assessed machine milking-induced short-term teat tissue changes and teat-end hyperkeratosis by palpation and visual inspection postmilking. Electronic on-farm milk meters were used to assess milking characteristics. Generalized linear mixed models were used to analyze the effect of treatment on the outcome variables. Compared with cows in group CON, the odds ratios (95% CI) of short-term teat tissue changes in early-, mid-, and late-lactation cows in group TRT were 0.62 (0.52-0.76), 0.61 (0.48-0.77), and 0.93 (0.76-1.14), respectively. The LSM (95% CI) for milking unit-on time in early-, mid-, and late-lactation animals, respectively, were 251 (248-253), 236 (234-238), and 220 s (218-222) for group TRT and 247 (245-249), 232 (230-234), and 214 s (213-216) for the CON group. The LSM (95% CI) for peak milk flow rate in early-, mid-, and late-lactation animals, respectively, were 5.75 (5.68-5.82), 5.77 (5.70-5.84), and 5.54 kg/min (5.48-5.59) for the TRT cows and 5.65 (5.58-5.72), 5.74 (5.68-5.81), and 5.45 kg/min (5.40-5.51) for the CON cows. The odds ratios (95% CI) of forced take-off in group TRT for early-, mid-, and late-lactation cows, respectively, were 0.39 (0.37-0.41), 0.32 (0.30-0.34), and 0.47 (0.44-0.52) compared with their respective CON groups. In this study, cows that were milked using flow-responsive vacuum and pulsation with early attachment of the milking unit had lower odds of short-term teat tissue changes and forced take-off, as well as a higher peak milk flow rate. Our data suggest that the application of flow-responsive vacuum and pulsation facilitates early attachment of the milking unit, improves teat tissue condition, and has the potential to improve parlor efficiency.