Effects of flow-responsive pulsation on teat tissue condition and milking performance in Holstein dairy cows

The objectives of this study were to assess the effect of a reduced liner-open phase applied through flow-responsive pulsation (FRP), as a method to provide supplemental stimulation, on teat tissue conditions and milking characteristics in dairy cows. In 2 switch-back trials, 156 Holstein cows milked 3 times daily were assigned to the FRP or conventional (CON) group in alternating sequences. Trial 1 lasted for 35 d and was split into 5 alternating 1-wk periods of FRP and CON. The duration of trial 2 was 84 d, consisting of 4 alternating 3-wk periods of FRP and CON. Premilking udder preparation for both groups consisted of predipping, forestripping, and wiping the teats. Upon milking unit attachment, the FRP cows were milked at a pulsation rate of 50 cycles/min and a pulsation ratio of 30:70 until the preset milk flow threshold of 0.5 kg/min was reached. When the threshold value of 0.5 kg/min was reached, the pulsation was automatically switched to milking mode, which consisted of a pulsation rate of 60 cycles/min and a pulsation ratio of 70:30. Cows in the CON group were milked by milking mode (pulsation rate, 60 cycles/min; pulsation ratio, 70:30) immediately after attachment of the milking unit. We assessed machine milking-induced short-term changes to the teat tissue by palpation and visual inspection during trial 1, and we assessed teat-end hyperkeratosis in trial 2. Electronic on-farm milk meters were used to assess milking characteristics: milk yield (kg/milking session), milking unit-on time (s), 2-min milk yield (kg), peak milk flow rate (kg/min), and duration of low milk flow rate (s). Generalized linear mixed models were used to analyze the effects of treatment on the outcome variables. The odds of machine milking-induced short-term changes to the teat tissue were lower for cows in the FRP group than for those in the CON group: odds ratio (95% CI) = 0.41 (0.31-0.55). There were no meaningful differences in the odds of teat-end hyperkeratosis between the FRP and CON groups: odds ratio (95% CI) = 1.05 (0.38-2.89). The LSM (95% CI) of milking characteristics in the FRP and CON groups were 14.3 (13.8-14.7) and 14.3 kg (13.8-14.7) for milk yield, respectively; 272 (264-281) and 270 s (262-278) for milking unit-on time, respectively; and 5.0 (4.8-5.1) and 4.9 kg/min (4.7-5.1) for peak milk flow rate, respectively. The FRP group had lower odds of bimodality than the CON group: odds ratio (95% CI) = 0.67 (0.61-0.74). In reference to CON, the odds ratios (95% CI) in FRP were 1.05 (0.76-1.46) for kick-off and 1.02 (0.85-1.23) for milking unit reattachment. In this study, cows that were milked using FRP had lower odds of postmilking short-term changes to the teat tissue and lower odds of bimodal milk flow. We conclude that FRP may foster adequate teat stimulation in cows before the initiation of milk harvest and has the potential to improve teat tissue conditions.