title: Effect of pulsation rest phase duration on teat end congestion.
abstract: The objective of this study was to quantify the effect of d-phase (rest phase) duration of pulsation on the teat canal cross-sectional area during the period of peak milk flow from bovine teats. A secondary objective was to test if the effect of d-phase duration on teat canal cross-sectional area was influenced by milking system vacuum level, milking phase (b-phase) duration, and liner overpressure. During the d-phase of the pulsation cycle, liner compression facilitates venous flow and removal of fluids accumulated in teat-end tissues. It was hypothesized that a short-duration d-phase would result in congestion of teat-end tissue and a corresponding reduction in the cross-sectional area of the teat canal. A quarter milking device, designed and built at the Milking Research and Instruction Laboratory at the University of Wisconsin-Madison, was used to implement an experiment to test this hypothesis. Pulsator rate and ratios were adjusted to achieve 7 levels of d-phase duration: 50, 100, 150, 175, 200, 250, and 300ms. These 7 d-phase durations were applied during one milking session and were repeated for 2 vacuum levels (40 and 50kPa), 2 milking phase durations (575 and 775ms), and 2 levels of liner overpressure (9.8 and 18kPa). We observed a significant reduction in the estimated cross-sectional area of the teat canal with d-phase durations of 50 and 100ms when compared with d-phase durations of 150, 175, 225, 250, and 300ms. No significant difference was found in the estimated cross-sectional area of the teat canal for d-phase durations from 150 to 300ms. No significant interaction was observed between the effect of d-phase and b-phase durations, vacuum level, or liner overpressure.
authors.affiliation: Animal and Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co. Cork, Ireland. Electronic address: john.upton@teagasc.ie.
authors.forename: J
authors.initials: J
authors.lastname: Upton
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison 53706.
authors.forename: J F
authors.initials: JF
authors.lastname: Penry
authors.affiliation: Aarhus University, Department of Engineering, DK-8000 Aarhus C, Denmark.
authors.forename: M D
authors.initials: MD
authors.lastname: Rasmussen
authors.affiliation: Biological Systems Engineering Department, University of Wisconsin, Madison 53706.
authors.forename: P D
authors.initials: PD
authors.lastname: Thompson
authors.affiliation: Biological Systems Engineering Department, University of Wisconsin, Madison 53706.
authors.forename: D J
authors.initials: DJ
authors.lastname: Reinemann
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying / Q000295:instrumentation*; D007774:Lactation; D008321:Mammary Glands, Animal; D008892:Milk; D014618:Vacuum
keywords: milk flow; milking; pulsation; teat congestion