title: Assessing liner performance using on-farm milk meters.
abstract: The primary objective of this study was to quantify and compare the interactive effects of liner compression, milking vacuum level, and pulsation settings on average milk flow rates for liners representing the range of liner compression of commercial liners. A secondary objective was to evaluate a methodology for assessing liner performance that can be applied on commercial dairy farms. Eight different liner types were assessed using 9 different combinations of milking system vacuum and pulsation settings applied to a herd of 80 cows with vacuum and pulsation conditions changed daily for 36d using a central composite experimental design. Liner response surfaces were created for explanatory variables milking system vacuum (Vsystem) and pulsator ratio (PR) and response variable average milk flow rate (AMF=total yield/total cups-on time) expressed as a fraction of the within-cow average flow rate for all treatments (average milk flow rate fraction, AMFf). Response surfaces were also created for between-liner comparisons for standardized conditions of claw vacuum and milk ratio (fraction of pulsation cycle during which milk is flowing). The highest AMFf was observed at the highest levels of Vsystem, PR, and overpressure. All liners showed an increase in AMF as milking conditions were changed from low to high standardized conditions of claw vacuum and milk ratio. Differences in AMF between liners were smallest at the most gentle milking conditions (low Vsystem and low milk ratio), and these between-liner differences in AMF increased as liner overpressure increased. Differences were noted with vacuum drop between Vsystem and claw vacuum depending on the liner venting system, with short milk tube vented liners having the greater vacuum drop than mouthpiece chamber vented liners. The accuracy of liner performance assessment in commercial parlors fitted with milk meters can be improved by using a central composite experimental design with a repeated center point treatment, rotating different clusters to different stalls (milk meters), and adjusting performance estimates for similar claw vacuum and pulsation conditions.
authors.affiliation: Department of Dairy Science, University of Wisconsin-Madison, Madison 53706. Electronic address: penry@wisc.edu.
authors.forename: J F
authors.initials: JF
authors.lastname: Penry
authors.affiliation: Department of Health, Animal Science and Food Safety, Universita degli Studi di Milano, 20133 Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Leonardi
authors.affiliation: Animal and Grassland Research and Innovation Centre, Teagasc Moorepark Fermoy, Co. Cork, Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Upton
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison 53706.
authors.forename: P D
authors.initials: PD
authors.lastname: Thompson
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison 53706.
authors.forename: D J
authors.initials: DJ
authors.lastname: Reinemann
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying; D000072480:Farms; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal; D008892:Milk
keywords: average milk flow rate; liner performance; milking speed; milking vacuum; pulsation settings