and mastitis riska storm in a teatcup在挤奶杯机和乳腺炎里斯卡风暴课件

Machines and Mastitis Risk: A Storm in a Teatcup Graeme Mein, Australia Douglas Reinemann, UW-Madison, USA Norm Schuring, Westfalia-Surge, USA Ian Ohnstad, ADAS, UK 2GAM mmch98 Herd & farm Herd & farm managementmanagement CowCow MilkingMilking managementmanagement MachineMachine Feeding Herd health Calving areas Muddy lanes Clean udders Yield Teat characteristics Immune system Relative Effects on MastitisRelative Effects on Mastitis 3GAM mmch98 Effects of milking Effects of milking on new infection rateon new infection rate MilkingMilking managementmanagement MachineMachine Hygiene Calm cows Visibly clean teats Timing of cup attachment Cluster removal technique Teat disinfection Contamination Teat health / colonization Bacterial penetration Table 1 IDF, 1987 Dispersing pathogens in udder Frequency /degree of emptying udder “What percentage of all infections are due “What percentage of all infections are due to milking machine factors?”to milking machine factors?” (Eberhard, Montreal, 1987)(Eberhard, Montreal, 1987) Range of responses:Range of responses: “We dont really know”“We dont really know” “ Probably quite low”“ Probably quite low” “Anywhere between 0% and 100%”“Anywhere between 0% and 100%” Machines and Mastitis Risk: A Storm in a Teatcup? 5GAM mmch98 Most new infections are due to Most new infections are due to factors other than the machinefactors other than the machine MilkingMilking managementmanagement MachineMachine Hygiene Calm cows Clean teats Teat disinfection Cluster removal Timing of cups on Contamination Teat health, colonization Liner slip, rough removal RPGs, other effects? 6-20% 6GAM mmch98 Infected Quarters (%) Peak Milking Rate (kg/qtr/min) Grindal & Hillerton, 1991 Extreme effects of the first three mechanisms Teatcup liners are damp, drippy places and Teatcup liners are damp, drippy places and contamination of teat skin is commoncontamination of teat skin is common Contamination of teat skin does not Contamination of teat skin does not necessarily lead to new infections:necessarily lead to new infections: NIRsNIRs remain low in control quarters of remain low in control quarters of most milking studies involving high most milking studies involving high bacterial challengebacterial challenge Two other instructive examples .Two other instructive examples . 1. Contamination:1. Contamination: A storm in a teatcup ? A storm in a teatcup ? High cyclic plus high irregular vacuum High cyclic plus high irregular vacuum fluctuations failed to produce high fluctuations failed to produce high NIRsNIRs in: in: the first series of challenge experiments the first series of challenge experiments in the UK when teatcups were in the UK when teatcups were notnot joined joined by a common claw by a common claw ( (Thiel Thiel et al. 1973)et al. 1973) the second series of challenge the second series of challenge experiments in Ireland when a stable liner experiments in Ireland when a stable liner was usedwas used ( (OSheaOShea & & OCallaghanOCallaghan, 1978), 1978) Examples of low NIR Examples of low NIR despite high bacterial challengedespite high bacterial challenge 1. Conclusions: contamination1. Conclusions: contamination A storm in a teatcup ?A storm in a teatcup ? Machine-inducedMachine-induced IMIs IMIs are low in the absence are low in the absence of teat damage of teat damage (which assists colonization (which assists colonization in or near the teat canal)in or near the teat canal) or high local winds or high local winds (that might impel pathogens into the canal)(that might impel pathogens into the canal) Milking machine effects are low relative to Milking machine effects are low relative to the effects of herd and milking managementthe effects of herd and milking management 2. Changing the resistance of the 2. Changing the resistance of the teat canal to bacterial invasionteat canal to bacterial invasion “Milking machines influence the level of “Milking machines influence the level of exposure to pathogens by their direct effect exposure to pathogens by their direct effect on the health of the teat duct or teat skin”on the health of the teat duct or teat skin” ( (DoddDodd, 1987 & 2003), 1987 & 2003) Teat canal integrityTeat canal integrity Congestion or edemaCongestion or edema Skin or orifice lesionsSkin or orifice lesions 11GAM mmch98 100:1 Infected Quarters (%) Duration of C+D phases (sec) Infected Quarters (%) (from Reitsma et al. 1981) Wide pulsator ratios increase the risk of mastitis 100:1 75:25 70:30 60:40 50:50 12GAM mmch98 Pulsation failure and mastitis No pulsation Short C + D phase Short liners Short liners + o/milking No pulsation x 5-20 (Bramley, 1978) x 2(Reitsma, 1981) x 2(Mein et al. 83) x 9(Mein et al. 86) 7 vs 0 (Lacy-Hulbert, 98) 13GAM mmch98 None Teat-end condition Increasing “strength” of pulsation Effect of pulsation Effect of pulsation on teat-end condition on teat-end condition GentleAggressivePositive pressure N S R VR 14GAM mmch98 None Teat-end condition Increasing “strength” of pulsation Association with NIR ? Association with NIR ? GentleAggressivePositive pressure N S R VR New infection risk NIR is increased by machine-induced NIR is increased by machine-induced changes in teat-end condition:changes in teat-end condition: Increased congestion or edemaIncreased congestion or edema Increased Increased hyperkeratosishyperkeratosis Slower removal & re-growth of keratin Slower removal & re-growth of keratin Teat orifice more open after milkingTeat orifice more open after milking 2. Teat damage & colonization:2. Teat damage & colonization: A storm in a teatcup ?A storm in a teatcup ? NIR is reduced if teat massage is effectiveNIR is reduced if teat massage is effective (= compressive load or over-pressure) (= compressive load or over-pressure) Compressive load depends on:Compressive load depends on: PulsatorPulsator ratio, B & D phases, rate ratio, B & D phases, rate Vacuum inside the liner barrelVacuum inside the liner barrel Liner material, geometry and tension Liner material, geometry and tension Teat size and shapeTeat size and shape Teat health and “teat massage”Teat health and “teat massage” Impacts due to acceleration and inertia of Impacts due to acceleration and inertia of small milk droplets that hit the teat-end.small milk droplets that hit the teat-end. Impacts may result in partial penetration Impacts may result in partial penetration of the teat canal:of the teat canal: Liner slips, machine stripping, rough take-offLiner slips, machine stripping, rough take-off Effects confined within an individual clusterEffects confined within an individual cluster Higher infection risk late in milkingHigher infection risk late in milking Lower risk with free-draining claws and tubesLower risk with free-draining claws and tubes 3. Producing forces to impel pathogens 3. Producing forces to impel pathogens into or through the teat canalinto or through the teat canal 18GAM mmch98 Cluster removal technique and NIR MM16, NIRD, unpub Effect of sudden air Effect of sudden air admission into a teatcupadmission into a teatcup Managing Milk Quality, Levesque, 1998 150 kPa/s (45 inHg/sec) Effect of sudden air Effect of sudden air admission into a teatcupadmission into a teatcup Vacuum changes in Vacuum changes in milkline milkline affect claw affect claw vacuum but rate of vacuum change is slow vacuum but rate of vacuum change is slow Managing Milk Quality, Levesque, 1998 Vacuum changes in Vacuum changes in milklinemilkline affect claw affect claw vacuum but rate of vacuum change is slowvacuum but rate of vacuum change is slow 15 kPa/s (4.5 inHg/sec) 3. Impacts and penetration:3. Impacts and penetration: A storm in a teatcup ?A storm in a teatcup ? Teat duct penetrated by 6 m/s jet speed (20 ft/s) Teat duct penetrated by 6 m/s jet speed (20 ft/s) but 2 m/s (6.5 ft/s) is too slowbut 2 m/s (6.5 ft/s) is too slow ( (ThielThiel et al. 1969) et al. 1969) Liners move much too slowly to generate high Liners move much too slowly to generate high air speedsair speeds (Spencer, 2003)(Spencer, 2003) Sudden air admission into a teatcup can Sudden air admission into a teatcup can generate air speeds 6 m/sgenerate air speeds 6 m/s ( (WoolfordWoolford et al. 1980) et al. 1980) Prime causes: liner slips, abrupt cluster Prime causes: liner slips, abrupt cluster detachment, vigorous machine strippingdetachment, vigorous machine stripping Likely conditions for impactsLikely conditions for impacts 6 inHg (from Levesque, 1998) 7.5 inHg 12 inHg Vacuum changes in Vacuum changes in milklinesmilklines or receiver are or receiver are too slow to generate air speeds 2 m/s too slow to generate air speeds 2 m/s within a clusterwithin a cluster Unstable Unstable milkline milkline or receiver vacuum may be or receiver vacuum may be associated with higher NIR but this is associated with higher NIR but this is unlikely to be a cause/effect relationshipunlikely to be a cause/effect relationship Impacts and penetration:Impacts and penetration: A storm in a teatcup ?A storm in a teatcup ? New Infection Risk is lower during lactation New Infection Risk is lowe