Presentation on theme: "Machines and Mastitis Risk: A Storm in a Teatcup Graeme Mein, Australia Douglas Reinemann, UW-Madison, USA Douglas Reinemann, UW-Madison, USA Norm Schuring,"— Presentation transcript:
Machines and Mastitis Risk: A Storm in a Teatcup Graeme Mein, Australia Douglas Reinemann, UW-Madison, USA Douglas Reinemann, UW-Madison, USA Norm Schuring, Westfalia-Surge, USA Ian Ohnstad, ADAS, UK
2 GAM mmch98 Herd & farm management Cow Milkingmanagement Machine Feeding Herd health Calving areas Muddy lanes Clean udders Yield Teat characteristics Immune system Relative Effects on Mastitis
3 GAM mmch98 Effects of milking on new infection rate Milkingmanagement Machine 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 to milking machine factors?” (Eberhard, Montreal, 1987) Range of responses: “We don’t 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?
5 GAM mmch98 Most new infections are due to factors other than the machine Milkingmanagement Machine 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%
6 GAM 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 contamination of teat skin is common Contamination of teat skin does not necessarily lead to new infections: NIRs remain low in control quarters of most milking studies involving high bacterial challenge NIRs remain low in control quarters of most milking studies involving high bacterial challenge Two other instructive examples... Two other instructive examples Contamination: A storm in a teatcup ? A storm in a teatcup ?
High cyclic plus high irregular vacuum fluctuations failed to produce high NIRs in: the first series of challenge experiments in the UK when teatcups were not joined by a common claw (Thiel et al. 1973) the first series of challenge experiments in the UK when teatcups were not joined by a common claw (Thiel et al. 1973) the second series of challenge experiments in Ireland when a stable liner was used (O’Shea & O’Callaghan, 1978) the second series of challenge experiments in Ireland when a stable liner was used (O’Shea & O’Callaghan, 1978) Examples of low NIR despite high bacterial challenge
1. Conclusions: contamination A storm in a teatcup ? Machine-induced IMIs are low in the absence of teat damage (which assists colonization in or near the teat canal) or high local winds (that might impel pathogens into the canal) Milking machine effects are low relative to the effects of herd and milking management
2. Changing the resistance of the teat canal to bacterial invasion “Milking machines influence the level of exposure to pathogens by their direct effect on the health of the teat duct or teat skin” (Dodd, 1987 & 2003) Teat canal integrity Congestion or edema Congestion or edema Skin or orifice lesions Skin or orifice lesions
11 GAM 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
12 GAM 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)
13 GAM mmch98 None Teat-end condition Increasing “strength” of pulsation Effect of pulsation on teat-end condition GentleAggressivePositive pressure N S R VR
14 GAM mmch98 None Teat-end condition Increasing “strength” of pulsation Association with NIR ? GentleAggressivePositive pressure N S R VR New infection risk
NIR is increased by machine-induced changes in teat-end condition: Increased congestion or edema Increased hyperkeratosis Slower removal & re-growth of keratin Teat orifice more ‘open’ after milking 2. Teat damage & colonization: A storm in a teatcup ?
NIR is reduced if teat massage is effective (= compressive load or over-pressure) (= compressive load or over-pressure) Compressive load depends on: Pulsator ratio, B & D phases, rate Vacuum inside the liner barrel Liner material, geometry and tension Teat size and shape Teat health and “teat massage”
‘Impacts’ due to acceleration and inertia of small milk droplets that hit the teat-end. ‘Impacts’ may result in partial penetration of the teat canal: ‘Impacts’ may result in partial penetration 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 into or through the teat canal
Effect of sudden air admission into a teatcup Managing Milk Quality, Levesque, 1998
150 kPa/s (45 inHg/sec) Effect of sudden air admission into a teatcup
Vacuum changes in milkline affect claw vacuum but rate of vacuum change is slow Managing Milk Quality, Levesque, 1998
Vacuum changes in milkline affect claw vacuum but rate of vacuum change is slow 15 kPa/s (4.5 inHg/sec)
3. Impacts and penetration: A storm in a teatcup ? Teat duct penetrated by 6 m/s jet speed (20 ft/s) but 2 m/s (6.5 ft/s) is too slow (Thiel et al. 1969) Liners move much too slowly to generate high air speeds (Spencer, 2003) Sudden air admission into a teatcup can generate air speeds > 6 m/s (Woolford et al. 1980) Prime causes: liner slips, abrupt cluster detachment, vigorous machine stripping
Vacuum changes in milklines or receiver are too slow to generate air speeds > 2 m/s within a cluster Unstable milkline or receiver vacuum may be associated with higher NIR but this is unlikely to be a cause/effect relationship Impacts and penetration: A storm in a teatcup ?
New Infection Risk is lower during lactation than in the dry period Regular milking has a positive effect ! - NIR reduced by regular flushing of canal Complete milk-out seems important but may be less so with more frequent milking per day 5. Frequency and degree of udder evacuation
Reducing the risk Reduce transient air inrush, especially late in milking: Stable liners, cluster positioning Free draining SMTs, claw and hose Calm cows (to reduce kick-offs) Gentle removal, no stripping Maintain effective teat massage Maintain healthy teat-ends Maintain healthy teat-ends