Machines and Mastitis Risk: A Storm in a Teatcup

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

Relative Effects on Mastitis Feeding Herd health Calving areas Muddy lanes Clean udders Milking management Herd & farm management Cow Machine Yield Teat characteristics Immune system

Effects of milking on new infection rate Hygiene Calm cows Visibly clean teats Timing of cup attachment Cluster removal technique Teat disinfection Milking management } Machine Contamination Table 1 IDF, 1987 Teat health / colonization Bacterial penetration Dispersing pathogens in udder Frequency /degree of emptying udder

Machines and Mastitis Risk:A Storm in a Teatcup? “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” “Anywhere between 0% and 100%”

Most new infections are due to factors other than the machine Hygiene Calm cows Clean teats Teat disinfection Cluster removal Timing of cups on Milking management } Machine Contamination 6-20% Teat health, colonization Liner slip, rough removal RPGs, other effects???

Extreme effects of the first three mechanisms Infected Quarters (%) Peak Milking Rate (kg/qtr/min) Grindal & Hillerton, 1991

1. Contamination: A storm in a teatcup ? • 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 • Two other instructive examples ...

Examples of low NIR despite high bacterial challenge • 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 second series of challenge experiments in Ireland when a stable liner was used(O’Shea & O’Callaghan, 1978)

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 Skin or orifice lesions

Wide pulsator ratios increase the risk of mastitis 100:1 100:1 75:25 Infected Quarters (%) Infected Quarters (%) 70:30 60:40 50:50 Duration of C+D phases (sec) (from Reitsma et al. 1981)

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) Pulsation failure and mastitis

Effect of pulsation on teat-end condition VR R Teat-end condition S N None Gentle Aggressive Positive pressure Increasing “strength” of pulsation

Association with NIR ? New infection risk VR Teat-end condition R S N None Gentle Aggressive Positive pressure Increasing “strength” of pulsation

2. Teat damage & colonization: A storm in a teatcup ? 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

Teat health and “teat massage” NIR is reduced if teat massage is effective (= 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

3. Producing forces to impel pathogens into or through the teat canal • ‘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: • Liner slips, machine stripping, rough take-off • Effects confined within an individual cluster • Higher infection risk late in milking • Lower risk with free-draining claws and tubes

Cluster removal technique and NIR MM16, NIRD, unpub

Effect of sudden air admission into a teatcup Managing Milk Quality, Levesque, 1998

Effect of sudden air admission into a teatcup 150 kPa/s (45 inHg/sec)

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

Likely conditions for ‘impacts’ 12 6 inHg inHg 7.5 inHg (from Levesque, 1998)

Impacts and penetration: A storm in a teatcup ? 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

5. Frequency and degree of udder evacuation 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

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

Machines and Mastitis Risk: A Storm in a Teatcup