Further short-term studies of the influence of the milking machine on the rate of new mastitis infections

In a series of short-term experiments cows were subjected to exaggerated bacterial challenge and accentuated milking machine conditions known to predispose to new mammary infection. The incidence of new intramammary infection was significantly greater in quarters with peak flow rates > 1*6 kg/min whether they were exposed to impacts (P < 0-05) or milking without pulsation (P < 0-001). The infection rates were much lower (P < 0 -001) in quarters milked with 'pulsation and shields' to protect against these two machine factors. Despite this, quarters with peak flow > 1-6 kg/min still showed a 12-fold increase in mastitis incidence compared with quarters with peak flow < 0-8 kg/min. Rates of milk flow have increased dramatically in the last 40 years through selection and breeding: whole udder peak flow rates in heifers have doubled from 1-9 to 3 -8 kg/min. Increased emphasis, therefore, should be placed on hygiene, husbandry and milking techniques to minimize bacterial numbers at teat ends to control mastitis as the drive for higher flow rate and yield make cows increasingly more susceptible to infection. These results suggest that the benefits of reduced infection rate from mastitis control are significantly underestimated since animals are now considerably more susceptible than 40 years ago.

Section: Generalmentioning

confidence: 99%

Influence of milk flow rate on new intramammary infection in dairy cows

Rj¹,

Je²

1991

“…These pressure changes have their origin in the pulsation mechanism and, under certain conditions, cause milk droplets, which may carry pathogens, to strike the teat and penetrate the teat duct (impacts). Impacts are most likely to occur towards the end of milking, when liners slip on the teats during milking, when the teatcup cluster is removed at the end of milking (159,36,75), if the air bleed in the clawpiece is blocked or if the diameter of short milk tubes is too narrow (214). These discoveries stimulated much further world-wide research (136,4).…”

Section: Milking Machine Researchmentioning

confidence: 99%

Reviews of the progress of Dairy Science: Mastitis control – progress and prospects

Bramley

Dodd

1984

211

116

Introduction Development of control methods Antibiotic therapy Hygiene Control schemes Milking machine research Mastitis awareness The value of current control methods Aetiology of mastitis Staphylococcus aureus Streptococcus agalactiae Streptococcus dysgalactiae Streptococcus uberis Coliforms Pseudomonas aeruginosa Mycoplasma bovis Corynebacteria General characteristics of bovine mastitis Stages in the infection process Exposure to pathogenic microorganisms CONTENTS PAGE 481 482 482 483 483 484 484 485 486 486 486 487 487 487 488 488 488 489 489 490 Penetration of the teat duct by pathogens Establishment of an intramammary infection Parasite factors Host factors Cellular and immune defence of the udder Nonspecific defence mechanisms Elimination of infections Culling Spontaneous recovery from infection Antibiotic therapy Dynamics of infection in dairy herds Effects of mastitis monitoring systems on awareness and control Conclusions References * Grant aided by the Agricultural and Food Research Council.

“…agalactiae and only one, in a quarter on the air vented treatment, showed clinical symptoms. In comparison with similarly designed experiments the rates of new infection were very low for both treatments (Thiel et al 1973;Cousins et al 1973). This suggests that the hydraulic milking gives a high degree of protection against machine-induced infections.…”

Section: Exptmentioning

confidence: 79%

“…The multi-valve claw (Griffin et al 1988) incorporates non-return ball valves which prevent inter-teatcup transfer of milk and air and thus provide positive protection against impacts and cross-contamination (Cousins et al 1973;Thiel et al 1973). When the multi-valve clawpiece was used in commercial herds that had adopted other mastitis control measures the new udder infections were lower by 14% and new clinical cases by 25% compared with milking with conventional machines.…”

mentioning

confidence: 99%

Effect of hydraulic milking on milking performance, teat condition and lipolysis

Grindal

Griffin²

1989

The term 'hydraulic milking' describes a new milking concept in which liner movement is restricted and the liner is flooded with milk beneath the teat. This condition, achieved with a multi-valve claw without air admission to the cluster, reduced milking time by 26% and increased milk flow rate by 20%. Four experiments describe the discovery of hydraulic milking and investigate its potential using equal or different levels of vacuum in the milkline and pulseline. Benefits from hydraulic milking include decreased lipolysis (<36%) and milk foam (75%), improved teat condition and a high degree of protection against machine-induced infections. Evidence of increased milk yield is inconclusive. Cluster removal is impeded by hydraulic milking and the multi-valve cluster requires modification to facilitate the process. Pulsation characteristics and vacuum levels developed for conventional milking appear adequate for hydraulic milking. Unorthodox vacuum conditions may be needed, however, to exploit fully this novel milking concept.The multi-valve claw (Griffin et al. 1988) incorporates non-return ball valves which prevent inter-teatcup transfer of milk and air and thus provide positive protection against impacts and cross-contamination Thiel et al. 1973). When the multi-valve clawpiece was used in commercial herds that had adopted other mastitis control measures the new udder infections were lower by 14% and new clinical cases by 25% compared with milking with conventional machines. The reductions were not statistically significant (P > O10) because of marked variation between herds (Griffin et al. 1988).To obtain a milking action similar to that with a conventional cluster the claw air bleed was replaced with an air bleed in each short milk tube (SMT). This increased air admission (14 1/min v. 7 1/min) slightly reduced operating vacuum, increased milking times and led to a small increase in milk lipolysis (Needs et al. 1986).To investigate these aspects and obtain information on the effect of air bleed blockage during farm use, experiments were performed in which the SMT air bleeds were omitted when using the multi-valve cluster. Under these conditions the liners and SMT were constantly flooded during milking. Because all the forces applied to the teat end within the liner are through a solid column of milk the new milking principle has been designated 'hydraulic milking'.• Present address: 8 Harold Close, Lower End, Leafield, Oxon. 0X8 9XX.