Evidence of penetration of the bovine teat duct by Escherichia coli in the interval between milkings

Abstract

SummaryIn 3 consecutive experiments, each using 20 cows, the application of Escherichia coli to teat ends after milking led to high rates of intramammary infection. These infections were not prevented by disinfection of the teats before milking, by the installation of shields in the short milk tubes of the milking cluster or by the use of an individual quarter milking cluster. Rates of infection were significantly lower when teat contamination was applied 1 h before milking compared to contamination applied immediately after milking.These data suggest that penetration of the teat duct by the E. coli occurred in the period between contamination and milking. Seventy four percent of infections occurred in hindquarters and there were variations in the susceptibility of cows to infection.

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

“…The latter organism may require a teat duct penetration process operating between milking and is dependent on contamination from environmental sources rather than from within the teat duct. Evidence has been produced to support such a mechanism for E. coli (199,18) and further evidence that material can rapidly penetrate the teat duct between milkings is furnished by the endotoxin experiments of Schultze and his colleagues (l97,198). It is still uncertain whether the penetration mechanism demonstrable by inoculating the solute endotoxin into the teat duct is a correct model of the way in which bacteria move through the duct.…”

“…In this respect it is interesting to note that infection in hind quarters is about 50 % commoner than in fore quarters. This might be related to the relative penetrability of their ducts because when heavy E. coli teat contamination was applied equally to all teats between milkings significantly more infections developed in hind quarters (18). In addition to these physical aspects of the teat duct being related to its defensive ability, biochemical factors may also be involved.…”

“…This is not unlikely since penetration occurs in unmilked cows and could happen during lactation when milk leaks from the teat in the milking interval, a relatively frequent event. There is evidence to suggest that the duct is particularly penetrable immediately after milking (18,198). If this is confirmed it may be possible by modifying milking equipment or management practices to reduce teat contamination at this time.…”

Asymptomatic Intramammary Infection with Multidrug-Resistant Gram-Negative Bacteria in a Research Dairy Farm: Incidence and Genetic Basis of Resistance

“…Given that the penetration of coliforms into the bovine teat duct during intermilking periods has been well documented [4,20], a better understanding of the antibiotic resistance mechanisms in the bacteria responsible for such asymptomatic cases is needed. In this study, we sought to determine the mechanisms of resistance in Enterobacteriaceae isolated from healthy dairy cows and to assess their genetic diversity.…”

The influence of laterality on mastitis incidence in dairy cattle - preliminary study

“…Exposure to environmental pathogens occurs between milkings [with the highest probability within 30 min (max. 60) after milkings] and is not limited to the milking process, which is in contrast to contagious pathogens Buckalew, 1972, 1977;Bramley et al, 1981;Eberhart et al, 1983).…”