Control programmes for contagious mastitis pathogens, primarily
agalactiae and Staphylococcus aureus, consisting of milking
hygiene, treatment or
isolation of infected cows and post-milking teat disinfection are relatively
(McDonald, 1970; Natzke, 1977; Fox & Gay, 1993). Similar control programmes
often ineffective in the prevention of intramammary infections caused by
environmental bacteria (Eberhart, 1977; Smith et al.
1985; Erskine et al. 1991; Smith
& Hogan, 1993). This disparity of success relates to the fact that
principal source of environmental mastitis pathogens is the cow's
rather than another
cow with an intramammary infection (Eberhart, 1977; Smith et al.
of environmental origin are particularly noteworthy because they may remain
common in well managed herds, and these infections often cause severe clinical
and high case fatality rates (Eberhart, 1977; Smith et al. 1985;
Erskine et al. 1991; Smith & Hogan, 1993).
Control programmes for environmental mastitis usually include premilking
disinfection, decreased use of water in udder preparation, increased
dietary vitamin E and selenium, improved sanitation of the environment
modification of cow behaviour in the post-milking period (Eberhart, 1977;
et al. 1984, 1985; Weiss et al. 1990; Erskine
et al. 1991; Smith & Hogan, 1993).
Environmental infections are thought to result when bacteria lacking specific
virulence factors penetrate the teat sphincter (Eberhart
et al. 1979; Smith et al.
1985). The bulk of these exposures are thought to occur between milkings.
of these infections is problematic because the cow's teat sphincter
remains open after
mechanical milking (McDonald, 1975a). Presumably, cows are predisposed
intramammary infections when the open teat sphincter is exposed when cows
down. Hence, dairy managers are advised to offer fresh feed to cows immediately
after milking to increase the likelihood that the teat sphincter will close
partly before cows become recumbent.
The purpose of this study was to determine the effect of feed availability
on post-milking behaviour in dairy cows. Specifically, the measured
dependent variable was
the length of time that cows remained standing after leaving the milking