Environmental mastitis in intensive high-producing dairy herds in New South Wales.
OBJECTIVE
To determine the prevalence of mastitis pathogens in high-producing intensive dairy herds in New South Wales.


METHODS
Field survey.


METHODS
Milk samples from the mastitis-affected quarter were collected from cows on five high-producing dairy farms in NSW. The 820 samples were cultured using standard microbiological culture techniques.


RESULTS
Bacteria or fungi were isolated from 83.3% of samples (683/820). More than two colony types were isolated from 16.7% of samples (137/820), two types from 6.6% (54/820), and one type from 52.3% (429/820). No bacteria were isolated from 24.4% (200/820) of the primary cultures, but enrichment cultures of these samples yielded single colony type bacterial isolates from 36.5% (73/200) of samples. Environmental pathogens, including coliforms, environmental Streptococcus and Staphylococcus spp., made up 91% (555/610) of isolates and accounted for 33.6% (205/610), 41.6% (254/610) and 15.7% (96/610), respectively, of isolates. Escherichia coli accounted for 76.1% (156/205) of the coliform isolates, Streptococcus uberis and Streptococcus dysgalactiae accounted for 32.3% (82/254) and 28.0% (71/254), respectively, of the environmental streptococcal isolates. Contagious pathogens were uncommon, comprising only 2.5% (15/610) of the total isolates.


CONCLUSIONS
The incidence and causes of mastitis are largely influenced by farm management. The relatively high prevalence of coliform mastitis in the intensive high-producing herds in this survey contrasts with the low incidence reported in surveys of pasture-based herds in Victoria. If the Australian dairy industry continues its current trend of intensification, coliform intra-mammary infections may emerge as an increasingly important cause of mastitis.
Shum
L W C
LW
University of Sydney, Camden, New South Wales, Australia.
McConnel
C S
CS
Gunn
A A
AA
House
J K
JK
D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D003612:Dairying / Q000379:methods*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000662:veterinary; D004783:Environmental Microbiology; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary; D005260:Female; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D009517:New South Wales / Q000453:epidemiology; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000662:veterinary; D013290:Streptococcal Infections / Q000453:epidemiology / Q000662:veterinary