title: Physical characteristics of the bovine teat canal and their influence on susceptibility to streptococcal infection.
abstract: Physical characteristics of the bovine teat canal were examined for their influence on susceptibility to intramammary infection. All quarters of 18 cows were inoculated with 2 x 10(5) cfu Streptococcus agalactiae (Trial 1) and 20 cows with 10(5) cfu Str. uberis (Trial 2) 3-4 mm into the teat canal every 3 d for 12 d. Incidence of quarter infection was similar for both pathogens, 30/72 (42%) in Trial 1 and 32/80 (40%) in Trial 2. Logistic regression analysis showed that probability of infection by Str. agalactiae increased significantly with an increase in quarter peak flow rate (P < 0.05) whereas probability of infection increased for Str. uberis with a decrease in teat canal length (P < 0.05). A significantly higher (P < 0.001) incidence of infection by Str. uberis was observed in quarters that contained a low wet weight (< 1.8 mg) of removable keratin compared with those that contained > 1.8 mg keratin, but there was no correlation between weight of keratin and length of the teat canal. Infections by Str. uberis took significantly less (P < 0.05) time to show a rise in somatic cell count above 7.5 x 10(5) cells/ml than Str. agalactiae. The results provide evidence that these pathogens use different mechanisms to pass through the teat canal.
authors.affiliation: Institute for Animal Health, Compton Laboratory, Newbury, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Lacy-Hulbert
authors.forename: J E
authors.initials: JE
authors.lastname: Hillerton
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying / Q000379:methods; D004198:Disease Susceptibility / Q000662:veterinary; D005260:Female; D007633:Keratins / Q000032:analysis; D007700:Kinetics; D007774:Lactation / Q000502:physiology; D008321:Mammary Glands, Animal / Q000382:microbiology / Q000473:pathology*; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D012044:Regression Analysis; D013290:Streptococcal Infections; D013292:Streptococcus agalactiae
chemical_list: D007633:Keratins