Variations in the susceptibility of lactating and non-lactating bovine udders to infection when infused with Escherichia coli.
Small numbers of Escherichia coli were infused into both lactating and non-lactating udders. Twelve of the 17 lactating quarters infused became infected, and all 12 showed clinical symptoms of udder disease. The 5 lactating quarters which did not become infected all had pre-infusion somatic cell counts greater than 300000 cells/ml milk, whilst all the quarters which became infected had cell counts less than 300000 cells/ml milk. E. coli was subsequently recovered from only 6 of the 16 non-lactating quarters infused. In only 2 of these quarters did clinical infection follow, both quarters being in a cow infused 2 d before calving. The remaining 4 quarters from which E. coli was recovered were all negative within 5 d of infusion. These differences in susceptibility are discussed, particularly with reference to the frequent occurrence of coliform mastitis at and shortly after calving.
D000818:Animals; D002417:Cattle; D002452:Cell Count; D004927:Escherichia coli Infections / Q000209:etiology*; D005260:Female; D007743:Labor, Obstetric; D007774:Lactation; D008321:Mammary Glands, Animal / Q000033:anatomy & histology / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000209:etiology*; D008892:Milk / Q000166:cytology / Q000382:microbiology; D011247:Pregnancy