Prevalence of Mastitis Pathogens Preceding and Following Parturition in Primiparous Beef Cows

Abstract Prevalence of intramammary infection was studied in primiparous beef cows preceding and following parturition. Aseptic mammary quarter samples were collected from Brahman-sired cows (Group 1; n = 19) on d −143, −30, and 110 ± 4 from parturition, and from Angus-sired cows (Group 2; n = 54) on d -36 and 37 ± 2 from parturition. In Group 1, 67.6, 55.6, and 9.3% of quarters sampled were infected with mastitis pathogens on d −143, −30, and 110 ± 4 from parturition, respectively. In Group 2, 35.3 and 10.4% of the quarters were infected on d −36 and 37 ± 2 from parturition, respectively. In Group 2, over 22% of the quarters that had previously been infected with Staphylococcus aureus, and over 26% of the quarters that had previously been infected with Staphylococcus species were still infected with the same organism on d 37 ± 2 postpartum. In Group 2, representative cows were selected for blood chemistry analyses (n = 30) and machine milking (n = 46). Serum potassium was higher (4.64 vs 4.36 ± 0.09 mmol/L; P