Stress and Uterine Bacterial Flora in Dairy Cows Following Clinically Normal and Abnormal Puerperium

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ACTH challenge tests for the assessment of stress on the first and third week postpartum and bacteriologic examination of uterine swabs on the second and fourth week, were conducted in dairy cows following clinically normal (n=12) and abnormal (n=21) puerperium. Postpartum ovarian activity and uterine involution were also investigated. The basal plasma cortisol concentrations (mean ± S.E.) during the first and third week postpartum were 3.1 ± 0.9 ng/ml and 3.4 ± 1.1 ng/ml in normal cows, and 6.5 ± 1.9 ng/ml and 4.9 ± 1.2 ng/ml in abnormal cows, respectively. The mean basal plasma cortisol values of abnormal cows were elevated and significantly higher (P<0.05) during the first week postpartum. Bacterial organisms were isolated from the uterus of 33.3% of normal and 61.9% of abnormal cows during the second week postpartum and in 33.3% of normal and 23.8% of abnormal cows during the fourth week. Resumption of ovarian activity was neither affected by puerperal disorders nor uterine bacterial infection. Uterine involution at 4 weeks postpartum was completed in all cows with normal puerperium and delayed in 23.8% of abnormal cows. The results indicate that cows with abnormal puerperium had significantly higher basal cortisol levels, and had higher occurrence of uterine bacterial infection during the second week when compared with normal cows.