Bacteriological and histological investigation of the postpartum bovine uterus in two Estonian dairy herds

Postpartum uterine infections, endometrial histology and resumption of ovar ian activity in cows were studied in 2 Estonian dairy herds with different herd sizes, milk yields and management systems. Ten cows at Farm A and 5 co ws at Farm B were studied in the experiment. All cows in the study had norm al calving performance. Endometrial biopsies for bacteriological and histol ogical examinations were collected once a week starting on the second week postpartum and continuing for 7 weeks postpartum. Milk progesterone samples were collected twice a week during the whole study period. In both herds, the uterine flora contained mainly facultative anaerobic bacteria (Streptoc occus spp., E. coli, Staphylococcus spp., Proteus vulgaris). Among obligate anaerobic bacteria only Bacteroides spp. were found. After 7 weeks of coll ection at farm A, a bacterial uterine flora still persisted in 2 of the cow s. At farm B, on the other hand, bacterial elimination was complete after 6 weeks. Presence of inflammatory cells in uterine histology specimens remai ned higher at the end of collection and resumption of ovarian activity was delayed at farm A. After 7 weeks postpartum, only 6 of the 10 cows at farm A had resumed ovarian cyclicity, while at farm B the first oestrous cycle h ad occurred in all cows. The study showed that differences regarding uterin e infections and their clearance occured between farms and, despite these d ifferences, cows with normal calving performance will effectively recover w ithout any treatment.