The Role of Inflammatory State During the Periparturient Period on the Uterine Health of Pasture-Based Dairy Cows
The transition from gestation to lactation is a period of great physiological and immunological stress, that can result in the development of metabolic and/or infectious diseases, and coincident systemic or localized inflammation. The occurrence of these disorders has often been associated with negative effects on reproductive outcomes. Reproductive performance of the herd is particularly critical in seasonal-calving grazing systems that rely on the synchrony of herd demand and pasture supply to maximize profitability. I hypothesized that excessive or prolonged systemic inflammation during the peripartum period is associated with compromised fertility in dairy cows, and that intervention strategies that return cows to within the bounds of a normal inflammatory state will improve reproductive health. Accordingly, a database was compiled encompassing 20 years of research and the data of over 2,500 New Zealand dairy cows. Using this database, we were able to characterize temporal profiles of analytes and inflammatory markers in grazing seasonal calving cows during the transition period. We then examined whether selected circulating inflammation markers were elevated in cows with an induced uterine infection, and whether they could be early indicators of cows at risk of unresolved uterine inflammation. From these retrospective studies, we could conclude that these markers were not specific to inflammation of the uterus; rather, that they were indicative of an inflammatory dysregulation during the peripartum period. Subsequently, a panel of circulating inflammation markers were investigated using a multivariate approach for their predictive potential during the early postpartum period to differentiate between cows that failed to resolve uterine inflammation and cows with no uterine inflammation. Three markers consistently contributed to the separation of uterine inflammation groups during the first three weeks postpartum. Finally, it was hypothesized that these markers would be decreased in circulation following treatment with non-steroidal anti-inflammatory drugs in the third to fourth week postpartum in cows that were positive for uterine inflammation at three weeks postpartum. Although, these markers were not affected by the treatment, anti-inflammatory effects on other peripheral markers were identified. Whether these effects were sustained and beneficial to reproductive outcomes provides direction for future studies.
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