Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2005
Publication Date: 7/1/2005
Citation: Vangroenweghe, F., Duchateau, L., Boutet, P., Rainard, P., Paape, M.J., Lekeux, P., Burvenich, C. 2005. Effect of carprofen treatment following experimentally induced escherichia coli mastitis in primiparous cows. Journal of Dairy Science. 88(7):2361-2376.
Interpretive Summary: Physiological factors have a major impact on the clinical outcome of E. coli mastitis. Early lactating cows, infected with E. coli, are much more severely affected than cows after peak lactation. This is mainly due to the impairment of early lactation leukocyte function which already starts a few weeks before parturition and only recovers several weeks post-partum. This pronounced immunodepression is not only related to parturition itself, it is influenced by several periparturient diseases and has a consequence on many other diseases, such as retained placenta. Besides stage of lactation, cow parity was also found to be an important physiological factor that influences severity of clinical mastitis. Blood PMN function was higher in younger animals than in cows after their 4th parturition. Moreover, white blood cell viability and oxidative burst have been found to be significantly different between primiparous cows and multiparous cows during the periparturient period. Using relative high E. coli inoculum doses, all primiparous cows reacted as moderate responders based on their quarter milk production in the non-infected quarter on d+2 post-infection. Based on a clinical severity scoring, all animals were scored as mild to moderate in their clinical response throughout the entire experimental challenge period.
Technical Abstract: The objective of the current study was to evaluate infection dynamics and innate host immune responses to high intramammary E. coli inoculum doses in periparturient primiparous dairy cows. In this experiment, high inoculum doses were used, because our main interest was bacterial clearance from the mammary quarters. Primiparous cows were inoculated with 1 x 104 (group A; n = 8) or 1 x 106 (group B; n = 8) CFU E. coli P4:O32 in their two left quarters during the periparturient period. Clinical examination and analysis of blood and milk parameters, including IL-8, C5a, LBP and sCD14, was performed from d-4 to d+3 relative to infection. Primiparous cows in group B performed a more rapid clinical response following IMI, resulting in typical clinical signs and changes in blood and milk parameters approximately 3 h earlier compared to primiparous cows in group A. Based on the average milk production in the uninfected quarters on d+2 post-inoculation, all heifers reacted as moderate responders. Distinct differences in the kinetic patterns of rectal temperature, SCC, IL-8, C5a, LBP and sCD14 were observed between both infusion groups during the early phase of inflammation. C5a and IL-8 increased before cellular influx into the infected glands, followed by increases in sCD14 and LBP. In conclusion, primiparous cows are able to efficiently clear an intramammary E. coli infection. Moreover, increasing the inoculum dose induces a more rapid inflammatory reaction, mainly due to early activation of the innate host immune response.