Proinflammatory cytokines and acute phase response profiles in periparturient dairy cows

Pro-inflammatory cytokines (PIC: IL-1, IL-6 and TNF-) raise body temperature, induce anorexia, increase catabolism and cause several endocrine and metabolic changes. PIC play key roles in the regulation of acute phase response (APR). However, in transition cows the relation between inflammation and health conditions and the link between PIC, inflammation start, APR, liver function and metabolic state need to be further investigated. Therefore, 10 multiparous cows were studied 4 wk before and after calving. Cows were daily monitored for health status, feed intake (DMI), milk yield, rectal temperature; body weight and BCS were measured every 2 wk. Blood was also frequently sampled and assayed for a wide metabolic and inflammatory (including IL-1and IL-6; ELISA methods) profile. One cow died 3 days after calving and was evaluated separately. The remaining 9 were retrospectively classified into 2 groups according to IL-6 plasma values peak: less (LOIL, 6 cows) or greater (UP-IL, 3 cows) than 650 pg/ml. Data were analyzed by the MIXED repeated procedure of SAS. Generally, IL- 1and IL-6 were already higher 2-4 wk before calving, in absence of clinical symptoms. The died cow had the highest levels of IL-6 (~2000 pg/ml). Both PIC tend to decrease thereafter, showing a short-lived increase at parturition. A rise of PIC was also noted in association with clinical events close to calving, while very low levels were observed in cows with mild ketosis. UP-IL cows suffered more severe diseases (e.g. mastitis), had lower DMI before calving, lost more body reserves and produced less milk. Moreover, UPIL (vs LO-IL) cows showed higher haptoglobin, bilirubin and urea and lower albumin and Zn levels in the wk before and after calving. Thus, high PIC values in dry period seem related to some subclinical events as confirmed by lower DMI as well as to critical metabolic and inflammatory conditions at calving time and thereafter (e.g. more severe diseases and APR).