Survey on Serum Amyloid A and Haptoglobin Concentrations in Normal or Sensitive to Rumen Acidosis Holstein Dairy Cows

　 BACKGROUND: Diagnosis and prognosis of inflammatory conditions based on acute phase proteins (APPs) level in blood has been exploited for a long time in human medicine and their changes in SARA condition is considered in veterinary medicine. OBJECTIVES: To evaluate the variations of serum amyloid A (SAA) and haptoglobin (Hp) as main acute phase proteins in cow with normal pH or cows that experienced rumen pH ≤5.8 during first days after parturition. METHODS: A total of 106 multiparous Holstein dairy cows were randomly selected after parturition in two different seasons of winter and summer 2017. Cows were divided into 2 groups as normal cows with pH >5.8 or rumen pH ≤5.8. Ruminal fluid samples were collected through stomach tube for rumen pH and blood samples were taken from the coccygeal vein of cows concurrently once per day at days 4, 11 and 18 post-partum. SAA and Hp were determined in blood samples. The PROC MIXED of SAS (2003) was used for all determined variables with repeated measures. BCS, parity and milk yield were included as fixed and cows as random effect. The significant level was declared at P≤0.05, and tendency toward significance was considered at 0.05 RESULTS: The results of experiment showed that rumen pH was lower (P<0.05) in summer samples than winter (6.33 vs. 6.46). Rumen pH was lower (P<0.0001) in cows composed by subjects with rumen pH ≤5.8 than pH >5.8. For all examined cows, SAA concentration was greater in winter than summer (P<0.001), as well as at day 4 than days 11 and 18 after calving (P<0.05).Also, Hp concentration was greater for winter samples than summer (P<0.05), and at day 18 than days 4 and 11 after calving (333.33 vs. 299.3 and 300.1 respectively) (P<0.05). SAA and Hp concentrations were not affected by rumen pH. There was no significant correlation between rumen pH and APPs concentrations in both groups of pH ≤5.8 and pH >5.8. CONCLUSIONS: Results showed that rumen pH ≤5.8 seems not to stimulate the APPs production