Subacute rumen acidosis in dairy herds: diagnostics tools.

Subacute rumen acidosis (SARA) represent one of the most important metabolic disorders in intensive dairy farms that affects rumen fermentations, animal welfare, productivity and profitability. The aim of the present study was to study SARA in intensive Italian dairy herds and to determine the correct clinical approach to diagnose this disease. During the last four years forty commercial dairy herds were investigated. Twelve cows in good body condition, between 5 and 60 day in milk and without clinical signs of disease were selected randomly from each herd, to perform rumenocentesis and obtain rumen fluid. Ruminal pH was determined immediately after sampling and concentration of SCFA in ruminal fluid was determined on samples after storage. Blood samples for hematochemical and hematological profiles were obtained from the same cows that had rumenocentesis performed by jugular venipuncture. Milk yield quality was determined in the cows were we performed the rumenocentesis. The herds were divided into three groups depending on the mean rumen pH: group A counted farms with average ruminal pH > 5.8 (normal), group B included farms with average ruminal pH between 5.6 and 5.8 (risk), and in group C, dairy farms presented an average ruminal pH < 5.6 (acidosis). Results were subject to ANOVA and correlation analysis using SIGMA STAT 3.05. We had no sampling problems with the 480 cows of our study series, and no animal developed any health problem during or after the procedure. In particular dairy herds show an average SCFA concentration of 121, 147 and 162 mmol/L for normal, risk and acidosis herds, respectively. The differences among particle size showed a light discordance between the three class of herd, a result which suggests more attention in TMR preparation and management, especially in large herds where the attitude of the personnel responsible for feeding the cows is of paramount importance. Milk yield quality were not statistical different in three groups. Statistically significant differences (p < 0.05) were observed for various blood parameters observed: these data suggest that modifications of some haematological parameters can be observed and in particular the total and differential WBC count were significantly higher in the dairy cows belonging to the farms affected by SARA.