CORRELATION BETWEEN RUMINAL PH AND SHORT CHAIN VOLATILE FATTY ACIDS CONCENTRATION IN DAIRY COWS

Subacute rumen acidosis (SARA) represents one of the most common disorder in the intensive dairy farms that affects ruminal fermentations, animal health, productivity and farm profitability. The aim of the present study was to determine the short chain volatile fatty acids (SCVFA) and pH in ruminal fluid of lactating dairy cows. Five commercial dairy herds suspected of SARA were investigated because of high incidence of laminitis, metritis and culling rate for various pathological conditions. Twelve cows in each herd were selected randomly among animal without clinical signs of disease, good body condition, and between 40 to 170 DIM to perform rumenocentesis to obtain rumen fluid. Ruminal fluid pH was determined immediately after sampling. Concentration of SCFA in ruminal fluid were determined on the stored samples (-80°C). Data on milk composition (fat, protein) and somatic cells. The results indicated the presence of SARA in tree herds (n° cows with rumen pH < 5.5 more than 33%) and a critical situation in the others (cows with rumen pH < 5.5 less than 33% and cows with rumen pH between 5.6 – 5.8 more than 33%). High concentration of SCFA can be at the base of a pathogenic rumen acidosis because there were negative correlation between rumen pH and the levels of lactate (r = -0.388; P<0.01), acetate (r = -0.706; P<0.01) and propionate (r = 0.733; P<0.01). Finally, interesting positive correlation was found between somatic cell count and n-valeriate rumen levels (r = 0.778; P<0.01).