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Research article - Peer-reviewed, 2015

Indicators of induced subacute ruminal acidosis (SARA) in Danish Holstein cows

Danscher AM, Li SC, Andersen PH, Khafipour E, Kristensen NB, Plaizier JC


The prevalence of subacute ruminal acidosis (SARA) in dairy cows is high with large impact on economy and welfare. Its current field diagnosis is based on point ruminal pH measurements by oral probe or rumenocentesis. These techniques are invasive and inaccurate, and better markers for the diagnosis of SARA are needed. The goal of this study was to evaluate clinical signs of SARA and to investigate the use of blood, faecal and urinary parameters as indicators of SARA. Six lactating, rumen cannulated, Danish Holstein cows were used in a cross-over study with three periods. The first and second periods included two cows on control diet and two cows on nutritional SARA challenge. The third period only included two cows on SARA challenge. Control diet was a conventional total mixed ration [45.5% dry matter (DM), 17.8% crude protein, 43.8% neutral detergent fibre, and 22.5% acid detergent fibre (DM basis)]. SARA challenge was conducted by substituting control diet with grain pellets (50% wheat/barley) over 3days to reach 40% grain in the diet. Ruminal pH was measured continuously. Blood samples were collected once daily at 7h after feeding. Samples of faeces and urine were collected at feeding, and at 7 and 12h after feeding. Blood samples were analysed for pCO2, pO2, pH, electrolytes, lactate, glucose, packed cell volume (PCV), and total plasma protein concentration. Milk composition, ruminal VFA, and pH of faeces and urine were measured. 
SARA was associated with decreased (P<0.05) minimum ruminal, faecal and urinary pH. Daily times and areas of ruminal pH below 5.8, and 5.6 were increased to levels representative for SARA. Significant differences were detected in milk composition and ruminal VFAs. Blood calcium concentration was decreased (P<0.05), and pCO2tended to be increased (P=0.10). Significant differences were not detected in other parameters. 
SARA challenge was associated with changes in faecal and urinary pH, blood calcium concentration and pCO2. These may be helpful as indicators of SARA. However changes were small, and diurnal variations were present. None of these parameters are able to stand alone as indicators of SARA.


Subacute ruminal acidosis; SARA; Bovine; Biomarkers; Diagnosis

Published in

Acta Veterinaria Scandinavica
2015, volume: 57, article number: 39

Authors' information

Danscher, Anne Mette
University of Copenhagen
Li, Shucong
University of Manitoba
Andersen, Pia Haubro (Haubro Andersen, Pia)
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Khafipour, Ehsan
University of Manitoba
Kristensen, Niels B.
Knowledge Centre for Agriculture
Plaizier, Jan C.
University of Manitoba

UKÄ Subject classification

Other Veterinary Science

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