title: Indicators of induced subacute ruminal acidosis (SARA) in Danish Holstein cows.
abstract: BACKGROUND
  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 3 days to reach 40% grain in the diet. Ruminal pH was measured continuously. Blood samples were collected once daily at 7 h after feeding. Samples of faeces and urine were collected at feeding, and at 7 and 12 h 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.
  
  
  RESULTS
  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 pCO2 tended to be increased (P = 0.10). Significant differences were not detected in other parameters.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegård Alle 5, 2630, Taastrup, Denmark. annemette@danscher.net.
authors.forename: Anne Mette
authors.initials: AM
authors.lastname: Danscher
authors.affiliation: Department of Animal Science, Faculty of Agricultural and Food Sciences, University of Manitoba, 201-12 Dafoe Road, Winnipeg, MB, R3T 2N2, Canada. shucong.li@umanitoba.ca.
authors.forename: Shucong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Ulls väg 14C (Ultuna), 756 51, Uppsala, Sweden. pia.haubro.andersen@slu.se.
authors.forename: Pia H
authors.initials: PH
authors.lastname: Andersen
authors.affiliation: Department of Animal Science, Faculty of Agricultural and Food Sciences, University of Manitoba, 201-12 Dafoe Road, Winnipeg, MB, R3T 2N2, Canada. Ehsan.Khafipour@umanitoba.ca.|Department of Medical Microbiology, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada. Ehsan.Khafipour@umanitoba.ca.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khafipour
authors.affiliation: Knowledge Centre for Agriculture, Cattle, SEGES, Agro Food Park 15, 8200, Aarhus N, Denmark. nbk@seges.dk.
authors.forename: Niels B
authors.initials: NB
authors.lastname: Kristensen
authors.affiliation: Department of Animal Science, Faculty of Agricultural and Food Sciences, University of Manitoba, 201-12 Dafoe Road, Winnipeg, MB, R3T 2N2, Canada. Kees.Plaizier@umanitoba.ca.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Plaizier
mesh_terms: D000138:Acidosis / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000378:metabolism / Q000652:urine; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D018592:Cross-Over Studies; D003718:Denmark; D005243:Feces / Q000737:chemistry; D005260:Female; D012417:Rumen / Q000502:physiology; D013272:Stomach Diseases / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*
chemical_list: D015415:Biomarkers