title: Effect of induced ruminal acidosis on blood variables in heifers.
abstract: BACKGROUND
  Ruminal acidosis is responsible for the onset of different pathologies in dairy and feedlot cattle, but there are major difficulties in the diagnosis. This study modelled the data obtained from various blood variables to identify those that could indicate the severity of ruminal acidosis. Six heifers were fed three experimental rations throughout three periods. The diets were characterised by different starch levels: high starch (HS), medium starch (MS) and low starch, as the control diet (CT). Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis. Blood samples were analysed for complete blood count, biochemical profile, venous blood gas, blood lipopolysaccharide (LPS) and LPS-binding proteins (LBP).
  
  
  RESULTS
  The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040). Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001). A canonical discriminant analysis (CDA) was used to classify the animals into four ruminal pH classes (normal, risk of acidosis, subacute ruminal acidosis and acute ruminal acidosis) using haemoglobin, mean platelet volume, β-hydroxybutyrate, glucose and reduced haemoglobin.
  
  
  CONCLUSIONS
  Although additional studies are necessary to confirm the reliability of these discriminant functions, the use of plasma variables in a multifactorial model appeared to be useful for the evaluation of ruminal acidosis severity.
authors: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, (PD) 35020, Italy.
authors: Giorgio
authors: G
authors: Marchesini
authors: Roberta
authors: R
authors: De Nardi
authors: Matteo
authors: M
authors: Gianesella
authors: Anna-Lisa
authors: AL
authors: Stefani
authors: Massimo
authors: M
authors: Morgante
authors: Antonio
authors: A
authors: Barberio
authors: Igino
authors: I
authors: Andrighetto
authors: Severino
authors: S
authors: Segato
mesh_terms: D000138:Acidosis / Q000097:blood / Q000378:metabolism / Q000662:veterinary*; D000209:Acute-Phase Proteins; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002352:Carrier Proteins / Q000097:blood; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood* / Q000378:metabolism; D004032:Diet / Q000662:veterinary; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004435:Eating; D005260:Female; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000097:blood; D008562:Membrane Glycoproteins / Q000097:blood; D012417:Rumen / Q000378:metabolism; D013213:Starch / Q000494:pharmacology; D013272:Stomach Diseases / Q000097:blood / Q000378:metabolism / Q000662:veterinary*; D000099231:Lipopolysaccharide-Binding Protein
chemical_list: D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D004040:Dietary Carbohydrates; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D013213:Starch; D000099231:Lipopolysaccharide-Binding Protein
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