title: Use of dicarboxylic acids and polyphenols to attenuate reticular pH drop and acute phase response in dairy heifers fed a high grain diet.
abstract: BACKGROUND
  The aim of this study was to determine the ability of two feed additives, a fumarate-malate (FM) and a polyphenol-essential oil mixture (PM), in attenuating the drop of ruminal pH and the metabolic and immune response resulting from an excessively high grain diet. Six heifers were used in a 3 × 3 Latin square experiment and fed a low starch (LS) diet for 14 d, followed by a high starch (HS) diet for 8 d (NDF 33.6%, starch 30.0% DM). In the last 5 days of each period, barley meal was added to decrease rumen pH. During HS feeding all animals were randomly assigned to one of the following three dietary treatments: no supplement/control (CT), a daily dose of 60 g/d of FM, or 100 g/d of PM. Reticular pH was continuously recorded using wireless boluses. On d 21 of each period, rumen fluid was collected by rumenocentesis (1400 h), together with blood (0800 h) and fecal samples (0800, 1400, and 2100 h).
  
  
  RESULTS
  The correlation coefficient of pH values obtained using the boluses and rumenocentesis was 0.83. Compared with CT and PM, the FM treatment led to a lower DMI. Nadir pH was lowest during CT (5.40, 5.69, and 5.62 for CT, FM and PM, respectively), confirming the effectiveness of both supplements in reducing the pH drop caused by high grain feeding. This result was confirmed by the highest average time spent daily below 5.6 pH (199, 16 and 18 min/d) and by the highest acetate to propionate ratio of the CT fed heifers. The PM decreased the concentrations of neutrophils (2.9, 3.2, and 2.8 10(9)/L) and acute phase proteins: SAA (37.1, 28.6 and 20.1 μg/mL), LBP (4.1, 3.8, and 2.9 μg/mL), and Hp (675, 695 and 601 μg/mL). Free lipopolysaccharides (LPS) were detected in blood and feces, but their concentrations were not affected by treatments, as the remaining blood variables.
  
  
  CONCLUSIONS
  Data suggest that both additives could be useful in attenuating the effects of excessive grain feeding on rumen pH, but the PM supplement was more effective than FM in reducing the inflammatory response compared to CT.
authors.affiliation: Department of Animal Medicine Production and Health, University of Padova, Legnaro, (PD) 35020, Italy. roberta.denardi@studenti.unipd.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: De Nardi
authors.affiliation: Department of Animal Medicine Production and Health, University of Padova, Legnaro, (PD) 35020, Italy. giorgio.marchesini@unipd.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Marchesini
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada. kees.plaizier@umanitoba.ca.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Plaizier
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada. shucong.li@umanitoba.ca.
authors.forename: Shucong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada. ehsan.khafipour@umanitoba.ca.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khafipour
authors.affiliation: Department of Animal Medicine Production and Health, University of Padova, Legnaro, (PD) 35020, Italy. rebecca.ricci@unipd.it.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ricci
authors.affiliation: Department of Animal Medicine Production and Health, University of Padova, Legnaro, (PD) 35020, Italy. igino.andrighetto@unipd.it.
authors.forename: Igino
authors.initials: I
authors.lastname: Andrighetto
authors.affiliation: Department of Animal Medicine Production and Health, University of Padova, Legnaro, (PD) 35020, Italy. severino.segato@unipd.it.
authors.forename: Severino
authors.initials: S
authors.lastname: Segato
mesh_terms: D000210:Acute-Phase Reaction / Q000517:prevention & control / Q000662:veterinary*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000209:etiology / Q000517:prevention & control*; D003998:Dicarboxylic Acids / Q000627:therapeutic use*; D004032:Diet / Q000009:adverse effects / Q000662:veterinary*; D004435:Eating; D002523:Edible Grain / Q000009:adverse effects; D005260:Female; D005503:Food Additives / Q000627:therapeutic use*; D005650:Fumarates / Q000627:therapeutic use; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000627:therapeutic use; D059808:Polyphenols / Q000627:therapeutic use*; D012159:Reticulum / Q000187:drug effects* / Q000378:metabolism; D012417:Rumen / Q000187:drug effects / Q000378:metabolism
chemical_list: D003998:Dicarboxylic Acids; D005503:Food Additives; D005650:Fumarates; D008293:Malates; D059808:Polyphenols