title: Effects of grain, fructose, and histidine on ruminal pH and fermentation products during an induced subacute acidosis protocol.
abstract: The effects of grain, fructose, and histidine on ruminal pH and fermentation products were studied in dairy cattle during an induced subacute acidosis protocol. Thirty Holstein heifers were randomly allocated to 5 treatment groups: (1) control (no grain); (2) grain [fed at a crushed triticale dry matter intake (DMI) of 1.2% of body weight (BW)]; (3) grain (0.8% of BW DMI)+fructose (0.4% of BW DMI); (4) grain (1.2% of BW DMI)+histidine (6 g/head); and (5) grain (0.8% of BW DMI)+fructose (0.4% of BW DMI)+histidine (6 g/head) in a partial factorial arrangement. Heifers were fed 1 kg of grain daily with ad libitum access to ryegrass silage and alfalfa hay for 10 d. Feed was withheld for 14 h before challenge day, on which heifers were fed 200 g of alfalfa hay and then the treatment diets immediately thereafter. Rumen samples were collected 5 min after diet ingestion, 60 min later, and at 3 subsequent 50-min intervals. Grain decreased ruminal pH and increased ammonia, total volatile fatty acid (VFA), acetate, butyrate, propionate, and valerate concentrations compared with controls. The addition of grain had no effect on ruminal D- and L-lactate concentrations. Fructose markedly decreased ruminal pH and markedly increased D- and L-lactate concentrations. Fructose increased total VFA and butyrate and decreased valerate concentrations. Although histidine did not have a marked effect on ruminal fermentation, increased concentrations of histamine were observed following feeding. This study demonstrates that the substitution of some grain for fructose can lower ruminal pH and increase VFA and lactate concentrations, warranting further investigation into the role of sugars on the risk of acidosis in dairy cattle.
authors.affiliation: Faculty of Veterinary Science, University of Sydney, Camden, New South Wales, Australia 2570. heleng@sbscibus.com.au
authors.forename: H M
authors.initials: HM
authors.lastname: Golder
authors.forename: P
authors.initials: P
authors.lastname: Celi
authors.forename: A R
authors.initials: AR
authors.lastname: Rabiee
authors.forename: C
authors.initials: C
authors.lastname: Heuer
authors.forename: E
authors.initials: E
authors.lastname: Bramley
authors.forename: D W
authors.initials: DW
authors.lastname: Miller
authors.forename: R
authors.initials: R
authors.lastname: King
authors.forename: I J
authors.initials: IJ
authors.lastname: Lean
mesh_terms: D000138:Acidosis / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*; D000641:Ammonia / Q000032:analysis; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000209:etiology* / Q000378:metabolism; D004032:Diet / Q000662:veterinary; D002523:Edible Grain; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D005285:Fermentation / Q000187:drug effects; D005632:Fructose / Q000008:administration & dosage*; D006632:Histamine / Q000097:blood; D006639:Histidine / Q000008:administration & dosage*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000032:analysis / Q000097:blood; D012417:Rumen / Q000737:chemistry / Q000378:metabolism*; D013272:Stomach Diseases / Q000209:etiology / Q000662:veterinary
chemical_list: D005232:Fatty Acids, Volatile; D005632:Fructose; D019344:Lactic Acid; D006639:Histidine; D000641:Ammonia; D006632:Histamine