title: Rumen lipopolysaccharide and inflammation during grain adaptation and subacute ruminal acidosis in steers.
abstract: Three rumen-fistulated Jersey steers were gradually adapted to a wheat-barley concentrate over a 4-wk period. Adaptation steps consisted of four 1-wk periods during which steers were fed diets with forage-to-concentrate (F:C) ratios of 100:0, 79:21, 59:41, and 39:61. The forage consisted of chopped hay (CH), and the concentrate consisted of pelleted concentrate containing 50% ground wheat and 50% ground barley. Steers were fed the all-forage diet ad libitum during wk 1. Feed offered in wk 2 to 4 was kept constant at the ad libitum intake during wk 1. On 2 d that were set 3 d apart during wk 5, subacute ruminal acidosis (SARA) was induced in the steers by feeding a diet with an F:C ratio of 24:76 by offering them 0.9 kg of CH at 0900 h followed by 2 meals of 3.0 kg each of wheat-barley pellets (WBP) at 1100 h and 1300 h and 0.9 kg of CH at 1700 h, to depress rumen pH for at least 3 h/d below 5.6. The average concentrate inclusion for the SARA induction diet was 76 +/- 10% DM. During stepwise adaptation, time with pH below 5.6 increased to an average of 121 min/d when the steers were consuming a diet containing 61% DM as WBP. Dietary inclusion of WBP at the rate of 76% DM induced SARA because the steers spent an average of 219 min/d with pH below 5.6. The free ruminal lipopolysaccharide (LPS) concentration increased from 6,310 endotoxin units (EU)/mL with the all-forage diet to 18,197 EU/mL with the 61% concentrate diet. The ruminal LPS concentration increased to 26,915 EU/mL when SARA was induced. Serum haptoglobin increased from 0.53 mg/mL when steers were on the all-forage diet to 1.90 mg/mL with the 61% concentrate diet and were not increased further by inducing SARA. The serum amyloid-A concentration was not affected by increasing dietary concentrate during stepwise adaptation to the concentrate, but increased from 71 to 163 microg/mL when SARA was induced. A gradual increase in dietary concentrate so that the F:C ratio decreased to 39:61 resulted in increased ruminal LPS concentrations. Subsequent induction of SARA further increased ruminal LPS and activated an inflammatory response.
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
authors.forename: G N
authors.initials: GN
authors.lastname: Gozho
authors.forename: D O
authors.initials: DO
authors.lastname: Krause
authors.forename: J C
authors.initials: JC
authors.lastname: Plaizier
mesh_terms: D000138:Acidosis / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D000222:Adaptation, Physiological; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000503:physiopathology*; D004032:Diet / Q000662:veterinary*; D004435:Eating / Q000502:physiology; D004755:Enterobacteriaceae / Q000302:isolation & purification; D006242:Haptoglobins / Q000032:analysis; D001467:Hordeum / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000032:analysis*; D008297:Male; D012417:Rumen / Q000737:chemistry*; D000685:Serum Amyloid A Protein / Q000032:analysis; D013997:Time Factors; D014908:Triticum / Q000378:metabolism
chemical_list: D006242:Haptoglobins; D008070:Lipopolysaccharides; D000685:Serum Amyloid A Protein