title: Effect of ruminal glucose infusion on dry matter intake, urinary nitrogen composition, and serum metabolite and hormone profiles in Ewes.
abstract: Twelve 18-mo-old Debouillet ewes were used to determine the effect of ruminal glucose infusion on DMI, on urinary ammonium (NH4+) and urea N (UUN) concentrations, and on serum metabolite and hormone profiles. Ewes were limit-fed a 90% concentrate diet for 30 d, stratified by BW into three groups (average BW = 82.6+/-1.1 kg), and assigned randomly to receive 0, 5, or 10 g of glucose/kg of BW via esophageal intubation. Urine was collected hourly for 12 h and blood (jugular venipuncture) at 30-min intervals for 12 h. After 12 h, ewes were housed individually, allowed free access to the diet, and DMI was recorded for 5 d. Venous blood pH averaged 7.49, 7.48, and 7.48 at 0 h and decreased (linear [L], P < .01) at 12 h (7.41, 7.36, and 7.26) with increasing glucose. Serum glucose increased (L, P = .06) at 3 and 6 h. Serum L(+)-lactate increased (L, P = .08) at 3, 6, and 9 h, whereas serum D(-)-lactate increased linearly (P = .09) at 6 and 9 h and quadratically (P < .10) at 12 h. After the glucose challenge, DMI decreased (L, P < .05). Urinary pH and NH4+ were not influenced by glucose infusion; however, UUN increased at 3 (quadratic [Q], P < .05), 4, 5, 6 (L, P = .03), and 7 h (Q, P < .05) and decreased at 11 and 12 h (L, P = .09). As glucose infusion increased, serum creatinine increased at 9 (L, P < .01) and 12 h (Q, P = .02). Generally, serum Na and P increased (P = .09), whereas K decreased (P < .05), with glucose infusion. Lactate dehydrogenase activity increased with glucose infusion (Q, P < .10) at 3, 6, 9, and 12 h. Increasing glucose infusion increased serum globulin (Q, P = .06), albumin, and total protein (L, P = .08). Serum prolactin and vasopressin were not influenced (P = .22) by glucose infusion. Serum insulin and aldosterone increased quadratically (P = .08), whereas serum growth hormone decreased linearly (P = .08) as a result of increasing glucose infusion. Results suggest that UUN, serum insulin, aldosterone, and several serum constituents may serve as markers of organic acid load in ruminants fed high-concentrate diets.
authors.affiliation: Department of Animal and Range Sciences, New Mexico State University, Las Cruces 88003-0003, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Brown
authors.forename: D M
authors.initials: DM
authors.lastname: Hallford
authors.forename: M L
authors.initials: ML
authors.lastname: Galyean
authors.forename: C R
authors.initials: CR
authors.lastname: Krehbiel
authors.forename: G
authors.initials: G
authors.lastname: Duff
mesh_terms: D000140:Acidosis, Lactic / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D002149:Energy Intake / Q000187:drug effects*; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D009584:Nitrogen / Q000652:urine*; D012417:Rumen; D012756:Sheep; D012757:Sheep Diseases / Q000378:metabolism*
chemical_list: D019344:Lactic Acid; D005947:Glucose; D009584:Nitrogen