title: D-lactate production and excretion in diarrheic calves.
abstract: The origin of D-lactate, the most important acid contributing to metabolic acidosis in the diarrheic calf, is unknown. We hypothesized that because D-lactate is produced only by microbes, gastrointestinal fermentation is the source. The objective of this study was to determine whether D-lactate production occurs in the rumen, colon, or both, and to measure D- and L-lactate concentrations in urine. Fecal, rumen, blood, and urine samples were obtained from 16 diarrheic and 11 healthy calves. Serum electrolyte concentrations were measured in both groups, and blood gas analyses were performed for diarrheic calves. All samples were analyzed for D- and L-lactate by high performance liquid chromatography (HPLC). Diarrheic calves were generally hyperkalemic with high serum anion gap, depressed serum bicarbonate, and low blood pH. L-lactate was markedly higher in rumen contents (22.7 mmol/ L [median]) and feces (8.6 mmol/L) of diarrheic calves than healthy calves (0.5 mmol/L and 5.1 mmol/L, respectively), but not different in serum or urine. Rumen, fecal, serum, and urine D-lactate concentrations were all significantly higher (P < .05) in diarrheic calves (17.0, 25.4, 13.9, and 19.2 mmol/L, respectively) than in healthy calves (0.5, 9.1, 1.4, and 0.5 mmol/L, respectively). Higher D-lactate concentrations in the rumen and feces of diarrheic calves suggests these sites as the source of D-lactate in blood and urine.
authors.affiliation: College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Julia B
authors.initials: JB
authors.lastname: Ewaschuk
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Naylor
authors.forename: Randi
authors.initials: R
authors.lastname: Palmer
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Whiting
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Zello
mesh_terms: D019342:Acetic Acid / Q000097:blood / Q000652:urine; D000136:Acid-Base Equilibrium / Q000502:physiology; D000140:Acidosis, Lactic / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D001639:Bicarbonates / Q000097:blood; D001784:Blood Gas Analysis / Q000662:veterinary; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D003967:Diarrhea / Q000378:metabolism / Q000662:veterinary*; D004573:Electrolytes / Q000097:blood; D005243:Feces / Q000737:chemistry; D006947:Hyperkalemia / Q000097:blood / Q000503:physiopathology / Q000662:veterinary; D019344:Lactic Acid / Q000378:metabolism*; D019289:Pyruvic Acid / Q000097:blood / Q000652:urine; D012417:Rumen / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D004573:Electrolytes; D019344:Lactic Acid; D019289:Pyruvic Acid; D019342:Acetic Acid