title: Metabolic responses of dairy cows and heifers to various intravenous dosages of glucagon.
abstract: To evaluate the ability of glucagon to improve carbohydrate status in dairy cows without an increase in blood lipids, glucagon was infused intravenously for 48 h into lactating cows and spayed heifers in three crossover experiments. During Experiment 1, glucagon (5 and 20 mg/d) was infused into four midlactation cows. Experiment 2 involved the infusion of 0, 2.5, 5.0, or 10 mg/d of glucagon into eight heifers; each heifer received two of the dosages. In Experiment 3, four early lactation cows were treated with 5 and 10 mg/d of glucagon. Glucagon consistently increased plasma glucose concentrations in a dose-dependent fashion throughout the 48-h periods. Plasma insulin was increased in a nondose-dependent manner by glucagon in Experiment 1. Plasma urea N was increased when glucagon was administered at 5 mg/d during Experiment 2 and tended to be decreased during Experiment 3. Nonesterified fatty acids in plasma were, in most cases, not affected; however, they were increased by glucagon at 10 mg/d during Experiment 2. Concentrations of beta-hydroxybutyrate were increased only by the 20-mg/d dosage. During Experiment 1, liver glycogen concentrations decreased by 2.1% (wet weight basis) for both dosages of glucagon, and concentrations of total lipid in the liver were increased by 0.6% (wet weight basis) by 20 mg/d of glucagon. Milk fat percentage was increased by glucagon, but milk volume and milk protein production were decreased during Experiment 1. Glucagon improved carbohydrate status over the 48-h periods in all experiments but did not increase plasma nonesterified fatty acids except at the 10-mg/d dosage in Experiment 2.
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011-3150, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Hippen
authors.forename: P
authors.initials: P
authors.lastname: She
authors.forename: J W
authors.initials: JW
authors.lastname: Young
authors.forename: D C
authors.initials: DC
authors.lastname: Beitz
authors.forename: G L
authors.initials: GL
authors.lastname: Lindberg
authors.forename: L F
authors.initials: LF
authors.lastname: Richardson
authors.forename: R W
authors.initials: RW
authors.lastname: Tucker
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001806:Blood Urea Nitrogen; D002417:Cattle / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000008:administration & dosage*; D006003:Glycogen / Q000378:metabolism; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D007774:Lactation; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008894:Milk Proteins; D006003:Glycogen; D005934:Glucagon; D020155:3-Hydroxybutyric Acid