Metabolic Responses of Lactating Dairy Cows to Single and Multiple Subcutaneous Injections of Glucagon

• Published in: Journal of dairy science 2003-06, Vol.86 (6), p.2072-2081
• Main Authors: Bobe, G, Sonon, R. N, Ametaj, B. N, Young, J. W, Beitz, D. C
• Format: Article
• Language: English
• Subjects: 3-Hydroxybutyric Acid - blood; Animal productions; Animals; Biological and medical sciences; Blood Glucose - analysis; Cattle - metabolism; Fatty Acids, Nonesterified - blood; Female; Fundamental and applied biological sciences. Psychology; Glucagon - administration & dosage; Glucagon - blood; Injections, Subcutaneous; Insulin - blood; Kinetics; Lactation; Terrestrial animal productions; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(03)73796-5

Continuous, intravenous infusions of glucagon improve carbohydrate status in lactating dairy cows without increasing concentrations of plasma NEFA. The objective was to test whether single subcutaneous injections and multiple subcutaneous injections of glucagon delivered at 8-h intervals over 14 d improve the carbohydrate status in lactating dairy cows without increasing concentrations of plasma BHBA and NEFA. In a single-injection experiment, four midlactation cows each were injected with 2.5 and 5 mg of glucagon 1 wk apart. In a multiple-injection experiment, nine cows, assigned randomly to three treatments, were injected subcutaneously with 0, 2.5, or 5 mg of glucagon every 8 h for 14 d, beginning at d 8 postpartum. Single subcutaneous injections of glucagon increased concentrations of plasma glucagon and single and multiple subcutaneous injections of glucagon increased concentrations of plasma glucose, with larger increases at the 5-mg dosage. Injections of 5 mg of glucagon increased concentrations of plasma insulin in both experiments, whereas the 2.5-mg dosage increased plasma insulin only in the multiple-injection experiment. The response of glucose and insulin to injections of 5 mg of glucagon persisted throughout the 14-d injection period. Concentrations of plasma NEFA decreased in the single-injection experiment, and concentrations of BHBA decreased after 5 mg of glucagon was injected in the multiple-injection experiment. These results document that both single and multiple injections of 5 mg of glucagon over 14 d consistently improve the carbohydrate status of dairy cows and decrease concentrations of plasma NEFA and BHBA.