Effects of short- or long-term infusions of acetate or propionate on luteinizing hormone, insulin, and metabolite concentrations in beef heifers.
Two trials were conducted to evaluate the effects of short- (Trial 1) or long-term (Trial 2) intraruminal isocaloric infusions of acetate or propionate on secretion of LH, insulin, and selected metabolites in short- or long-term energy-restricted beef heifers. In Trial 1, 16 Angus heifers were assigned on d 6 to 12 of a synchronized estrous cycle (estrus = d 0) to a body weight-maintenance (BWM; n = 4) or an energy-restricted, body weight-loss (BWL; n = 12) treatment. On d 12 of a synchronized estrous cycle, heifers received PGF2alpha to synchronize estrus, and 12 h later BWL heifers received intraruminal, isocaloric infusions of acetate, propionate, or vehicle for 6 h and BWM heifers received vehicle concurrently. Mean plasma LH and LH pulse frequencies and amplitudes were not affected by treatment (P > .05). In contrast, infusion of propionate increased plasma insulin (P < .05) and reduced plasma concentration of NEFA (P < .05). In Trial 2, six ovariectomized Angus heifers were energy-restricted for 30 d. On d 14 and 26 of restriction, heifers began receiving intraruminal isocaloric infusions of acetate or propionate for 96 h in a switchback approach. Intraruminal infusions of vehicle for 6 h preceded infusions of acetate or propionate. Jugular blood was collected at 12-min intervals during infusions of vehicle and during the last 6 h of infusion of acetate or propionate. Mean concentration of LH and amplitude of pulses of LH were lower during acetate vs propionate or vehicle infusion (P < .05). Infusion of propionate increased insulin relative to acetate or vehicle infusion (P < .05). Plasma NEFA were reduced by infusion of propionate (P < .05) and increased by infusion of acetate (P < .05).
DiCostanzo
A
A
Department of Animal Science, University of Minnesota, St. Paul 55108, USA. dicos001@tc.umn.edu
Williams
J E
JE
Keisler
D H
DH
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000085:Acetates / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001806:Blood Urea Nitrogen; D002417:Cattle / Q000097:blood*; D004734:Energy Metabolism; D004971:Estrus; D005260:Female; D007328:Insulin / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D006109:Poaceae; D011422:Propionates / Q000008:administration & dosage / Q000494:pharmacology*; D011863:Radioimmunoassay / Q000662:veterinary; D013997:Time Factors
D000085:Acetates; D001786:Blood Glucose; D007328:Insulin; D011422:Propionates; D007986:Luteinizing Hormone; D020155:3-Hydroxybutyric Acid