title: Effects of monensin and stage of lactation on variation of blood metabolites within twenty-four hours in dairy cows.
abstract: Effects of prepartum administration of a monensin controlled release capsule (CRC) and stage of lactation on variation of blood metabolites within 24 h were determined in 16 dairy cows. Cows were fed a total mixed ration ad libitum twice daily at 0700 and 1300 h. At calving, cows were switched from a close-up dry cow diet to a lactating cow diet. Cows were blood sampled every 3 h for 24 h at 3 stages of lactation, including 1 wk before calving (wk -1), 1 wk after calving (wk 1), and 6 wk after calving (wk 6). Serum concentrations of glucose, beta-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and urea exhibited significant variation within 24 h. Glucose and NEFA were, respectively, 0.09 and 0.08 mM lower between 1030 and 2230 h than between 2230 and 1030 h. beta-Hydroxybutyrate and urea were, respectively, 95.1 and 0.49 mM higher between 1030 and 2230 h than between 2230 and 1030 h. Monensin did not significantly affect glucose, NEFA, and urea in this study. Monensin reduced BHBA at wk 1, but not at wk -1 or wk 6. Glucose was lower and BHBA and NEFA were higher at wk 1 compared with wk -1 and wk 6. Urea was higher at wk 6 compared with wk -1. The variation within 24 h of glucose, BHBA, and NEFA were not affected by monensin and stage of lactation. Diurnal variation of urea was affected by stage of lactation, but not by monensin.
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, R3T 2N2, Canada. plaizier@ms.umanitoba.ca
authors.forename: J C
authors.initials: JC
authors.lastname: Plaizier
authors.forename: A M
authors.initials: AM
authors.lastname: Fairfield
authors.forename: P A
authors.initials: PA
authors.lastname: Azevedo
authors.forename: A
authors.initials: A
authors.lastname: Nikkhah
authors.forename: T F
authors.initials: TF
authors.lastname: Duffield
authors.forename: G H
authors.initials: GH
authors.lastname: Crow
authors.forename: R
authors.initials: R
authors.lastname: Bagg
authors.forename: P
authors.initials: P
authors.lastname: Dick
authors.forename: B W
authors.initials: BW
authors.lastname: McBride
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002170:Canada; D002417:Cattle / Q000097:blood*; D002940:Circadian Rhythm / Q000187:drug effects*; D003692:Delayed-Action Preparations; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005285:Fermentation / Q000187:drug effects; D007662:Ketosis / Q000517:prevention & control / Q000662:veterinary; D007774:Lactation / Q000502:physiology*; D008985:Monensin / Q000008:administration & dosage* / Q000009:adverse effects*; D010919:Placebos; D049590:Postpartum Period; D011247:Pregnancy; D012417:Rumen / Q000378:metabolism; D014508:Urea / Q000097:blood
chemical_list: D001786:Blood Glucose; D003692:Delayed-Action Preparations; D005230:Fatty Acids, Nonesterified; D010919:Placebos; D014508:Urea; D008985:Monensin; D020155:3-Hydroxybutyric Acid