title: Dry period plane of energy: Effects on glucose tolerance in transition dairy cows.
abstract: Overfeeding energy in the dry period can affect glucose metabolism and the energy balance of transition dairy cows with potential detrimental effects on the ability to successfully adapt to early lactation. The objectives of this study were to investigate the effect of different dry cow feeding strategies on glucose tolerance and on resting concentrations of blood glucose, glucagon, insulin, nonesterified fatty acids (NEFA), and β-hydroxybutyrate (BHB) in the peripartum period. Cows entering second or greater lactation were enrolled at dry-off (57 d before expected parturition) into 1 of 3 treatment groups following a randomized block design: cows that received a total mixed ration (TMR) formulated to meet but not exceed energy requirements during the dry period (n=28, controlled energy); cows that received a TMR supplying approximately 150% of energy requirements during the dry period (n=28, high energy); and cows that were fed the same diet as the controlled energy group for the first 28 d, after which the TMR was formulated to supply approximately 125% of energy requirements until calving (n=28, intermediate energy). Intravenous glucose tolerance tests (IVGTT) with rapid administration of 0.25 g of glucose/kg of body weight were performed 28 and 10d before expected parturition, as well as at 4 and 21 d after calving. Area under the curve for insulin and glucose, maximal concentration and time to half-maximal concentration of insulin and glucose, and clearance rates were calculated. Insulin resistance (IR) indices were calculated from baseline samples obtained during IVGTT and Spearman rank correlations determined between IVGTT parameters and IR indices. Treatment did not affect IVGTT parameters at any of the 4 time points. Correlation between IR indices and IVGTT parameters was generally poor. Overfeeding cows energy in excess of predicted requirements by approximately 50% during the entire dry period resulted in decreased postpartum basal plasma glucose and insulin, as well as increased glucagon, BHB, and NEFA concentrations after calving compared with cows fed a controlled energy diet during the dry period. In conclusion, overfeeding energy during the entire dry period or close-up period alone did not affect glucose tolerance as assessed by IVGTT but energy uptake during the dry period was associated with changes in peripartal resting concentrations of glucose, as well as postpartum insulin, glucagon, NEFA, and BHB concentrations.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY 14853.
authors.forename: S
authors.initials: S
authors.lastname: Mann
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, NY 14853.
authors.forename: F A
authors.initials: FA
authors.lastname: Leal Yepes
authors.affiliation: Département des sciences animales, Université Laval, Québec, G1V 0A6, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Duplessis
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: J J
authors.initials: JJ
authors.lastname: Wakshlag
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, NY 14853.
authors.forename: T R
authors.initials: TR
authors.lastname: Overton
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: B P
authors.initials: BP
authors.lastname: Cummings
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY 14853. Electronic address: dvn2@cornell.edu.
authors.forename: D V
authors.initials: DV
authors.lastname: Nydam
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005951:Glucose Tolerance Test / Q000662:veterinary*; D007328:Insulin / Q000097:blood; D007774:Lactation; D009751:Nutritional Requirements; D036801:Parturition; D058725:Peripartum Period / Q000097:blood
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005934:Glucagon; D020155:3-Hydroxybutyric Acid
keywords: dairy cow; energy; glucose; insulin; transition period