title: Evaluation of the effects of pregnancy on insulin sensitivity, insulin secretion, and glucose dynamics in Thoroughbred mares.
abstract: OBJECTIVE
  To characterize the effects of pregnancy on insulin sensitivity (SI) and glucose dynamics in pasture-maintained mares fed supplemental feeds of differing energy composition.
  
  
  METHODS
  Pregnant (n = 22) and nonpregnant (10) healthy Thoroughbred mares.
  
  
  METHODS
  Pregnant and nonpregnant mares underwent frequently sampled intravenous glucose tolerance tests at 2 times (period 1, 25 to 31 weeks of gestation; period 2, 47 weeks of gestation). Following period 1 measurements, mares were provided a high-starch (HS; 39% starch) or high-fat and -fiber (14% fat and 70% fiber) supplemental feed. From a subset of mares (n = 12), blood samples were collected hourly for 24 hours to assess glycemic and insulinemic response to feeding while pastured. The minimal model of glucose and insulin dynamics was used to estimate SI, glucose effectiveness, and acute insulin response to glucose from tolerance testing data.
  
  
  RESULTS
  Pregnant mares during period 1 had a lower SI and glucose effectiveness and higher acute insulin response to glucose than did nonpregnant mares. The SI value decreased in nonpregnant but not pregnant mares from periods 1 to 2. Pregnant mares fed HS feed had a greater glycemic and insulinemic response to feeding than did any other group.
  
  
  CONCLUSIONS
  Pregnant mares had slower glucose clearance and greater insulin secretion at 28 weeks of gestation than did nonpregnant mares. Glucose and insulin responses to meal feeding, particularly with HS feed, were greater in pregnant mares, indicating that pregnancy enhanced the postprandial glycemic and insulinemic effects of starch-rich feed supplements.
authors.affiliation: Department of Animal and Poultry Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: Lindsey A
authors.initials: LA
authors.lastname: George
authors.forename: W Burton
authors.initials: WB
authors.lastname: Staniar
authors.forename: Tania A
authors.initials: TA
authors.lastname: Cubitt
authors.forename: Kibby H
authors.initials: KH
authors.lastname: Treiber
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Harris
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Geor
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D002149:Energy Intake; D005260:Female; D005951:Glucose Tolerance Test / Q000662:veterinary; D006736:Horses / Q000097:blood / Q000502:physiology*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D010375:Pedigree; D011247:Pregnancy / Q000097:blood / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D007328:Insulin