title: Associations between prebreeding serum micronutrient concentrations and pregnancy outcome in beef cows.
abstract: OBJECTIVE
  To determine associations between serum concentrations of copper, molybdenum, selenium, vitamin A, and vitamin E measured in beef cows at the start of the community pasture breeding season and pregnancy status at the end of the season.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  771 beef cows from 39 cow-calf herds.
  
  
  METHODS
  Serum micronutrient concentrations were measured in samples collected from cows on arrival at 5 different community pastures in Saskatchewan, Canada, in May 2008. Cows were palpated transrectally to determine pregnancy status in October 2008. Herd owners and professional herd managers were surveyed to collect individual data for cows (age, calving date, and history of exposure to bulls before the start of the breeding season) and information on herd and breeding management. Associations between animal-, herd-, and pasture-level variables and pregnancy status were examined.
  
  
  RESULTS
  Serum concentrations of selenium, molybdenum, vitamin A, and vitamin E were not associated with pregnancy status after accounting for prebreeding body condition score, age, and calving-to-breeding interval. Serum copper concentrations were more commonly assessed as below adequate than were other micronutrients. Decreased serum copper concentrations were associated with increased odds of nonpregnancy in cows < 10 years of age.
  
  
  CONCLUSIONS
  Prebreeding micronutrient supplementation programs should be carefully managed in herds with poor reproductive performance in areas known to be copper deficient, and evaluation of serum copper concentrations from a subset of cows should be considered before the start of the breeding season.
authors.affiliation: Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Van De Weyer
authors.forename: Steve H
authors.initials: SH
authors.lastname: Hendrick
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Waldner
mesh_terms: D000818:Animals; D002417:Cattle; D015331:Cohort Studies; D005260:Female; D018977:Micronutrients / Q000097:blood*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary*; D011270:Pregnancy, Animal
chemical_list: D018977:Micronutrients