title: Long-term fluctuations and effect of age on serum concentrations of certain fat-soluble vitamins in dairy cows.
abstract: BACKGROUND
  There is insufficient evidence in the literature concerning the fluctuations and correlations of serum fat-soluble vitamin concentrations during lactation in dairy cows and the potential effect of age of the animals on these values.
  
  
  OBJECTIVE
  The objectives of this study were to determine fluctuations in mean serum concentrations of the fat-soluble vitamins A and E and b-carotene and the correlations among them in clinically healthy dairy cows, from the last month of the dry period until the end of lactation, and to investigate whether age was a factor that affects these serum concentrations.
  
  
  METHODS
  Forty-five clinically healthy Holstein cows were assigned to 2 groups based on age. Group A consisted of 23 cows 4 years old (mean +/- SD, 3.24 +/- 0.44 years), and group B consisted of 22 cows >4 years old (6.68 +/- 1.66 years). Blood samples for determination of serum beta-carotene, vitamin A, and vitamin E concentrations were collected from each animal just before the start of study (1 month prior to expected parturition), at parturition, and thereafter, at monthly intervals until the end of lactation.
  
  
  RESULTS
  There was a significant positive correlation between beta-carotene, vitamin A, and vitamin E values. Mean serum concentrations of beta-carotene, vitamin A, and vitamin E were significantly higher in younger animals.
  
  
  CONCLUSIONS
  To our knowledge, this is the first evidence that age is a factor affecting serum concentrations of fat-soluble vitamins in dairy cows.
authors.affiliation: Clinic of Productive Animal Medicine, School of Veterinary Medicine, Aristotle University of Thessaloniki, Greece.
authors.forename: P D
authors.initials: PD
authors.lastname: Katsoulos
authors.forename: N
authors.initials: N
authors.lastname: Roubies
authors.forename: N
authors.initials: N
authors.lastname: Panousis
authors.forename: P
authors.initials: P
authors.lastname: Karatzanos
authors.forename: H
authors.initials: H
authors.lastname: Karatzias
mesh_terms: D000375:Aging / Q000097:blood*; D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000097:blood*; D005260:Female; D007774:Lactation / Q000097:blood; D036801:Parturition / Q000097:blood; D013997:Time Factors; D014801:Vitamin A / Q000097:blood*; D014810:Vitamin E / Q000097:blood*; D019207:beta Carotene / Q000097:blood*
chemical_list: D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E