title: Effect of forage to concentrate ratio on disappearance of vitamins A and E during in vitro ruminal fermentation.
abstract: The effects of forage to concentrate ratio and the commercial form of vitamins A and E on in vitro ruminal disappearance of retinol and alpha-tocopherol were studied. Ruminally fistulated cows were fed diets with either 80 or 50% forage. In vitro substrates that were similar to those fed to the donor cows were incubated with buffered ruminal fluid for 24 h. Different commercial forms of vitamin E (spray-dried, silicic acid adsorbate, and lipid-encased forms) and vitamin A (gelatin beadlet and lipid-encased forms) were added to the flasks. The vitamin E was all-rac-alpha-tocopheryl acetate, and the vitamin A was all-trans-retinyl acetate. The amount of alpha-tocopherol in the flasks was not affected by diet or form of vitamin E and did not change over the 24-h incubation. Retinol disappearance was not affected by form of vitamin A but was substantially higher for the 50% forage diet than for the 80% forage diet (72 vs. 20% at 24 h). These data suggest that ruminal metabolism of vitamin E is minimal and not affected by forage to concentrate ratio. Additionally, vitamin A destruction in the rumen was much higher when cows were fed a typical lactation diet than when fed a typical dry cow diet.
authors.affiliation: Department of Dairy Science, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691, USA.
authors.forename: W P
authors.initials: WP
authors.lastname: Weiss
authors.forename: K L
authors.initials: KL
authors.lastname: Smith
authors.forename: J S
authors.initials: JS
authors.lastname: Hogan
authors.forename: T E
authors.initials: TE
authors.lastname: Steiner
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004032:Diet; D005260:Female; D005285:Fermentation; D007700:Kinetics; D007774:Lactation; D008297:Male; D012417:Rumen / Q000378:metabolism*; D014801:Vitamin A / Q000008:administration & dosage / Q000378:metabolism*; D014810:Vitamin E / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D014801:Vitamin A; D014810:Vitamin E