title: Dietary beta-carotene elevates plasma steady-state and tissue concentrations of beta-carotene and enhances vitamin A balance in preruminant calves.
abstract: Preruminant calves are regarded as a model for studying beta-carotene bioavailability in humans. The objectives of this trial were to determine the relationship between multiple beta-carotene doses and plasma steady-state concentration, accumulation in selected tissues, and vitamin A balance in liver. Seventy newborn Holstein calves in six treatments (n = 10/treatment) were fed a complete milk replacer diet low in vitamin A and supplemented with beta-carotene doses of 0, 0.23, 0.46, 0.92, 1.84 or 3.68 mumol/(kg body wt.d) for 28 d. Ten calves were killed on d 1. Plasma beta-carotene increased in relation to log transformations of dose and time (P < 0.05) in all supplemented calves and steady state was attained after 4 wk. For doses up to 0.92 mumol/(kg body wt.d), the dose-response relationship was linear. A dose-dependent accumulation of beta-carotene was found for liver, heart, lungs, adrenals and adipose tissue. All-trans-beta-carotene was the only isomer in plasma and adrenals and the predominant isomer in the remaining tissues. In liver, vitamin A increased with beta-carotene uptake. Hepatic balance between vitamin A accumulation and loss was achieved at beta-carotene intake of 0.36 mumol/(kg body wt.d) for a calf of 45 kg. It is concluded that preruminant calves within 1 mo of age utilize beta-carotene as a source of vitamin A, and that for testing bioavailability of beta-carotene sources, doses up to 0.92 mumol beta-carotene/(kg body wt.d) are most appropriate.
authors.affiliation: Animal Nutrition Research Station, BASF Aktiengesellschaft, Offenbach, Germany.
authors.forename: P P
authors.initials: PP
authors.lastname: Hoppe
authors.forename: B P
authors.initials: BP
authors.lastname: Chew
authors.forename: A
authors.initials: A
authors.lastname: Safer
authors.forename: I
authors.initials: I
authors.lastname: Stegemann
authors.forename: H K
authors.initials: HK
authors.lastname: Biesalski
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000378:metabolism; D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001682:Biological Availability; D002338:Carotenoids / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000592:standards; D004305:Dose-Response Relationship, Drug; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D014801:Vitamin A / Q000378:metabolism*; D019207:beta Carotene
chemical_list: D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids