Evaluation of the pre-ruminant calf as a model for the study of beta-carotene metabolism in the human
Poor, Christopher Lee
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Permalink
https://hdl.handle.net/2142/20386
Description
Title
Evaluation of the pre-ruminant calf as a model for the study of beta-carotene metabolism in the human
Author(s)
Poor, Christopher Lee
Issue Date
1994
Doctoral Committee Chair(s)
Fahey, George C.
Department of Study
Nutritional Sciences
Discipline
Nutritional Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Culture and Nutrition
Health Sciences, Nutrition
Language
eng
Abstract
This manuscript chronicles the evaluation and development of the preruminant calf as a model for the study of the absorption, transport and metabolism of $\beta$-carotene in the human. The pattern of serum appearance and disappearance of $\beta$-carotene following oral dosing was favorably compared to humans, and kinetic analysis of serum curves resulted in a serum elimination constant (0.006/h) which was identical to that reported from a study of human infants. Tissue distribution of a recently-absorbed dose of $\beta$-carotene also compared well to reports from human tissues, with adrenal and liver tissues containing the highest concentrations. Concentrations in kidney, lung, spleen and adipose tissues were also significantly elevated after a dose of $\beta$-carotene. The preruminant calf has shown the ability to absorb $\beta$-carotene from both purified and vegetable sources. Conversion of $\beta$-carotene to vitamin A in vivo also was demonstrated using radiolabeled $\beta$-carotene, and radiolabeled retinol and retinyl esters were recovered from liver, adrenal and intestinal tissues. Radiolabeled intermediates in the conversion of $\beta$-carotene to vitamin A were not detected.
This work has demonstrated the appropriateness of the preruminant calf model. The usefulness of the model for a given study must be determined after careful consideration of the strengths and weaknesses of the model. The hindrance of the calf's relatively great size, special needs for housing, handling and slaughter facilities and high expense must be balanced against the unique value of an animal which can easily provide multiple blood samples, will readily consume unusual foods and is large, docile and hardy enough to undergo various surgical procedures.
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