Evaluation of the Preruminant Calf as a Model for the Study of Human Carotenoid Metabolism ,

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Abstract
This study evaluated the preruminant calf as an animal model for the study of human carotenoid metabolism. Fifteen newborn male Holstein calves were fed a carotenoid-free milk replacer diet to maintain them in the preruminant state. After a 7-d adjustment period, three calves were killed and 12 calves received a single oral dose (20 mg) of β-carotene in the form of water-soluble beadlets. Blood samples were collected periodically and samples of various tissues were collected when the calves were killed. Three animals each were killed by exsanguination at 1, 3, 6 and 11 d post-dosing. Serum β-carotene concentrations peaked between 12 and 30 h post-dosing and declined slowly afterwards. Serum data were fitted to a two-compartment model and yielded an elimination constant (k2) that was similar to reported human values. Adrenal tissue showed significant concentrations of β-carotene by 24 h post-dosing, and levels were still elevated at 264 h. Liver, spleen and lung β-carotene concentrations were significantly elevated by 24 h and rapidly declined thereafter. Adipose and kidney peak β-carotene concentrations were observed at 72 and 144 h, respectively. Heart and muscle did not display significant changes in β-carotene concentrations. The preruminant calf shows promise as an animal model for the study of absorption and metabolism of carotenoids by humans.