FERRETS (MUSTELA-PUTOIUS-FURO) INEFFICIENTLY CONVERT BETA-CAROTENE TOVITAMIN-A

The ferret has recently been used as a model to evaluate the absorptio n and metabolism of several carotenoids; however, little is known abou t the vitamin A (V/A) requirements of this species or the ability of f errets to convert dietary beta-carotene beta C) to VA, Three studies w ere conducted to estimate the daily utilization of VA in ferrets and t o determine the effect of prior VA status on the ability of ferrets to utilize beta C as a source of VA. Weanling male ferrets were fed a pe lleted, low carotenoid, semipurified diet either with (+VA) or without VA (-VA) for 21- to 35-d prefeeding periods, Upon initiation of the e xperiments, several ferrets were killed to determine base-line VA stat us. The remaining ferrets were fed VA, beta C, or VA and beta C in pel leted feed (Studies 1-3) or liquid carrier (Study 3) for 16-21 additio nal days. Hepatic: VA and beta C concentrations were used as the prima ry indicators of VA status, although serum and adrenal VA and beta C a lso were measured. The results showed the following: 1) provision of b eta C at up to a 15:1 weight ratio of beta C to VA in pelleted feed or liquid carrier was not sufficient to maintain hepatic VA stores after a -VA prefeeding period; 2) the daily utilization rate of VA by ferre ts ranged from 80 to 171 mu g in the three studies; 3) the ferret was confirmed to be a species that has the majority of its serum VA in est er form; and 4) feeding -VA diets significantly reduced serum retinyl esters but had less effect on serum retinol. We conclude that although ferrets can convert beta C to VA, the process is inefficient, The fer ret model can be most appropriately used when studying the biological effect of tissue PC stores on VA status and is less appropriate for th e evaluation of dietary beta C conversion to VA.