Adaptations to fasting in the American mink (Mustela vison): nitrogen metabolism.
The aim of this study was to investigate the adaptations of protein metabolism to seasonal fasting in an actively wintering boreal carnivore. Fifty farm-bred male American minks Mustela vison were divided into a fed control group and four experimental groups fasted for 2, 3, 5 or 7 days. The responses of nitrogen metabolism to wintertime food deprivation were determined by measuring the rate of weight loss, the tissue total protein concentrations and the plasma amino acid, urea, ammonia, uric acid and total protein levels. The mink has relatively poor adaptations to food deprivation, as it is not able to prolong phase II of fasting with fat as the major metabolic fuel. Instead, the species has to derive a part of its energy requirements from the breakdown of body proteins. The end product of protein catabolism--urea--accumulates in its circulation, and the mink may not be able to recycle urea-N. Although the mink can still have a high body fat percent at the end of the 7-day fast, it appears to enter phase III of fasting with stimulated proteolysis during this period.
Mustonen
Anne-Mari
AM
Department of Biology, University of Joensuu, P.O. Box 111, 80101 Joensuu, Finland. ammusto@cc.joensuu.fi
Puukka
Matti
M
Pyykönen
Teija
T
Nieminen
Petteri
P
D000222:Adaptation, Physiological; D000596:Amino Acids / Q000097:blood; D000641:Ammonia / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002852:Chromatography, Ion Exchange; D005215:Fasting / Q000378:metabolism / Q000502:physiology*; D005387:Finland; D008907:Mink / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012621:Seasons; D014508:Urea / Q000097:blood; D014527:Uric Acid / Q000097:blood
D000596:Amino Acids; D011506:Proteins; D014527:Uric Acid; D000641:Ammonia; D014508:Urea; D009584:Nitrogen