Adaptations of the raccoon dog (Nyctereutes procyonoides) to wintering--effects of restricted feeding or periodic fasting on lipids, sex steroids and reproduction.
The raccoon dog (Nyctereutes procyonoides) is an omnivorous canid with autumnal hyperphagia and fattening followed by mid-winter passivity and fasting in boreal latitudes with seasonal snow cover. The effects of two different feeding levels (400 or 200 kcal/animal/d) or fasting (5-week fasting+1-week feeding+3-week fasting) on plasma lipids, sex steroids and reproductive success of farm-bred raccoon dogs (n=60 females and 24 males) were studied in winter. The body masses, body mass indices (BMIs) and levels of plasma triacylglycerols (TG), total cholesterol and low- and high-density lipoprotein cholesterol did not differ between the fed and the restrictively fed animals. During fasting, the plasma TG concentrations increased and the BMIs decreased, indicating the release of fatty acids from adipose tissue. After the fasting periods, the levels of plasma cholesterol and high-density lipoprotein cholesterol increased, whereas the TG levels decreased indicating the rebuilding of energy reserves. The fact that the different wintertime feeding regimes had no impact on the plasma glucose, total protein, cortisol, estradiol, progesterone or testosterone levels, or on the reproductive success, indicates versatile adaptive capacity in the species.
Asikainen
Juha
J
Department of Biology, University of Joensuu, Joensuu, Finland. juha.asikainen@joensuu.fi
Mustonen
Anne-Mari
AM
Pyykönen
Teija
T
Hänninen
Sari
S
Mononen
Jaakko
J
Nieminen
Petteri
P
D000222:Adaptation, Physiological / Q000502:physiology*; D000273:Adipose Tissue; D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D001835:Body Weight; D003404:Creatinine / Q000097:blood; D004734:Energy Metabolism; D004958:Estradiol / Q000097:blood; D005215:Fasting / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D008055:Lipids / Q000097:blood*; D008297:Male; D011374:Progesterone / Q000097:blood; D046031:Raccoon Dogs / Q000502:physiology*; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D013256:Steroids / Q000097:blood*; D013739:Testosterone / Q000097:blood; D013997:Time Factors
D001798:Blood Proteins; D008055:Lipids; D013256:Steroids; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D003404:Creatinine