Preference for Safflower Oil in Rats Exposed to a Cold Environment under Free-Feeding Conditions

Abstract

ABSTRACT. There are several benefits to a high-fat diet for animals exposed to cold, including improved tolerance to severe cold conditions and increased survival rates in cold environments. It is therefore of interest to examine whether animals exposed to cold will selectively consume lipids. We examined the intake of safflower oil (SO) by rats exposed to cold (4 ± 2°C) under a feeding condition in which the rats were given free access to SO. Rats exposed to cold consumed more SO than those housed at 25 ± 2°C. This finding suggests that rats prefer SO in a cold environment. There was no significant difference in the ratio of calories of SO ingested to that of matter (standard laboratory chow plus SO) ingested between rats exposed to cold and those at 25 ± 2°C. The high SO intake also affected cold tolerance and metabolite kinetics in the rats. Factors that affected the SO intake of rats exposed to cold are also discussed. KEY WORDS: cold exposure, cold tolerance, interscapular adipose tissue, rats, safflower oil.J. Vet. Med. Sci. 67 (7): [653][654][655][656][657][658] 2005 There are several benefits to a high-fat diet for animals exposed to cold, including improved tolerance to severe cold conditions and increased survival rates in cold environments [5,15,18]. Previous studies have examined diets that included a higher portion of lipid than standard diets. Thus, animals were forced to eat a high-fat diet to satisfy their energy needs and to obtain essential nutrients. However, whether animals prefer lipids in a cold environment has not been studied. It is therefore of interest to examine whether animals exposed to cold will selectively consume lipids. Safflower oil (SO) has often been used as a lipid in experiments related to diet [8, 20-22, 26, 27]. Thus, in the present study we examined the SO intake of rats exposed to cold (4 ± 2°C) under a free-feeding condition in which both SO and a standard laboratory chow were available ad libitum. We also measured rectal temperature upon acute cold exposure (ACE: -20°C in a cold room, 60 min) to evaluate the effect of ingestion of SO on cold tolerance of rats compared with rats not given SO [15]. Changes in the blood levels of glucose, nonesterified fatty acids (NEFA), and β-hydroxybutyrate caused by ACE were also measured to evaluate changes in the use of these substances by cold exposure [15]. The interscapular brown adipose tissue (IBAT) was weighed to assess its generation of heat [10,15]. MATERIALS AND METHODSMale Slc: Wistar rats 9 week of age (Japan SLC, Shizuoka, Japan) were divided into 4 groups with 2 rats per cage (Fig. 1). Two groups were housed at room temperature (25 ± 2°C) for 4 week and then exposed to cold (4 ± 2°C, using a cold room) for the following 3 week period. The 1st group served as controls exposed to the cold environment (CECNT), and the 2nd group had access to SO (CESO). The other 2 groups were fed at room temperature for 7 week.One group served as controls housed at room temperature (RTCNT), and the other group had access to SO (RTSO). A...

Preferential Fat Intake of Pups Nursed by Dams Fed Low Fat Diet during Pregnancy and Lactation Is Higher than That of Pups Nursed by Dams Fed Control Diet and High Fat Diet

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“…The large variations that exist in food choice, especially for fat preference, can be linked to animal strain, age, environment, genetic background, parental nutrition, feeding history and modifications of energy expenditure such as food deprivation and exercise (14)(15)(16)(17)(18). We are particularly interested in examining whether dams' dietary fat types during pregnancy and lactation influence the preferential fat intake of their pups after weaning.…”

Exposure to Dams' Low-Fat High-Carbohydrate Diet during Pregnancy and Lactation Establishes a Preference for Fat by Their Offspring

“…The large variations that exist in food choice, especially for fat preference, can be linked to animal strain, age, environment, genetic background or prenatal nutrition, feeding history and modifications of energy expenditure such as exercise and food deprivation (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). We were particularly interested in examining whether dams' dietary fat types during pregnancy and lactation influence the preferential fat intake of their pups after weaning.…”