Preference for safflower oil in rats exposed to a cold environment under free-feeding conditions

Exposure to dams' low-fat high-carbohydrate diet during pregnancy and lactation establishes a preference for fat by their offspring

To investigate the causes why pups of dams fed a low-fat high-carbohydrate diet (LFD) showed strong preference for fat, two groups of pregnant rats were fed either the LFD or the control-diet (CTD) during pregnancy and lactation. After weaning, pups in both groups were divided into two groups. Two groups were offered a self-selection regimen of either a carbohydrate-protein diet (CPD) or a fat-protein diet (FPD) (the LFD-CF and the CTD-CF groups) and the remaining groups were fed the same diet as their dams (the LFD and the CTD groups) for 5 wk. Although the body weight of pups fed the LFD was lower than that of pups fed the CTD, the body weight of the LFD-CF group caught up with that of the CTD group. The ratio of FPD intake [FPD intake (g)/total intake (g)] by the LFD-CF group was higher than that of the CTD-CF group. In both dams and their pups, although no significant difference in the plasma glucose concentration was observed between the LFD and the CTD groups, the plasma insulin and triacylglycerol (TG) concentrations of the LFD group were higher than those of the CTD group. However, the self-selection diet appeared to prevent an increase in the plasma insulin and TG concentrations. Therefore, it was supposed that although pups of dams fed the LFD showed strong preference for fat in order to achieve optimal growth, the dietary selection pattern after weaning was associated with the depletion in plasma insulin.

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

To investigate the effect of dams' dietary fat type during pregnancy and lactation on fat choice of pups, three groups of dams were fed one of three diets: a low fat diet (LFD), a control diet (CTD) or a high fat diet (HFD). After weaning their pups were offered a self-selection regimen of both a fat protein diet (FPD) and a carbohydrate protein diet (CPD) for 3 wk. Although the ratio of FPD intake [FPD intake (g)/total intake (g)] by pups nursed by dams fed LFD during the self-selection period was higher than that by pups nursed by dams fed CTD and HFD, no significant difference in the ratio was observed between pups nursed by dams fed CTD and HFD. It was considered that pups nursed by dams fed CTD and HFD self-selected FPD and CPD in an adequate fat energy ratio (F ratio) compared to that of AIN-93G and AIN-93M. The ratio of FPD intake by pups of these three groups was 16-21% within the first week after weaning. Although pups nursed by dams fed CTD continued to consume the same ratio of FPD during the self-selection period, the ratio of pups nursed by dams fed LFD increased and that of pups nursed by dams fed HFD decreased. These findings indicate that: [1] pups nursed by dams fed CTD and HFD have the ability to consume FPD and CPD in an adequate F ratio, and [2] preferential fat intake of pups nursed by dams fed LFD is stronger than that of pups nursed by dams fed CTD and HFD.