EFFECTS OF CANOLA OIL-BASED HIGH-FAT DIETS ON GROWTH, FAT DEPOSITION AND SERUM TRIGLYCERIDE AND CHOLESTEROL LEVELS IN LINES OF MICE SELECTED FOR HIGH AND LOW-FAT PERCENTAGE
Ls. Benyon et al., EFFECTS OF CANOLA OIL-BASED HIGH-FAT DIETS ON GROWTH, FAT DEPOSITION AND SERUM TRIGLYCERIDE AND CHOLESTEROL LEVELS IN LINES OF MICE SELECTED FOR HIGH AND LOW-FAT PERCENTAGE, Brazilian journal of genetics, 20(2), 1997, pp. 203-213
This study was conducted to determine if there are biologically import
ant interactions of: genotypes of mice, differing in polygenically con
trolled body fat percentage, with levels of dietary fat from Canola oi
l which is rich in monounsaturated fat and low in saturated fat. Four
levels of fat (12.5, 25, 37.5 and 50% of dietary energy) were provided
nd libitum from four to seven, or four to 10 weeks of age to three li
nes of mice (HF, high body fat content; LF, low body fat content, and
RC, random control with intermediate fat content). The lines were deve
loped by directional selection for epididymal fat pad weight as a perc
entage of body weight (EFP%) which is highly correlated with body fat
percentage. The HF line exceeded (P < 0.05) LF in weight gain, feed in
take, feed efficiency, body weight, EFP% and serum cholesterol and tri
glyceride levels. Body water percentage, a measure of lean tissue perc
entage, and liver weight as a percentage of body weight were greater:(
P < 0.05) in the LF line compared to HF. The 50% fat diet resulted in
a reduction (P < 0.05) in energy intake, suggesting low palatability.
Mice consuming 12.5, 25 and 37.5% fat did not differ in growth rate (P
> 0.05), but feed efficiency at 25 and 37.5% was greater (P < 0.05) t
han at 12.5% since feed intake on a weight basis was reduced. There we
re no important biological effects of diet on EFP% or serum cholestero
l level. At seven weeks of age serum triglyceride levels increased as
dietary fat increased from 12.5 to 37.5% fat, but no clear trend was a
pparent. However, the LF line displayed a resistance to change in trig
lyceride levels as fat level increased. In general, while statisticall
y significant genotype by dietary level interactions were detected for
some traits, there were no biologically important interactions since
the ranking of lines was not affected when compared across different l
evels of fat. The effects of dietary monounsaturated fat levels were g
enerally smaller than the genetic line differences established by sele
ction for high and low body fat percentage.