The fatty acid composition of the plasma free fatty acid and adipose
tissue triacylglycerol fractions
was determined in lean and fat selection lines of Texel-Oxford and Scottish
Blackface sheep at the 6th
year of divergent selection. The mean proportion of 18[ratio ]2n-6 in the
triacylglycerol of subcutaneous
backfat was 1·3-fold higher in the phenotypically fatter
sheep in the fat lines than in the
phenotypically leaner sheep in the lean lines. Regression analysis
indicated a positive relationship
between this fatty acid and backfat depth whereas the proportion of
18[ratio ]1n-9 in the tissue
triacylglycerol was negatively related to fatness. The proportions of
18[ratio ]2n-6 and of other
polyunsaturated fatty acids in the plasma free fatty acid fraction were
much higher than in adipose
triacylglycerol. For the Scottish Blackface sheep in the fed state, the
mean proportion of 18[ratio ]2n-6 in
plasma free fatty acid (measured on all sheep) was 1·4-fold greater
in the fat line than in the lean line.
Regression analysis indicated a positive relationship between the plasma
content of this fatty acid and
backfat thickness whereas the proportion of 18[ratio ]1n-9 in plasma free
fatty acid showed a negative
relationship with fatness. The relationship between the plasma proportion
of 18[ratio ]2n-6 and fatness was
not observed after 48 h of fasting; instead, the plasma proportion of
18[ratio ]0 was found to be positively
related to fatness in the fasted state. In summary, this paper shows
how plasma and adipose tissue
fatty acid profiles differ, and it quantifies the effects of
selection on the plasma profiles. Possible
reasons for the difference in fatty acid profiles between adipose
tissue and plasma are discussed in the
paper. It is suggested that plasma 18[ratio ]2n-6 levels during the
early post-weaning growth period should
be investigated as indicators of future fatness.
Comparison of free fatty acid composition between low-fat and full-fat goat milk cheeses stored for 3 months under refrigeration
