Changes in fatty acid profiles in different lipid classes during late development of turkey embryos from two genetic lines. 
Fatty acid (FA) profiles in embryonic yolk sacs (YS) and livers were studied in embryos from a randombred turkey line (RBC2) and a line selected for body weight at 16 wk (F line).  There were no differences in FA profiles of fresh yolk lipids.  During the course of incubation, oleic acid (C18:1) was higher and linoleic acid (C18:2) was lower in YS triglyceride (TG) and phospholipid (PL) subclasses in F line compared with RBC2 embryos.  In both lines, the C18:1 content of YS cholesteryl esters (CE) increased from 58 to 63% during the last 6 d of incubation.  From 22 to 28 d of incubation, there was a constant C18:1 concentration in hepatic CE, which was > 60% of total hepatic CE FA.  As incubation proceeded, palmitic acid (C16:0) and C18:1 in hepatic TG decreased from 27 to 16% and 37 to 34%, respectively.  The stearic acid (C18:0) in TG increased from 12% at Day 22 to 32% of total FA at hatch (Day 28) in RBC2 embryos compared with a lesser increase in the F line (11.8 to 18.6%).  In hepatic PL, arachidonic acid (C20:4) decreased, whereas both C16:0 and C18:0 increased from 22 to 28 d of incubation.  During this same time period, there was an overall decline in docosahexaenoic acid (C22:6) only in the RBC2.  On Days 26 and 28, F line embryos had greater concentrations of C22:6 and C20:4 in hepatic PL than did RBC2.  These results suggest that selection for increased BW has changed the proportional incorporation of different FA into embryonic lipids.