CHANGES IN FATTY-ACID PROFILES IN DIFFERENT LIPID CLASSES DURING LATEDEVELOPMENT OF TURKEY EMBRYOS FROM 2 GENETIC LINES

Fatty acid (FA) profiles in embryonic yolk sacs (YS) and livers were s tudied in embryos from a randombred turkey Line (RBC2) and a line sele cted for body weight at 16 wk (F line). There were no differences in F A profiles of fresh yolk lipids. During the course of incubation, olei c acid (C-18:1) was higher and linoleic acid (C-18:2) was lower in YS triglyceride (TG) and phospholipid (PL) subclasses in F line compared with RBC2 embryos. In both lines, the C-18:1 content of YS cholesteryl esters (CE) increased from 58 to 63% during the last 6 d of incubatio n. From 22 to 28 d of incubation, there was a constant C-18:1 concentr ation in hepatic CE, which was > 60% of total hepatic CE FA. As incuba tion proceeded, palmitic acid (C-16:0) and C-18:1 in hepatic TG decrea sed from 27 to 16% and 37 to 34%, respectively. The stearic acid (C-18 :0) in TG increased from 12% at Day 22 to 32% of total FA at hatch (Da y 28) in RBC2 embryos compared with a lesser increase in the F line (1 1.8 to 18.6%). In hepatic FL, arachidonic acid (C-20:4) decreased, whe reas both C-16:0 and C-18:0 increased from 22 to 28 d of incubation. D uring this same time period, there was an overall decline in docosahex aenoic acid (C-22:6) only in the RBC2. On Days 26 and 28, F line embry os had greater concentrations of C-22:6 and C-20:4 in hepatic PL than did RBC2. These results suggest that selection for increased BW has ch anged the proportional incorporation of different FA into embryonic li pids.