Effect of Different Fatty Acid Profiles in the Maternal and Finishing Diet on Liver Fatty Acid Profile and Gene Expression

The objective of this study was to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation to ewes during late gestation on finishing lamb liver tissue (LT) fatty acid (FA) profile and gene expression. Lambs born from ewes supplemented with Ca salts of the PUFA EPA and DHA, or palm FA distillate (PFAD) high in palmitic and oleic acid at 0.39% DM during the last 50 d of gestation were used. Lambs were weaned at 60 d of age and adapted to a high concentrate diet for 1.5 mo. After adaptation, 74 Hampshire x Dorset cross lambs (28 pens) were blocked by initial BW when the finishing period started and used in a 2x2 factorial arrangement of treatments using the factors of dam diet and lamb diets containing PUFA or PFAD at 1.5% DM. Lambs were slaughtered after 42 d of supplementation and LT samples were obtained for FA analysis and gene expression analysis of 27 genes. A lamb x dam treatment interaction (P=0.01) was observed for the omega-6:omega-3 FA ratio; lambs that were supplemented with PUFA and born from PFAD ewes had the lowest ratio, and lambs born from PFAD ewes and supplemented with PFAD during the finishing period had the highest ratio. Concentrations of EPA and DHA in lamb liver were significantly greater (P<0.001) with PUFA supplementation vs. PFAD supplementation during the finishing period, but there was no effect of dam diet (P>0.10). Only one significant dam effect was observed for cis-9 C18:1 (P=0.05), where concentrations were greater in lambs from PFAD ewes. There were no lamb x dam treatment interactions observed for the 27 genes measured (P>0.10). A significant dam effect was observed for hormone sensitive lipase (P=0.02), where mRNA expression was greater in lambs from PUFA supplemented ewes. Significant lamb treatment effects were observed for stearoyl-CoA desaturase (P<0.001), fatty acid synthase (P<0.001), Δ⁵-desaturase (P<0.001) and Δ⁶-desaturase (P<0.001), where mRNA expression was decreased with PUFA compared to PFAD supplementation during the finishing period. Expression of lipoprotein lipase (P = 0.01) was decreased in PUFA vs. PFAD lambs. These changes in mRNA expression suggest that lipogenesis may be decreased and lipolysis increased in lamb LT with PUFA vs. PFAD supplementation during the finishing period. These results suggest that little interaction exists between FA supplementation of dams during late gestation and supplementation of FA to lambs during the finishing period on liver FA and gene expression.