Abstract

The focus of the present study was to investigate how the different chemical and botanical composition of two different pasture types, Calafatal pasture (CP) and naturalized pasture (NP), affect gene/protein expression levels of lipogenic enzymes and transcription factors (ACC, FAS, SCD1, and SREBP-1c) as well as the concentrations of their fatty acid products in subcutaneous adipose tissue of Chilota lambs. Sixteen male Chilota lambs kept under different grazing conditions, CP versus NP, in Chiloé Archipelago (Chile) were included in the experiment. QRT-PCR, western blot and fatty acid analysis were performed of subcutaneous adipose tissue samples. Compared to NP, CP diet induced a 1.51-fold increase of ACACA expression, a 1.60-fold rise of FASN expression and a 1.56-fold elevation of SREBF1 expression. SCD gene expression did not significantly differ between both feeding groups. Different pasture types did not affect protein expression levels of lipogenic enzymes (ACC, FAS, and SCD1) and transcription factor pSREBP-1c (precursor form) and mSREBP-1c (mature form) in subcutaneous fat of lambs. Amounts of single and the sum of saturated fatty acids were significantly higher in subcutaneous fat samples of lambs fed NP than of lambs fed CP. Concentrations of single PUFA and the sum n-3 and n-6 PUFA and the n-6/n-3 PUFA ratio were not affected by different pasture types. The inclusion of different adipose tissue depots and more sampling "endpoints" during animal growth may be beneficial to comprehensively elucidate the mechanisms by which dietary PUFA intervention affects the lipid metabolism of adipose tissues in lambs.