Corn oil or corn grain supplementation to steers grazing endophyte-free tall fescue. II. Effects on subcutaneous fatty acid content and lipogenic gene expression.

摘要: Twenty-eight Angus steers (289 kg) were finished on a high-concentrate diet (85% concentrate: 15% roughage; CONC), or endophyte-free tall fescue pastures with corn grain supplement (0.52% of BW; PC), oil plus soybean hull (0.10% BW 0.45% hulls; PO), no (pasture only; PA). Subcutaneous adipose tissues processed for total cellular RNA extraction and fatty acid composition by GLC. Relative expression genes involved in lipogenesis [fatty synthase (FASN), acetyl-CoA carboxylase, lipoprotein lipase, stearoyl-CoA desaturase (SCD)] activators transcription [(peroxisome proliferator-activated receptor-gamma), C/EBPalpha, sterol regulatory binding protein-1, signal transducer activator transcription-5, Spot-14] was determined real-time quantitative PCR. Housekeeping gene (glyceraldehyde 3-phosphate dehydrogenase beta-actin) used analysis to normalize data. Total content greatest (P 0.05) between PO PA. Corn supplementation increased the cis-9, trans-11 CLA isomer compared Oil < 0.001) linoleic (C18:2) 56, 98 262% CONC, PC, PA, respectively. mRNA SCD upregulated 46-, 18- 7-fold, respectively, FASN also = 0.004) 9- 5-fold, CONC PC Grain feeding, either supplemented pasture, increase MUFA de novo acids subcutaneous tissue. Upregulation feeding reduced tissue concentrations suggest that decreased result limited substrate (trans-11 vaccenic acid) availability.