Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2006
Publication Date: 4/15/2006
Citation: Baldwin, R.L., Mcleod, K., Baumann, R.G., Connor, E.E. 2006. Influence of carbohydrate infusion on lipogenic enzyme and regulatory protein gene expression in growing beef steer [abstract]. Experimental Biology Meeting. FASEB Journal 20, Abstract #LB380.
Technical Abstract: Shifting carbohydrate (CHO) digestion from the rumen to the small intestine of cattle increases in vitro rates of lipogensis and in vivo adiposity, especially in visceral adipose depots. Accordingly, 40 beef steers (243 ± 2 kg BW were used to determine the effects of site and complexity of CHO infusion on expression of genes encoding for lipogenic enzymes and regulatory proteins in subcutaneous (SC), mesenteric (MES) and omental (OM) adipose. Treatments included a forage based diet fed at 161 (LI) or 214 Kcal ME•(kg BW.75)-1•d-1, LI plus ruminal (R) or abomasal (A) infusion of starch hydrolysate (SH), and LI plus abomasal infusion of glucose (AG). Isoenergetic infusion of starch and glucose required rates of 12.6 and 14.4 g•(kg BW.75)-1•d-1, respectively. After 35 d, adipose was harvested, RNA isolated, and used for RT-PCR quantification of selected genes. Although gene expression in SC was unaffected by treatment, expression in visceral adipose was highly responsive to dietary energy intake (DME) and CHO. Greater DME increased (P<.05) expression of FAS, ACC, spot14, ChREBP, and SREBP, SREBP -1, SREBP -2, and SCAP in MES, but not OM. For MES, AG increased (P<.05) ACC, spot14, SREBP-2 and SCAP expression compare with ASH, whereas SH infusion did not alter gene expression. For OM, expression of ACC, SREBP-1 and ChREBP was greater (P<.05) for ASH vs RSH, while expression of FAS, ACC, spot14, SREBP, SREBP-2, and SCAP was greater (P<.05) for AG vs ASH. Both DME and site of digestion and complexity of CHO affect expression of lipogenic enzyme and regulatory genes of the visceral adipose depots while SC adipose is resilient to dietary manipulations.