Effects of dietary roughage levels on the expression of adipogenic transcription factors in Wagyu steers.

We hypothesized that dietary roughage level would alter the expression levels of adipogenic transcription factors in adipose tissue of Japanese black (Wagyu) steers. Steers were fed whole crop rice silage at three levels: (1) high-roughage feeding group, fed 8kg silage and 5kg concentrate (HR); (2) middle roughage feeding group, fed 5kg silage and 6kg concentrate (MR); and (3) low roughage feeding group, fed 2kg silage and 7kg concentrate (LR) from 22 to 30months of age. In subcutaneous adipose tissue, there were no significant differences in the expression of the adipogenic transcription factors and adipocyte size among feeding groups. In mesenteric adipose tissue, the expression of C/EBPα in the LR and MR groups was significantly higher than that in the HR group. Adipocyte size in the mesenteric adipose tissue of the LR group was significantly larger than that of the HR group. In intermuscular adipose tissue, the expression of C/EBPβ-LAP in the LR group was significantly higher than that in the HR group, and the expression of C/EBPβ-LIP in the LR and MR groups was significantly higher than that in the HR group. Adipocyte size in the intermuscular adipose tissue of the LR and MR groups was significantly smaller than that of the HR group. These results suggest that dietary roughage revel affects the adipose tissue depot-specific differences in C/EBP family expression pattern and adipocyte cellularity in Wagyu steers.