DIETARY WHOLE COTTONSEED DEPRESSES LIPOGENESIS BUT HAS NO EFFECT ON STEAROYL COENZYME DESATURASE ACTIVITY IN BOVINE SUBCUTANEOUS ADIPOSE-TISSUE

The primary objective of this study was to determine the effect oi lon g-term feeding of whole cottonseed (WCS) on lipogenesis and stearoyl c oenzyme A desaturase activity in growing steers. Brangus steers were f ed either a control, cornbased diet (n = 11) or 30% WCS (n = 12). The 30% WCS contributed an estimated 6.6% additional lipid to the diet. St eers fed the added WCS had greater live weights (P = 0.04) and kidney, pelvic, and heart fat (P = 0.005). Subcutaneous fat thickness was not different (P = 0.20) between treatment groups, although WCS elicited an increase in the proportion of large diameter subcutaneous adipocyte s. The rate of [U-C-14]acetate incorporation into fatty acids in subcu taneous adipose tissue was reduced by dietary WCS (171.4 vs 122.1 nmol x 100 mg adipose tissue(-1) x 2 hr(-1), P = 0.03), indicating that th e increased dietary fat depressed de novo lipogenesis. Hepatic desatur ase activity was much lower than that of subcutaneous adipose tissue, a feature common to cattle. We anticipated that added WCS also would d epress stearoyl-coenzyme A desaturase activity in subcutaneous adipose tissue and liver due to its cyclopropene fatty acid content. Instead, desaturase activity was numerically (although not significantly) grea ter in liver (P = 0.37) and adipose tissue (P = 0.23). (C) 1997 Elsevi er Science Inc.