Relative Contributions of Acetate, Lactate and Glucose to Lipogenesis in Bovine Intramuscular and Subcutaneous Adipose Tissue

Abstract

Intramuscular adipose tissue from the fifth-eighth thoracic vertebrae region of the longissimus dorsi muscle, and portions of the overlying subcutaneous adipose tissue, were obtained at 16 and 18 months of age from Angus steers fed ad libitum either a corn silage (low energy) or ground corn (high energy) diet. Carcass weight, backfat thickness, and kidney, pelvic and heart fat were significantly greater in the steers fed the high energy diet; however, there were no significant differences in marbling scores between diet groups. Additionally, feeding steers the high energy diet did not result in differences in adipocyte diameter or number of adipose cells per gram tissue in either adipose tissue depot. Intramuscular adipocytes had a peak diameter (the diameter represented by the greatest number of cells) of 104 +/- 2 microns; peak diameter in subcutaneous adipose tissue was 141 +/- 5 microns. The activities of ATP-citrate lyase and NADP-malate dehydrogenase increased with age in the subcutaneous adipose tissue; feeding steers the high energy diet increased enzyme activities further. Age and diet had no effect on enzyme activities in intramuscular adipose tissue. A similar pattern was observed for the incorporation of lipogenic precursors into fatty acids. Acetate provided 70-80% of the acetyl units to in vitro lipogenesis in subcutaneous adipose tissue, but only 10-25% in intramuscular adipose tissue. Conversely, glucose provided 1-10% of the acetyl units in subcutaneous adipose tissue, but 50-75% in the intramuscular depot.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of genes involved in adipogenesis and lipid metabolism in subcutaneous adipose tissue and longissimus muscle in low-marbled Pirenaica beef cattle

“…Results in this study show greater expression of PPARG in the SC AT in most of the groups but overexpression of CEBPA and SREBF1 in the LM, which seems puzzling and could perhaps be related to some tissue-specific trait, given, for instance, the greater contribution of glucose to fatty acid biosynthesis and the higher rates of this last-mentioned process in IM adipose cells embedded in muscle fibres than in the SC fat cells (Smith and Crouse, 1984).…”

Performance and carcass characteristics of lambs fed on diets supplemented with glycerin from biodiesel production

“…This effect might have occurred due to possible changes related to the proportion of volatile fatty acids, which may possibly alter fat deposition on the carcass and possibly the meat fatty acid profile (Abo El-Nor, 2010). According to Smith & Crouse (1994), in research done with Angus bovines, the glucose originated from the propionic acid is responsible for up to 10% of the acetyl units in the subcutaneous fat tissue, and 50 to 75% of the intramuscular fat tissue. This may suggest, in the present study, that diets containing glycerin did not increase the proportion of propionate in the rumen, as Kristensen & Raun (2007).…”

Revue bibliographique : Variations quantitatives et métabolisme des lipides dans les tissus adipeux et le foie au cours du cycle gestation-lactation 2e partie : chez la brebis et la vache

“…Le métabolisme des lipides dans le foie de ruminant a été décrit par Rémésy et al (1984, 1986 Ballard, 1967Ballard et al, 1969Ballard et al, , 1972Hood et a/., 1972 ; Ingle et al, 1972a, b ;Vézinhet, 1976 ;Liepa et al, 1978 ;Prior, 1978 ;Smith et Crouse, 1984 …”