title: Lipogenesis and stearoyl-CoA desaturase gene expression and enzyme activity in adipose tissue of short- and long-fed Angus and Wagyu steers fed corn- or hay-based diets.
abstract: Angus and Wagyu steers consuming high-roughage diets exhibit large differences in adipose tissue fatty acid composition, but there are no differences in terminal measures of stearoyl-CoA desaturase (SCD) activity or gene expression. Also, adipose tissue lipids of cattle fed corn-based diets have greater MUFA:SFA ratios than cattle fed hay-based diets. We hypothesized that any changes in SCD gene expression and activity would precede similar changes in adipose tissue lipogenesis between short- and long-fed endpoints. Furthermore, changes in SCD activity and gene expression between production endpoints would differ between corn- and hay-fed steers and between Wagyu and Angus steers. Angus (n = 8) and Wagyu (n = 8) steers were fed a corn-based diet for 8 mo (short-fed; 16 mo of age) or 16 mo (long-fed; 24 mo of age), whereas another group of Angus (n = 8) and Wagyu (n = 8) steers was fed a hay-based diet for 12 mo (short-fed; 20 mo of age) or 20 mo (long-fed; 28 mo of age) to match the end point BW of the corn-fed steers. Acetate incorporation into lipids in vitro was greater (P < 0.01) in corn-fed steers than in hay-fed steers and tended (P = 0.06) to be greater in Wagyu than in Angus s.c. adipose tissue because the rate in Wagyu was twice that of Angus adipose tissue in the corn-fed, short-fed steers. There were diet x end point interactions for lipogenesis in i.m. and s.c. adipose tissues (both P < 0.01) because lipogenesis was 60 to 90% lower in the long-fed cattle than in short-fed cattle fed the corn-based diet. The greatest SCD enzyme activity in Angus s.c. adipose tissue was observed at 24 mo of age (corn-based diet), but activity in Wagyu adipose tissue was greatest at 28 mo of age (hay-based diet; breed x diet x end point interaction, P = 0.08). For short- vs. long-fed endpoints in Angus, s.c. adipose tissue SCD activity was less (hay diet) or the same (corn diet). Conversely, SCD gene expression was greatest in long-fed Wagyu steers fed the hay- or corn-based diets (breed x end point interaction; P < 0.01). Contrary to our hypotheses, SCD activity increased over time, whereas lipogenesis from acetate decreased. However, the developmental pattern of SCD gene expression and activity differed markedly between hay-fed Angus and Wagyu adipose tissues, which may explain the differences in the MUFA:SFA ratios observed in adipose tissues from these cattle.
authors.affiliation: Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.
authors.forename: K Y
authors.initials: KY
authors.lastname: Chung
authors.forename: D K
authors.initials: DK
authors.lastname: Lunt
authors.forename: H
authors.initials: H
authors.lastname: Kawachi
authors.forename: H
authors.initials: H
authors.lastname: Yano
authors.forename: S B
authors.initials: SB
authors.lastname: Smith
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle / Q000502:physiology*; D017931:DNA Primers / Q000737:chemistry; D004032:Diet / Q000662:veterinary*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D050155:Lipogenesis / Q000502:physiology*; D008297:Male; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012333:RNA, Messenger / Q000032:analysis; D013230:Stearoyl-CoA Desaturase / Q000032:analysis / Q000096:biosynthesis*; D013997:Time Factors; D003313:Zea mays / Q000378:metabolism
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D013230:Stearoyl-CoA Desaturase