title: Lipopolysaccharide derived from the rumen down-regulates stearoyl-CoA desaturase 1 expression and alters fatty acid composition in the liver of dairy cows fed a high-concentrate diet.
abstract: BACKGROUND
  Dairy cows are often fed a high-concentrate diet to meet lactating demands, yet long-term concentrate feeding induces subacute ruminal acidosis (SARA) and leads to a decrease in milk fat. Stearoyl-CoA desaturase1 (SCD1) participates in fatty acid biosynthesis in the liver of lactating ruminants. Here, we conducted this study to investigate the impact of lipopolysaccharide derived from the rumen on SCD1 expression and on fatty acid composition in the liver of dairy cows fed a high-concentrate diet. Eight multiparous mid-lactating Holstein cows (455 ± 28 kg) were randomly assigned into two groups in the experiment and were fed a low-concentrate diet (LC) or high-concentrate diet (HC) for 18 weeks.
  
  
  RESULTS
  The results showed that the total volatile fatty acids and lactic acid accumulated in the rumen, leading to a decreased rumen pH and elevated lipopolysaccharides (LPSs) in the HC group. The long chain fatty acid profile in the rumen and hepatic vein was remarkably altered in the animals fed the HC diet. The triglyceride (TG), non-esterified fatty acid (NEFA) and total cholesterol (TCH) content in the plasma was significantly decreased, whereas plasma glucose and insulin levels were increased. The expression of SCD1 in the liver was significantly down-regulated in the HC group. In regards to transcriptional regulators, the expression of sterol regulatory element binding transcription factors (SREBF1c, SREBF2) and SREBP cleavage activating protein (SCAP) was down-regulated, while peroxisome proliferator-activated receptor α (PPARα) was up-regulated.
  
  
  CONCLUSIONS
  These data indicate that lipopolysaccharide derived from the rumen down-regulates stearoyl-CoA desaturase 1 expression and alters fatty acid composition in the liver of dairy cows fed a high-concentrate diet.
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. 2012107100@njau.edu.cn.
authors: Tianle
authors: T
authors: Xu
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. taohuifromls@163.com.
authors: Hui
authors: H
authors: Tao
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. 2011207036@njau.edu.cn.
authors: Guangjun
authors: G
authors: Chang
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. zhangkai11895452@126.com.
authors: Kai
authors: K
authors: Zhang
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. 2012807136@njau.edu.cn.
authors: Lei
authors: L
authors: Xu
authors: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. xzshen@njau.edu.cn.
authors: Xiangzhen
authors: X
authors: Shen
mesh_terms: D000821:Animal Feed; D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D004032:Diet / Q000009:adverse effects / Q000662:veterinary*; D015536:Down-Regulation; D005227:Fatty Acids / Q000032:analysis*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000032:analysis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008099:Liver / Q000737:chemistry / Q000187:drug effects*; D008892:Milk / Q000737:chemistry; D012417:Rumen / Q000737:chemistry* / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis
chemical_list: D005227:Fatty Acids; D005232:Fatty Acids, Volatile; D008070:Lipopolysaccharides; D019344:Lactic Acid; D013230:Stearoyl-CoA Desaturase