Bile Acid Extraction Rate in the Liver of Cows Fed High-Fat Diet and Lipid Profiles in the Portal and Hepatic Veins

The purposes of this study are to assess the responses of increased supplemental dietary fat in the cow, without upsetting rumen fermentation, on the bile acid (BA) extraction rate in the liver and to determine whether this diet would affect the postprandial lipid profiles in the portal and hepatic venous blood. Six Holstein cows were equipped with catheters fitted in the portal and hepatic veins. Two cows each were assigned randomly to a sequence of three dietary treatments of 21-day period. The methodology of this study was based on the supplementation of the basal concentrate diet with 0 (control), 5, or 10% calcium salts of fatty acids (CSFA). The total bile acids were significantly increased in the portal and hepatic veins with the 5% CSFA diet, whereas no increase occurred with the 10% CSFA diet. Data obtained in this study showed that 10% CSFA diet failed to stimulate BA secretion to exceed the values obtained with 5% CSFA-diet. Moreover, there was no change in the hepatic extraction rate of BA in animals fed either the 0 or 5% CSFA diets which ranged from 2.4 to 6.5-fold and 3.1 to 7.3-fold, respectively. However, the extraction rate increased sharply with the 10% CSFA diet (27-fold). The median portal and hepatic concentrations of total lipids, triglycerides, total cholesterol, phospholipids and non-esterified fatty acids did not show any significant increase during feeding of the control diet. Moreover, feeding either the 5 or 10% CSFA diet did not significantly increase these values in either vein.