title: Net volatile fatty acid absorption in nonlactating holstein cows.
abstract: Net absorption of volatile fatty acids was measured in four nonlactating Holstein cows fed orchardgrass-clover silage ad libitum and 50 g trace mineralized salt daily. Cows ranged in age from 2 to 4 yr and in body weight from 326 to 525 kg. Portal blood flow and volatile fatty acid concentrations of portal and arterial plasma were determined at 30-min (three cows) or 90-min (one cow) intervals for about 12 h. Mean portal blood flow was 836 liters/h. Mean volatile fatty acid concentrations of portal plasma and differences of portal-arterial concentrations were (mM): acetate 2.00, .67; propionate .264, .228; isobutyrate .022, .017; n-butyrate .057, .038; 2-methylbutyrate .017, .014; 3-methylbutyrate .007, .005; and n-valerate .012, .008. Mean net volatile fatty acid absorption was 682 mmol/h. Acetate and propionate accounted for 91% of net volatile fatty acid absorption on a molar basis and 85% on an energy basis. Net energy absorbed as volatile fatty acid was 5.43 Mcal/cow per day, which was about 35% of calculated metabolizable energy intake. Portal blood flow was maximal 1.5 h postfeeding, and net volatile fatty acid absorption was maximal 2.5 h postfeeding.
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004734:Energy Metabolism; D005232:Fatty Acids, Volatile / Q000097:blood / Q000378:metabolism*; D005260:Female; D007408:Intestinal Absorption; D011169:Portal Vein
chemical_list: D005232:Fatty Acids, Volatile