title: Ruminal biohydrogenation as affected by tannins in vitro.
abstract: The aim of the present work was to study the effects of tannins from carob (CT; Ceratonia siliqua), acacia leaves (AT; Acacia cyanophylla) and quebracho (QT; Schinopsis lorentzii) on ruminal biohydrogenation in vitro. The tannins extracted from CT, AT and QT were incubated for 12 h in glass syringes in cow buffered ruminal fluid (BRF) with hay or hay plus concentrate as a substrate. Within each feed, three concentrations of tannins were used (0.0, 0.6 and 1.0 mg/ml BRF). The branched-chain volatile fatty acids, the branched-chain fatty acids and the microbial protein concentration were reduced (P < 0.05) by tannins. In the tannin-containing fermenters, vaccenic acid was accumulated (+23 %, P < 0.01) while stearic acid was reduced ( - 16 %, P < 0.0005). The concentration of total conjugated linoleic acid (CLA) isomers in the BRF was not affected by tannins. The assay on linoleic acid isomerase (LA-I) showed that the enzyme activity (nmol CLA produced/min per mg protein) was unaffected by the inclusion of tannins in the fermenters. However, the CLA produced by LA-I (nmol/ml per min) was lower in the presence of tannins. These results suggest that tannins reduce ruminal biohydrogenation through the inhibition of the activity of ruminal micro-organisms.
authors.affiliation: Sezione di Scienze delle Produzioni Animali, University of Catania, DACPA, via Valdisavoia 5, Catania 95123, Italy. vvasta@unict.it
authors.forename: Valentina
authors.initials: V
authors.lastname: Vasta
authors.forename: Harinder P S
authors.initials: HP
authors.lastname: Makkar
authors.forename: Marcello
authors.initials: M
authors.lastname: Mele
authors.forename: Alessandro
authors.initials: A
authors.lastname: Priolo
mesh_terms: D000045:Acacia; D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004063:Digestion; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000378:metabolism; D005285:Fermentation; D005685:Galactans; D006865:Hydrogenation; D007535:Isomerases / Q000032:analysis / Q000378:metabolism; D044243:Linoleic Acids, Conjugated / Q000378:metabolism*; D008351:Mannans; D053149:Plant Gums; D006109:Poaceae; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology; D013634:Tannins / Q000494:pharmacology*
chemical_list: D005232:Fatty Acids, Volatile; D005685:Galactans; D044243:Linoleic Acids, Conjugated; D008351:Mannans; D053149:Plant Gums; D013634:Tannins; D007535:Isomerases; C017471:locust bean gum