Abstract
The objectives of this study were to examine the effects of Propionibacterium freudenreichii (strain T54; PB) and flaxseed oil (FO) in a total mixed ration on ruminal fermentation, CH4 production and fatty acid biohydrogenation in two artificial rumens (RUSITEC). The experiment consisted of 8 d of adaptation and 12 d of sample collection with four replicate fermenters per treatment. Treatments were: (1) CON; (2) PB; (3) FO (60 g kg(-1) DM with autoclaved PB); (4) FOPB (60 g kg(-1) DM with PB). Disappearance of DM (g kg(-1) DM) and gas production (mL g(-1) DM) were not affected by treatment (P > 0.05). Inclusion of FOPB increased (P = 0.01) total volatile fatty acid (VFA) production (mmol d(-1)), compared with CON and PB. The acetate: propionate ratio was reduced (P < 0.001) in all treatments, compared with CON. Methane production (mL g(-1) DM or mL g(-1) DMD) was lowest (P < 0.001) with PB (27.1%); however, FO (14.3%) and FOPB (19.3%) also reduced CH4 compared with CON. Fatty acid profiles for PB were similar (P > 0.05) to CON for most fatty acids. Concentrations of 18: 3n-3 were greater (P < 0.001) in FO and FOPB in both digesta and effluent, compared with CON. Propionibacterium freudenreichii had very little effect on ruminal biohydrogenation, but reduced CH4 production under the current conditions as a result of increasing propionate production.