Ruminant Nutrition: Gut Physiology, Fermentation, and Digestion

摘要

The study objective was to evaluate effect of 2 probiotic supplements onin vitro nutrient digestibility, methane (CH4) and volatile fatty acid (VFA)production using in vitro batch fermentation assay. Three ruminally-cannulatedcows were used in a 3 × 3 Latin Square design and fed either basalcorn silage-based TMR without probiotics (Control; CON), the basal diettop-dressed with mixture of Lactobacillus animalis and Propionibacteriumfreudenreichii at 3 × 109 cfu/day (BOV) or the basal diet top-dressedwith BOV and mixture of Bacillus subtilis and B. licheniformis at 11.8× 109 cfu/day (BOVC). Each experimental period was 28-d, and rumenfluid was collected from each cow, 3 h after feeding on d 22, 24, 27, and28 of the experimental period for 4 runs of in vitro batch fermentationassay per period. Rumen fluid collected from each donor cow correspondedto the specific dietary treatment the cow was receiving. Additionally,2 more treatments (BOV+ and BOVC+) were included in the assay byadding extra dose (1.62 mg/mL) of the 2 probiotic supplements (BOVand BOVC) to the vials containing their respective rumen fluids. A cornsilage-based TMR (1mm; 0.5 g) used as substrate was incubated in serumvials with respective rumen fluid buffered with Van soest medium and reducingagent at 39°C. Data were analyzed using GLIMMIX procedure ofSAS and differences were considered significant at P ≤ 0.05. Treatmentswere used as fixed effects while cow and run were considered random factors.No treatment effects were observed on digestibility parameters. TheBOV and BOV+ inocula decreased molar proportion of butyrate (13.8 and13.6%), compared with CON (14.3%), while BOVC+ tended (P = 0.07)to decreased molar proportion of butyrate. BOV+ lowered gas production(143.9 vs 162.8 mL/g DMD), and tended to reduce CH4 production (9.07vs 11.6 mg/g DMD), compared with CON. BOVC reduced ruminal acetate(50.2 vs 51.1%) and tended to reduce isovalerate (P = 0.07) molarproportion. In conclusion, probiotic supplementation did not change invitro nutrient digestibility; however, it tended to lower CH_4 production.