No abstract

The objective of this study was to investigate the effects of adding engineered biocarbon to a high-forage diet on ruminal fermentation, nutrient digestion, and enteric methane (CH4) production in a semi-continuous culture artificial rumen system (RUSITEC). The experiment was a completely randomized block design with four treatments assigned to sixteen fermentation vessels (four/treatment) in two RUSITEC apparatuses. The basal diet consisted of 60% barley silage, 27% barley grain, 10% canola meal, and 3% supplement (DM basis) with biocarbon added at 0, 0.5, 1, and 2% of substrate DM. The study period was 17 d, with a 10-d adaptation and 7-d sample collection period. Increasing biocarbon linearly increased (P < 0.05) disappearance of DM, OM, CP, ADF and NDF. Compared to control, increasing biocarbon enhanced (P < 0.01) production of total VFA, acetate, propionate, branch-chained VFAs, and tended to increase (P = 0.06) NH3-N. Microbial protein synthesis linearly increased (P = 0.01) with increasing biocarbon. Addition of biocarbon reduced overall CH4 production compared with the control (P ≤ 0.05). There were no differences (P > 0.05) in production of total gas, large or small peptides, or in the number of protozoa as a result of addition of biocarbon to the diet. Addition of biocarbon to a forage diet increased DM digestibility by up to 2%, while lowering enteric CH4 production and enhancing microbial protein synthesis in in vitro semi- continuous culture fermenters.

The present study compared the greenhouse gas (GHG) emissions, and breeding herd and land requirements of Canadian beef production in 1981 and 2011. In the analysis, temporal and regional differences in feed types, feeding systems, cattle categories, average daily gains and carcass weights were considered. Emissions were estimated using life-cycle assessment (cradle to farm gate), based primarily on Holos, a Canadian whole-farm emissions model. In 2011, beef production in Canada required only 71% of the breeding herd (i.e. cows, bulls, calves and replacement heifers) and 76% of the land needed to produce the same amount of liveweight for slaughter as in 1981. Compared with 1981, in 2011 the same amount of slaughter weight was produced, with a 14% decline in CH4 emissions, 15% decline in N2O emissions and a 12% decline in CO2 emissions from fossil fuel use. Enteric CH4 production accounted for 73% of total GHG emissions in both years. The estimated intensity of GHG emissions per kilogram of liveweight that left the farm was 14.0 kg CO2 equivalents for 1981 and 12.0 kg CO2 equivalents for 2011, a decline of 14%. A significant reduction in GHG intensity over the past three decades occurred as a result of increased average daily gain and slaughter weight, improved reproductive efficiency, reduced time to slaughter, increased crop yields and a shift towards high-grain diets that enabled cattle to be marketed at an earlier age. Future studies are necessary to examine the impact of beef production on other sustainability metrics, including water use, air quality, biodiversity and provision of ecosystems services.

Twenty ruminally cannulated beef heifers were fed a high corn grain diet in a randomized block design to determine the effect of three direct fed microbial (DFM) strains of Propionibacterium on ruminal fermentation, nutrient digestibility and methane (CH 4 ) emissions. The heifers were blocked in five groups on the basis of BW and used in five 28-day periods. Dietary treatments included (1) Control and three strains of Propionibacterium (2) P169, (3) P5, and (4) P54. Strains were administered directly into the rumen at 5 × 10 9 CFU with 10 g of a maltodextrin carrier in a gel capsule; Control heifers received carrier only. All heifers were fed the basal diet (10 : 90 forage to concentrate, dry matter basis). Rumen contents were collected on days 15 and 18, ruminal pH was measured continuously between days 15 and 22, enteric CH 4 emissions were measured between days 19 and 22 and diet digestibility was measured from days 25 to 28. Mean ruminal pH was 5.91 and was not affected by treatments. Similarly, duration of time that pH < 5.8 and 5.6 was not affected by treatment. Likewise, total and major volatile fatty acid profiles were similar among all treatments. No effects were observed on dry matter intake and total tract digestibility of nutrients. Total enteric CH 4 production (g/day) was not affected by Propionibacterium strains and averaged 139 g/day. Similarly, mean CH 4 yield (g CH 4 /kg of dry matter intake) was similar for all the treatments. The relative abundance of total Propionibacteria in the rumen increased with administration of DFM and were greater 3 h post-dosing relative to Control, but returned to baseline levels before feeding. Populations of Propionibacterium P169 were higher at 3 and 9 h as compared with the levels at 0 h. In conclusion, moderate persistency of the inoculated strains within the ruminal microbiome and pre-existing high propionate production due to elevated levels of starch fermentation might have reduced the efficacy of Propionibacterium strains to increase molar proportion of propionate and subsequently reduce CH 4 emissions.

The objective of this study was to test the efficacy of different Propionibacterium strains in mitigating methane (CH4) emissions in beef heifers fed a high-forage diet. Twenty ruminally cannulated beef heifers were used in a randomized block design with 28-d periods. Treatments included 1) Control, 2) Propionibacterium acidipropionici strain P169, 3) Propionibacterium acidipropionici strain P5, and 4) Propionibacterium jensenii strain P54. Strains (5 × 10(9) CFU) were administered daily directly into the rumen in 10 g of a maltodextrin carrier in a gel capsule. Control heifers received the carrier only. All heifers were fed a basal diet (70:30 forage to concentrate, DM basis) based on barley silage and corn grain. No treatment effects were observed for overall DMI (P = 0.78) or DMI in chambers (P = 0.29). Dry matter intake was 12 to 29% less in the chambers, with intake depression numerically lower in heifers receiving Propionibacterium than Control. Mean ruminal pH averaged 6.47 and was not affected by treatments (P = 0.34). Likewise, no treatment differences were observed for ruminal concentrations of total VFA (P = 0.24) and ammonia-N (P = 0.49) or for molar proportion of individual VFA. Total daily enteric CH4 production was not affected by Propionibacterium strains as compared to Control and averaged 178 g/d (P = 0.69). However, enteric CH4 emission intensity (g CH4/kg of DMI) was reduced by 12, 8, and 13% with P169, P5, and P54 as compared to Control, respectively (P = 0.03). No treatment effects were observed for total tract digestibility of nutrients. Likewise, total universal bacterial (P = 0.22) and methanogen (P = 0.64) counts were similar among treatments. However, the relative abundance of total Propionibacteria tended to increase with inoculation as compared to Control (P = 0.06). The relative abundance of Propionibacterium P169 tended to be greater at 3 h postdosing, but returned to pretreatment (0 h) levels within 9 h, suggesting it failed to persist at detectable levels in the rumen. In conclusion, Propionibacterium spp. did not reduce total enteric CH4 production, possibly due to their inability to persist and integrate into the ruminal microbial community. However, CH4 emission intensity was reduced with Propionibacterium strains, a response attributed to the numerically greater DMI of heifers receiving Propionibacterium.