This study investigated the effects of three pine-based biochar products on nutrient disappearance, total gas and methane (CH4) production, rumen fermentation, microbial protein synthesis, and rumen microbiota in a rumen simulation technique (RUSITEC) fed a barley-silage-based total mixed ration (TMR). Treatments consisted of 10 g TMR supplemented with no biochar (control) and three different biochars (CP016, CP024, and CP028) included at 20 g·kg−1 DM. Treatments were assigned to 16 fermenters (n = 4 per treatment) in two RUSITEC units in a randomized block design for a 17 d experimental period. Data were analyzed using MIXED procedure in SAS, with treatment and day of sampling as fixed effects and RUSITEC unit and fermenters as random effects. Biochar did not affect nutrient disappearance (P > 0.05), nor total gas or CH4, irrespective of unit of expression. The volatile fatty acid, NH3-N, total protozoa, and microbial protein synthesis were not affected by biochar inclusion (P > 0.05). Alpha and beta diversity and rumen microbiota families were not affected by biochar inclusion (P > 0.05). In conclusion, biochar did not reduce CH4 emissions nor affect nutrient disappearance, rumen fermentation, microbial protein synthesis, or rumen microbiota in the RUSITEC.
Breeding ruminants for low methane (CH4) emissions can be permanent and cumulative, but requires a better understanding of the variability of CH4 production among animals to accurately assess low-CH4 phenotypes. Our objectives were to: 1) investigate the variation in CH4 production among and within growing beef cattle, 2) identify low-CH4 emitters, and 3) examine relationships between CH4 production and intake, feeding behavior, growth, and rumen fermentation. Crossbred beef heifers (n=77; body weight=450 kg) were allocated to 3 pens and offered a finishing diet of 90% concentrate and 10% silage (dry matter (DM) basis). The study was conducted over 3 consecutive 6-week periods (126 days). GrowSafe bunks measured individual animal DM intake (DMI) and rumen fluid was sampled orally each period. A GreenFeed system measured individual animal emissions for 2 weeks/period. Methane production was calculated by animal within period using visits that were ≥3 min with fluxes compiled into six 4-h blocks corresponding to time of day, and averaged over blocks to obtain an average daily emission for the period. Animals with <12 visits and <5 blocks were omitted for the period and animals with ≥2 periods of complete CH4 data were used in the final analysis (n=52). Animals were ranked based on CH4 yield (g/kg DMI) from low to high, and grouped as Very-low (≤10% of animals), Low (11-25%), Intermediate (26-74%), High (75-89%), and Very high (≥90%) emitters (mean ± SD, 12.6 ± 2.16). The CH4 yield was 16% less (P<0.05) for Very-low compared with Intermediate animals due to lower CH4 production (g/d, P<0.05), with no differences in DMI (P>0.05). However, the period × grouping interaction (P<0.001) for CH4 yield indicated that the ranking of animals changed over time, although there were no extreme changes in rankings. Total VFA concentration decreased as CH4 yield decreased, but molar proportions of VFA remained unchanged, suggesting lower extent of ruminal digestion rather than a shift in fermentation. There were no differences in feeding behavior or average daily gain among groupings (P>0.05). The between-animal coefficient of variation in CH4 yield of 17.3% enabled identification of low CH4-emmitting finishing beef cattle. However, accurate selection of low CH4-emitting animals should be based on repeated CH4 measurements over the production cycle.
This study investigated the effects of engineered biocarbon on nutrient digestibility, rumen fermentation, total gas and methane (CH4) emissions, and microbial protein synthesis in a rumen simulation technique (RUSITEC) fed a barley silage-based TMR. The basal diet consisted of 60% barley silage, 27% barley grain, 10% canola meal and 3% minerals. Three pine-based biocarbon products CP016, CP024 and CP028. were added at 2% of substrate DM. Biocarbons differed in bulk density, surface area, pore volume, pH, but had similar chemical compositions. Treatments were assigned to sixteen vessels (n = 4/treatment) in two RUSITEC apparatuses in a randomized block design. The experiment period was 17 d, with a 10-d adaptation and 7-d sample collection period. Data were analyzed using the PROC MIXED in SAS, with treatment (T), day (D) and TxD interactions as fixed effects and RUSITEC apparatus and fermenters as random effects. Compared to the control, biocarbon did not affect total gas (P = 0.98), the amount of CH4 produced per unit of DM incubated (P = 0.48) or per unit of DM digested (P = 0.27). Biocarbon treatments averaged 6.5 g of CH4 /g DM incubated and 9.06 g CH4 /g DM digested as compared to 7.1 g of CH4 /g DM incubated and 10.46 g CH4 / g DM digested in the control, respectively. Biocarbon CP024 had the greatest numerical reduction, followed by CP028 then CP016 in all CH4 associated parameters. Biocarbon addition did not affect the disappearance of DM (P = 0.63), OM (P = 0.34), CP (P = 0.48), NDF (P = 0.12), or VFA (P = 0.65) and ammonia N levels (P = 0.99) and protozoal counts (P = 0.72). The amount of bacterial nitrogen (mg/d) associated with feed particles increased (P < 0.003), suggesting that biocarbon may have enhanced colonization. In conclusion, engineered biocarbon did not reduce CH4 emissions in the RUSITEC.
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