The Effects of Biochar and Fat Supplementation on Microbial Fermentation in Batch Cultures
Biochar is a byproduct formed by burning green waste for carbon sequestering in a process called pyrolysis. Biochar can be used as a soil amendment to benefit plant yield and it has also been used to supplement cattle, though benefits in ruminants are still being explored. Previous research in incubated rumen fluid has shown a numerical decrease in methane production (Hansen, et al. 2012). Cattle erupt methane as a hydrogen sink in the reduced rumen environment. Without a way to remove hydrogen microbes, the rumen cannot ferment, and cattle would not be able to utilize the nutrients provided to them. Therefore, more research is necessary to confirm that decreasing methane production with biochar does not also result from depressing neutral detergent fiber (NDF) digestibility, a major component of dairy cattle diets. The objectives of this study were to observe NDF, volatile fatty acid (VFA) production, and methane gas output with supplementation of a biochar product in rumen fluid batch cultures. The treatments were control, biochar (BC), and biochar bolus (BCB, biochar with electrolytes). The diet provided was a high forage diet with concentrate pellets (33.3%), orchard grass (44.4%), alfalfa (22.2%), and either no supplemented fat or 3% dry matter (DM) as corn oil (CO). The BC and BCB were dosed at either 1%, 2% or 4% of total DM. Separately, four round bottom flasks were used for gas production measurements as smaller culture tubes would not produce enough gas volume. The flasks were fed either HF or HF with BC at 2%. Disappearance of NDF did not change with treatment (P=0.1846), but CO increased disappearance (P=0.0537). Total VFA production increased with BC and BCB treatment (P=0.0139). Although methane gas production was not significant, there was a numerical reduction of 23.1 mg produced in 24 hours (P < 0.1597). Therefore, Biochar could reduce methane output without causing harm to NDF and VFA when implemented as a feed additive. With the current stress on agricultural practices to decrease environmental impacts, feeding biochar as a methane mitigation strategy could be crucial to the dairy industry while simultaneously utilizing a waste product.