Effects of biochar source, level of inclusion, and particle size on in vitro dry matter disappearance, total gas, and methane production and ruminal fermentation parameters in a barley silage-based diet

This study evaluated the effects of biochar differing in source, inclusion level, and particle size on dry matter disappearance (DMD), total gas and methane (CH4) production, and ruminal fermentation in a barley silage-based diet. The seven biochar products used were coconut (CP001 and CP014) or pine (CP002, CP015, CP016, CP023, CP024)-based. Experiment 1 (Exp. 1) evaluated these biochars at 4.5%, 13.5%, and 22.5% level of diet inclusion, whereas Experiment 2 ( Exp. 2) evaluated CP002, CP016, and CP023 at 2.25% and 4.50% of the diet at <0.5, 0.5-2.0, >2.0 mm particle size. Data were analyzed using PROC MIXED in SAS as a randomized complete block design, with biochar source, inclusion level, and particle size (Exp. 2 only) as fixed effects with run and replicate as random effects. Increasing level of biochar inclusion linearly (P < 0.01) decreased DMD in Exp. 1 and did not influence DMD (P > 0.05) in Exp. 2. Total gas, CH4 (mL.g(-1) DMD), and ruminal fermentation parameters were not affected by product, inclusion level, or particle size (P > 0.05). In conclusion, biochar of varying source and particle size did not mitigate CH4 production, but reduced DMD at higher inclusion levels in the barley silage-based diet.