Cashew nutshell liquid reduces in vitro methane production from a finishing beef cattle diet

The objective of this experiment was to assess the effects of cashew nutshell liquid (CNSL) or palm oil (PO) treatment on in vitro true DM digestibility, total gas, CH 4 , VFA, and NH 3 production. The CNSL and PO products were blended with 50% CNSL or PO and 50% amor-phous silica to facilitate mixing the treatments with the dried and ground basal substrate, which included monen-sin sodium. The basal substrate was a high-concentrate (9% roughage DM basis) finishing beef cattle diet. The current experiment employed a 2 × 4 + 1 design, with 4 inclusion levels of the CNSL or PO treatments of 0.33%, 0.67%, 1.00%, or 1.33% of diet and a treatment with no CNSL or PO. All data were analyzed by a mixed effects regression, with a linear coefficient of inclusion × additive source (CNSL or PO) interaction term. The CNSL inclusion reduced 48-h gas production (mL/g of DM) by −7.86 mL per 1% inclusion, whereas the PO treatment did not reduce gas production, and the CNSL and PO coefficients differed. The CNSL treatment decreased CH 4 production (mL/g of DM) by 0.79 mL per 1% inclusion, with the greatest CNSL inclusion having 20% lesser CH 4 compared with the 0% inclusion treatment. The PO inclusion reduced CH 4 by 11%, but the CNSL and PO coefficients tended to differ. The CNSL treatment increased propionate production by 2.03 mmol/L per 1% inclusion, whereas the PO treatment reduced propionate production by 1.79 mmol/L per 1% inclusion, and these coefficients were different. The CNSL decreased the acetate-to-propionate ratio (A:P) by 0.039 mmol/mmol for each 1% inclusion. The PO treatment co-efficient was not different from zero for A:P, and PO and CNSL coefficients were different. The CNSL treatment reduced CH 4 by 20% at its highest inclusion, and this mitigation appears to be driven by reduced A:P.