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

Authors: BECK, MATT - Texas A&M University; Gunter, Stacey; Kalscheur, Kenneth; MAEDA, KOKI - Japanese International Research Center For Agricultural Sciences (JIRCAS) - Japan; THOMPSON, LOGAN - Kansas State University; Koziel, Jacek; Hiltbrunner, Beau; Castleberry, Bobbie; LONG, NATHAN - Texas A&M University; GOUVEA, VINNI - Texas A&M Agrilife

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2025
Publication Date: 4/1/2026
Citation: Beck, M., Gunter, S.A., Kalscheur, K., Maeda, K., Thompson, L., Koziel, J.A., Hiltbrunner, B.T., Castleberry, B., Long, N., Gouvea, V. 2026. Cashew nutshell liquid reduces in vitro methane production from a finishing beef cattle diet. Applied Animal Science. 42(2):135-144. https://doi.org/10.15232/aas.2025-02753.
DOI: https://doi.org/10.15232/aas.2025-02753

Interpretive Summary: Cashew nut shell liquid is a by-product of the cashew industry hat is concentrated in southeast Asia. Research by ARS scientist analyzed the value of this by-product as a ruminal metabolism modifier for cattle consuming high-concentrate diets. This research has shown that the inclusion of this cashew nut shell liquid at 1% of dietary dry matter decreases enteric methane emission by more than 15% compared to non-supplemented control diets when analyzed in an in vitro system. This change in methane emission seems to be driven by a decrease in ruminal acetate production and an increase in proportionate production. This change in the volatile fatty acid profile in the ruminal fluid should result in feedlot cattle that are more energetically efficient. Cashew nut shell liquid as a feed addictive for feedlot cattle is justified.

Technical Abstract: The objective of this experiment was to assess the impacts of cashew nutshell liquid (CNSL) or palm oil (OIL) treatment on in vitro true DM digestibility (IVTDMD), total gas, CH4, volatile fatty acid (VFA), and NH3 production. The CNSL and OIL products used in the current experiment were blended with 50% CNSL or OIL and 50% amorphous silica to facilitate mixing the treatments with the dried and ground basal substrate. The basal substrate used was a high concentrate (9% roughage DM basis) finishing diet. The current experiment employed a 4×4 + 1 design, with four inclusion levels of the CNSL or OIL treatments of 0.66%, 1.33%, 2%, or 2.66% of diet and a treatment with no CNSL or OIL. All data were analyzed by a mixed effects regression, with a linear coefficient of inclusion × additive source (CNSL or OIL) interaction term. The CNSL inclusion significantly reduced (P < 0.01) 48-hour gas production (mL/g DM) by -3.87 mL per 1% inclusion, while the OIL treatment tended (P = 0.06) to reduce gas production, with the CNSL and OIL coefficients being different (P = 0.01). The CNSL treatment decreased (P < 0.01) CH4 production (mL/g DM) by 0.29 mL per 1% inclusion, with the greatest CNSL inclusion having 15.2% lower CH4 compared with the 0% inclusion treatment. The OIL inclusion only tended (P = 0.10) to reduce CH4 and the CNSL and OIL coefficients were not different (P = 0.12). The CNSL treatment increased (P < 0.01) propionate production by 0.98 mmol/L per 1% inclusion, while the OIL treatment reduced (P = 0.01) propionate production by 0.83 mmol/L per 1% inclusion and these coefficients were different (P < 0.01). The CNSL decreased (P < 0.01) the acetate-to-propionate ratio (A:P) by 0.017 mmol/mmol for each 1% inclusion. The OIL treatment coefficient was not different (P = 0.54) from 0 for A:P and OIL and CNSL coefficients were different (P < 0.01). The CNSL treatment reduced CH4 by 15.2% at its highest inclusion and this mitigation appears to be driven by reduced A:P.