Cashew nut shell liquid mitigates enteric methane emissions

Cashew nut shell liquid (CNSL) is an effective rumen modulator that reduces methane emissions and shifts fermentation patterns without adverse effects on animal performance, found a meta-analysis performed by Slamet Widodo, a Doctoral Degree Student in Natural Resources and Environmental Management Science at Indonesia’s IPB University, together with his team.

This parallel meta-analysis was conducted using data from 11 in vitro and 16 in vivo studies. Using the meta and metafor packages in R software, the weighted mean difference (WMD) was estimated under a random-effects model to assess the effects of CNSL on enteric methane emissions, rumen fermentation characteristics, and production performance.

Supplementation with CNSL demonstrated a significant mitigation potential in the in vitro systems, with a 51.91% reduction in methane production (p < 0.04) and a 19.03% increase in propionate concentration (p < 0.001).

This mechanistic potential was validated in vivo, where CNSL significantly shifted fermentation stoichiometry (+22.15% propionate; −6.30% acetate) and reduced methane yield (g/kg dry matter intake) by 20.14% (p = 0.006).

Supplementation with CNSL reduced emissions across both systems without compromising in vitro dry matter digestibility (p = 0.69) or in vivo dry matter intake (p = 0.51) and milk yield (p = 0.55).

Subgroup analysis revealed that efficacy was species-dependent, with swamp buffalo and beef cattle exhibiting stronger propionate responses than dairy cattle.