Mitigating enteric methane emissions with Madhuca longifolia phenolic extract supplementation in forages and diets through in vitro fermentation to support climate-resilient livestock production

Abstract

Reducing enteric methane emissions from livestock is a key environmental challenge, as methane is a major pollutant. The complexity of animal biology and diverse diet compositions make it difficult to develop strategy to control methane production. This study examined the use of plant phenolic extracts of Madhuca longifolia (ML-7) as a feed additive combined with various ruminant diets and dosages to find an effective supplement to reduce methane emissions. Seven feeds were assessed: two dry forages (wheat and oat straw), two green fodders (berseem and napier), and three mixed diets formulated with straw bases: wheat (Diet-1), oat (Diet-2) and sorghum (Diet-3), each combined with berseem and concentrate in a 2:1:1 ratio. The nutritive value of each feed was assessed, followed by measuring total gas, methane and in vitro fermentation after supplementing all feeds with ML-7 at different levels (0, 0.2, 0.6 and 1.0%). Diet-3 had the highest (18.98 Mj kg⁻¹) gross energy while oat straw had the lowest (18.25 Mj kg⁻¹). Berseem had the best nutritional profile. Supplementing feeds with ML-7 extract significantly reduced total gas and methane production across the tested feeds. However, DMD declined significantly in diet-3 and napier grass. ML-7 had no effect on short-chain fatty acid production in the tested diets, although SCFA production decreased significantly with 1.0% ML-7 supplementation in dry and green fodder. The methane reduction pattern was diet-1 > napier > berseem, diet-2, diet-3, wheat straw, and oat straw. Total volatile fatty acids decreased most in diet-3, followed by diet-2, diet-1, napier, berseem, and other dry roughages. ML-7 supplementation had minimal impact on total protozoa populations but significantly reduced holotrichs. Supplementing ML-7 extract to feeds at 0.6–1.0% levels shows potential for reducing methane emissions in ruminants without disrupting rumen fermentation, promoting sustainable livestock production and a climate-friendly environment by reducing methane emissions.