USE OF BIOCHAR IN RUMINANT FEEDING — A LITERATURE REVIEW

Abstract

This study aimed to synthesize and critically evaluate evidence on biochar use in ruminant feeding, focusing on rumen fermentation, nutrient digestibility, enteric methane mitigation, productive performance, and toxicological safety. A literature review was conducted, gathering 28 studies—including primary research and previous reviews—covering different feedstocks, production conditions, and experimental designs in both laboratory and animal trials. Results indicate that heterogeneity, rather than uniform efficacy, is the most consistent feature: pioneering studies reported substantial methane reductions, but most recent publications failed to reproduce these effects, even in long-term trials. Effects on digestibility and metabolic parameters proved mechanistically plausible yet inconsistent across studies, with contradictory results for the same variable across different materials. Regarding safety, it depends directly on feedstock quality and production process and cannot be treated as an intrinsic material property, given the risk of contaminant exposure in products outside recognized certification standards. It is concluded that biochar use in ruminant nutrition cannot be generically recommended, requiring full material characterization prior to use, along with realistic expectations regarding methane effects and attention to product acceptability by the animals.