Clay additives reduced methane and ammonia and digestibility of fibre and organic matter was moderately enhanced, accompanied by improvements in weight gain and milk fat yield. These responses varied depending on the type and dose of clay mineral.
Clays are increasingly incorporated as feed additives for ruminants, partly inspired by animals’ natural geophagic behaviour. However, their effects on rumen function and productivity remain inconsistent in the literature.
This meta-analysis synthesised 39 controlled studies (73 treatment means) to quantitatively evaluate the effects of clay supplementation on fermentation, digestibility, metabolic health, and productivity.