Review: Feed residues of glyphosate - potential consequences for livestock health and productivity.

Glyphosate is the active ingredient in a wide range of herbicides used for weed control, including weed control in genetically modified, glyphosate-insensitive crops. In addition, glyphosate herbicides are used for pre-harvest desiccation of glyphosate-sensitive crops. Together, the use of glyphosate leads to residues in livestock feed. In addition to its herbicidal property, glyphosate has documented antimicrobial and mineral-chelating properties. The aim of the present paper is to address, based on the published literature and own observations, whether dietary glyphosate residues may affect livestock gut microbiota and/or mineral status potentially with derived unfavourable effects on animal health and productivity. However, and as reported, literature on the potential effects of glyphosate on livestock is very scarce and mainly reporting in vitro studies; hence, a solid basis of in vivo studies with livestock in physiological and productive phases, particularly sensitive to disorders in mineral status and in the gut microbiota, is needed for drawing final conclusions.