How much soil do cattle ingest? A review.

Beef and dairy cattle commonly ingest soil when consuming forage-based diets in paddock feeding situations. However, the extent of this soil intake is poorly understood in the Australian environment and under Australian grazing systems. Therefore, the aim of the current literature review was to examine soil ingestion in cattle and the factors that affect ingestion. We found 11 studies containing soil-ingestion data, based in England, France, New Zealand and USA but none from Australia. A wide range in soil ingestion rates was reported and intake varied considerably with season, forage-pasture type, pasture-on-offer, stocking rate and grazing conditions. Generally, soil ingestion was lower in beef cattle than in dairy cattle. We considered the differences in reported levels, variables around those differences, and reliability of methodology used, and compared results with existing international guidelines. For Australian applications, we deduced and recommended that 0.5 kg/head.day is used until field-based research is conducted in Australia which might provide a more specific value for Australian conditions. Our review will inform future livestock management, particularly on contaminated agricultural land. In Australia, there is a poor understanding of how much soil cattle ingest while grazing. We conducted a literature review and found 11 papers to inform our views, but there were no published papers from Australia. Ingestion levels varied among countries, and between dairy and beef enterprises. We estimated that cattle ingest about 0.5 kg/head.day; however, this varies according to circumstance. Research is required in Australian environment to better inform managers. [ABSTRACT FROM AUTHOR]