Data on soil ingestion in horses are lacking in contrast to other free-range animals. The
importance of soil as a vector for environmental pollutants to food is less relevant in horses but
several disorders secondary to soil ingestion, such as sand colic or enteritis have been reported.
Therefore, soil ingestion has been studied on Irish sport horses grazing at three offered levels of daily
herbage: 2, 3 and 4% of their body weight. Soil ingestion was estimated by the faecal recovery of a
soil natural marker. Horses had 4.5, 4.1 and 3.7% of soil in their total intake respectively for the 2,
3 and 4% herbage offers. The 4% offer presented significantly less intake (543 g/d) compared to the
more restricted offers (624 and 648 g respectively for 3 and 2%). The post-grazing sward height was
significantly lower on the 2% offer (3.1 cm) compared to the higher offers (4.1 and 4.4 cm respectively
for 3 and 4%). Thus, restricted herbage allowance made grazing closer to the ground and increased
soil ingestion. The sward height appeared to be a reliable indicator to manage animal withdrawal
from a pasture to limit soil ingestion and the risk of gastrointestinal pathologies caused by it.