Effect of ingestion of soil on faecal losses and retention of Mg, Ca, P, K, and Na in sheep fed two levels of dried grass

Eighteen wethers, aged about 2 years, fed dried grass at 600 and 900 g dry matter (DM)/day were used to study the effect of soil ingestion (100 g/day) on faecal loss and apparent absorption and retention of Mg, Ca, P, K, and Na. The soils investigated were Waikiwi silt loam and Egmont brown loam. The Egmont soil increased the apparent absorption and retention of P, but the increase was significant (P < 0.05) only at the higher intake of DM. For Mg and Ca both soils at lower DM intake significantly decreased the faecal loss (Mg, P < 0.05; Ca, P < 0.01) and significantly increased the apparent absorption (P < 0.01) and retention (Mg, P < 0.05; Ca, P < 0.01). A similar effect on the Mg and Ca balance was found in the Egmont soil at the higher DM intake. The ingestion of soil did not significantly influence the faecal loss or apparent absorption of K and Na. The implications of ingested soil on the macro-element balance of the grazing sheep are discussed.