Effect of soil ingestion on certain mineral elements in the bovine gastrointestinal tract

Soils of different types were fed to Hereford steers to determine effects of soil on total and soluble mineral concentrations in the gastro intestinal tract contents. All animals received 4.5 kg grass hay and 3.6 kg commercial dairy concentrate daily. Treatments consisted of controls (2 steers), sandy loam soil (2 steers), red clay subsoil (3 steers) or fine particle from sandy loam soil (2 steers). The amount of individual soil fed per day to each animal in soil fed groups was .9 kg and this was mixed with moistened concentrate. The steers were slaughtered after at least two weeks on the treatments and the digestive tracts were divided into the following sections: rumen-reticulum, omasum, abomasum, small intestine, cecum, and large intestine. The contents of each gastro intestinal section were weighed and sampled. Digesta as collected and ultracentrifuge supernatants of digesta were analyzed for calcium, magnesium, sodium, potassium and phosphorous. Dry matter, ash, and total and soluble mineral concentrations were determined. The largest amount of dry matter was found in the rumen, while the abomasum had the smallest amount. However, feeding soil did not greatly increase total dry matter contents in sections posterior to the rumen. Average ash of the digestive tract contents was doubled by feeding soil. Total and soluble mineral contents measured were not increased by feeding soil, due to the low individual mineral concentrations found in the soil. Anterior to the cecum, mineral solubilities averaged Na > K > P > Mg > Ca in the concentrations. In most cases, minerals were most soluble in the abomasal contents. The soil fed reduced the solubilities of magnesium and phosphorus, had no affect on sodium and potassium, but did increase the solubility of calcium.