Soil ingestion by dairy cattle.

Sets of 5 to 10 random fecal samples were obtained from animals of various management groups of nine dairy herds. Titanium content of feces and soils to which the animals had access was determined by x-ray fluorescence spectroscopy. Titanium of feces was the indicator of soil ingestion, which was calculated for 60% digestibility of the total ration dry matter. Mean soil ingestion +/- standard error as a percent of dry matter intake by groups of lactating cows ranged from .14 +/- .02 to .53 +/- .05 for those confined to concrete, .35 +/- .06 to .64 +/- .18 for those housed in freestall barns with soil bedding, and .60 +/- .07 to .96 +/- .22 for those with access to unpaved lots with no vegetation. Mean soil ingestion as a percent of dry matter intake by groups of yearling heifers and dry cows ranged from .52 +/- .11 to .81 +/- .19 for those confined to concrete, .25 +/- .04 to 2.41 +/- .26 for those with access to unpaved lots with no vegetation, 1.56 +/- .21 to 3.77 +/- 1.50 for those with access to unpaved lots with sparse vegetation, and 1.38 +/- .33 to 2.43 +/- .50 for those on pasture but receiving supplemental feed. Sensitivity of the method depended on the titanium content of the soils which was four to five times greater in clay than in sandy soils. Over all observations, the percent soil of feces was related to the percent ash of feces with the orthogonal linear regression equation, Soil = .69 Ash--5.1 (squared correlations, .62).