Ingestion of soil by dairy cows

Abstract

Analysis of faeces for titanium by the X-ray fluorescence technique is shown to be a rapid and reliable method of determining soil content of faeces. Ingestion of soil by dairy cows has been followed monthly on a herd basis over the 1967–8 season on a limited number of town supply herds in the Kaitoke and Wairarapa districts, and on Nos. 1, 2, and 3 Dairy Units at Massey University. Mean soil ingestion per cow on the private farms ranges from about 400 to 700 lb per year. Soil ingestion at Massey ranges from about 400 lb per year on the lighter-stocked No. 1 Unit (town milk supply) to over 1,000 lb of soil per cow per year on the heavily-stocked No. 3 Unit. Animals wintered on paddocks on No. 3 Unit ingest more soil than do the platform-wintered herd. Ingestion of soil on an individual animal basis at No. 5 Dairy Farm at Ruakura Agricultural Research Centre was followed weekly from individual faeces samples collected over the 1965–6 season. Soil ingestions range from approximately 200 to 800 lb per cow per year, and can differ by a factor of two for different animals in the same herd. Evidence is presented to demonstrate that some twins may show inherited tendencies to either low or high soil ingestions. Soil content of faeces may provide some measure of the grazing behaviour of an animal. While yearly intakes of soil can reach approximately 1,0001b, this is still less than about 2% of the weight of fresh pasture consumed. The possible importance of ingested soil as a source of DDT and microelements for animals is discussed.