Modified flotation technique for quantitative determination of mite populations in feedstuffs.

Modifications are described to a previously published technique for quantitative determination of mite populations in animal feedingstuffs. In the modified method, the oil phase is kerosene instead of a mixture of kerosene and tetralin (1 + 1), and aqueous industrial methylated spirit is substituted for aqueous ethanol in the aqueous phase. Emulsion formation at the interface is considerably reduced by incorporating a pre-extraction stage. Examination of mites on the filter paper is made easier and quicker by staining them with Phloxin B. Trials carried out with known numbers of mites in samples of dairy feed concentrates indicate mean recoveries of 84-96% throughout the range tested. The results show that the accuracy of the technique is not affected by the level of infestation.