HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Johnson, J. C. Articles by Knox, F. E. Search for Related Content PubMed PubMed Citation Articles by Johnson, J. C., Jr. Articles by Knox, F. E.

Persistence of Chlorpyrifos-methyl in Corn Silage and Effects of Feeding Dairy Cows the Treated Silage

Department of Animal Science, Georgia Coastal Plain Experiment Station, Tifton 31794

R. L. Jones, D. B. Leuck and M. C. Bowman

Southern Grain Insects Research Laboratory ARS, USDA Tifton, Georgia 31794

F. E. Knox

Animal Parasite Research Laboratory USDA, ARS Tifton, Georgia 31794

ABSTRACT

Corn was sprayed in the field at dent stage of maturity with chlorpyrifos-methyi [O, 0,-dimethyl 0-(3, 5, 6-trichloro-2-pyridyl) phosphorothioate] at .56, 1.12, and 2.24 kg per hectare, ensiled 1 day later, and methodology for detection of residues was developed. Losses of total residues (chlorpyrifos-methyi and its pyridinol hydrolysis product) through 83 days of ensiling were equivalent to 55, 71, and 76% of that applied. Beginning 83 days post ensiling, control and treated silages were fed to 16 cows, 4 per treatment, for 42 days during which chlorpyrifos-methyi averaged .35, .87, and 1.85 ppm, and was stable. The pyridinol averaged .44, .79, and 1.75 ppm but continued to decline and during the last week of feeding averaged only 32% of that in silage fed the 1st wk. Residue intakes amounted to .009, .022, and .054 mg chlorpyrifos-methyi and .012, .020, and .051 mg of pyridinolAg body weight and failed to affect silage intake, milk production, blood cholinesterase activity, or body weight gains. Traces of chlorpyrifos-methyi (.003 ppm or less) were only in milk from cows on the 2.24 kg treatment. Milk from all cows fed treated silage contained traces of the pyridinol (.011 ppm or less). No trace of the O-analog of chlorpyrifos-methyi was in any sample, and all milk, urine, and feces were free of residues within 1 wk after the cows were withdrawn from treated silage.