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1579871 
Technical Report 
Excretory pathway of terbacil ( Sinbar ) in lactating cows 
Gutenmann, WH; Lisk, DJ 
1969 
HAPAB/70/00387 
Agr 
1022-3 
HAPAB Terbacil (3-tert-butyl-5-chloro-6-methyluracil; Sinbar ) was fed to dairy cows to study its metabolism. The pure, recrystallized compound in absolute ethanol was thoroughly mixed with the evening grain. One Holstein dairy cow was catheterized and fed terbacil at 5 ppm ( based on a dairy ration of 50 lb ) for 4 days. Morning and evening subsamples of total mixed milk were taken 1 day prior to feeding ( control sample ), daily throughout the feeding period and for 6 days thereafter. Total daily urine and manure samples were similarly collected, weighed, mixed and subsampled during the same test period. All samples were immediately frozen prior to analysis. A second Holstein diary cow fed 30 ppm terbacil similarly in the ration for 4 days but only milk samples were collected. The in vitro studies included stability of the herbicide when incubated with rumen fluid and its possible metabolism in the presence of the 10,000-G supernate fraction of beef liver was also investigated ( freshly slaughtered Angus steer ). The extraction and isolation of terbacil from the various body fluids and excreta are detailed from previously reported methods. Final analysis of terbacil was by electron affinity gas chromatograph equipped with a battery-operated No. A-4071, 6-cc electron affinity detector ( 56 mcc radium-226 ). At levels of 5 and 30 ppm in the diet, intact terbacil was excreted in the milk at levels of up to 0.03 and 0.08 ppm, respectively. No residues of the intact herbicide were found in the urine or feces. The compound was stable when incubated with fresh rumen fluid, beef liver homogenate or the 10,000-G supernatant microsomal beef liver fraction for periods of 8 and 2 hr and 30 min, respectively. Attempts to determine possible urinary conjugates of terbacil by acid hydrolysis of the urine prior to extraction and analysis were unsuccessful. TOXICOLOGY AND PHARMACOLOGY 70/03/00, 120 1969 
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