Cattle excretion

Tilmicosin, (20-deoxo-20-(3,5-dimethylpiperidin-l-yl)-desmycosin) is a new macrolide antibiotic which is being developed for treatment of bovine respiratory disease by single subcutaneous injection into cattle. Excretion, tissue residue, and metabolism studies were conducted with " C-tilmicosin-treated cattle and rats. Radioactivity was excreted primarily in the feces after parenteral dosing of cattle and oral dosing of rats. Among edible tissues from treated cattle, liver and kidney contained the highest concentrations of radioactivity. The most abundant metabolite was N-desmethyl tilmicosin. Comparative metabolism studies with cattle and rats indicated that the pattern of metabolism was the same for both species. 

About 50% of copper in food is absorbed, usually under equitibrium conditions, and stored in the tiver and muscles. Excretion is mainly via the bile, and only a few percent of the absorbed amount is found in urine. The excretion of copper from the human body is influenced by molybdenum. A low molybdenum concentration in the diet causes a low excretion of copper, and a high intake results in a considerable increase in copper excretion (68). This copper—molybdenum relationship appears to correlate with copper deficiency symptoms in cattle. It has been suggested that, at the pH of the intestine, copper and molybdate ions react to form biologically unavailable copper molybdate (69). 

After exerting their action in the organism, natural and synthetic hormones are catabolized in the liver by conjugation to glucuronide and/or sulfate moieties, forming more polar conjugated forms which are excreted via urine. This is the main route of hormone excretion in humans and pigs. A fraction of hormones is also excreted in a free form via feces in animals such as sheep and cattle this is the main route for hormone excretion (Table 3) [66, 67],... 

In studies with normal adult animals, orally administered radiocerium moves rapidly through the gastrointestinal tract. About 0.96 of a cerium nitrate solution administered orally to rats was excreted within 24 hours (Sagan and Lengemann, 1973). However, external irradiation of the gastrointestinal tract with a 137Cs source (800 R) delayed excretion of the radiocerium. Only about 0.85 of the administered cerium was excreted by 3 days but 0.992 was excreted by 4 days. In swine, 0.98 of an oral dose of radiocerium was excreted by 3 days (Miller et al., 1969) while in cattle, radiocerium placed in the rumen required 3.7 days for 0.9 of the dose to be excreted. Fecal excretion of the cerium still occurred after 4 days. When radiocerium was placed in the abomasum of cattle, it was almost entirely voided in 1.2 days. 

Miller, J. K., Perry, S. C., Chandler, P. T. and Craig, R. G. (1967). Evaluation of radiocerium as a nonabsorbed reference material for determining gastrointestinal sites of nutrient absorption and excretion in cattle, J. Dairy Sci. 50, 355. 

Oral treatment of sheep and cattle (Bos spp.) with diflubenzuron is followed by absorption of the compound through the gastrointestinal tract, metabolism, and elimination of residues through the urine, feces, and, to a very limited extent, milk. Intact diflubenzuron is eliminated in the feces of orally dosed cattle and sheep (Ivie 1978). Major metabolites of diflubenzuron excreted by cattle and sheep result from hydroxylation on the difluorobenzoyl and chlorophenyl rings, and by cleavage between the carbonyl and amide groups to produce metabolites that are excreted free or as conjugates (Ivie 1978). Cattle dosed repeatedly with diflubenzuron had detectable residues only in liver... 

The effects of leucaena and mimosine on nonruminants can be reduced to some extent by diet supplementation with ferrous sulfates. Mimosine forms a complex with iron, which is excreted in the feces. Zinc supplementation has reduced the toxicity in cattle and it is believed that copper and zinc ions bind more strongly to mimosine than most other amino acids. 

Some minor routes of excretion exist sweat, hair, saliva, semen, milk. While these routes out of the body do not count for much as excretory processes, excretion of some chemicals into milk can be important because it constitutes an exposure pathway for infants, if the milk is from their mothers, and for many people if it is from dairy cattle. Many fat-soluble chemicals follow this pathway out of the body, dissolved in the fatty portion of the milk. Excretion of chemicals through milk is common enough to prompt considerable attention from toxicologists. 

The indirect source of PBBs in soil was the contaminated farms in Michigan. Approximately 650 pounds (290 kg) of PBBs were mixed in cattle feeds that were delivered to Michi n farms during 1973 1974 (Fries 1985b). About 50% of this amount was excreted in the feces of the exposed animals and remained on the famis in places of fecal deposition and manure disposal (Fries 1985b). Soil in fields that received contaminated manure contained as high as 300 g/kg PBBs, whereas soil in resurfaced cattle exercise lots contained as high as 1,000 2,000 g/kg of PBBs (Fries 1985b). 

The absorption of spectinomycin is poor via the oral route, but rapid and extensive after intramuscular injection. It is not extensively metabolized in animals and rapidly excreted in the urine (16). Following subcutaneous injections of spectinomycin sulfate to cattle, 70-83% of the dose was excreted in the urine and 62-64% of this was parent spectinomycin (17). Several minor metabolites were found in the urine that consisted mostly of dihydroxyspectinomycin and two acetylated isomers, and an unusual ammoniated spectinomycin metabolite and its acetylated derivative. There was also some evidence, but it was not compelling, for a spectinomycin sulfate conjugate. Dihydrospectinomycin and parent spectinomycin were the only identifiable major components found in the liver and the kidney, respectively. Liver and kidney retained the highest concentrations of total residues throughout the 15-day withdrawal period. 

Results of pharmacokinetic studies of streptomycin are in most cases also applicable to dihydrostreptomycin and vice versa. In animals, the absorption of both streptomycin and dihydrostreptomycin is poor via the oral route but rapid after intramuscular administration. In cattle, peak serum levels were obtained 1 h after intramuscular injection of either streptomycin or dihydrostreptomycin (18), whereas serum concentrations produced in sheep and horses paralleled those obtained in cattle (19). As a result, most of an oral dose is recovered in the feces whereas most of a parenteral dose is recovered in the urine. However, if kidney function is severely impaired, little of an intramuscularly administered dose is excreted in the urine. 

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