Related Experiment Videos
Rumen involvement in sheep tannic acid metabolism
1School of Veterinary Science, University of Queensland, Australia.
Veterinary and Human Toxicology
|October 1, 1995
Summary
Tannic acid (TA) causes methemoglobinemia in sheep through its rumen metabolite pyrogallol (PYR). Direct abomasal administration of TA leads to liver and kidney necrosis, likely from unmetabolized TA, not its metabolites.
Area of Science:
- Veterinary Pharmacology
- Toxicology
- Animal Metabolism
Background:
- Tannic acid (TA) is a plant polyphenol with potential toxicity.
- Understanding TA metabolism is crucial for animal health, especially in ruminants.
Purpose of the Study:
- To investigate the metabolism and toxic effects of tannic acid (TA) in sheep via different administration routes.
- To identify TA metabolites and correlate them with observed toxicological outcomes.
Main Methods:
- Sheep were administered tannic acid (TA) orally (p.o.), intra-abomasally, and intraperitoneally (i.p.).
- High-performance liquid chromatography (HPLC) was used to quantify TA and its phenolic metabolites in biological samples (ruminal fluid, abomasal fluid, plasma, urine).
- Correlations between TA/metabolite concentrations and toxicological findings (methemoglobinemia, liver/kidney necrosis) were analyzed.
Main Results:
- Oral TA administration led to gallic acid (GA) and pyrogallol (PYR) in rumen fluid and plasma, and GA, PYR, and 4-O-methyl gallic acid (40MGA) in urine, with rising PYR levels.
- Intra-abomasal TA administration resulted in TA, GA, and ellagic acid (EA) in abomasal fluid and plasma, and GA, 40MGA, and PYR in urine.
- TA in plasma after intra-abomasal dosing correlated with liver necrosis; PYR in rumen fluid after oral dosing correlated with methemoglobinemia.
Conclusions:
- Methemoglobinemia in sheep receiving oral TA is caused by the rumen-produced metabolite pyrogallol (PYR).
- Liver and kidney necrosis from intra-abomasal TA administration are likely due to unmetabolized TA, not its phenolic metabolites.