Browsing Journal of Range Management, Volume 45, Number 1 (January 1992) by Title
Now showing items 21-22 of 22
Tannin chemistry in relation to digestionTannins are a diverse group of compounds which precipitate protein. The impact of tannins on herbivory has been difficult to assess because of diversity in tannin chemistry and in animal physiology. We have evaluated the effects of tannin on large ruminants (deer, sheep) using artificial diets containing well-defined tannins, and have compared the results to those obtained with natural forages. The different effects of condensed tannins and gallotannins on herbivores are related to the chemical stability of the tannins. Commercial tannic acid does not have the same effects on herbivores as gallotannins in natural forages. Molecular weight apparently determines the metabolic fate of gallotannins from various sources.
Toxification and detoxification of plant compounds by ruminants: An overviewImproved usage of rangelands for livestock production requires better ways to reduce losses caused by poisonous plants, such as management practices to minimize ingestion and treatments to improve animal tolerance of ingested poisonous plants. In ruminants, gastrointestinal microbes can detoxify plant compounds, and this capacity has been enhanced in a few cases by deliberate modification of rumen microbial populations. Some plants are poisonous because ingested plant material is made toxic by microbial fermentation in the rumen, and better understanding of such toxifications will provide opportunities to diminish poisonings of that type. Absorption of toxic substances from the gastrointestinal tract into blood and lymph may be modified by feeding binding agents such as clay, resins, and indigestible fibers, or by pharmaceuticals that interfere with absorption of toxicants. Agents that induce or inhibit biotransformational enzymes in tissues of the host animal might modify animal tolerance of some plant toxicants. Provision of substances that serve as co-substrates of detoxification can enhance animal tolerance of other types of plant toxicants. Some reports that illustrate these approaches have been reviewed, and questions have been raised to stimulate further research.