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United States Department of Agriculture

Agricultural Research Service

Title: Occurrence of condensed tannins in wheat and feasibility for reducing pasture bloat

Authors
item Mackown, Charles
item Carver, Brett - OKLAHOMA STATE UNIV.
item Edwards, Jeffrey - OKLAHOMA STATE UNIV.

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 26, 2008
Publication Date: November 1, 2008
Citation: Mackown, C.T., Carver, B.F., Edwards, J.T. 2008. Occurrence of condensed tannins in wheat and feasibility for reducing pasture bloat. Crop Science. 48:2470-2480.

Interpretive Summary: Even though winter wheat pasture in the southern Great Plains is considered excellent forage, devastating losses of stocker cattle can occur due to pasture bloat. Tannins are known to reduce the incidence and severity of bloat. We examined tannins in adapted wheat varieties that are commonly grazed and a set of 221 diverse breeding lines. This allowed us to evaluate the feasibility of using conventional breeding methods to give producers improved wheat varieties with high tannin to reduce the incidence of bloat. Tannin reactive substances (phenolic acids and condensed tannins) were detected in extracts from adapted varieties and experimental lines. Differences in phenolic acids among the experimental lines were significant (range, 14.8-32.8 mg/g dry weight); those of condensed tannin were not (range 1.46-4.82 mg/g dry weight). While we observed marked differences in tannin substances among the experimentals, even the greatest amounts detected are unlikely sufficient to render the forage bloat-safe. Perhaps those experimental lines with the most abundant tannin levels could be used in a traditional breeding program to increase the level of tannins in wheat forage. These results will be useful to wheat breeders seeking to develop varieties better suited for use in the southern Great Plains.

Technical Abstract: Frothy bloat can be a serious problem with winter wheat (Triticum aestivum L.) pastures, the primary source of cool-season forage in the southern Great Plains. Some forage contains tannins that reduce the incidence and severity of bloat and promote better use of forage protein. The objective of our research was to measure tannin content and variability in wheat cultivars and experimental lines to determine the feasibility of using traditional breeding methods to give producers a choice to reduce the incidence of bloat. Forage samples of 16 adapted winter wheat cultivars in one experiment and 221 diverse breeding lines and four check cultivars in another experiment were evaluated. Tannin reactive substances (phenolic acids and condensed tannins) were detected in extracts from the 16 adapted winter wheat cultivars. Differences in extractable phenolic acids (tannic acid equivalents) among the experimental lines were significant (range, 14.8-32.8 mg/g dry wt; mean, 23.4 mg/g dry wt; mean, 23.4 mg/g dry wt), but condensed tannin differences (quebracho equivalents) were not significant (range 1.46-4.82 mg/g dry wt; 2.67 mg/g dry wt). While we observed marked differences in tannin substances among the experimental lines, even the greatest amounts detected are unlikely sufficient to render the forage bloat-safe. Perhaps those experimental lines with the most abundant tannin levels could be used in a traditional breeding program to increase the level of tannins in wheat forage. A test of the heritability of tannin concentration would provide evidence that tannin concentrations could be increased using a conventional breeding approach.

Last Modified: 12/22/2014
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