Changes in Concentrations of Tannins, Total Phenolics, Crude Protein, and in vitro Digestibility of Browse Due to Mastication and Insalivation by Cattle

Document Type

Article

Journal/Book Title/Conference

Journal of Range Management

Volume

40

Issue

5

Publication Date

9-1987

First Page

409

Last Page

411

Abstract

The feasibility of using esophageal extrusa to monitor dietary tannin levels was studied using 4 shrub species (Purshia tridentata, Quercus gambelil, Cercocarpus montanus and Acer grandidentatum). Browse samples were hand-harvested in late summer. Half of the sample for each species was fed to esophageally fistulated cattle, while the other half served as an unmasticated control. Extrusa and control samples were analyzed for total phenolics (Folin-Denis), tannin using 3 methods (vanillin-HCl, proanthocyanidins, and astringency), crude protein, and in vitro organic matter digestibility (IVOMD). Tannin levels were reduced to 10% to 60% in extrusa, depending on plant species and method of tannin analysis. Changes in the nutritional constituents of extrusa were limited but oak extrusa was higher in IVOMD than oak control samples. Tannins may have bound to plant or salivary proteins or to mucous membranes in the mouth during mastication and insalivation. Our results indicate that esophageal extrusa is not suitable for monitoring dietary tannin levels.

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