FORAGE PRESERVATION METHODS ALTER PROTEIN INTERACTIONS WITH CONDENSED TANNINS AND POLYPHENOLS

Authors: Grabber, John; DAVIDSON, C - UW MADISON; Massingill, Lee

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2004
Publication Date: 11/2/2004
Citation: Grabber, J.H., Davidson, C.L., Massingill, L.J..2004. Forage preservation methods alter protein interactions with condensed tannins and polyphenols. In: ASA-CSSA-SSSA Annual Meeting Abstracts, October 31-November 4, 2004, Seattle, Washington. 2004 CDROM.

Interpretive Summary:

Technical Abstract: The effects of tannins and polyphenols on forage protein solubility and degradability are normally studied with freeze-dried samples but this may not accurately reflect protein characteristics in forages fed as silage and hay. In 2002 and 2003, cuttings of alfalfa, birdsfoot trefoil, and red clover were fresh frozen and freeze dried or mown and wilted before preservation as silage or hay. Forages were assayed for buffer-soluble N (BSN), protease degradable N (PDN), and protease undegradable N (PUN). When averaged over preservation methods, alfalfa contained 518 g/kg of BSN, 245 g/kg PDN, and 236 g/kg of PUN, low tannin trefoil contained 501 g/kg of BSN, 232 g/kg PDN, and 267 g/kg of PUN, high tannin trefoil contained 456 g/kg of BSN, 218 g/kg PDN, and 327 g/kg of PUN, and red clover with polyphenols contained 370 g/kg of BSN, 299 g/kg PDN, and 331 g/kg of PUN. Averaged over forages, freeze-dried samples contained 332 g/kg of BSN, 374 g/kg PDN, and 294 g/kg of PUN, hays contained 391 g/kg of BSN, 294 g/kg PDN, and 315 g/kg of PUN, and silages contained 671 g/kg of BSN, 65 g/kg PDN, and 264 g/kg of PUN. The impact of tannins and polyphenols on forage N fractions varied considerably between preservation methods. Therefore, forage samples must be conserved in the form they will be fed to accurately characterize the nutritional impact of protein interactions with tanninsand polyphenols