Interactions of polyethylene glycol and polyvinyl pyrrolidone of various molecular weights with tannins and their uses in nutritional evaluation of tannin-rich feeds and fodders

acide gras alcoholes alcohols alcool arbre arbuste arbustos complexation complexing crude fibre digestibilidad digestibility evaluation fatty acids feuille fibra bruta fibre brute hojas in vitro experimentation in vivo experimentation leaves molecular weight nutritive value organic matter peso molecular ph polimeros polymere polymers proteine proteins shrubs taninos tannin tannins trees tropical zones valeur nutritive valor nutritivo zona tropical zone tropicale