Factors affecting in vitro formation of tannin‐protein complexes

Abstract

In interaction of condensed tannins from Desmodium intortum and Lotus pedunculatus and tannic acid (hydrolysable tannin) with salivary mucoproteins (from sheep and goats), plant leaf proteins and bovine serum albumin were evaluated. These studies were carried out over a p H range of 2.0-9.0 and different inorganic ion conditions to simulate conditions in which dietary proteins would interact with tannins in a ruminant digestive tract. Insoluble tanninprotein interactions were found at pH 4.5-5.5 for bovine serum albumin and 3.5-5.5 for plant leaf protein. The present study showed that pH alone was not the sole determinant for tannin-protein complex formation, since tannin-protein complexation was found in the pH range 6.0-6.5 when different inorganic ions were added to the solutions. Insoluble complexes were not formed with salivary proteins, although precipitation by tannic acid was achieved at 5°C. This suggests that tannins may form soluble rather than insoluble complexes with salivary proteins. It was concluded that purified F1 leaf protein (the major protei occurring in leaf tissue) ought to be used as the test protein for evaluating tannin-protein interactions for in uitro assay procedures. Using this method it was calculated that 27-43% and 19-40Y0 of available plant protein may interact with condensed tannins from Desmodium intorturn and Lotus pedunculatus, respectively.

Comparison of the Precipitation of Alfalfa Leaf Protein and Bovine Serum Albumin by Tannins in the Radial Diffusion Method

“…Neither puriÐed CT from quebracho nor hydrolysable tannins from TA precipitated AALP at either protein level. These results agreed with those of Perez-Maldonado et al (1995), who found that more plant leaf protein was precipitated by CT from Desmodium intortum and L otus pedunculatus than by TA when samples were incubated in a ruminal environment. TA and puriÐed CT from quebracho precipitated more BSA than puriÐed CT from forages.…”

Effect of different drying systems for the conservation of olive leaves on their nutritive value for ruminants

“…Their response to drying more closely resembled the forage samples studied by Mahyuddin et al [13]. In particular, crude protein digestibility was found to be zero in three of the conserved samples and much reduced in others, implying the formation of a more stable complex than is typical of tannin-protein interactions [20] It was suggested previously that removal of leaves from twigs and branches had a negative effect on both OMD and CPD [8]. Although removal of leaves might, in the short term, promote autolysis and loss of cell content, there is little to suggest that this is significant in the longer term.…”

Effect of additives on fermentation of cassava leaf silage and ruminal fluid of west african dwarf goats

“…The contents were reduced in the period of ensiling, and may relate to the formation of tannin-protein complexes. Maldonado et al (1995) reported that insoluble tannin and plant leaf protein complex was established in the pH range of 3.5-5.5. In ensiling sorghum, Rodriguez et al (1998) reported that tannin concentration decreased with increase in the duration of fermentation.…”