Use of Tannin-Binding Chemicals to Assay for Tannis and Their Negative Postingestive Effects in Ruminants

Animal Feed Science and Technology (Impact Factor: 2). 04/2001; 91(1):60-81. DOI: 10.1016/S0377-8401(01)00234-6
Source: OAI


Synthetic polymers such as water-soluble polyvinyl pyrrolidone (PVP), water-insoluble polyvinyl polypyrrolidone (PVPP), and water-soluble polyethylene glycol (PEG) contain sufficient oxygen molecules in a chain to form strong hydrogen bonds with the phenolic and hydroxyl groups in tannins. This review deals with the practical uses of tannin-binding agents, particularly PEG, in tannins assays and for determining the negative effects of tannins on feed intake and digestion in ruminants. A gravimetric method to assay tannins by precipitation with PVPP is specific for tannins and does not require standards. The extractability of tannins from plant tissues can be reduced by drying samples at temperatures above 50°C and is dependent on many other factors, such as content and types of plant proteins. Therefore, it is not feasible to recommend a single, optimal protocol for all plant samples. A method to assay tannins which is based on measuring the amount of binding of PEG to plant samples was shown to be simple and accurate. It can also overcome some of these extractability problems. The following biological effects of tannins were investigated in studies where tannin anti-nutritional effects were partially or completely neutralised by varying levels of PEG supplementation. (1) Effects on appetite: the negative effects of tannins on appetite can occur in the short-term (within 20-60 min) and the long-term (days and weeks), Astringency and adverse postingestive influences of tannins on the epithelium of the oral cavity and the foregut cause short-term effects on food intake. Long-term effects can be related to reduction in the concentration of ammonia and volatile fatty acids (VFA) in rumen fluids, which can in turn serve as metabolic cues for deficiency of nitrogen (ammonia), energy (VFA), or both. (2) Effects on digestion: increasing content of tannins in foliage can be associated with an increase in bound protein and with reduced degradation rate of the degradable matter in the rumen, but there is no corresponding increase of the non-degradable fraction. Consequently, organic matter, protein, and cell wall digestibility are inversely related to tannin concentrations. (3) Inducing digestive responses: if a significant amount of tannins reach the duodenum, they may markedly reduce the intestinal activity of pancreatic enzymes (trypsin and amylase) and amino acids absorption from the intestine. Condensed tannins can also reduce the content of fluid and particulate matter in the rumen, accelerate the passage of liquid from the abomasum, and delay the passage of digesta in the intestine. The overall effect is a delay in the passage of fluid and particulate matter throughout the entire gastrointestinal tract. It is hypothesised that these responses are largely the consequence of the interaction of tannins with digestive enzymes and the epithelium lining the digestive tract.

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    • "Neither fixation nor embedding in PEG alters the histochemical results, with the exception of the false-negative results obtained when using T3 for the detection of polyphenols, lignins and flavonoidic derivatives. This was most likely attributed to the precipitation of phenols and tannins (Henning 2002) through strong hydrogen bonds between hydroxyl groups in phenols and PEG (Silanikove et al. 2001). Patel and Foss (1964) showed that PEG molecules bind with phenols, and Gehrig et al. (2000) described a protocol of RNA (ribonucleic acid) extraction that uses PEG to remove an excess of polyphenols. "
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    ABSTRACT: Histochemical analyses in plants are commonly performed on hand-made sections of fresh materials. The disadvantages of embedding in historesin, paraffin or paraplast® are the alterations of cellular contents, high costs and few evident results, depending on the test. The polyethylene-glycol (PEG), as a low cost, hydrophilic medium, that maintains most of the cell features similar to fresh conditions, may be useful for obtaining good histochemical results in thinner and homogeneous sections. The current study aims to compare the efficiency of PEG as an embedding medium for histochemical analyses of primary and secondary metabolites accumulation, with hand-made sections of fresh samples (T1). Also, the influence of the use of Karnovsky’s solution as a fixative (T2) was tested, and compared to the embedding in PEG (T3). The samples herein analyzed comprise leaves, stems, seeds and insect galls of different plant species. Neither the Karnovsky's fixative nor the embedding in PEG altered the histochemical results for starch, lipids, terpenoids, proteins and reducing sugars for the results in T1, T2, and T3. However, the PEG binds to phenols as tannins, flavonoids and lignins, presenting false negatives in T3.
    Journal of Histochemistry and Cytochemistry 08/2014; 62(8):577-583. DOI:10.1369/0022155414538265 · 1.96 Impact Factor
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    • "Although fodder trees have such important nutritional merits, there are also reports that most tropical browse plants has been found to contain some secondary compounds having anti-nutritional property that may limit their wider utilization and nutritional potential (Melaku 2001; Aganga and Tshwenyane 2003; Assefa 2007). For instance, high level of tannin in forages reduced digestibility of CP (Silanikove et al. 2001) and lower carcass yield and quality (Priolo et al. 2005). Production of herbaceous and tree forage legumes through integration with food or cash crops to serve as supplemental feeds can be among the potential options to improve nutrient supply to livestock (Alemayehu 2006). "
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    ABSTRACT: Abstracts Twenty-four yearling male local Washera lambs with an average initial body weight of 18.14 ± 1.07 kg were used to assess the nutritional value of Millettia ferruginea. Experimental animals were grouped into six blocks of four animals, and each animal was randomly assigned to one of the four dietary treatment feeds. The treatments used were; Sole natural pasture grass hay (T1), and 150, 300, 450 g DM Millettia ferruginea leaf hay with ad libitum natural pasture grass hay assigned for (T2), (T3) and (T4), respectively. The feeding trial was carried out for 80 days followed by a 10 days of digestibility trial. Carcasses of each experimental animal were evaluated at the end of the digestibility experiment. Millettia ferruginea leaf hay had 224.6, 556.6, 360.7and 127.4 g/kg crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL), respectively. The average intakes of Millettia ferruginea leaf hay were 0, 133, 263 and 253 g/day for T1, T2, T3 and T4, in that order. The proportions of Millettia ferruginea leaf hay intake from the total dry matter (DM) were 0, 23.5, 44.1, and 43.3% for T1, T2, T3 and T4, respectively. The total DM intake was not significant but showed a trend of T1 > T3 > T4 > T2. CP intake was higher for T3 and T4 with the least intake for T1. Final body weight measurement was higher for T3 and T1 but lower and negative for T2 and T4. Generally, body weight measurements were not consistent in the supplemented groups throughout the trial period. The weight of heart, spleen, and liver were higher for the supplemented groups compared to the sole grass hay. From the results of the current study, it can be concluded that, Millettia ferruginea had some limiting factors, which prevented the animal from efficiently utilize it. Therefore, this study revealed the indispensable role of animal feeding experiments with target animals to examine such impacts.
    SpringerPlus 01/2014; 3(1):50. DOI:10.1186/2193-1801-3-50
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    • "Corresponding author: carbohydrates and starches, thereby decreasing their ruminal degradation (McSweeney et al., 2001; Silanikove et al., 2001). Tannins are divided into two major groups: hydrolyzable and condensed tannins. "
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    ABSTRACT: The purpose of this study was to evaluate the voluntary intake and digestibility of three sorghum (Sorghum bicolor, L. Moench) hybrid silages in sheep. The hybrids used were H1-BRS 655 (CMSXS 222 A × CMSXS 235 R), with tannin; H2-(ATF54 A × CMSXS 235 R), without tannin; and H3-BRS 610 (CMSXS 232 A × CMSXS 234 R), without tannin. The intake and digestibility of dry matter (DM), gross energy (GE), neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP) were measured. Eighteen crossbred sheep weighing 59.4 kg (±8.3) were used in the trial. A completely randomized design with three treatments (hybrids) and six repetitions (sheep) was used. There were no differences in the DM intake or apparent digestibility among the hybrids. Silage of hybrid BRS 610 displayed higher digestibility coefficients for CP, NDF, ADF, and GE compared with the other silages, which did not differ from each other. The neutral detergent fiber, ADF and digestible energy (DE) intakes were similar among the hybrids silages. All of the hybrids resulted in a positive N balance in sheep. The levels of DE were superior in hybrid silage BRS 610 in comparison with the other hybrids. Sorghum hybrid BRS 610 silage exhibited superior nutritional value compared with the other hybrids, which is most likely in part due to the absence of tannins. Sorghum silage made with hybrid BRS 610 (CMSXS 232 A × CMSXS 234 R) presents superior gross energy, crude protein, neutral detergent fiber and acid detergent fiber digestibility coefficients, as well as greater digestible energy levels than BRS 655 (CMSXS 222 A × CMSXS 235 R) and (ATF54 A × CMSXS 235 R).
    Revista Brasileira de Zootecnia 01/2014; 43(1):14-19. DOI:10.1590/S1516-35982014000100003 · 0.36 Impact Factor
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