Dietary Tannins Research Articles

An Extract of Sericea Lespedeza Modulates Production of Inflammatory Markers in Pathogen Associated Molecular Pattern (PAMP) Activated Ruminant Blood

<p>Programs based on antibiotics are failing to control diseases due to increase in resistance of pathogens to antibiotics. Food safety, animal welfare and public health concerns have fueled interest in the use of plant-based alternatives. This study was conducted to evaluate the effect of a plant (Sericea Lespedeza, SL), and pathogen associated molecular patterns (PAMPs) (Lipopolysaccharide (LPS) and peptidoglycan (PGN)) on gene activation in ruminant blood. A water extract of SL, was used as a source of plant-derived tannins. Blood was collected from Holstein-Friesian cows (N = 4), Spanish × Boer goats (N = 4), St Croix sheep (N = 4) and incubated with 100 ng/mL of SL in the presence or absence of LPS or PGN. Samples maintained in Phosphate-buffered saline (PBS) served as negative control. The total protein concentration, WNT5a, and prostaglandin E2 in plasma were determined. Total RNA was isolated, reverse transcribed and Real time-PCR was performed using gene specific primers for TLR2, TLR4, WNT5a, and FZD. TLR2 and FZD were up-regulated in response to PAMPs. WNT5a and TLR4 genes were undetected in PAMP treated blood. SL regulated protein and prostaglandin concentration in all species. SL reduced PGE2 in sheep and cow blood. WNT5a was only secreted in LPS treated cow blood. Transcription and translation of genes involved in innate and adaptive immunity and the WNT signaling pathway in ruminant blood were responsive to diverse PAMPS, and can be modulated by SL. This suggests that dietary tannins may promote the health of ruminants. Further studies are needed to determine the significance of these changes in immune gene expression on ruminant health.</p>

Effect of quebracho-chestnut tannin extracts at 2 dietary crude protein levels on performance, rumen fermentation, and nitrogen partitioning in dairy cows

Our objective was to determine the effects of a tannin mixture extract on lactating cow performance, rumen fermentation, and N partitioning, and whether responses were affected by dietary crude protein (CP). The experiment was conducted as a split-plot with 24 Holstein cows (mean ± standard deviation; 669±55kg of body weight; 87±36 d in milk; 8 ruminally cannulated) randomly assigned to a diet of [dry matter (DM) basis] 15.3 or 16.6% CP (whole plot) and 0, 0.45, 0.90, or 1.80% of a tannin mixture in three 4×4 Latin squares within each level of CP (sub-plot). Tannin extract mixture was from quebracho and chestnut trees (2:1 ratio). Dietary CP level did not influence responses to tannin supplementation. A linear decrease in DM intake (25.5 to 23.4kg/d) was found, as well as a linear increase in milk/DM intake (1.62 to 1.75) and a trend for a linear decrease in fat-and-protein-corrected milk (38.4 to 37.1kg/d) with increasing levels of tannin supplementation. In addition, there was a negative linear effect for milk urea N (14.0 to 12.9mg/dL), milk protein yield (1.20 to 1.15kg), and concentration (2.87 to 2.83%). Furthermore, the change in milk protein concentration tended to be quadratic, and predicted maximum was 2.89% for a tannin mixture fed at 0.47% of dietary DM. Tannin supplementation reduced ruminal NH3-N (11.3 to 8.8mg/dL), total branched-chain volatile fatty acid concentration (2.97 to 2.47mol/100mol), DM, organic matter, CP, and neutral detergent fiber digestibility. Dietary tannin had no effect on intake N (587±63g/d), milk N (175±32g/d), or N utilization efficiency (29.7±4.4%). However, feeding tannin extracts linearly increased fecal N excretion (214 to 256g/d), but reduced urinary N (213 to 177g/d) and urinary urea N (141 to 116g/d) excretion. Decreasing dietary CP did not influence milk production, but increased N utilization efficiency (milk N/N intake; 0.27 to 0.33), and decreased milk urea N (15.4 to 11.8mg/dL), ruminal NH3-N (11.0 to 9.3mg/dL), apparent digestibility of DM (66.1 to 62.6%), organic matter (68.2 to 64.3%), and CP (62.9 to 55.9%), as well as urinary N excretion (168 vs. 232g/d). Results of this study indicated beneficial effects of 0.45% tannin extract in the diet on milk protein content. Increasing tannin extract levels in the diet lowered urinary N excretion, but had detrimental effects on DM intake, milk protein content, milk protein yield, and nutrient digestibility.

The Impact of Diet on Expression of Genes Involved in Innate Immunity in Goat Blood

<p>Sericea Lespedeza (SL), is a high-quality, low input forage that suppresses gastro-intestinal parasites in goats. The effect of dietary SL on the expression of genes involved in innate immunity in goats has not been established. The objective of this study was to evaluate the impact of a diet containing SL on the expression of genes involved in innate immunity in goat blood. Blood was collected by jugular venipuncture from goats fed a diet of 75% SL (n = 9) and a control group (n = 7), fed a SL free diet. Blood was used to evaluate expression of (CD-14, TLR-2, TLR-4, IL-10, IL-8, IL-2, INF-r, and TNF-a). Serum was extracted and used for evaluation of the secretion of pro-inflammatory cytokines (TNF-a, IFNr, granulocyte colony stimulating factor (GCSF), granulocyte-macrophage colony-stimulating factor (GMCSF), IL-1a, IL-8, IP-10 and RANTES) using a commercial ELISA kit. The level of gene expression of CD-14, TLR-2, TLR-4, IL-10, IL-8, IL-2, INF-r, and TNF-a was higher in treated animals compared to control. The <em>Sericea Lespedeza</em> diet affected the secretion of pro-inflammatory cytokines by increasing the serum levels of TNF-a, IFNr, GCSF, GMCSF, IL-1a, IP-10 (<em>P</em> < 0.0002), and by decreasing (<em>P</em> < 0.0001) IL-8 and RANTES in blood from goats fed SL. This suggests that dietary tannins modulate gene expression and may affect the goat's innate immune response in blood. Further research is needed to understand and harness the effect of dietary condensed tannins to modulate innate immunity in goats.</p>

Effects of dietary tannic acid on the growth, hepatic gene expression, and antioxidant enzyme activity in Brandt's voles (Microtus brandti).

This study was designed to investigate the physiological and biochemical responses of Brandt's voles to the persistent presence of dietary tannic acid. The diet for animals in the experimental group was supplemented with 3% dietary tannic acid for 5weeks. The control group received a commercial lab chow. No significant differences were detected in body weight, organ (heart, kidney, and liver) weights, and organ parameters between animals from two groups. However, voles in the experimental group had significantly higher daily food intake, increased contents of proline and histidine in saliva and feces after protein hydrolysis, and elevated hepatic expression of transferrin than the control. Our results suggested the existence of adaptive strategies developed in Brandt's voles to overcome the adverse effects of dietary tannic acid. (1) Food consumption was increased to satisfy their nutritional demands. (2) The secretion of tannic-acid-binding salivary proteins was promoted. (3) The absorption of iron was enhanced. These alterations contributed to neutralize the negative effects of tannic acid and maintain body mass in animals supplemented with tannic acid. As the result of the consumption of tannic acid, hepatic expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase was significantly decreased, while the overall potential of the antioxidant system, characterized by increased hepatic enzymatic activities of catalase and glutathione peroxidase, was enhanced. Our results also implied the involvement of tannic acid in the regulation of lipid metabolism and oxidative stress in voles.

Utility of the browser’s behavioural and physiological strategies in coping with dietary tannins: Are exogenous tannin-inactivating treatments necessary?

The desire to reduce feeding costs in small-ruminant production systems has led to increased reliance on non-conventional locally available browse products as protein supplements. Browse products contain variable quantities of tannins, whose nutritional effects on the animal can be positive or negative. Because of the lack of rapid evaluation techniques and methods that can differentiate, accurately, between potentially beneficial and harmful tannins, most researchers employ a 'safety first' approach in which tannin-inactivating treatments are applied to browse products to protect the animal and enhance feed utilization. This is despite the fact that browsing herbivores are known to have various behavioural and physiological strategies to cope with a number of anti-nutritional plant compounds, which include tannins. In this paper, the authors explore the rationale behind recommending the use of tannin-neutralization strategies when feeding animals with browse leaves and fruits. Are browsing herbivores' own coping strategies sufficient to protect them from suboptimal nutrition and possible toxicity caused by tannins or is intervention always required? In an attempt to answer this question, this review presents the current state of knowledge of tannins in ruminant nutrition before summarizing the strategies that browsing herbivores use to cope with tannins and their potential utility in various rearing systems. Finally, the utility of exogenous tannin inactivation strategies and the animals' own coping strategies are compared. Feeding scenarios are identified in which exogenous inactivation strategies may be worthwhile.

Howler Monkeys (Alouatta palliata mexicana) Produce Tannin-Binding Salivary Proteins

Dietary tannins are ubiquitous in woody plants and may have serious negative effects on herbivores by inducing a loss of dietary protein and producing toxins if they are hydrolyzed in the gut. Many herbivorous mammals counter the negative effects of tannins through tannin-binding salivary proteins (TBSPs) that inactivate tannins by forming insoluble complexes and prevent them from interacting with other more valuable proteins. Howlers are the most folivorous New World primates and ingest foods with varying tannin content. We studied the presence of TBSPs in six wild mantled howlers (Alouatta palliata mexicana) immediately after capture and in captivity when fed on two diets composed of natural ingredients: a mixture of fruit and leaves or only leaves. Protein concentration was determined in whole saliva samples, followed by gel electrophoresis. We identified two protein bands of 17 and 25 kDa that have tannin-binding capacity. Although the monkeys ate almost twice as much condensed tannins in the leaf diet than in the fruits and leaves diet (7 vs. 4 g/d dry matter) the salivary protein concentration did not differ between the two diets (leaf diet: 3.29 ± SE 0.82 vs. fruit and leaves diet: 3.42 ± SE 0.62 mg/ml) and we found no additional protein bands in response to either diet. We suggest that the continuous expression of TBSPs is part of a dietary strategy that enables howlers to consume diets with variable tannin contents, thus partly explaining their dietary flexibility. Although the importance of salivary proteins to arboreal primates is broadly accepted, to our knowledge this is the first report of TBSPs in any Neotropical primate.

Response to dietary tannin challenges in view of the browser/grazer dichotomy in an Ethiopian setting: Bonga sheep versus Kaffa goats.

It has been suggested that goats (typical browser) are better adapted to digest tannin-rich diets than sheep (typical grazer). To evaluate this, Bonga sheep and Kaffa goats were used in a 2 × 3 randomized crossover design with two species, three diets, and three periods (15-day adaptation + 7-day collection). The dietary treatments consisted of grass-based hay only (tannin-free diet = FT), a high-tannin diet (36 % Albizia schimperiana (AS) + 9 % Ficus elastica (FE) + 55 % FT (HT)), and HT + polyethylene glycol 6000 (PEG). Animals were individually fed at 50 g dry matter (DM)/kg body weight (BW) and had free access to clean drinking water and mineralized salt licks. Nutrient intake, apparent nutrient digestibility, nutrient conversion ratios, and live weight changes were determined. Condensed tannin concentrations in AS and FE were 110 and 191 g/kg DM, respectively. Both sheep and goats ate 47 % more of HT than FT, and dry matter intake further increased by 9 % when PEG was added, with clear difference in effect size between goats and sheep (P < 0.001). The effects of the tannin-rich diet and PEG addition were similarly positive for DM digestibility between sheep and goats, but crude protein (CP) digestibility was higher in HT + PEG-fed goats than in sheep fed the same diet. However, PEG addition induced a larger improvement in growth performance and feed efficiency ratio in sheep than in goat (P < 0.001). The addition of PEG as a tannin binder improved digestion and performance in both species, but with the highest effect size in sheep.

Effects of tannins on fruit selection in three southern African frugivorous birds

Tannins are common secondary compounds in plant material and are known for their ability to bind to protein which reduces nitrogen availability in the diet. In fruits, these compounds are responsible for their astringency which is thought to result in reduced food intake. In this study, the repellent effects of tannins were examined in three species of frugivorous birds: red-winged starlings Onychognathus morio, speckled mousebirds Colius striatus and Cape white-eyes Zosterops virens. Birds were fed artificial fruit diets containing varying levels of tannins in paired choice tests with the amount of food eaten by birds used to determine preference. Red-winged starlings were attracted to the control diet, indifferent to the medium tannin diet and deterred by the high tannin diet whereas speckled mousebirds and Cape white-eyes were not deterred at all concentrations. The discrepancy in the results was attributed to differences in taste sensitivity, tolerance levels and detoxification mechanisms of secondary compounds between species. Because fruit selection and ultimately fruit removal rates affect plant community composition, the disparity in the results suggests that frugivorous birds do not contribute equally to plant community dynamics. However, plant secondary compounds in fruits are diverse and their effects are similarly diverse and there is potential that different groups of secondary compounds generate disparate effects. Similar studies on other types of secondary compounds may thus contribute towards a broader understanding of the role of secondary compounds in mediating fruit-frugivore interactions.

Genetic and biochemical approaches towards unravelling the degradation of gallotannins by Streptococcus gallolyticus.

BackgroundHerbivores have developed mechanisms to overcome adverse effects of dietary tannins through the presence of tannin-resistant bacteria. Tannin degradation is an unusual characteristic among bacteria. Streptococcus gallolyticus is a common tannin-degrader inhabitant of the gut of herbivores where plant tannins are abundant. The biochemical pathway for tannin degradation followed by S. gallolyticus implies the action of tannase and gallate decarboxylase enzymes to produce pyrogallol, as final product. From these proteins, only a tannase (TanBSg) has been characterized so far, remaining still unknown relevant proteins involved in the degradation of tannins.ResultsIn addition to TanBSg, genome analysis of S. gallolyticus subsp. gallolyticus strains revealed the presence of an additional protein similar to tannases, TanASg (GALLO_0933). Interestingly, this analysis also indicated that only S. gallolyticus strains belonging to the subspecies “gallolyticus” possessed tannase copies. This observation was confirmed by PCR on representative strains from different subspecies. In S. gallolyticus subsp. gallolyticus the genes encoding gallate decarboxylase are clustered together and close to TanBSg, however, TanASg is not located in the vicinity of other genes involved in tannin metabolism. The expression of the genes enconding gallate decarboxylase and the two tannases was induced upon methyl gallate exposure. As TanBSg has been previously characterized, in this work the tannase activity of TanASg was demonstrated in presence of phenolic acid esters. TanASg showed optimum activity at pH 6.0 and 37°C. As compared to the tannin-degrader Lactobacillus plantarum strains, S. gallolyticus presented several advantages for tannin degradation. Most of the L. plantarum strains possessed only one tannase enzyme (TanBLp), whereas all the S. gallolytcius subsp. gallolyticus strains analyzed possesses both TanASg and TanBSg proteins. More interestingly, upon methyl gallate induction, only the tanBLp gene was induced from the L. plantarum tannases; in contrast, both tannase genes were highly induced in S. gallolyticus. Finally, both S. gallolyticus tannase proteins presented higher activity than their L. plantarum counterparts.ConclusionsThe specific features showed by S. gallolyticus subsp. gallolyticus in relation to tannin degradation indicated that strains from this subspecies could be considered so far the best bacterial cellular factories for tannin degradation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0154-8) contains supplementary material, which is available to authorized users.

Induction of salivary proteins modifies measures of both orosensory and postingestive feedback during exposure to a tannic acid diet.

There are hundreds of proteins in saliva. Although it has long been hypothesized that these proteins modulate taste by interacting with taste receptors or taste stimuli, the functional impact of these proteins on feeding remains relatively unexplored. We have developed a new technique for saliva collection that does not interfere with daily behavioral testing and allows us to explore the relationship between feeding behavior and salivary protein expression. First, we monitored the alterations in salivary protein expression while simultaneously monitoring the animals' feeding behavior and meal patterns on a custom control diet or on the same diet mixed with 3% tannic acid. We demonstrated that six protein bands increased in density with dietary tannic acid exposure. Several of these bands were significantly correlated with behaviors thought to represent both orosensory and postingestive signaling. In a follow-up experiment, unconditioned licking to 0.01–3% tannic acid solutions was measured during a brief-access taste test before and after exposure to the tannic acid diet. In this experiment, rats with salivary proteins upregulated found the tannin solution less aversive (i.e., licked more) than those in the control condition. These data suggest a role for salivary proteins in mediating changes in both orosensory and postingestive feedback.

Exploitation of tannins to modulate rumen ecosystem and ruminants performance: A review

Tannins are polyphenolic polymers of relatively high molecular weight with the capacity to form complexes mainly with proteins due to the presence of a large number of phenolic hydroxyl groups. They are widely distributed in nutritionally important forage trees, shrubs and legumes, cereals and grains, which are considered as anti-nutritional compounds due to their adverse effects on intake and animal performance. However, tannins modulate rumen fermentation favorably such as reducing protein degradation in the rumen, prevention of bloat, inhibition of methanogenesis and increasing conjugated linoleic acid concentrations in ruminant-derived foods. The inclusion of tannins in diets has been shown to improve body weight and wool growth, milk yields and reproductive performance. This review discusses the effects of tannins on nutrient metabolism, rumen fermentation, and microbial populations bacteria, protozoa, fungi and archaea), metabolism of tannins, microbial tolerance mechanisms to tannins, inhibition of methanogenesis, and performance of animals. This review seeks to highlight the practical significance of tannins on ruminant nutrition in developing countries. It will also review approaches to counter the negative effects of tannins.

The bilateral parotidomegaly (hypertrophy) induced by acorn consumption in pigs is dependent on individual׳s age but not on intake duration

Polyphenolic compounds, namely dietary tannins, are biologically active substances capable to induce an increased proline rich proteins (PRPs) content in the salivary secretions of the parotid gland, in different animal species and in man. In general terms, a pulsed increased secretion of salivary PRPs could be observed mainly in browsing animal species and to a lesser extent in grazers, which rely on an evolutionary adaptation to cope with seasonal feeding stuffs, varying in tannin content. Therefore, PRPs secretion might appear to be a first line of defense from severe intoxications, which can occur in animals incapable to code for tannin binding proteins (TBP) in the saliva. Pigs appeared to be tolerant to high intake of raw acorns, known to be rich in hydrolysable tannins. The parotid gland (PG) response to an experimental acorn combined diet (50% inclusion of raw shredded acorns in the diet, as fed, high in hydrolysable tannins: 25g tannic acid equivalents TAE/kg dry matter in the diet) offered to pigs (growing vs. finishing pigs) was studied and compared to the morphometry and functional activity of the PG in pigs fed on a control conventional diet (0% acorns in the diet). A total of 32 cross-bred pigs were involved in two feeding trials (1 vs. 4 weeks of experimental feeding) and divided into groups according to the experimental diets (0% vs. 50% acorns included in the diet). The bilateral parotidomegaly (hypertrophy of the parotid gland) occurred constantly and significantly (p<0.01) in the totality of pigs fed with the acorn combined diets, displaying different extents of hypertrophy, according to the age of the pigs: growers, 2–3 folds of the control PG vs. finishers, 1.30–1.40 folds of the respective control PG, either after an exposure of 1 or 4 weeks. No statistic significance could be pointed out after 1 week vs. 4 weeks of experimental feeding, testing on a tannin concentration of 25g TAE/kg DM from acorns in the diet offered, either to growers and to finishers. The morphometry and functionality of the PG is more strongly stimulated in the growing pigs than observed in the finishing pigs, independently of the duration of consumption of the acorn combined diet, rich in hydrolysable tannins.

RUMINAL BIOHYDROGENATION PATTERN OF POLY-UNSATURATED FATTY ACID AS INFLUENCED BY DIETARY TANNIN

Abstract Large amounts of polyunsaturated fatty acids undergo transformation processes in the rumen through microbial biohydrogenation to form fatty acids with higher saturation degree. The respective process explains the high content of saturated fatty acids in products of ruminants and the potential risk of consumers’ health by consuming such products. Various nutritional approaches have been attempted to modulate biohydrogenation process in order to obtain healthier fatty acid profile from consumers’ perspective. The present paper is aimed to review the influence of dietary tannin, a naturally produced plant secondary compound, on the pattern of polyunsaturated fatty acids biohydrogenation occurring in the rumen. The effect of tannin on some key fatty acids involved in biohydrogenation process is presented together with the underlying mechanisms, particularly from up-to-date research results. Accordingly, different form of tannin as well as different level of the application are also discussed. Key words: Tannin, biohydrogenation, fatty acid, ruminant

Effects of Fruit By-product Extracts Supplementation on Growth Performance and Nutrient Digestibility in Growing Pigs

ABSTRACT A total of 96 pigs [(Landrace × Yorkshire) × Duroc] with an initial BW of 27.94 ± 0.92 kg were used in a 6-week experiment to determine the effects of dietary supplementation with fruit by-product extracts on growth performance and nutrient digestibility in growing pigs. Pigs were randomly allotted to four treatments : 1) CON (basal diet), 2) PRO (CON + 0.5% procyanidin), 3) HES (CON + 0.5% hesperidin), 4) TAN (CON + 0.5% tannin). There were six replications per treatment with four pigs per pen. Supplementation had no effect ( p >0.05) on average daily gain, average daily feed intake, and G/F. The apparent total tract digestibility (ATTD) of dry matter and nitrogen was increased ( p <0.05) in the HES treatment relative to the PRO treatment. Pigs fed the HES and TAN diets had greater ( p <0.05) ATTD of energy than pigs fed PRO diet. The ATTD of ash was greatest( p <0.05) in HES treatments. In addition, the ATTD of calcium was greater ( p <0.05) in HES treatments than in CON and PRO treatments. Overall, the results of this study indicated that dietary supplementation with 0.5% fruit by-products did not affect growth performance, but inclusion of 0.5% hesperidin increased nutrient digestibility in growing pigs.(

Tannic acid-dependent modulation of selected Lactobacillus plantarum traits linked to gastrointestinal survival.

BackgroundOwing to its antimicrobial properties dietary tannins may alter the functional efficacy of probiotic lactobacilli in the gastrointestinal (GI)-tract influencing their growth, viability and molecular adaptation to the intestinal environment.Methods and FindingsThe effects of tannic acid on Lactobacillus plantarum WCFS1 were studied by in vitro growth monitoring and visualizing the morphological alteration on the cell wall using transmission electron microscopy. Growth upon tannic acid was characterized by dose-dependent reductions of initial viable counts and extended lag phases. Lag phase-cells growing upon 0.5 mM tannic acid were abnormally shaped and experienced disturbance on the cell wall such as roughness, occasional leakage and release of cell debris, but resumed growth later at tannic acid concentrations high as 2.5 mM. To gain insight on how the response to tannic acid influenced the molecular adaptation of L. plantarum to the GI-tract conditions, gene expression of selected biomarkers for GI-survival was assessed by RT-qPCR on cDNA templates synthetized from mRNA samples obtained from cells treated with 0.5 or 2 mM tannic acid. Tannic acid-dependent gene induction was confirmed for selected genes highly expressed in the gut or with confirmed roles in GI-survival. No differential expression was observed for the pbp2A gene, a biomarker negatively related with GI-survival. However PBP2A was not labeled by Bocillin FL, a fluorescent dye-labeled penicillin V derivative, in the presence of tannic acid which suggests for enhanced GI-survival reportedly associated with the inactivation of this function.ConclusionsProbiotic L. plantarum WCFS1 is able to overcome the toxic effects of tannic acid. This dietary constituent modulates molecular traits linked to the adaptation to intestinal environment in ways previously shown to enhance GI-survival.

Pigs use endogenous proline to cope with acorn (Quercus pubescens Willd.) combined diets high in hydrolysable tannins

Detrimental effects due to high intake of dietary tannins are described in the literature in different animal species after acorn (fruit of Genus Quercus) ingestion. By contrast, pigs seem to tolerate dietary regimes with considerable amounts of acorns. This study investigates whether the esophageal mucosa (pars non glandularis) of the stomach might be a susceptible target for the onset of injuries and whether salivary proline rich proteins (PRPs) can be a valid defense to preserve its integrity, when a large amount of ripe shredded acorns (Quercus pubescens Willd.) is combined in the diet for growing pigs. A matched pair approach was used to divide a total of 16 crossbred growing pigs (14.2–27.6kg BW) into 2 groups (n=4 in each, homogeneous for BW) for 8 days of experimental feeding (two replicates): the control group was fed with a conventional complete diet for pigs (pelleted; 890g DM/kg; based on cereals and soybean meal). The acorn-fed group was offered a combined diet, 70% of ripe shredded acorns (612g DM/kg of fresh matter; Tannic Acid Equivalent, 0.516g TAE/kg DM) and 30% of the complete pelleted diet, as fed. Stomach ingesta were analyzed for chemical composition and proline content; on gross inspection, the gastric mucosa was exteriorized and scored (on a 0–5 point scale) for prevalence and severity of injuries. A sort of “tanning effect” underlined the edges of the cardiac gland region (CGR) in all the stomachs from the acorn-fed group, inducing to consider the high affinity of acorn tannins for PRP, such as gastric mucins. No signs of injury could be identified after both dietary treatments. The differential between the dietary proline intake and proline content in the stomach constantly showed a negative value (−46.1±9.72%) in the acorn-fed group, in contrast to the positive disappearance of proline in control group (39.3±25.4%). Therefore, endogenous proline for “buffering” purposes was considered to be a defense mechanism, either as a salivary or gastric mucus component.

Short- to medium-term effects of consumption of quebracho tannins on saliva production and composition in sheep and goats1

Eight Merino sheep (49.4 ± 4.23 kg BW) and 8 Alpine goats (53.2 ± 2.51 kg BW) were used to study the effect of ingestion of quebracho tannins on salivation. Four sheep and 4 goats were individually fed a daily allotment of 20 g DM of alfalfa hay/kg BW (Control). Another 4 sheep and 4 goats were also given 20 g DM of alfalfa hay/kg BW supplemented with 50 g of quebracho/kg DM (Tannin) for a period of 64 d. The saliva secretion from the left parotid gland was collected by insertion of a polyvinyl chloride catheter into the parotid duct and the amount of parotid saliva produced recorded over three 48-h periods on d 1 and 2 (P1), d 31 and 32 (P2), and d 61 and 62 (P3) after the tannin feeding was initiated. The total amount of saliva produced was estimated from rumen water kinetics determined on d 4, d 34, and d 64 of the experiment. Experimental design was completely randomized, with repeated measures on each experimental unit, performing separate analysis for sheep and goats. Parotid saliva production was not affected by the sampling period in either animal species receiving the Control diet. Corresponding values for sheep were 2.04, 2.12, and 2.27 L/d (P = 0.89) and for goats 1.65, 1.79, and 1.86 L/d (P = 0.95). Sheep fed the Tannin diet produced 55, 73, and 107% of the amount of saliva recorded in sheep fed the Control diet on P1, P2, or P3, respectively. Corresponding values in goats were 88, 130, and 134% on P1, P2, or P3, respectively. Estimated total saliva production was not affected (P = 0.50 for sheep and P = 0.97 for goats) by the ingestion of quebracho. There was no difference (P > 0.10) in osmotic pressure, P, Mg, Ca, urea, and protein concentrations in parotid saliva. There were, however, differences in Na and K concentrations in response to the ingestion of quebracho tannins, with Na concentrations increasing (P = 0.05) and K concentrations decreasing (P = 0.04) in sheep saliva and pH increasing (P = 0.05) in goat saliva. In conclusion, the inclusion of quebracho at 50 g/kg DM for 64 d does not appear to alter saliva production in sheep and goats.

Tropical tannin-rich fodder intake modifies saliva-binding capacity in growing sheep

We evaluated the effect of feeding dietary tannins from Lysiloma latisiliquum fresh forage on the saliva tannin-binding capacity of hair sheep lambs without previous exposure to tannin-rich (TR) fodder. Twenty-four hair sheep lambs (13.6±3.04 kg LW) were fed a tannin-free diet at the beginning of the experimental period (from day 10 to 13). On day 14, lambs were distributed into three groups (n=8): control group (CG), fed with the tannin-free diet (from D10 to D112); tannin short-term group (TST), fed the basal diet and 650 g of L. latisiliquum forage (from D14 to D55); tannin long-term group (TLT), fed the basal diet and 650 g of L. latisiliquum forage (from D14 to D112). Saliva samples were collected from the mouth of each lamb in the morning before feeding time on D10 and D14 (baseline period), on D49 and D56 (period 1) and on D97 and D112 (period 2). The tannin binding response of salivary protein (∆% turbidity) was determined with the haze development test (HDT) using either tannic acid or L. latisiliquum forage acetone extract. A turbidity protein index (TPI) was calculated as (∆% turbidity/[salivary protein (mg)]). Differences in HDT and TPI in the different groups were compared by repeated measures ANOVA using Proc Mixed. All groups had similar ∆% turbidity throughout the experiment (P>0.05). At baseline and period 1, the TPI of the different groups was similar (P>0.05). On period 2 the TLT group showed higher TPI compared with CG (P<0.05). Meanwhile, CG and TST showed similar salivary TPI. The saliva of hair sheep lambs consuming TR L. latisiliquum fresh fodder (TLT group) increased their TPI compared with control lambs not exposed to tannins.

Effect of the inclusion of quebracho tannins in a diet rich in linoleic acid on milk fatty acid composition in dairy ewes

Despite controversy surrounding the ability of tannins to modulate the fatty acid (FA) profile of ruminant-derived products, reports on this issue are still very limited for dairy sheep. This study was conducted to examine the effect of the inclusion of quebracho tannins in a diet rich in linoleic acid on ewe performance and milk FA composition. Thirty-six lactating ewes were distributed into 6 lots and allocated to 2 treatments (3 lots/treatment): control or quebracho. All sheep received a total mixed ration based on alfalfa hay and a concentrate (forage:concentrate ratio of 40:60) supplemented with 20g of sunflower oil/kg of dry matter plus 0 (control diet) or 20g of an extract of quebracho tannins/kg of dry matter (QUE diet). Milk production and composition were analyzed on d 0, 3, 6, 9, 12, 15, 18, 21, 24, and 27 on treatments, and milk FA profile on d 0, 3, 6, 12, 18, and 27. On d 27, samples of rumen fluid were collected for pH, and lactate, ammonia, and volatile FA concentration analysis. Feeding the QUE diet had no apparent effect on animal performance and hardly modified ruminal fermentation characteristics, except for a reduction in the molar proportions of minor volatile FA. Dietary tannins increased the milk concentration of several 18:1 and 18:2 isomers and decreased that of branched-chain FA. Some of these changes were relatively constant throughout the experiment (e.g., cis-12 18:1 and trans-9,cis-12 18:2), whereas others varied over time (e.g., trans-10 18:1, which increased gradually with the QUE diet). Significant differences between treatments in trans-11 18:1 and cis-9,trans-11 conjugated linoleic acid were only observed on d 3. Overall, addition of quebracho tannins to a diet rich in linoleic acid did not prove useful to beneficially modify milk FA composition, especially over the long term.

Effect of dietary protein level and quebracho tannin on consumption of pine needles (Pinus ponderosa) by beef cows

<h2>ABSTRACT</h2> Ponderosa pine trees occupy over 15 million hectares of rangeland in western North America. Pregnant cows often consume pine needles (PN), and subsequently abort. The protein-to-energy ratio may be important in the ability of cattle to tolerate dietary terpenes. Tannins often co-occur with terpenes and may also influence diet selection. The objective of this experiment was to determine if the protein-to-energy ratio or the addition of quebracho tannin to cattle diets would influence PN consumption. In trial 1, 15 cows in moderate body condition were assigned to high (15.4% CP), medium (10.2% CP), or low (4.9% CP) dietary protein treatments for 12 d. In trial 2, 15 cows were assigned to high (5%), medium (2.5%), or no (0%) quebracho tannin diets for 8 d. In both trials, green PN were offered at 0930 h for 90 min. There was a treatment effect (P = 0.05) and a treatment × day interaction (P = 0.01) for PN consumption, as cattle on the high CP treatment consumed more PN than cattle on the medium and low CP diets for 4 and 6 d, respectively. Initially, treatments did not differ (P > 0.09), but from d 3 to 9 cattle on the high CP treatment ate more PN than the other treatments. There was a day × treatment interaction (P = 0.002) for PN consumption; cattle on the 2.5% tannin treatment consumed less PN than did animals on the other treatments. Cattle are apparently unable to tolerate high quantities of PN terpenes on a low-protein diet. Tannins may influence PN consumption, but the mechanism is unknown.