Addition Of Tannins Research Articles

Impact of Condensed Tannin and Sulfur Dioxide Addition on Acetaldehyde Accumulation and Anthocyanin Profile of Vitis vinifera L. Cv. Cabernet Sauvignon Wines During Alcoholic Fermentation

Acetaldehyde is a key carbonyl by-product during red wine alcoholic fermentation; it is reactive and takes part in certain reactions involving anthocyanin. The aim of this study was to investigate the influence of SO2 and condensed tannin on the acetaldehyde accumulation of Saccharomyces cerevisiae (S. cerevisiae) during alcoholic fermentation and the ripple effect on wine anthocyanin. In this study, six sets of Cabernet Sauvignon alcoholic fermentation with two different sulfur levels (HS and LS) were carried out by adding exogenous condensed tannins before fermentation (T0) in the acetaldehyde rise period (TA) of S. cerevisiae and at the end of fermentation (TE), separately. The acetaldehyde evolution was identified during fermentation and anthocyanin was analyzed comparatively. The results showed that HS treatment slowed down the degradation of acetaldehyde, while tannins accelerated the degradation of acetaldehyde during alcoholic fermentation, especially TA wines. Furthermore, TA wines possessed a unique anthocyanin profile after fermentation regardless of SO2 level compared with other wines. These results suggest that acetaldehyde-mediated anthocyanin polymerization most likely occurs timely at the acetaldehyde production phase of S. cerevisiae during alcoholic fermentation, and managing tannin addition time during production could be used to regulate the anthocyanin profile.

The influence of tannin on the improvement of adhesive properties of urea-formaldehyde resin

This study aimed to examine the properties of urea-formaldehyde (UF) adhesive with the addition of tannin, to determine whether it is possible to obtain so-called, bio-adhesives for wood with better mechanical properties compared to commercial UF. Tannin-based UF resins, with four different concentrations of tannin (5, 10, 15, and 20%), were prepared, and adhesive properties were tested and compared with properties of pure UF. Testing of tensile shear strength showed that the addition of tannin in UF adhesive formulation significantly increases its performance compared to pure UF adhesive. It was found that tensile shear strength increased with increasing concentration of tannin, while UF-tannin adhesives with tannin concentrations of 15% and 20% showed higher tensile shear strength than the corresponding pure UF adhesive. Therefore, it can be concluded that tannin-based UF adhesive can be a good candidate for application as an environmentally-friendly wood adhesive due to improvement in terms of adhesive and mechanical properties.

Evaluation of increasing levels of condensed tannin extracted from Acacia mearnsii on performance, carcass traits, meat quality, methane emission, and health of finishing Nellore bulls

The objective of this study was to evaluate the impact of increasing levels of condensed tannin extracted from Acacia mearnsii on the performance, carcass traits, meat quality, methane (CH4) emissions, and health of finishing Nellore bulls in a feedlot system. Eighty 20-month-old Nellore bulls (426.7 ± 24.46 kg of body weight (BW)) were individually housed with ad libitum access to feed and water. The study followed a completely randomized design with five treatments, each consisting of sixteen animals. Treatments included a negative control (no additives), 3 levels of tannin (0.8, 1.6, and 3.2 g of tannin/kg DM; Tanfeed®, Tanac Company), and a positive control (28 mg/kg DM monensin; Elanco®). Animals underwent a 21-day adaptation period with three step-up adaptation diets before entering the 89-day finishing phase. The adaptation dietary program consisted of ad libitum feeding with 3 adaptation diets over 21 days, in which the finishing phase lasted 89 days. The adaptation dietary program consisted of ad libitum feeding of 3 step-up adaptation diets for 3 weeks (21 d). The concentrate level of the diet (DM basis) increased from 40 % to 50 % in week 1, 50–56 % in week 2, and 56–75 % in week 3 (finishing diet). The experimental period (adaptation + finishing phases) lasted 110 d. The diet was formulated to meet the requirements while considering an average daily gain (ADG) of 1.6 kg/d. Enteric CH4 emissions were estimated using the sulfur hexafluoride (SF6) tracer gas technique. Performance and carcass traits, except for shear force and ash in meat, were not affected by increasing levels of dietary tannin or monensin (P>0.10). Regression analysis indicated a quadratic effect on shear force, with the lowest value observed at 1.6 g/kg DM of dietary tannin inclusion (P=0.05). Ash in meat increased quadratically with tannin inclusion, peaking at 1.6 g/kg DM of tannin addition, differing from monensin-treated bulls (P=0.05). However, CH4 emission as g/d decreased quadratically with increasing tannin levels (P<0.01), reaching the lowest emission at 0.8 g/kg DM of tannin inclusion, differing from monensin treatment (P<0.01). Also, CH4 emission intensity (g/kg DMI at CH4 sampling period) tended to decrease quadratically with tannin inclusion (P=0.09), with the lowest intensity observed at 0.8 g/kg DM of tannin inclusion, but not differing from monensin-treated bulls. Liver abscess and rumen scores were not impacted by tannin level in the diet (P = 0.26 and 0.19, respectively); however, the odds of having a liver (0 to A+ scale) and ruminitis score (0-10 scale) of 0 was 0.178 less for monensin-treated bulls compared to control and 0.224 less for monensin than tannin-treated bulls at 3.2 g/kg DM of inclusion, respectively. Overall, condensed tannin effectively reduced meat shear force and CH4 emissionin finishing Nellore bulls in a dose-dependent manner, without detrimental effects on performance.

Effects of Tannin Supplementation in Diet on the Resistance to Ammonia Stress of Pacific White Shrimp Litopenaeus vannamei

Tannin (TA), as a natural phenolic compound with strong antioxidant activity, has been used as a feed additive for various animals. In this study, we fed a diet containing 800 mg/kg of tannin on Litopenaeus vannamei for 56 days and then subjected to acute ammonia stress for 48 hr to investigate the effect of dietary tannin on the ammonia stress response of L. vannamei through transcriptomic and metabolomic analysis. The transcriptome analysis indicated that ammonia stress-induced differential expression of 4,185 genes, while tannin-fed shrimp only had 964 differentially expressed genes. Compared with the TA_0 group, 59 pathways were significantly altered, and the pathways of “starch and sucrose metabolism,” “retinol metabolism,” “arachidonic acid metabolism,” “lysosome,” and “amino sugar and nucleotide sugar metabolism” were highly enriched in the TS_0 group. Compared with the TS_0 group, six pathways were significantly altered, and the pathways of “dilated cardiomyopathy,” “complement and coagulation cascades,” “cardiac muscle contraction,” “fructose and mannose metabolism,” “cGMP-PKG signaling pathway,” and “beta-alanine metabolism” were significantly enriched in the TS_800 group. Metabolomic analysis showed that a total of 107 differential metabolites (DMs) were identified in the TS_0 vs. TA_0 group, while 75 DMs were identified in the TS_800 vs. TS_0 group. Based on KEGG annotation, it was found that a large amount of DM was significantly enriched in amino acid metabolism pathways in the TS_0 group, including “arginine and proline metabolism,” “alanine, aspartic acid, and glutamic acid metabolism,” “β-Alanine metabolism and tyrosine metabolism” indicated that tannins affect the metabolism of amino acids. The integration of DEGs and DMs indicates that dietary tannins highly alter the digestion and absorption functions of proteins, as well as the biosynthesis and metabolism of amino acids. This study provides new insights into the adaptation of Pacific white shrimp to ammonia stress and the addition of tannins to feed to enhance immune function.

Chestnut Wood Tannins in Broiler Diets: Pharmacokinetics, Serum Levels during Rearing, and Intestinal Absorption Pattern of Gallic Acid.

Studies on the bioavailability, serum levels, and absorption of hydrolyzable tannin compounds are lacking. In this study, we performed a pharmacokinetic trial, measured the serum levels of compounds in broilers that were reared with different feed added or not with tannins, and tested the digestibility of tannins throughout the intestinal tract. Only gallic acid and 4-O-methyl gallic acid were found in the serum. Moreover, gallic acid showed a 41.8% absolute oral bioavailability and a 72.3% relative bioavailability of gallic acid from chestnut extract compared to the standard. The rapid metabolization caused alternating serum levels during the day and night. These patterns were not affected by the feed type or the previous addition of tannins in the feed. The absorption and metabolization in the intestines occurred gradually throughout the intestinal tract. The latter was true for gallic acid as well as ellagic acid, which was not found in the serum. We can conclude that components from chestnut tannins are absorbed throughout all components of the intestinal tract and are eliminated quickly with little interaction from the feed and previous addition of tannins. Moreover, ellagic acid seems to be absorbed but would remain accumulated in the intestinal tissue or be metabolized by the microbiome.

Evaluation of perilla seeds (Perilla frutescens) based on nutrient digestibility and pH in vitro tilley and terry

The study was carried out to evaluate the provision of perilla seeds (Perilla frutescens) with the addition of tannins to pH, IVDMD (in vitro dry matter digestibility), and IVOMD (in vitro organic matter digestibility) in the rumen and post rumen. The research used according Completely Randomized Design with four treatments and four replications: T1 = 100% perilla seeds, T2 = 100% perilla seeds + 1% tannin, T3 = 90% basal ration + 10% perilla seeds, T4 = 90% basal ration + 10% perilla seeds + 1% tannin. The method used in vitro two-stage digestibility to the observed of stage I (rumen) and stage II (total). The variables evaluated in this study included IVDMD stage I, IVDMD stage II, IVOMD stage I, IVOMD stage II, and pH. The results showed that giving perilla seeds with the addition of tannin had a pH value obtained in accordance with the pH standard in the rumen (P>0.05); IVDMD stage I and stage II respectively 22.91-35.85% and 36.01-44.15% (P<0.05); IVOMD stage I and stage II were 38.15-48.36% (P<0.05) and 50.04-55.35% (P<0.05), respectively. The conclusion of this research was carried out to give perilla seeds at a level of 10% and 1% tannin in the ration had diverse nutrient digestibility in the rumen and post-rumen. However, it does not affect the pH of the rumen.

Soil greenhouse gas flux and nitrogen mineralization following manure application from tannin-fed dairy cows.

Growing concerns about environmental impacts of dairy farms have driven producers to address greenhouse gas (GHG) emissions and nitrogen (N) losses from soil following land application of dairy manure. Tannin dietary additives have proved to be a successful intervention for mitigating GHG and ammonia (NH3 ) emissions at the barn scale. However, it is unknown how land application of dairy manure from cows fed tannin diets affects crop-soil nitrogen dynamics and soil GHG flux. To test this, cows were fed diets at three levels of tannins (0.0%, 0.4%, and 1.8% of dry matter intake) and their manure was field applied at two N rates (240 and 360kg N ha-1 ). Soil NH4 + -N, NO3 - -N, corn silage yield, and soil GHG flux were then measured over a full growing season. Soils amended with tannin manure had lower initial NH4 + -N concentrations and lower total mineral N (NH4 + -N + NO3 - -N) concentrations 19 days after application, compared to soils amended with no tannin manures. Despite lower early season N availability in tannin-fertilized plots, there were no differences in corn silage yield. No differences in soil GHG and NH3 emissions were observed between manure-amended treatments. These results demonstrate that while tannin addition to dairy cow feed does not offer short-term GHG or NH3 emissions reductions after field manure application, it can promote slower soil N mineralization that may reduce reactive N loss after initial application.

Injectable, rapid self-healing, antioxidant and antibacterial nanocellulose-tannin hydrogels formed via metal-ligand coordination for drug delivery and wound dressing

Nanocellulose-based hydrogels have attracted increasingly attention due to their biocompatibility, biodegradability, and hydrophilic properties. In this work, we proposed a simple route to fabricate composite hydrogels using TEMPO oxidized cellulose nanofibrils (TOCNF) and tannin through metal-ligand coordination. Calcium ions were utilized to rapidly cross-link the carboxyl groups on TOCNF and the tannins' catechol moieties via metal-ligand bonding, resulting in the formation of TOCNF-Ca2+-T composite hydrogels. The incorporation of tannins endowed the hydrogel with high antioxidant and antibacterial properties. The rheological analysis revealed that the addition of tannin led to an improved gel strength of the composite hydrogel. The hydrogel was injectable and could autonomously self-healed in 1 min without any trigger. Tetracycline hydrochloride (TH) was successfully loaded into the composite hydrogels, achieving a maximum encapsulation rate of 97.32%. TOCNF-Ca2+-40%T demonstrated a cumulative drug release of 36% at pH 1.3 and 86% at pH 7.4, indicating its pH-responsive nature. These hydrogels, derived from plant sources, exhibited high antibacterial and antioxidant properties, as well as biocompatibility, rapid self-healing, and injectability, which open up new possibilities for applications in wound dressing and drug delivery.

Study on preparation of tannin-hydroxymethylated furfuryl alcohol adhesives

To improve the water resistance of tannin adhesives, bio-sourced furfuryl alcohol was used to react with trace formaldehyde to synthesize hydroxymethylated furfuryl alcohol as a modifier for tannin adhesives. The bonding performance of tannin-hydroxymethylated furfuryl alcohol(T-PFA) with different pH values, amount of formaldehyde addition and mass ratio of tannin to furfuryl alcohol were studied by preparing laboratory three-layer plywood and evaluating their shear strength. At the same time, resorcinol and 5-hydroxymethylfurfural (HMF) were used as model compounds to prepare resorcinol-HMF resins and then were analyzed by means of electrospray ionization mass spectrometry(ESI-MS), nuclear magnetic resonance carbon(13C NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy, which aimed to explain their reaction mechanisms more clearly. The results showed that resorcinol could react with hydroxymethylfurfural and produce a branched macromolecular structure, thus demonstrating the feasibility of preparing wood adhesives with hydroxymethyl furfuryl alcohol modified tannins. In addition, plywood test results indicated that a T-PFA adhesive shows a good bonding performance and water resistance with a shear strength as high as 0.80 MPa after soaking in boiling water for 3h, which satisfied the requirements of Chinese National Standards GB/T 9846-2015(≥0.7 MPa).

Starch films loaded with tannin: the study of rheological and physical properties

Recently, the research on innovative food packaging has been oriented toward biodegradable materials to lower the environmental impact generated by conventional plastics. The films often carry functional additives interacting with the matrix and modifying its physical properties. In this work tannin, a scarcely exploited active additive, was used to obtain potato starch-based films, and its content was optimized on the basis of mechanical and microscopic tests. Rheological measurements were adopted to evaluate the tannin-starch interaction and the microstructure of the film forming solutions (FFSs). Their thickness, color, thermal conductivity, elastic modulus (Eel), elongation at break (EAB), surface wettability and water solubility were evaluated. Furthermore, microstructure was investigated through Fourier-transform infrared spectroscopy (FTIR), polarized light (POM) and scanning electron microscopy (SEM).It was observed that all FFSs behave as weak gels and tannin addition weakens the gel structure and decreases the gelatinization temperature from about 60 °C to 57 °C. Plastic and deformable films (Eel = 1.96 MPa and EAB = 189 %) were obtained at low tannin fractions, whereas, at a higher concentration, stiffer films (Eel = 12 MPa and EAB = 10 %), with hydrophobic behavior were produced. Among the tested tannin fractions, an intermediate value of 1.7 % (w/w) was found to be promising for industrial purposes.

Condensed tannin addition decreased soil nitrate but increased soil enzyme activities in subtropical forest soil

Condensed tannin addition decreased soil nitrate but increased soil enzyme activities in subtropical forest soil

Solid-Phase Extraction Followed by Gas Chromatography–Mass Spectrometry for Revealing the Effects of the Application of Bentonite, Tannins, and Their Combination during Fermentation in the Production of White Wine

To investigate the effects of the application of bentonite, tannins, and their combination in alcoholic fermentation, Malvazija istarska (Vitis vinifera L.) white grape must was treated with 95 g/L of bentonite, 25 g/L of a hydrolysable tannin preparation, while the third treatment received the aforementioned doses of both agents. Control grape must was fermented without bentonite and exogenous tannins. All of the produced wines were additionally fined after fermentation with doses of bentonite needed to achieve complete protein stability. Wines were analyzed both after fermentation and after additional bentonite fining. Standard physicochemical parameters were determined by the OIV methods, and phenols were analyzed by high-performance liquid chromatography with diode-array detection (HPLC-DAD), while the concentrations of free and bound volatile aroma compounds were obtained after solid-phase extraction (SPE) followed by gas chromatography–mass spectrometry (GC-MS). Bentonite and tannins in fermentation generally reduced the total dose of bentonite needed for complete stabilization. Treatments with bentonite slightly decreased the concentration of total dry extract, while tannins preserved total acidity. The negative effect of bentonite on flavonoids was more severe. Tannins in fermentation preserved more hydroxycinnamoyltartaric acids with respect to control wine, and this effect was additionally enhanced by bentonite. Volatile and bound aroma composition was affected by all the treatments, while the addition of tannins resulted in higher concentrations of several important odoriferous esters, such as ethyl hexanoate, ethyl decanoate, and hexyl acetate. Additional fining with bentonite to complete protein stabilization annulled some of the positive effects observed after fermentation.

Digestibility and nitrogen balance of goats on high and low protein rations supplemented with a commercial tannin feed-additive

ABSTRACTDespite the increasing importance of goat production in response to high demand for their products and their relative robustness to environmental stressors, and in contrast to other ruminant species, little data is available on how tannin extract feeding affects their feed intake, nutrient digestion and nitrogen (N) metabolism. Therefore, a trial in Oman investigated the respective variables by using a commercial tannin feed additive. In a 4 (treatments) x 3 (periods) x 2 (animals) Youden square, two weaned Batinah bucks each were fed a high or low protein diet of Rhodes grass hay and crushed barley grain, with or without the addition of a chestnut and quebracho tannin extract at 2 g/kg metabolic weight. Feed offered, feed refused and faeces and urine excreted were quantified to determine diet digestibility, total N excretion, N retention and rumen microbial protein synthesis (MPS). Due to their young age and low live weight, feed intake of goats was relatively low. Crude protein level and tannin addition had no statistically significant effect on dry matter (DM) and N intake, DM digestibility, N excretion in faeces and urine, as well as MPS. In consequence, no benefit of tannin feeding could be confirmed for the goats’ N retention, irrespective of diet composition. These results indicate, on one hand, an effective neutralisation of the tested tannin extract along the gastrointestinal tract of goats, but on the other hand, that stimulation of MPS or N retention by tannins cannot be evidenced when diet components are present that simultaneously release energy and protein, as is the case with barley.

Prevention of Protein Degradation Using Ensiling Coffee Husk

The purpose of this research is to provide protein protective compounds during the ensiling process using local materials, namely coffee husk waste. The type of coffee used was robusta. Dry coffee husk (moisture &lt;15%) was ground using a Wiley mill (2 mm sieve). The extraction of tannins from coffee husk waste was performed by the Soxhlation method using ethanol organic solvent (70%). The research involved four treatments and five replications, namely P0= elephant grass silage without tannins; P1= elephant grass silage with the mixture of 3g coffee husk tannins per 1kg fresh silage; P2= elephant grass silage with the mixture of 6g coffee husk tannins per 1kg fresh silage; and P3= elephant grass silage with the mixture of 9g coffee husk tannins per 1kg fresh silage. A completely randomized design (CRD) was employed. The significantly different results were then tested using Duncan's Multiple Test (DMRT). In summary, the addition of coffee husk tannins with a dose of 9g per 1kg of fresh silage presented the best quality elephant grass silage.

Effects of Sorghum Grain Tannin Addition in Refrigerated Pork Meat against Lipid Oxidation

Effects of Sorghum Grain Tannin Addition in Refrigerated Pork Meat against Lipid Oxidation

Low Allergenicity in Processed Wheat Flour Products Using Tannins from Agri-Food Wastes.

The present study aimed to investigate the effect of the addition of tannins from unutilized resources on wheat allergen reduction, antioxidant properties, and quality by substituting 3%, 5%, and 10% of the flour with chestnut inner skin (CIS) and young persimmon fruit (YPF) powders to produce cookies. The enzyme-linked immunosorbent assay and Western blotting showed significantly lower wheat allergen content in CIS- or YPF-substituted cookies than in control cookies, and this effect was pronounced for CIS-substituted cookies. In addition, the tannin content and antioxidant properties of the CIS- or YPF-substituted cookies were markedly higher than those of the control cookies. Quality analysis of the CIS- and YPF-substituted cookies showed that the specific volume and spread factor, which are quality indicators for cookies, were slightly lower in the CIS- and YPF-substituted cookies than in the control cookies. Compared to the control, CIS substitution did not affect the breaking stress and total energy values of the cookies; however, YPF substitution at 10% increased these values. Color was also affected by the addition of CIS and YPF. The results suggest that the addition of CIS and YPF can reduce wheat allergens in cookies and improve tannin content and antioxidant properties.

Dietary tannin and different breeds alter the fatty acid profile and sensory properties of artisanal goat coalho cheese

The study evaluated the influence of tannin in the diets of goats of two different breeds regarding composition and sensory quality of artisanal goat coalho cheese. The milk used was obtained from goats of the indigenous Canindé and Repartida breeds. The goats were divided into four groups: Canindé without tannin (CAN-C); Canindé with tannin (CAN-T); Repartida without tannin (REP-C); and Repartida with tannin (REP-T), representing two breeds and two dietary treatments, without and with inclusion of tannin (Acacia mearnsii). The effect of dietary tannins on the goat coalho cheese profile changed according to breed. In the physicochemical parameters, the addition of tannin in the diet increased ash only in CAN-T cheese and the total solids content was reduced only in REP-T cheese. In the fatty acid profile, the effect of the tannins in the diet led to variations according to the breed, but in general this addition resulted in an increase in polyunsaturated fatty acids in REP-T cheese, with emphasis in conjugated linoleic acid (CLA). Other results were the reduction of monounsaturated fatty acids with the presence of tannin, lower atherogenicity index with dietary tannins only in the REP-T, group and the higher thrombogenicity index with dietary tannins in the CAN-T animals. In the cheese sensory profile, untrained tasters found significant differences. The addition of tannins positively influenced the appearance of CAN-T cheese, and also improved the overall flavor and global impression, but did not lead to modifications of REP-T cheese. Therefore, the effect of tannins changed according to goat breed, and these factors led to relevant changes in the physicochemical, lipid and sensory characteristics of the cheeses.

Effect of Tannins Addition on Thermal Stability of Furfurylated Wood.

This article presents the effect of the addition of condensed tannins, used as a reticulation agent, on the polymerization of furfuryl alcohol during wood furfurylation, as well as the effect of these condensed tannins on the thermal stability of modified wood. Three kinds of dicarboxylic acids (adipic acid, succinic acid, and tartaric acid), as well as glyoxal, used as model of a wood reticulation agent, were used to catalyze the polymerization of furfuryl alcohol or tannin-furfuryl alcohol solutions. Impregnation of furfuryl alcohol or tannin-furfuryl alcohol solution into the wood, followed by curing at 103 °C for a specific duration, was performed for the wood modification. The thermal stability of the obtained tannin-furfuryl alcohol polymers and their corresponding modified woods was investigated. The leaching resistance and dimensional stability of the modified woods were also evaluated. Results indicated that the partial substitution of furfuryl alcohol by the tannins improved the polymerization reactivity in conditions where furfuryl alcohol alone did not lead to the formation of a solid polymeric material. The thermal stability and leaching resistance of the furfurylated wood in the presence of tannins were improved. Dimensional stability was also improved for furfurylated samples, but the effect of tannin addition was not so obvious, depending on the acidic catalyst used.

Facile Fabrication of High-Performance Composite Films Comprising Polyvinyl Alcohol as Matrix and Phenolic Tree Extracts.

Given that tree extracts such as tannin and lignin can be efficiently used as modifying materials, this helps to verify the global trend of energy saving and environment protection. Thus, bio-based biodegradable composite film incorporating tannin and lignin as additives, together with polyvinyl alcohol (PVOH) as a matrix (denoted TLP), was prepared. Its easy preparation process endows it with high industrial value in comparison to some bio-based films with complex preparation process such as cellulose-based films. Furthermore, imaging with scanning electron microscopy (SEM) shows that the surface of tannin- and lignin-modified polyvinyl alcohol film was smooth, free of pores or cracks. Moreover, the addition of lignin and tannin improved the tensile strength of the film, which reached 31.3 MPa as indicated by mechanical characterization. This was accounted for by using Fourier transform infrared (FTIR) and electrospray ionization mass (ESI-MS) spectroscopy, which showed that the physical blending of lignin and tannin with PVOH was accompanied by chemical interactions that gave rise to weakening of the prevailing hydrogen bonding in PVOH film. In consequence, the addition of tannin and lignin acquired the composite film good resistance against the light in the ultraviolet and visible range (UV-VL). Furthermore, the film exhibited biodegradability with a mass loss about 4.22% when contaminated with Penicillium sp. for 12 days.

Dietary Supplementation of Chestnut Tannins in Prepartum Dairy Cows Improves Antioxidant Defense Mechanisms Interacting with Thyroid Status.

Cows in the peripartal period undergo changes in thyroid hormones and are susceptible to lipomobilization and/or oxidative stress. The addition of chestnut tannins as polyphenolic compounds in the diet may improve feed efficiency and prevent oxidative stress-related health disorders in transition cows. However, the relationship between chestnut tannin supplementation and thyroid function, which plays an important role in metabolic regulation, has not been investigated in dairy cows. This study was conducted to investigate the effects of chestnut tannin supplementation during the close-up period on thyroid status and to evaluate the interaction between thyroid hormones and oxidative stress biomarkers in prepartum dairy cows. Forty multiparous Holstein cows were fed either a diet containing chestnut tannins (CNTs, n = 20, 1.96 g chestnut tannins/kg feed, dry matter) or a non-supplemented diet (CON, n = 20) during the last 25 ± 2 days of gestation. Blood samples were collected on the first day of study (before chestnut tannin supplementation) and d 5 before parturition to measure hormonal and oxidative stress indices. Serum concentrations of T3 (p = 0.04) and T4 (p = 0.05) were higher in CNT cows than in the CON group on day 5 before parturition. Thyroid status of CNT cows was associated with higher serum total antioxidant capacity (T-AOC, p < 0.01), activities of superoxide dismutase (SOD, p = 0.03) and glutathione peroxidase (GPx, p = 0.01), and reduced glutathione concentration (GSH, p = 0.05). Serum thiobarbituric acid reactive substances (TBARS) were lower (p = 0.04) which was associated with lower aspartate aminotransferase (AST, p = 0.02), and lactate dehydrogenase (LDH, p = 0.01) activities in the CNT than in the CON group. Estradiol and progesterone did not differ between CNT and CON cows. Chestnut tannin supplementation improves antioxidant protection, prevents oxidation-reduction processes, reduces the degree of liver cell membrane damage, and protects thyroid tissue from damage, allowing higher T3 and T4 synthesis. Considering the importance of the thyroid hormone status before parturition, mechanisms of thyroid hormone regulation in CNT-supplemented dairy cows require more detailed investigations.