In vitro effects of and interactions between tannins and saponins and fate of tannins in the rumen

The rate of fermentation of hay was not affected by purified tannins from Ouercus incana and Dichostachys cinerea at 0.13 mg ml^?1 of the in vitro medium whereas a decrease of 4% in the rate was observed for Acioa barteri tannins at this level. At 0.23 mg and 0.47 mg of tannins per ml, the decrease in rate varied from 4 to 13% and 13 to 20%, respectively. The decrease in in vitro true digestibility of dry matter was 3, 6 and 7% for Q incana, D cinerea and A barteri, respectively, at a tannin concentration of 0.47 mg ml^?1, and 17, 21 and 27%, respectively, at 0.93 mg ml^?1. There was no change in the potential extent of digestion up to 0.47 mg ml^?1 for any of the tannins studied. These results suggested that the rate of digestion is affected to a greater extent than the potential extent of digestion or the in vitro true digestibility and that different tannins even at the same level have different degrees of effect. Tannin-saponin interactions were studied using tannic acid (TA), quebracho tannin (QT) and quillaja saponin (S) at different concentrations (0.2, 0.4 and 0.6 mg ml^?1) alone and in combination with each other. The decrease in the rate of digestion and true digestibility was additive when both the TA and the S were present. Similar results were obtained when TA was replaced by QT except that the effects with QT were more marked as compared to TA at the same concentration. Saponins had little effect on the potential extent of digestion and true digestibility. These tannins also decreased the production of short-chain fatty acid (SCFA) and their molar proportions (acetate decreased whereas propionate increased). Efficiency of microbial protein synthesis, expressed as the ratio of ¹⁵N incorporation per unit of SCFA production, was higher with both S and the tannins studied. A substantial amount (71–93%) of tannins soluble in aqueous acetone was released from leaves of some trees and shrubs on incubation in the in vitro medium for 48 h. The rumen liquor was not capable of degrading oligomeric condensed tannins.     

Assessment of the effect of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen fermentation and methane production in vitro

BACKGROUND: Tannins added to animal diets may have a positive effect on energy and protein utilisation in the rumen. The objective of this study was to examine the impact of different sources and concentrations (20, 50, 100, 150 and 200 g kg^?1 dry matter (DM)) of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen microbial fermentation in vitro. The experiment also included a negative control with no tannins (control) and a positive control with monensin (10 mg L^?1). RESULTS: In vitro gas production and total volatile fatty acid (VFA) concentration decreased as tannin concentration increased. Addition of acacia, chestnut or valonea tannins at ≥ 50 g kg^?1 or quebracho tannins at ≥ 100 g kg^?1 resulted in a decrease (up to 40%) in methane (CH₄) production compared with the control. Valonea tannins were the only tannin source that reduced (?11%) CH₄ production at 50 g kg^?1 without affecting VFA concentration. Tannin treatments reduced ammonia (NH₃) and branched‐chain VFA concentrations, indicating a reduction in ruminal protein degradation. Monensin reduced CH₄ production (?37%) and NH₃ concentration (?20%) without affecting total VFA concentration. CONCLUSION: Supplying acacia, chestnut or valonea tannins at 50 g kg^?1 has the potential to reduce CH₄ production and ruminal protein degradation with minimum detrimental effects on efficiency of ruminal fermentation. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Effect of inoculated corn silage enriched with sunflower oil on rumen fermentation and lipid metabolism in an artificial rumen (RUSITEC)

BACKGROUND: Some rumen isolates are able to produce conjugated linoleic acid (CLA) from linoleic acid (LA) in vitro. Effects of providing diets containing corn silage (CS) and lucerne hay to an artificial rumen (RUSITEC) in which the corn was not inoculated (CS), or inoculated with Lactobacillus plantarum CCM 4000 (CS + LP), Lactobacillus fermentum LF2 (CS + LF) or Enterococcus faecium CCM 4231 (CS + EF) and supplied with sunflower oil (SO; 30 g kg^?1; w/w) on rumen metabolism were examined. RESULTS: The SO affected the outputs of all fatty acids. TVA output of uninoculated CS with SO was lower as compared to inoculated CS. The interaction of the CS × SO in the daily output of TVA was detected (P < 0.001). The biohydrogenation of oleic, linoleic, α‐linolenic and total fatty acids was influenced by SO (P < 0.05 and P < 0.001). CONCLUSION: Inoculated silage induces changes in the rumen metabolism which might be related to differences observed in the extent of rumen BH of PUFA in RUSITEC. SO supplementation might positively enhances the production of some rumen intermediates; however, relationships between inoculated silages and oil supplementation can be presumed in the daily production of trans‐vaccenic acid. Copyright © 2009 Society of Chemical Industry     

Effect of humic acid on fermentation and ciliate protozoan population in rumen fluid of sheep in vitro

BACKGROUND: Humic acid (HA) as a product of decomposition of animal and plant tissue is used in animal production as a feed supplement, antimicrobial product and growth stimulator. The objective of the present in vitro study was to investigate the effects of dietary humic acid as a commercial Humacid 60 Basic (H60B) feed additive preparation on rumen fermentation and the ciliate protozoan population in the rumen fluid of sheep using a high fibre (HF) and high concentrate (HC) diet in batch cultures and artificial rumen (RUSITEC). RESULTS: Production of total volatile fatty acids (VFAs) was significantly decreased (P < 0.001) for batch cultures by the HF‐H60B diet. The HF‐H60B diet decreased ammonia N in RUSITEC (P < 0.001). An increase in the population of Enoploplastron triloricatum, Isotricha spp. and Ophryoscolex c. tricoronatus with the HF‐H60B diet and Diploplastron affine with the HC‐H60B was observed. The H60B did not affect the total ciliate population and Entodinium spp. CONCLUSION: It can be concluded that dietary humic acid preparations are not effective as dietary antiprotozoal agents. Humic acid might enhance microbial growth and energy efficiency in doses up to 10 g kg^?1 DM of diet. Copyright © 2009 Society of Chemical Industry     

Comparison of biological and chemical methods,and internal and external standards,for assaying tannins in Spanish shrub species

Tannin contents of stems, flowers and leaves of four shrub species (Erica arborea, Erica australis, Cytisus cantabricus and Genista occidentalis) were chemically assessed using two colorimetric assays (butanol–HCl and Folin–Ciocalteu) and several standards (tannic acid, purified quebracho condensed tannins (CT) and purified CT extracted from each species). A method based on the biological activity of tannins in the rumen was also used for assaying tannins. Depending on the species, the use of quebracho tannin as standard over‐ or underestimated CT contents, in comparison to the use of the respective internal standard. However, the high correlationship observed between in vitro gas production in the presence or absence of polyethylene glycol (PEG) and CT contents estimated from quebracho suggests that this standard could be used for a quicker estimate of the nutritive value of tannin‐containing plants. Tannin contents obtained by the Folin–Ciocalteu method, using tannic acid as standard, were also related to their activity on rumen fermentation. The use of the in vitro gas production technique, in the absence or presence of PEG, may provide more useful information than the chemical assays when the final aim of tannin analysis is to assess the nutritive value of feedstuffs for ruminants. Copyright © 2004 Society of Chemical Industry     

Fermentation characteristics,aerobic stability and ruminal degradation of ensiled pea/wheat bi‐crop forages treated with two microbial inoculants,formic acid or quebracho tannins

This study evaluated the effects of two commonly used microbial inoculants (Lactobacillus buchneri (LB) and Lactobacillus plantarum (LP)), formic acid (FA) and quebracho tannins (QT) on the fermentation quality, aerobic stability and in situ rumen degradation of pea/wheat bi‐crop forages. Precision‐chopped spring pea (Pisum sativum, var Magnus) and wheat (Triticum aestivum, var Axona) bi‐crops (3:1 pea/wheat ratio) harvested at a combined dry matter (DM) content of 301 g kg^?1 were used for the study. The bi‐crops were conserved without (Control) or with inoculants based on lactic acid bacteria (LB (10⁵ CFU g^?1 fresh weight (FW)) or LP (10⁶ CFU g^?1 FW)), QT (16 g kg^?1 FW) or FA (2.5 g kg^?1 FW) in laboratory silos of 1.5 kg capacity, with each treatment being replicated six times. The pH, chemical composition, aerobic stability and in situ rumen degradation of DM, nitrogen (N) and neutral detergent fibre (NDF) after 112 days of ensilage were measured. The average pH at silo opening was 4.0, suggesting that the silages were well fermented. There were no significant effects of additive treatment on water‐soluble carbohydrate, total N, soluble N, ammonia N and NDF. Lactic acid and acetic acid were the main fermentation products. High concentrations of acetic acid were found in all the treatments, indicating a heterofermentative pathway. Although FA treatment gave the most aerobically stable silage, the Control and QT‐treated silages did not heat up by more than 1 °C until after 6 days of exposure to air. There were no effects of additives on DM degradation characteristics. However, the inoculants increased the rate of N and NDF degradation in the rumen, and both FA and QT reduced the effective and potential degradation of N. © 2001 Society of Chemical Industry     

In vitro effects of phlorotannins from Ascophyllum nodosum (brown seaweed) on rumen bacterial populations and fermentation

BACKGROUND: Use of brown algae (seaweed) in ruminant diets is increasing, but the effects of its phlorotannins (PT) on rumen microbial ecology have not been determined. Mixed forage (50:25:25 ground barley silage–alfalfa hay–grass hay) was used as substrate in a batch culture ruminal incubation that included PT extracted from Ascophyllum nodosum, with and without polyethylene glycol. Principal ruminal bacteria were quantified using real‐time polymerase chain reaction. RESULTS: At 500 µg mL^?1, PT reduced growth of Fibrobacter succinogenes by 78%, 83% and 65% at 6, 12 and 24 h (P < 0.001), Ruminococcus albus at 24 h only (P < 0.01) and did not affect R. flavefaciens. Non‐cellulolytic bacteria Selenomonas ruminantium, Ruminobacter amylophilus and Prevotella bryantii were increased (P < 0.001) by PT at 12 and 24 h. Effects of PT on fermentation products (gas production, volatile fatty acid profiles and ammonia accumulation) were consistent with alterations in rumen microbial populations. CONCLUSION: The effects of PT on ruminal bacteria were species‐dependent, which suggests that diet may mediate PT effects on animal performance. The variation in sensitivity of ruminal bacteria to PT reflects previously reported effects of condensed tannins from terrestrial plants on microbial populations. Copyright © 2009 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

The effect of supplementing red deer (Cervus elaphus) with different forms of ascorbic acid upon the concentration of ascorbic acid in rumen fluid and blood plasma

Two indoor experiments were conducted at the Massey University Deer Research Unit to study whether the blood plasma ascorbic acid (AA) concentration in farmed red deer (Cervus elaphus) could be raised, using a single large intraruminal administration of AA (2.7 g kg^?1 live weight) prior to a simulated slaughter situation. Deer fistulated in the rumen were individually fed chaffed lucerne hay ad libitum at 30 min intervals; feed was then withdrawn 8 h before AA was administered, and fasting continued during the period of rumen fluid and blood sampling (30 h of fasting in total). Blood (jugular vein) and rumen fluid samples were taken 15 min before and at various intervals after dosing with AA. Rumen fluid pH values were also recorded. In Experiment 1 the effects of administration of pure ascorbic acid (AA), ethyl cellulose‐coated ascorbic acid (EC) and silicone‐coated ascorbic acid (SC) were compared. All three types increased rumen fluid and blood plasma AA concentrations to a desirable level (500 µg ml^?1 blood plasma or greater), with the maximum concentrations in both sites occurring 1 h after administration. The area under the concentration versus time curve (AUC), the area under the curve corrected for baseline concentration (AUCB) and the maximum concentration (MAX) of AA in both rumen fluid and blood plasma were not significantly different among the three formulations of AA, indicating that all three were degraded at similar rates in the rumen and that their bioavailabilities were similar. Rumen pH decreased from approximately 7.0 to 5.0 within 1 h of administering each compound, increased to 6.0 after 4 h and then progressively increased to approximately 7.0 after 22 h. Experiment 2 was conducted to investigate the rumen‐buffering effect after dosing with AA with and without added sodium bicarbonate. Including NaHCO₃ increased rumen pH by approximately 1 unit during the first hour after dosing and by 0.7–0.4 units thereafter. AUC and AUCB for rumen fluid were significantly lower for the AA + NaHCO₃ group of deer than for the AA group (p < 0.05), indicating that increasing rumen pH increased the rate of ruminal destruction of AA. AUC, AUCB and MAX of AA in blood plasma were not statistically different between the two treatments (p > 0.05). It was concluded that the single large intraruminal AA dose technique could be used to consistently increase AUC, AUCB and MAX of AA in both rumen fluid and blood plasma. Methods for improving the efficiency of the technique are discussed. © 2002 Society of Chemical Industry     

Effect of adding an anaerobic fungal culture isolated from a wild blue bull (Boselophus tragocamelus) to rumen fluid from buffaloes on in vitro fibrolytic enzyme activity,fermentation and degradation of tannins and tannin‐containing Kachnar tree (Bauhinia variegata) leaves and wheat straw

The study investigated the effects of adding an anaerobic fungus (Piromyces sp FNG5; isolated from the faeces of a wild blue bull) to the rumen fluid of buffaloes consuming a basal diet of wheat straw and concentrates on in vitro enzyme activities, fermentation and degradation of tannins and tannin‐rich tree leaves and wheat straw. In experiment 1, strained rumen fluid was incubated for 24 and 48 h, in quadruplicate, with or without fungal culture using condensed tannin‐rich Bauhinia variegata leaves as substrates. In experiment 2, in vitro incubation medium containing wheat straw and different concentrations of added tannic acid (0–1.2 mg mL^?1) were incubated for 48 h, in quadruplicate, with strained buffalo rumen fluid with or without fungal culture. In experiment 3, tolerance of the fungal isolate to tannic acid was tested by estimating fungal growth in pure culture medium containing different concentrations (0–50 g L^?1) of tannic acid. In in vitro studies with Bauhinia variegata tree leaves, addition of the fungal isolate to buffalo strained rumen liquor resulted in significant (P < 0.01) increase in neutral detergent fibre (NDF) digestibility and activities of carboxymethyl cellulase (P < 0.05) and xylanase (P < 0.05) at 24 h fermentation. There was 12.35% increase (P < 0.01) in condensed tannin (CT) degradation on addition of the fungal isolate at 48 h fermentation. In in vitro studies with wheat straw, addition of the fungus caused an increase in apparent digestibility (P < 0.01), true digestibility (P < 0.05), NDF digestibility (P < 0.05), activities of carboxymethyl cellulase (P < 0.001), β‐glucosidase (P < 0.001), xylanase (P < 0.001), acetyl esterase (P < 0.001) and degradation of tannic acid (P < 0.05). Rumen liquor from buffaloes which had never been exposed to tannin‐containing diet had been found to have substantial inherent tannic acid‐degrading ability (degraded 55.3% of added tannic acid within 24 h of fermentation). The fungus could tolerate tannic acid concentration up to 20 g L^?1 in growth medium. The results of this study suggest that introduction of an anaerobic fungal isolate with superior lignocellulolytic activity isolated from the faeces of a wild herbivore may improve fibre digestion from tannin‐containing feeds and degradation of tannins in the rumen of buffaloes. Copyright © 2005 Society of Chemical Industry     

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

The precipitation of protein by condensed and hydrolysable tannins was evaluated with the radial diffusion method of Hagerman (1987) using bovine serum albumin (BSA) and isolated leaf protein from fresh alfalfa (Medicago sativa). Alfalfa leaf protein (AALP) was included at two concentrations, 25 and 156 mg N litre^-1, at pH 6·8 and 39°C to simulate rumen conditions. The condensed tannins were purified from lyophilised samples of Arachis pintoi, Desmodium ovalifolium, Gliricidia sepium, Manihot esculenta and quebracho (Schinopsis balansae). Hydrolysable tannins from tannic acid (TA) were used as well. There was a significant interaction (P<0·001) between tannin and protein source, and protein level on protein precipitation. Most purified condensed tannins (CTs) precipitated more AALP than BSA when protein was included at the same level. Purified CT from quebracho and hydrolysable tannin from TA failed to precipitate AALP at both protein levels. In a second experiment, tannins from crude plant extracts were studied in the radial diffusion method using BSA and two levels of AALP. The crude plant extracts were obtained from lyophilised plant samples of A pintoi, Centrosema macrocarpum, Clitoria ternatea, D ovalifolium, Erythrina berteroana, E poepigiana, G sepium, M esculenta, Pueraria montana and P phaseoloides. The protein precipitated by soluble tannins in the plant samples was correlated to the total phenolic content and to the soluble CT estimated by the acid butanol assay or by the radial diffusion method. Tannins from different plant species precipitated different amounts of BSA and AALP. Therefore, the measures of the biological activity of tannins based on BSA precipitation may not reflect the ability of tannins to precipitate proteins of plant origin such as those commonly found in the diets of herbivores. The present study offers the possibility of using the radial diffusion method with plant proteins at precipitation conditions similar to those in the rumen. © 1997 SCI.     

Condensed tannins in tropical fodder crops and their in vitro biological activity: Part 2

With the aim to evaluate the biological activity of purified condensed tannins of tropical forages we conducted two in vitro experiments. In the first, using a radial diffusion technique, the protein precipitation of free condensed tannins (FCT) from Manihot esculenta, leucaena leucocephala, Arachis pintoi, Guazuma ulmyfolia, Gliricidia sepium and of tannic acid on bovine serum albumin (ASB), papain, pepsin and trypsin at pH 5.0 and 6.8 was evaluated with a three‐way analysis of variance. Significant effects (P ≤ 0.05) for the tannin type, protein source, pH and their interactions were observed. Pepsin showed the highest protein precipitation (PP) at a pH of 5.0 (82.9 µg) with FCT of G ulmyfolia and the lowest (0 and 0.2 µg) of BSA with G sepium and A pintoi at pH 6.8. Experiments were then conducted using completely randomized designs in order to observe the effect of adding 0, 1.25 or 2.50 mg of FCT from M esculenta and L leucocephala to the rumen fluid‐buffer in an in vitro dry matter digestibility test (IVDMD) of Medicago sativa and Brachiaria decumbens, The IVDMD value of M sativa (757 g kg^?1) decreased with L leucocephala tannins, although with those of M esculenta it was increased (824 g kg^?1 and 871 g kg^?1, respectively) for 1.25 and 2.5 mg of FCT. The IVDMD value of B decumbens (774 g kg^?1 without tannins) diminished with any tannin and any dose (P < 0.05). We conclude that there are differences in the FCT contents of fodder crops and in their biological activity measured as the capacity to precipitate proteins, which is modified by the type of tannin, the protein and the pH. The result of an IVDMD is regulated by the type of tannin and its dose. Copyright © 2004 Society of Chemical Industry     

Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

The ratios of degradation characteristics of forages in the rumen of dairy cows: effect of variety and stage of maturity

In situ digestive characteristics of neutral detergent fibre (NDF), non‐fibre carbohydrates (NFC) and crude protein (CP) in alfalfa and timothy were determined in the rumen of dairy cows. Two varieties of alfalfa (Pioneer and Beaver) and timothy (Climax and Joliotte) were grown in western Canada and cut at three maturity stages (alfalfa: 1 = early bud, 2 = late bud, 3 = early bloom; timothy: 1 = joint, 2 = pre – bloom head, 3 = full head). Measured ruminal degradation characteristics were soluble fraction (NFC, CP), undegradable fraction (NDF, CP), lag time (NDF) and rate of degradation of the insoluble but degradable fraction (NDF, NFC, CP). All measured characteristics showed large differences between the two forage species (alfalfa vs timothy) and to a lesser extent between the maturity stages and varieties. Mean total rumen available NDF (248.6 vs 282.5 g kg^?1 dry matter (DM)), NFC (200.5 vs 106.1 g kg^?1 DM) and CP (139.7 vs 44.5 g kg^?1 DM) differed (p < 0.01) between alfalfa and timothy. Based on the measured characteristics, degradation ratios were calculated between total rumen available N and carbohydrates (FN/FCHO), soluble N and carbohydrates (SN/SCHO) and rumen available insoluble N and carbohydrates (EN/ECHO). The ratios showed large differences between the two forages species and to a lesser extent between the varieties and stages of maturity. Alfalfa species had significantly higher (p < 0.01) ratios of FN/FCHO (49.8 vs 18.3 g kg^?1), SN/SCHO (115.0 vs 36.1 g kg^?1) and EN/ECHO (28.3 vs 12.0 g kg^?1) than timothy. These results indicate that alfalfa varieties exhibited a superior rumen fermentation ratio (optimum FN/FCHO = 25–33 g N kg^?1 carbohydrates). The results also suggest a potential N loss in alfalfa and N shortage in timothy. Comparing the two varieties of alfalfa, no differences (p > 0.05) were found in the ratios of FN/FCHO and EN/ECHO, but a significant difference (p < 0.05) was found in SN/SCHO (132.3 vs 97.6 g kg^?1). However, comparing the two varieties of timothy, there were significant differences (p < 0.01) in FN/FCHO (23.8 vs 12.8 g kg^?1) and EN/ECHO (15.3 vs 8.7 g kg^?1) ratios but not in SN/SCHO ratio (p > 0.05), indicating large differences between legume and grass. As plant maturity advanced from stage 1 to stage 3, there were no significant changes in all ratios in alfalfa and timothy except the EN/ECHO ratio in timothy (14.3, 13.4 and 8.3 g kg^?1 at stages 1, 2 and 3 respectively). It was concluded that the degradation characteristic ratios were dependent on species, variety and/or stage of maturity. Such ratios could be used to optimise a dairy diet composition with regard to rumen fermentation. Copyright © 2004 Society of Chemical Industry     

Effects of dietary quebracho tannin on nutrient utilisation and tissue metabolism in sheep and rats

The effect of feeding quebracho tannin, a mixture of condensed tannins, on dietary nutrient utilisation and nitrogen (N) retention and its effects on the gastrointestinal (GI) tract was investigated in sheep and rats. Sheep (n = 24) were fed on a pelleted diet of dried grass alone (controls) or containing quebracho tannin at 50 g kg⁻¹ diet dry matter (DM) (tannin-fed animals) at a level sufficient to achieve a daily liveweight gain (DLWG) of 100 g day⁻¹. Complete collections of faeces and urine were made for two seven-day periods after two and six weeks of feeding these diets (n = 6 per group). Apparent digestibilities of dry matter, N and neutral detergent fibre (NDF) were significantly (P < 0.001) reduced in tannin-fed animals at both measurement periods. No evidence was obtained to suggest that rumen micro-organisms can adapt to the presence of dietary tannins with prolonged feeding. Tannin-fed animals excreted significantly (P < 0.01) more N in faeces and less in urine than controls suggesting an alteration in N metabolism. Histological examination of samples of the GI tract obtained from pairs of sheep slaughtered after two, five and seven weeks of feeding the diets indicated ulceration and an increase in mucosal histiocytes, particularly in the jejunum and ileum of most tannin-fed animals. In a subsequent experiment, rats were fed ad libitum a ground chow containing either cellulose or quebracho tannin at 40 g kg⁻¹ DM. Tannin-fed rats had significantly (P < 0.05) reduced feed intakes, DLWG, N retention and body fat deposition compared to controls. Protein synthesis rates in the duodenal mucosa were not increased in tannin-fed rats suggesting that enterocyte proliferation was not stimulated in this region of the GI tract. These studies indicate that feeding quebracho tannin to ruminants has both ruminal and post-ruminal effects that, together, result in reduced nutrient utilisation and impaired animal performance. © 1999 Society of Chemical Industry     

Uptake of small neutral peptides by mixed rumen microorganisms in vitro

The metabolism of a range of neutral di- and oligopeptides and peptide p-nitroanilides was investigated in strained ruminal fluid diluted with anaerobic buffer. Peptide uptake was assayed by decrease in fluorescamine-reactive material in extracellular fluid, and peptide p-nitroanilide hydrolysis by diazotisation of the released p-nitroaniline. Addition of glucose and dithiothreitol did not alter uptake of di- or trialanine. Calculated V_max for di- and trialanine uptake were 1.4 and 1.9 nmol min^?1 mg DM^?1, corresponding K_m were 0.30 and 0.14 mmol litre^?1. Dipeptide uptake was 0.72 to 0.90 nmol min^?1 mg DM^?1, except for glycylproline, which was taken up at 0.43 nmol min^?1 mg DM^?1. There was a wider range for tripeptide uptake (0.5 to 1.6 nmol min^?1 mg DM^?1), with trialanine being taken up most rapidly. Tetra- and pentaalanine were removed at 0.93 and 0.71 nmol min^?1 mg DM^?1. Uptake of amino acid residues as alanine oligopeptides was two to three times more rapid than uptake as dialanine. These data suggest that peptides would accumulate in rumen fluid during hydrolysis of rapidly degraded proteins, but peptide uptake would exceed rate of release from more slowly degraded proteins. Rates of hydrolysis of eight peptide p-nitroanilides were 0.56 to 1.53 nmol min^?1 mg DM^?1, and were of similar magnitude to uptake of di- and tripeptides; proline-containing p-nitroanilides were also more slowly metabolised.     

Effect of feeding complete feed block containing Prosopis cineraria leaves and polyethylene glycol (PEG)‐6000 on nutrient intake,its utilization,rumen fermentation pattern and rumen enzyme profile in kids

A study was carried out to determine the effect of replacing the cake portion of concentrate mixture with 5 parts polyethylene glycol (PEG)‐6000 in a complete feed block (CFB) containing Prosopis cineraria leaves on the performance, rumen fermentation pattern and rumen enzyme profile of kids under an intensive system of rearing. Eighteen weaners of Sirohi goat of similar body weight (16.0 ± 0.5 kg) and age (90 ± 5 days) were divided into three equal groups. They were housed in individual cages in a side open asbestos roof shed with mud floor. All the kids received CFBs containing 50 parts P cineraria leaves and 50 parts concentrate mixture. CFB offered to the first group had high protein (183.8 g kg^?1; HP), that offered to the second group had low protein (131.3 g kg^?1; LP) and that offered to the third group had low protein (124.7 g kg^?1) but contained PEG‐6000 (LP‐PEG). The concentrate mixtures in LP and LP‐PEG were without groundnut cake, whereas in LP‐PEG, groundnut cake was replaced by barley and 5 parts PEG‐6000 were incorporated. CFBs were similar in their nutritive value except for crude protein (CP). Prosopis leaves utilized in the CFB contained (g kg^?1 dry matter) 129.1 CP, 535.5 neutral detergent fibre, 395.8 acid detergent fibre and 222.8 acid detergent lignin. There were significant differences in dry matter intake (g day^?1) between HP (1102), LP (1108) and LP‐PEG (1194); the trend in Metabolizable energy intake was similar. During the growth trial, LP kids consumed maximum amount of feed (76.91 kg) followed by HP (75.73 kg) and LP‐PEG (73.12 kg). However, maximum feed efficiency (feed consumed kg^?1 live weight gain) was recorded in LP‐PEG kids (9.59) followed by HP (10.64) and LP (11.60). These differences were statistically significant (p < 0.05). Although there was no significant difference in the digestibility of dry matter among the groups, there was significant difference in the digestibility of CP, neutral detergent fibre and acid detergent fibre. The digestibility of CP was 0.591, 0.484 and 0.645, that of neutral detergent fibre was 0.397, 0.308 and 0.499 and that of acid detergent fibre was 0.168, 0.154 and 0.282 in HP, LP and LP‐PEG, respectively. Rumen metabolites studied 6 h after feeding revealed that there were significant (p < 0.05) differences in the concentrations of ammonia N, tri‐chloro acetic acid precipitable N and total volatile fatty acids among the three groups, but not pH. The rumen enzyme concentrations showed significant (p < 0.05) differences for α‐amylase, whereas the differences were non‐significant for CMcase and protease. After 90 days of feeding trial, the maximum weight gain was recorded in LP‐PEG (7.62 kg) followed by HP (7.23 kg) and LP (6.53 kg). It can be concluded that, when kids are reared under an intensive system on complete feed blocks containing Prosopis leaves, high protein concentrate can be replaced with a low protein concentrate containing 5 parts PEG, which would not only alleviate the negative effects of tannin but would also spare expensive groundnut protein. Copyright © 2005 Society of Chemical Industry     

Gel filtration studies of peptide metabolism by rumen microorganisms

Peptide metabolism by rumen microorganisms was investigated by gel filtration using Sephadex G-25 with water as eluant. Protein hydrolysates containing a mixture of peptides were used to calibrate the column. Total peptide in each fraction was estimated from its A₂₀₆, and free peptide amino groups were analysed by fluorescamine, thus enabling the average peptide M_r to be calculated. Three different protein hydrolysates produced similar, nearly linear, relations between log M_r and elution volume for peptides between 300 and 2000 Da. Trypticase, a pancreatic hydrolysate of casein, was metabolised rapidly in rumen fluid in vitro. Hydrolysis appeared to be complete after 6 h, leaving a small residual peptide concentration which persisted up to 24 h, equivalent to about 15% of the original peptide concentration of 2 g litre^?1. Residual peptides from casein hydrolysis were 0.05 g litre^?1 at 24 h. Peptides accumulated in rumen fluid of sheep receiving dietary ionophores. Two hours after feeding, the accumulation with monensin appeared to be of peptides of a wide M_r range, while tetronasin caused an accumulation mainly of smaller, <570 Da, peptides. Treatment of Trypticase with acetic anhydride afforded 76% protection of its peptides from degradation to ammonia in a 6-h incubation. When Trypticase was fractionated by gel filtration then acetylated, none of the fractions was protected significantly better than others.     

Complexes of the condensed tannins of sainfoin (Onobrychis viciifolia scop.) with fraction 1 leaf protein and with submaxillary mucoprotein,and their reversal by polyethylene glycol and pH

In vitro studies were made to determine the nature of complexes formed between the condensed tannins (i.e. pro-anthocyanidins or flavolans) of sainfoin (Onobrychis viciifolia) and either the major soluble dietary protein, Fraction 1 protein, of green leaves, or bovine salivary mucoprotein. Fraction 1 protein, uniformly labelled with ¹⁴C, formed only insoluble complexes with these tannins. Bovine salivary mucoprotein produced insoluble complexes only at temperatures below 25°C. Fraction 1 protein complexes were stable between pH 3.5 and pH 7.0. At pHs below 3.0 greater than 90% of the protein was solubilised in the presence of PEG but at pH 8.0 only 30% of the protein was released from the complex. In vivo experiments with sheep fed sainfoin, confirmed the stability of the tannin-Fraction 1 complexes in the rumen (pH 6.5) and break-up of the complexes in anterior duodenal samples (pH 2.5) as shown by the extractability of condensed tannin from the complex. The significance of these results with respect to (a) bloat in cattle, (b) nitrogen metabolism of ruminants, is discussed. Polyethylene-glycol, mol.wt. 4000 (PEG) exchanged with protein in the complex releasing protein into solution. The effectiveness of PEG was dependent on the amount of tannin in the complex and the age of the complex at the time of addition of PEG. The results explain the observation that PEG is unsuitable as a marker for rumen volume determination when animals are fed herbage that contains condensed tannins. A method for determining any deleterious effects of tannins on nitrogen metabolism by ruminants, is suggested.     

The effect of feeding pods of multipurpose trees (MPTs) on the degradability of dry matter and cell wall constituents of maize stover and alfalfa incubated in the rumen of sheep

This study evaluated the effects of feeding alfalfa and pods of tree legumes on rumen pH and ammonia concentration as well as in sacco degradability of dry matter and fibre constituents of maize stover, alfalfa hay and their neutral detergent extracts. The feeds were incubated in the rumens of five South African Merino sheep fed individually in an incomplete (5 × 4) Latin square design using five diets. The diets comprised equal proportions of pasture hay and either alfalfa (Alfalfa diet) or pods of Acacia sieberiana (Sieberiana diet), Acacia nilotica (Nilotica diet) or Leucaena leucocephala (Leucaena diet). The fifth diet was composed of pasture hay alone (Hay diet) and served as a negative control. Supplementation of hay with either legume pods or alfalfa significantly (p < 0.05) increased rumen ammonia concentration from 56 to a maximum of 86 mg l^?1. The pH of the rumen fluid ranged between 6.2 and 6.5 for all diets, but variations in pH were not significant. Diet did not affect (p > 0.05) the degradability constants lag time (LT), slowly degradable fraction (B), potential degradability (PD), effective degradability (ED) and rate of degradation (C) of dry matter (DM) but significantly (p < 0.01) affected ED of the fibre constituents of the incubated feeds. The effective degradabilities of the incubated feeds differed (p < 0.001), with alfalfa and maize stover having average values of 555 and 318 g kg^?1 DM respectively. The rate of degradation of alfalfa was also higher (p < 0.01) than that of maize stover. Neutral detergent extraction improved ED of the cell wall constituents of maize stover but produced the opposite effect for alfalfa. The interactions between incubation feed and extract were significant (p < 0.01) for ED and C of neutral detergent fibre and hemicellulose. The observations show that pods from tree legumes are comparable to alfalfa in the provision of rumen ammonia but limit microbial activity in the degradability of fibre constituents. They also show that maize stover and alfalfa differ in their degradabilities and that the differences may be attributed to their cell wall chemistry. © 2001 Society of Chemical Industry