Defaunating capacity of tropical fodder trees: Effects of polyethylene glycol and its relationship to in vitro gas production

Tropical tree foliage supplementation in ruminants improves rumen fermentation and the bacterial profile and decreases methane production

The main of this study was to evaluate the effect of supplementation of tropical tree foliage in ruminant diets on the in vitro fermentation, bacterial population, volatile fatty acids (VFAs), and enteric CH4 production. Seven experimental diets were evaluated: a control treatment of Pennisetum purpureum (T7) and six treatments of P. purpureum supplemented (30%) with the foliage of Neomillspaughia emargiata (T1), Tabernaemontana amygdalifolia (T2), Caesalpinia gaumeri (T3), Piscidia piscipula (T4), Leucaena leucocephala (T5), and Havardia albicans (T6). The T2, T7, and T5 treatments had the highest (p < 0.05) digestibility of dry matter. Overall, supplementation increased (p < 0.05) the concentrations of propionic and butyric acid and decreased acetic acid. Methanogenic bacteria decreased (p < 0.05) in T1, T2, T5, and T6. Ruminococcus albus decreased in T1, T2, T3, and T5 and Selenomonas ruminiantum increased in T3. Fibrobacter succinogenes increased, except in T5. Methane production decreased (p < 0.05) in T1, T4, T5, and T6. The supplementation with Leucaena leucocephala, Tabernaemontana amygdalifolia, Neomillspaughia emargiata, Piscidia piscipula, Havardia albicans, and Caesalpinia gaumeri is a potential alternative nutritional strategy for ruminants that results in positive changes in VFAs profile, a decrease on CH4 production and methanogenic bacteria, and changes on fibrolytic and non-fibrolytic bacteria composition.HIGHLIGHTSTropical tree foliage supplementation increased propionic and butyric acid and decreased acetic acid concentrations.Fibrolytic, non-fibrolytic, and Methanogenic bacteria were selectively modulated with the supplementation of tropical tree foliage.The enteric methane (CH4) production decreased with the supplementation of tree foliage.The supplementation of Tabernaemontana amygdalifolia and Leucaena leucocephala had the highest digestibility and is a potential alternative nutritional strategy for ruminants.

An in vitro rumen incubation method to study exsheathment kinetics of Haemonchus contortus third-stage infective larvae

This study developed and evaluated an in vitro rumen incubation (IVRI) method to describe the exsheathment kinetics of Haemonchus contortus third-stage infective larvae (L₃) in ruminal liquor (RL). The specific objectives were (i) to standardize the IVRI method to facilitate the contact between L₃ and RL as well as the larval recovery, and (ii) to apply the IVRI method to describe the exsheathment kinetics of H. contortus and to select the best fitting nonlinear model. Incubation devices containing H. contortus larvae were incubated according to the IVRI technique in cattle RL or PBS. The incubation conditions included RL mixed with a nitrogen-rich media, maintained at 39 °C, with pH = 7.0, vented with CO₂ and manual agitation. The larvae were recovered after 0, 1, 3, 6, 9, 12, and 24 h. The exsheathed and ensheathed larvae were counted to estimate the exsheathment (%) in RL or PBS. Exsheathment in RL was analyzed with nonlinear regression models: Exponential, Gompertz, Logistic, Log-Logistic, and Weibull. The models' fit was compared to select the one that best described the exsheathment kinetics. The exsheathment in RL reached 6.52%, 20.65%, 58.22%, 69.24%, 73.08%, and 77.20% in 1, 3, 6, 9, 12, and 24 h, respectively. Although the Gompertz, Weibull, and Logistic models were adequate to describe the observed exsheathment, the Log-Logistic model had the best fit. The IVRI method using bovine RL represents a suitable tool for the study of the in vitro exsheathment kinetics of H. contortus L₃.

Rumen Function and In Vitro Gas Production of Diets Influenced by Two Levels of Tannin-Rich Forage

The aim of this research was to evaluate the effect of the inclusion of Acacia mearnsii (AM) at different levels of inclusion on ruminal digestion and in vitro gas production. A. mearnsii forage was incorporated in the diet at different levels of 0 (AM0), 20 (AM20), and 40 (AM40) %. In situ degradation of dry matter (DM) and organic matter (OM) showed differences between treatments (P < 0.05), obtaining the highest value of the degradation of soluble fraction (A), insoluble but potentially degradable fraction (B), degradation rate in % per hour (c), potential degradation (A + B), and effective degradation for all passage rates in % h (0.02, 0.05, and 0.08) in AM0 with respect to AM20 and AM40. The in vitro digestibility of DM and OM was higher (P < 0.05) in AM0 with approximately 23.6% and 22.8% of DM and OM, respectively, compared to treatments AM20 and AM40. Cumulative gas production (PG) and gas production asymptote (B) were lower at AM0 and AM20 versus AM40; however, gas production rate (c) and total CH4 production were lower at AM40 with about 40.1 mL CH4/0.500 g fermented DM versus AM0 and AM20. Under the conditions of this study, it is concluded that the incorporation of A. mearnsii (20% and 40%) in the feed of ruminants negatively affected the digestion of nutrients; however, it reduced the production of CH4, which may be associated with the low activity of microorganisms toward the substrate due to the possible tannin/nutrient complex. This shows that in animals with little history of consuming plants rich in tannin, more than 3% of tannin could not be incorporated into the diet.

Effect of the addition of Enterolobium cyclocarpum pods and Gliricidia sepium forage to Brachiaria brizantha on dry matter degradation, volatile fatty acid concentration, and in vitro methane production

The purpose of this study was to determine the in vitro fermentation and methane (CH₄) production in the grass Brachiaria brizantha (B) alone or when mixed with Gliricidia sepium forage (G) and/or Enterolobium cyclocarpum pods (E). Theses substrates were incubated in the following proportions: B100 (B100%), B85E15 (B85% + E15%), B85G15 (B85% + G15%), B85GE15 (B85% + G7.5% + E7.5%), and B70GE30 (B70% + G15% + E15%). Dry matter degradation (DMD), volatile fatty acid (VFA) concentration, and CH₄ production were measured at 12, 24, and 48 h of incubation. Experimental design was a randomized complete block. At 48-h incubation, DMD ranged between 46.5 and 51.2% (P = 0.0015). The lowest cumulative gas production (CGP) was observed in B85E15 and B85G15 (160 mL CGP/g organic matter, on average). At 48 h, B85G15 and B100 produced 28.8 and 30.2 mg CH4/g DMD, respectively, while B85E15 or the mixtures, 33.5 mg CH₄/g DMD, on average (P ≤ 0.05). B85E15 and B70G30 had the highest concentration of total VFA (P ≤ 0.05). Results showed that B85E15 and B70GE30 favor DMD and increased total production of VFA and CH₄ at 48 h. Supplementing livestock feed with legume forages and pods allows improves the nutritional quality of the diet and the fermentation patterns.

Mitigating the anti-nutritional effect of polyphenols on in vitro digestibility and fermentation characteristics of browse species in north western Ethiopia

Browse species are important sources of forage for livestock in Ethiopia, especially during the dry season, when the quality and quantity of green herbage is limited. However, browse species have anti-nutritional factors, such as polyphenols. This study evaluated the extent to which polyethylene glycol (PEG) can reduce the anti-nutritional effects of polyphenols whose extent is expected to vary depending on the species type and season on the in vitro fermentation of these plant samples. We selected ten browse species commonly used as livestock feed based on their tannin content, and sixty samples of the leaf and twig of these species were collected during the wet and dry seasons. The study was designed as 10 × 2 × 2 factorial arrangement with 10 browse species (Acacia nilotica, Crateva adonsonia, Dombeya torrida, Ekebergia capensis, Ensete ventricosum, Erythrina brucei, Maesa lanceolate, Sesbania sesban, Stereospermum kunthianum, and Terminalia laxiflora), 2 seasons (wet and dry) and 2 states of PEG (with and without PEG). The effects of tannin on the nutritive characteristics were also evaluated by adding PEG as a tannin-binding agent. The chemical composition and in vitro fermentation products of these samples differed significantly (p < 0.001) among browse species. Specifically, total extractable phenol (TEP) ranged from 26.3 to 250.3 g/kg, total extractable tannin (TET) from 22.8 to 210.9 g/kg, and condensed tannin (CT) from 11.1 to 141.3 g/kg, respectively. Season, species, and their interaction have a significant (p < 0.05) effect on the chemical composition and fermentation characteristics of most browse species. The addition of PEG increased gas production (GP), in vitro organic matter digestibility (IVOMD), metabolizable energy (ME) concentration, dry matter degradability (DMD), and volatile fatty acids (VFA), on average, by 76.8%, 47.9%, 42.2%, 21.2%, and 20.2%, respectively. Secondary polyphenols (TEP, TET, CT, and SCT) were significantly (p < 0.001) and negatively correlated with GP, IVOMD, ME, and VFA. Preferable species namely E. ventricosum, S. sesban, M. lanceolata, E. capensis, and A. nilotica were selected for supplementation in terms of their chemical composition, IVOMD, and mitigating effects of PEG on anti-nutritional functions of their secondary compounds. In conclusion, PEG markedly reduced the anti-nutritional effects of polyphenols and improved the in vitro fermentation of browse species harvested in contrasting seasons.

Effect of tree foliage supplementation of tropical grass diet on in vitro digestibility and fermentation, microbial biomass synthesis and enteric methane production in ruminants

The objective of this study was to evaluate the influence of tree foliage species supplemented in ruminant diets based on Pennisetum purpureum on the in vitro digestibility and fermentation, microbial biomass synthesis and enteric methane production. Seven experimental diets were evaluated, including a control treatment based on P. purpureum (PT) grass, and six additional treatments supplemented with 30.0% foliage from Neomillspaughia emargiata (NE), Tabernaemontana amygdalifolia (TA), Caesalpinia gaumeri (CG), Piscidia piscipula (PP), Leucaena leucocephala (LL) and Havardia albicans (HA). A randomised complete block design repeated in two periods (block) was used. The highest gas production (P < 0.05) was recorded in treatments TA and PT (237 and 228 mL g-1, respectively). The highest in vitro digestibility of dry matter (IVDMD) and organic matter (IVOMD) (P < 0.05) was recorded in the control treatment PT (57.9% and 66.1%, respectively). Treatments LL, NE, TA and PP promoted greater microbial biomass synthesis (290, 223, 220 and 213 mg g-1, respectively) (P < 0.05). The proportion of propionic acid also increased in these latter treatments and in treatments CG and HA (P < 0.05). Additionally, treatments LL, PP, NE and TA decreased methane production (25.8, 29.5, 30.6 and 31.8 L kg-1 of digested dry matter, respectively). In conclusion, supplementation with L. leucocephala, P. piscipula, N. emargiata and T. amygdalifolia in ruminant diets based on P. purpureum is one feed alternative that can promote greater efficiency and synthesis of microbial biomass, increase the proportions of propionic and butyric acid and decrease the production of enteric methane by 15.6 to 31.6%.

Differences in the nutrient concentrations, in vitro methanogenic potential and other fermentative traits of tropical grasses and legumes for beef production systems in northern Australia

BACKGROUND

In northern Australia, beef cattle grazed extensively on tropical rangelands are responsible for 5% of the nation's total greenhouse gas emissions. Methane (CH₄ ) is a potent greenhouse gas and in grazing ruminants might be mitigated by selecting forages that, when consumed, produce less CH₄ when fermented by rumen microbes. This study examined variability in the in vitro fermentation patterns, including CH₄ production of selected tropical grasses and legumes, to identify candidates for CH₄ mitigation in grazing livestock in northern Australia.

RESULTS

Nutritive values and fermentation parameters varied between plant species and across seasons. Grasses with a relatively low methanogenic potential were Urochloa mosambicensis (wet summer), Bothriochloa decipiens (autumn), Sorghum plumosum (winter) and Andropogon gayanus (spring), while the legumes were Calliandra calothyrsus (wet summer and autumn), Stylosanthes scabra (winter) and Desmanthus leptophyllus (spring). There was some correlation between CH₄ production and overall fermentation (volatile fatty acid concentrations) in grasses (R² = 0.67), but not in legumes (R² = 0.01) and there were multiple plants that had lower CH₄ not associated with reduction in microbial activity.

CONCLUSION

Differences in nutrient concentrations of tropical grasses and legumes may provide opportunities for productive grazing on these pastures, while offering some CH₄ mitigation options in the context of northern Australian extensive beef farming systems. © 2017 Society of Chemical Industry.

Anthelmintic activity of acetone-water extracts against Haemonchus contortus eggs: interactions between tannins and other plant secondary compounds

This study aimed at (i) describing the effects of acetone-water extracts obtained from a range of different plant materials, on the hatching process of Haemonchus contortus eggs under in vitro conditions and (ii) identifying the role of tannins and other plant secondary compounds (PSC), on these AH effects by using polyvinylpolypyrrolidone (PVPP), an inhibitor of tannins and other polyphenols. An egg hatch assay (EHA) was used to determine the AH effect. Acetone-water (70:30) extracts from different foliages (Lysiloma latisiliquum, Laguncularia racemosa, Rizophora mangle, Avicennia germinans) and plant by-products (Theobroma cacao seed husk and pulp, and percolated Coffea arabica) were obtained. Fresh H. contortus eggs were incubated in PBS with increasing concentrations of each extract (0, 600, 1200, 2400 and 3600 μg/ml PBS). A general linear model was used to determine the dose effect of each extract. A mild ovicidal activity was only recorded for T. cacao extracts (seed husk and pulp). The main anthelmintic (AH) effect for all the extracts, except for C. arabica, was to block the eclosion of larvated eggs. The use of PVPP at 3600 μg/ml PBS showed that tannins of the L. racemosa extract were responsible for blocking eclosion of larvated eggs. Extracts of L. latisiliquum, A. germinans, T. cacao seed husk and pulp also blocked eclosion of larvated eggs but the addition of PVPP indicated that tannins were not responsible for that activity. In contrast, it suggested unfavorable interactions between polyphenols and other PSC contained in those extracts, limiting the AH effect on the egg hatching process. The present results suggest that the interactions between tannins and other PSC are complex and may reduce the AH effects against H. contortus eggs.

Effect of replacing oat fodder with fresh and chopped oak leaves on in vitro rumen fermentation, digestibility and metabolizable energy

AIM

A study was conducted to evaluate the effect of replacing oat fodder (OF) with fresh oak leaves (FOL) or chopped oak leaves (COL) on rumen fermentation and digestibility through in vitro gas production technique (IVGPT).

MATERIALS AND METHODS

Nine different diets were prepared by mixing OF with oak leaves (either FOL or COL) in different ratios (100:0, 75:25, 50:50, 25:75, and 0:100). The rations were evaluated through Hohenheim IVGPT with 200 mg substrate and 30 ml of buffered rumen liquor. All the syringes were incubated at 39°C for 24 h in buffered rumen liquor of cattle. After 24 h, the total gas production was recorded, and the contents were analyzed for in vitro methane production, protozoa no. and ammonia-N.

RESULTS

Chopping (p<0.01) reduced the tannin fractions as well as non-tannin phenol. Increase in levels of oak decreased total gas production, methane, organic matter (OM) digestibility, and metabolizable energy (ME) values. The polyphenol content of the substrate did not show any significant difference on the protozoal count.

CONCLUSION

In vitro studies revealed that the addition of oak leaves reduced the methane production and ammonia nitrogen levels; however, it also decreased the OM digestibility and ME values linearly as the level of the oak leaves increased in the diet. Chopping was effective only at lower inclusion levels. Further studies, especially in vivo studies, are needed to explore the safe inclusion levels of oak leaves in the diet of ruminants.

In vitro methane and gas production characteristics of Eragrostis trichopophora substrate supplemented with different browse foliage

An in vitro gas production study was conducted to evaluate the potential of six browse species (high, medium and low condensed tannin concentrations) collected from the Kalahari Desert as antimethanogenic additives to an Eragrostis trichopophora-based substrate. The browse species studied were Acacia luederitzii, Monechma incanum, Acacia erioloba, Acacia haematoxylon, Olea europaea and Acacia mellifera. The edible forage dry matter of the browse species were incubated with Eragrostis trichopophora in a 30 : 70 (w/w) ratio by adding 40 mL of a buffered rumen fluid at 39°C for 48 h. Gas and methane production at different time intervals after incubation were determined whereas the volatile fatty acids concentration was evaluated after 48 h. Acacia luederitzii and M. incanum foliage decreased methane production by more than 50%, but simultaneously decreased digestibility, and rumen fermentation parameters such as volatile fatty acids concentration. Tannin extracts from A. luederitzii could possibly be used as a dietary alternative to reduce methane production; however, there is a need to determine an optimum level of inclusion that may not compromise the efficiency of rumen fermentation and overall digestibility of the diet.

A tannin-blocking agent does not modify the preference of sheep towards tannin-containing plants

Sheep have been suggested to use their senses to perceive plant properties and associate their intake with consequences after ingestion. However, sheep with browsing experience do not seem to select against tannin-rich browsing materials in cafeteria trials. Thus, the objective of the present study was to evaluate the relationship between the chemical composition, selectivity index (SI), preference and intake rate (IR) of tannin-containing forage trees offered to sheep in cafeteria experiments. Four trees were selected for their condensed tannin content and their varying biological activities. Havardia albicans (high biological activity), Leucaena leucocephala (medium biological activity), Acacia gaumeri (low biological activity) and Brosimum alicastrum (very low biological activity) were used in this study. Ten hair sheep (23.7kg±1.43LW) with eight months of browsing experience in native vegetation were used in this study. Polyethylene glycol (PEG 3600MW) was administered to five sheep during all experiments. In experiment 1, fresh foliage from all trees was offered ad libitum for 4h. In experiment 2, B. alicastrum was withdrawn and the preference was determined again. The forage preference in experiment 1 was A. gaumeri (14.77gDM/kgLW)>B. alicastrum (11.77gDM/kgLW)>H. albicans (3.71gDM/kgLW)=L. leucocephala (1.87gDM/kgLW) (P<0.05). The preference in experiment 2 was A. gaumeri>H. albicans=L. leucocephala. PEG administration had no effect on the preference or IR. The intake rate seemed to have been affected by the plant density. Moreover, fiber compounds were found to be better predictors of DM intake than polyphenolic compounds at levels typically found in the evaluated forages. It was concluded that tannins and PEG did not modify the preferences of sheep in cafeteria trials. Thus, tannins are not involved in the preference regulation of animals with browsing experience.

In vitro acaricidal effect of tannin-rich plants against the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The objectives of this study were to evaluate the in vitro acaricidal effects of lyophilized extracts of four tannin rich plants (Acacia pennatula, Piscidia piscipula, Leucaena leucocephala and Lysiloma latisiliquum) against diverse stages of Rhipicephalus (Boophilus) microplus, and to asses whether tannins were involved in the acaricidal effect using polyethylene glycol (PEG) to block tannins. Larval immersion (LIT) and adult immersion (AIT) tests were used to evaluate the acaricidal effect of each of the lyophilized extracts against larval and adult stages of R. microplus respectively. Larvae and adult ticks were exposed to increasing concentrations of each plant extract (0, 1200, 2400, 4800, 9600 and 19,200 μg ml(-1)) for 10 min. Larval mortality was recorded at 48 h post-incubation. Adult mortality was recorded daily over 14 days, at which point their reproductive efficiency was evaluated. PEG was added to the extracts to verify whether tannins were involved in the acaricidal effect. The effect on egg laying inhibition and larval mortality was analyzed using the GLM procedure in SAS. A Kruskal-Wallis test was used to assess the effect of PEG on LIT results. Calculation of the lethal concentration 50 (LC50) was performed using a probit analysis. All extracts reduced the viability of R. microplus larval stages (P<0.001), and viability was restored with the addition of PEG suggesting an important role of tannins in the acaricidal effect (P<0.001). The LC50 values of L. latisiliquum and P. piscipula plant extracts were 6.402 and 2.466 μg ml(-1). None of the tannin-rich plant extracts affected adult mortality (P>0.05). Lysiloma latisiliquum extract inhibited egg hatching of R. microplus (P<0.01). Tannin-rich plant extracts from A. pennatula, P. piscipula, L. leucocephala and L. latisiliquum showed potential acaricidal activity. Further in vivo studies are needed to confirm this finding.

The effect and mode of action of saponins on the microbial populations and fermentation in the rumen and ruminant production

The growing public concerns over chemical residues in animal-derived foods and threats of antibiotic-resistant bacteria have renewed interest in exploring safer alternatives to chemical feed additives in ruminant livestock. Various bioactive phytochemicals including saponins appear to be potential 'natural' alternatives to 'chemical' additives in modulating rumen fermentation favourably and animal performance. Saponins are a diverse group of glycosides present in many families of plants. The primary effect of saponins in the rumen appears to be to inhibit the protozoa (defaunation), which might increase the efficiency of microbial protein synthesis and protein flow to the duodenum. Furthermore, saponins may decrease methane production via defaunation and/or directly by decreasing the activities (i.e. rate of methanogenesis or expression of methane-producing genes) and numbers of methanogens. Saponins may also selectively affect specific rumen bacteria and fungi, which may alter the rumen metabolism beneficially or adversely. The ammonia-adsorption and modulation of digesta passage in the rumen by saponins have also been implicated in altering rumen metabolism, but their physiological responses are likely to be negligible compared with microbiological effects. The effects of saponins on rumen fermentation have not been found to be consistent. These discrepancies appear to be related to the chemical structure and dosage of saponins, diet composition, microbial community and adaptation of microbiota to saponins. There is need for systematic research based on chemical structures of saponins, nutrient composition of diets and their effects on rumen microbial ecosystem to obtain consistent results. The present paper reviews and discusses the effects and mode of action of saponins on microbial community and fermentation in the rumen, and ruminant performance.

Dietary phytochemicals as rumen modifiers: a review of the effects on microbial populations

In the recent years, the exploration of bioactive phytochemicals as natural feed additives has been of great interest among nutritionists and rumen microbiologists to modify the rumen fermentation favorably such as defaunation, inhibition of methanogenesis, improvement in protein metabolism, and increasing conjugated linoleic acid content in ruminant derived foods. Many phytochemicals such as saponins, essential oils, tannins and flavonoids from a wide range of plants have been identified, which have potential values for rumen manipulation and enhancing animal productivity as alternatives to chemical feed additives. However, their effectiveness in ruminant production has not been proved to be consistent and conclusive. This review discusses the effects of phytochemicals such as saponins, tannins and essential oils on the rumen microbial populations, i.e., bacteria, protozoa, fungi and archaea with highlighting molecular diversity of microbial community in the rumen. There are contrasting reports of the effects of these phytoadditives on the rumen fermentation and rumen microbes probably depending upon the interactions among the chemical structures and levels of phytochemicals used, nutrient composition of diets and microbial components in the rumen. The study of chemical structure-activity relationships is required to exploit the phytochemicals for obtaining target responses without adversely affecting beneficial microbial populations. A greater understanding of the modulatory effects of phytochemicals on the rumen microbial populations together with fermentation will allow a better management of the rumen ecosystem and a practical application of this feed additive technology in livestock production.

Efficiency of Sesbania sesban and Acacia angustissima in limiting methanogenesis and increasing ruminally available nitrogen in a tropical grass-based diet depends on accession

Novel strategies to improve nutrient-poor tropical diets for ruminants should aim to increase feeding value and, simultaneously, reduce emissions of the greenhouse gas methane. Both aims were addressed in the present in vitro experiment when supplementing a low quality, tropical grass (Brachiaria humidicola; Centro Internacional de Agricultura Tropical accession number 6133) with foliage from various leguminous multi-purpose shrubs, all of them containing plant secondary metabolites in different concentrations. In detail, foliage of Acacia angustissima from the International Livestock Research Institute ( ILRI; accessions no. 459 and 15132), Sesbania sesban (ILRI 10865 and 15019), Samanea saman (ILRI 14884), and leafy crop residues of the grain legume Cajanus cajan (ILRI 16555) were supplemented at 200 g/kg dry matter. Additionally, a combination of C. cajan and S. sesban 10865 was tested. Effects on methanogenesis, ruminal nitrogen turnover and other fermentation traits were determined with the rumen simulation technique Rusitec. All supplements enhanced the fermentable nutrient supply, especially ruminally degradable crude protein, and improved the calculated microbial efficiency in nitrogen utilisation. Methanogenesis was limited by one accession of S. sesban (10865) and, less clearly, by one A. angustissima accession (459), while the other supplements remained ineffective. The first mentioned accessions proved to be far richer in several plant secondary metabolites, especially saponins and tannins. Provided in combination, C. cajan and S. sesban 10865 supported each other in their effects on nitrogen usage and total methane release. Accordingly, a combination strategy might provide, after being verified in vivo, a particularly promising option to improve low quality, tropical diets at limited environmental impact thus facilitating its adoption by stakeholders.

Effect of dietary Enterolobium cyclocarpum on microbial protein flow and nutrient digestibility in sheep maintained fauna-free, with total mixed fauna or with Entodinium caudatum monofauna

Three groups of five wethers with ruminal and duodenal cannulas and maintained as either fauna-free (FF) or inoculated with total mixed fauna (TF) or Entodinium caudatum as a single-species monofauna (EN) were used in an experiment with two 28 d periods. In the first period, the sheep were fed a control barley-based diet (40:60 concentrate to silage DM) and in the second period the diet was supplemented with 187 g DM of Enterolobium cyclocarpum for the last 12 d of the period. The diets of period 1 and 2 were isonitrogenous. There was no effect of fauna on apparent ruminal and total tract organic matter and fibre digestion, but bacterial and microbial N flow and efficiency were improved in FF sheep compared to TF sheep. In period 2, protozoal numbers were reduced between 31 and 88 % 2 h after feeding E. cyclocarpum for the third to twelfth day of supplementation and by an average of 25 % in samples collected over the 24 h feeding cycle. Supplementation of the diet with E. cyclocarpum and the consequent protozoal reduction in TF and EN sheep improved the flow of non-ammonia N and bacterial N to the small intestine and the efficiency of microbial synthesis. However, E. cyclocarpum reduced ruminal organic matter digestion, especially in faunated sheep, and total tract organic matter, N and fibre digestion. Thus, a reduction in the protozoal cell numbers of 25 % was sufficient to achieve the beneficial effects of reduced fauna on the bacterial protein supply, but diet digestibility was reduced.