Rumen Contents Of Sheep Research Articles

Rumen Development of Tianhua Mutton Sheep Was Better than That of Gansu Alpine Fine Wool Sheep under Grazing Conditions.

The purpose of this experiment was to investigate the differences in rumen tissue morphology, volatile fatty acid content, and rumen microflora between Tianhua mutton sheep and Gansu alpine fine wool sheep under the same grazing conditions. Twelve 30-day-old lambs were randomly selected from two different flocks in Duolong Village and grazed together for a period of 150 days. The rumen tissue was fixed with 4% paraformaldehyde and brought back to the laboratory for H&E staining, the volatile fatty acid content of the rumen contents was detected by gas chromatography, and the rumen flora structure was sequenced by full-length sequencing of the bacterial 16S rRNA gene using the PacBio sequencing platform. The acetic acid and total acid contents of the rumen contents of Tianhua mutton sheep were significantly higher than those of Gansu alpine fine wool sheep (p < 0.05). The rumen papillae height of Tianhua mutton sheep was significantly higher than that of Gansu alpine fine wool sheep (p < 0.05). The diversity and richness of the rumen flora of Tianhua mutton sheep were higher than those of Gansu alpine fine wool sheep, and Beta analysis showed that the microflora structure of the two fine wool sheep was significantly different. At the phylum level, Firmicutes and Bacteroidetes dominated the rumen flora of Tianhua mutton sheep and Gansu alpine fine wool sheep. At the genus level, the dominant strains were Christensenellaceae_R_7_group and Rikenellaceae_RC9_gut_group. LEfSe analysis showed that Prevotella was a highly abundant differential species in Tianhua mutton sheep and lachnospiraccac was a highly abundant differential species in Gansu alpine fine wool sheep. Finally, both the KEGG and COG databases showed that the enrichment of biometabolic pathways, such as replication and repair and translation, were significantly higher in Tianhua mutton sheep than in Gansu alpine fine wool sheep (p < 0.05). In general, there were some similarities between Tianhua mutton sheep and Gansu alpine fine wool sheep in the rumen tissue morphology, rumen fermentation ability, and rumen flora structure. However, Tianhua mutton sheep had a better performance in the rumen acetic acid content, rumen papillae height, and beneficial bacteria content. These differences may be one of the reasons why Tianhua mutton sheep are more suitable for growing in alpine pastoral areas than Gansu alpine fine wool sheep.

Isolation and characterization of tanninolytic bacteria from sheep rumen contents: Assessment of tannin degrading, fibrolytic and feed digestibility potential

To counteract the negative effects of phytotannins, ruminants host a diverse community of bacteria that break down tannins. These bacteria not only possess tanninolytic activity but also have other functional relevance which has not been properly examined. Therefore, the present study was conducted to isolate and characterize tannin degrading bacteria (TDB) with possible fibrolytic activity from rumen of sheep fed tannin-rich diet. Based on the development of a clear zone on tannin-enriched agar plates, a total of 24 isolates were screened as tannin hydrolyzing bacteria. Majority of the isolates were gram positive cocci. The isolates could tolerate phenolic monomers such as ferulic acid, gallic acid, vanillic acid up to 30 mM and pyrogallol up to 10 mM however, the isolates failed to grow in presence of syringic acid, p-coumaric acid and p-hydroxybenzoic acid. Highest tannase activity was observed in isolate TDB23 while, lowest in isolates TDB2 and TDB5. In terms of fibrolytic activity, maximum endoglucanase, exoglucanase, and FPase activity was observed in isolate TDB9. In vitro digestibility of Prosopis cineraria leaves was considerably enhanced by inoculation of isolate TDB23 followed by TDB9. Therefore, the screened isolates demonstrated promising tannin and fibre degrading potential which can be further explored as direct-fed microbial in ruminants for effective utilization of tannin-rich fibrous feeds.

Complete genome sequence of Methanosphaera sp. ISO3-F5, a rumen methylotrophic methanogen.

Methanosphaera spp. are methylotrophic methanogenic archaea and members of the order Methanobacteriales with few cultured representatives. Methanosphaera sp. ISO3-F5 was isolated from sheep rumen contents in New Zealand. Here, we report its complete genome, consisting of a large chromosome and a megaplasmid (GenBank accession numbers CP118753 and CP118754, respectively).

Genomic insights into the physiology of Quinella, an iconic uncultured rumen bacterium

Quinella is a genus of iconic rumen bacteria first reported in 1913. There are no cultures of these bacteria, and information on their physiology is scarce and contradictory. Increased abundance of Quinella was previously found in the rumens of some sheep that emit low amounts of methane (CH4) relative to their feed intake, but whether Quinella contributes to low CH4 emissions is not known. Here, we concentrate Quinella cells from sheep rumen contents, extract and sequence DNA, and reconstruct Quinella genomes that are >90% complete with as little as 0.20% contamination. Bioinformatic analyses of the encoded proteins indicate that lactate and propionate formation are major fermentation pathways. The presence of a gene encoding a potential uptake hydrogenase suggests that Quinella might be able to use free hydrogen (H2). None of the inferred metabolic pathways is predicted to produce H2, a major precursor of CH4, which is consistent with the lower CH4 emissions from those sheep with high abundances of this bacterium.

COMPARATIVE EVALUATION ON THE POTENTIALS OF SHEEP RUMEN CONTENTS FOR BIOGAS GENERATION

Biogas refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. It is as a clean biofuel produced by microorganism during anaerobic digestion of organic matter. The study was carried out to determine the potentials of sheep rumen contents for biogas production through anaerobic digestion. Proximate analysis was carried out on the substrate. The results shows that nitrogen, potassium and phosphorus have 0.58 ± 0.02 (mg/ml), 425 ± 5.00 (mg/ml), and 2.57 ± 0.03 (mg/ml) respectively. After proximate analysis, four (4) local digesters with capacity of 500g tins were designed and used for the collection of gas via passage pipe systems. The digesters were used to digest the slurry (mixture of Sheep rumen content and water) which were mixed in the ratio of 2:1 for a period of eight weeks (56 days) retention time until the biogas reduced significantly. The pH values of the slurries were adjusted to neutral. The digesters were stirred thrice daily to avoid scum formation in the digesters and allow for easy escape of gas produced. The total average yield of the gas produced were 820 cm3, 1070 cm3, 780 cm3, and 660 cm3 for D1, D2, D3, and D4 respectively. Isolation of Microorganisms were caried during the production where B. subtilis, E. coli, P. aeruginosa, and S. aureus were found. Biogas production from organic wastes which is an eco-friendly, which helps to solve most countries energy crisis.

Redescription of Polyplastron alaskum Dehority, 1974 (Ciliophora, Entodiniomorphida), a Rare Rumen Ciliate Species from Domestic and Wild Sheep

The present study redescribes the species Polyplastron alaskum based on morphological characterization and provides, for the first time, data on its infraciliary bands pattern. Polyplastron alaskum was described in Alaskan dall montain sheep (Ovis dalli), and registered again only in the present study, 45 years later, inhabiting the rumen contents of domestic sheep (Ovis aries) in northeastern Brazil. All the taxonomic characters observed in the original description was observed in the present study. The infraciliary pattern in Polyplastron alaskum is slightly different of Diplodinium-type, observed in some ophryoscolecids belonging to the subfamily Diplodiniinae.

Occurrence and expression of genes encoding methyl-compound production in rumen bacteria

BackgroundDigestive processes in the rumen lead to the release of methyl-compounds, mainly methanol and methylamines, which are used by methyltrophic methanogens to form methane, an important agricultural greenhouse gas. Methylamines are produced from plant phosphatidylcholine degradation, by choline trimethylamine lyase, while methanol comes from demethoxylation of dietary pectins via pectin methylesterase activity. We have screened rumen metagenomic and metatranscriptomic datasets, metagenome assembled genomes, and the Hungate1000 genomes to identify organisms capable of producing methyl-compounds. We also describe the enrichment of pectin-degrading and methane-forming microbes from sheep rumen contents and the analysis of their genomes via metagenomic assembly.ResultsScreens of metagenomic data using the protein domains of choline trimethylamine lyase (CutC), and activator protein (CutD) found good matches only to Olsenella umbonata and to Caecibacter, while the Hungate1000 genomes and metagenome assembled genomes from the cattle rumen found bacteria within the phyla Actinobacteria, Firmicutes and Proteobacteria. The cutC and cutD genes clustered with genes that encode structural components of bacterial microcompartment proteins. Prevotella was the dominant genus encoding pectin methyl esterases, with smaller numbers of sequences identified from other fibre-degrading rumen bacteria. Some large pectin methyl esterases (> 2100 aa) were found to be encoded in Butyrivibrio genomes. The pectin-utilising, methane-producing consortium was composed of (i) a putative pectin-degrading bacterium (phylum Tenericutes, class Mollicutes), (ii) a galacturonate-using Sphaerochaeta sp. predicted to produce acetate, lactate, and ethanol, and (iii) a methylotrophic methanogen, Methanosphaera sp., with the ability to form methane via a primary ethanol-dependent, hydrogen-independent, methanogenesis pathway.ConclusionsThe main bacteria that produce methyl-compounds have been identified in ruminants. Their enzymatic activities can now be targeted with the aim of finding ways to reduce the supply of methyl-compound substrates to methanogens, and thereby limit methylotrophic methanogenesis in the rumen.

Comparative metagenomic analyses of sheep and cow rumen contents and their effect on methane production of anaerobic batch fermentation

Comparative metagenomic analyses of sheep and cow rumen contents and their effect on methane production of anaerobic batch fermentation

Specific pH Sensor Based on Nitrogen/Carbon Nanotube-Modified Commercial Field-Effect Transistor for Detection of Rumen pH in Ruminants In Situ

A small and stroke resistant pH sensor was fabricated using a commercial metal-oxide field-effect transistor and was modified with single-walled carbon nanotubes (SWCNTs) for direct evaluation of the rumen pH in cows via a stomach tube. Integrated circuit (IC: BS250) was selected as the selective probe for pH detection. For this purpose, the plastic cover on the surface of the drain was drilled to bare the drain surface, followed by modification with nitrogen-doped SWCNTs by the hot-wall chemical vapor deposition process. According to the figures of merit, fabricated sensor was linear from 4.2 to 8.1 pH unit. Detection limit was 1.23 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> M. Relative standard deviation for five replicate analyses was 3.47%. Based on 90% of maximum response, the response times were estimated to be ~60 s for in vivo and ~12.4 s for in vitro measurements. Calibration sensitivity was measured to -62.1 pH/decade. No interference was observed after setting at least 200-fold of interfering agents, such as PO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3-</sup> , SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-</sup> , Ca <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> , globulin, and acetic acid in a rumen fluid with 6.61 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> M of H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> . The ease of conducting of the sensor to the rumen through a stomach tube and in situ measurement of the rumen pH was evaluated in four dairy cows. The results were reliable compared with those obtained by a glass membrane electrode on samples drained by rumenocentesis. Slaughterhouse testing of the sensor on rumen contents of sheep (n=8) and cows (n=2) revealed that its relative error percentage could approach to maximum 10% compared with glass membrane sensors.

Reclassification of Eubacterium rectale (Hauduroy et al. 1937) Prévot 1938 in a new genus Agathobacter gen. nov. as Agathobacter rectalis comb. nov., and description of Agathobacter ruminis sp. nov., isolated from the rumen contents of sheep and cows.

Three strains of a butyrate-producing bacterium were isolated from the rumen contents of grazing sheep and cows. The strains were anaerobic, with Gram-positive cell walls, straight-to-slightly-curved, rod-shaped, non-spore-forming and single flagellate. C14 : 1, C14 : 0, C16 : 0 and C16 : 1 were the predominant fatty acids. The cell-wall peptidoglycan type was A1γ. The DNA G+C content varied from 41.4 to 42.2 mol%. 16S rRNA gene sequence similarities between the isolates and Eubacterium rectale, Roseburia hominis and Roseburia intestinalis were found to be 96, 95 and 95 %, respectively. The phylogenetic tree showed that the strains constituted a different taxon, separate from other taxa with validly published names and forming a cluster with strains of Eubacterium rectale. On the basis of phenotypic, chemotaxonomic and phylogenetic results (16S RNA, dnaK, groEL, atpA genes), the isolates are considered to represent a novel species of a new genus of the family Lachnospiraceae, for which the name Agathobacter ruminis gen. nov., sp. nov. is proposed (type strain JK623T = DSM 29029T = LMG 28559T). We also propose the transfer of Eubacterium rectale to the new genus as Agathobacter rectalis gen. nov., comb nov. This new genus represents saccharoclastic, chemo-organotrophic and obligatory anaerobic, non-spore-forming rods with Gram-positive membrane. The main fermentation products on peptone yeast glucose (PYG) medium were butyrate, acetate, hydrogen and lactate. The type species of the genus is Agathobacter rectalis gen. nov., comb nov. (Prévot, 1938) with type strain ATCC 33656T ( = JCM 17463T).

Characterization of a novel xylanase gene from rumen content of Hu sheep.

A novel xylanase gene, xyn-lxy, was cloned from a metagenomic fosmid library, which was previously constructed from the rumen contents of Hu sheep and was functionally characterized in Escherichia coli. The open reading frame was composed of 1923 bp and encoded for 640 amino acids, including a catalytic domain of glycosyl hydrolase family 10 and carbohydrate-binding module 9. The gene showed 97 % identity with uncultured bacterium Contig1552 but low similarity with xylanases from known cellulolytic-degrading microorganisms in the rumen. The recombinant XYN-LXY showed a specific activity of 664.7 U mg(-1). The optimal temperature and pH of the enzyme were 50 °C and 6.0, respectively. Specifically, XYN-LXY was exclusively activated by Mn(2+) among all of the cations and reducing agents tested in this study. An enzymatic hydrolysis assay revealed that XYN-LXY degraded birchwood xylan into xylooligosaccharide with a low degree of polymerization. After incubation for 4 h, the concentration of the dominant product, xylobiose, was 2.297 ± 0.175 mg ml(-1) (74.07 % of total product) followed by xylose with a concentration of 0.656 ± 0.010 mg ml(-1) (21.14 % of total product). The XYN-LXY exhibited deep degradation effects on the xylan substrate, which were rarely observed with endo-xylanase, making it a promising candidate for industrial application, especially in biofuel production.

Effects of inorganic and organic selenium on the fatty acid composition of rumen contents of sheep and the rumen bacteria and ciliated protozoa

The impact of 3 months of daily administration of equimolar doses of inorganic and organic Selenium (Se) on the fatty acid composition of rumen contents and rumen bacteria and protozoa was studied. Twelve sheep were fed a basal diet of meadow hay (1380g dry matter/sheep) and ground barley grain (450g dry matter/sheep) containing a background Se concentration of 0.16mg/kg DM. The sheep were randomly divided into three groups and fed the basal diet only (Control) or identical diets supplemented with inorganic (Na2SeO3; ISe) or organic Se (selenized yeast; OSe) in equimolar amounts of Se of 0.4mg/kg of feed DM. The fatty acid (FA) profile was determined in the total rumen contents (TRC), bacterial fraction (BF) and ciliated protozoal fraction (PF). In the TRC, supplementation with OSe decreased the concentration of C18:2cis-9, trans-11 (P<0.05) and increased the concentration of α-linolenic acid (C18:3 n3; LNA; P<0.01). In the BF of the ISe group the content of myristic acid (C14:0; P<0.05), palmitic acid (P<0.01) and medium chain fatty acids (P<0.01) were lower, and the content of long chain fatty acids (P<0.05), stearic acid (C18:0; P<0.01), arachidic acid (C20:0; P<0.001) and behenic acid (C22:0; P<0.01) were increased. The OSe increased the concentration of caprilic acid (C8:0; P<0.001), eicosatetraenoic acid (C20:4 n6; P<0.01) and eicosatrienoic acid (C20:3 n3; P<0.01) in the BF. In the PF the ISe decreased the concentration of docosahexaenoic acid (C22:6 n3) and tricosylic acid (C23:0; P<0.05). The addition of OSe increased the content of LNA (P<0.01) and decreased the content of palmitooleic acid (C16:1; P<0.05) in the PF. Our results point to the probable impact of OSe on the intake of dietary polyunsaturated fatty acids (PUFA) by rumen microbes, especially by rumen ciliates, and on the biohydrogenation of PUFA to more saturated FA.

Effects of preservation procedures of rumen inoculum on in vitro microbial diversity and fermentation

Sheep rumen contents were used as inoculum for an in vitro semi-continuous incubation system to study whether preservation method affects microbial fermentation pattern. Rumen fluid was filtered and either used immediately as inoculum (CTL) or dispensed into 110 mm × 16 mm tubes, that were stored refrigerated at 6 °C for 4 h (REF) or frozen at −20 °C (FRZ), frozen in liquid N (FLN) or added with 0.04 glycerol and frozen in liquid N (FGL) for 48 h. Frozen inocula were thawed at 39 °C for 2 min before use (16 ml per bottle). Two 24 h incubations with four bottles per treatment were completed. The microbial utilisation of added glycerol after thawing in FGL increased total gas production ( P<0.05) and 24 h volatile fatty acid (VFA) production ( P<0.05), and also increased propionate and butyrate proportions at the expense of acetate. The other freezing inocula ( i.e., FLN and FRZ) reduced the rate of gas production (as ml/g dry matter per hour), compared with CTL in the first 2 and 4 h of incubation ( P<0.05), but this was compensated by increased fermentation at 8 and 12 h, respectively. Differences in gas production did not manifest a different VFA pattern at either 6 or 24 h incubation. Bacterial diversity was slightly affected by the preservation process, and the similarity index between untreated inocula and the 24 h incubated CTL samples was 0.690–0.724. Similarity between bacterial communities in FRZ and FLN with that in CTL after incubation was 0.678. The freezing preservation method of rumen inocula for subsequent in vitro gas production studies does not affect microbial fermentation pattern or bacterial biodiversity, provided that processing is rapid enough by using a high surface to volume ratio. Freezing in liquid N is more appropriate than at −20 °C.

Isolation and identification of cellulose-binding proteins from sheep rumen contents.

To extend our understanding of the mechanisms of plant cell wall degradation in the rumen, cellulose-binding proteins (CBPs) from the contents of a sheep rumen were directly isolated and identified using a metaproteomics approach. The rumen CBPs were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and some CBPs revealed endoglucanase activities toward carboxymethyl cellulose. Using mass spectrometry analyses, four CBPs were identified and annotated as known proteins from the predominant rumen cellulolytic bacterium Fibrobacter succinogenes: tetratricopeptide repeat domain protein, OmpA family protein, fibro-slime domain protein, and cellulose-binding endoglucanase F (EGF). Another CBP was identified as the cellulosomal glycosyl hydrolase family 6 exoglucanase, Cel6A, of Piromyces equi. F. succinogenes cells expressing EGF were found to be major members of the bacterial community on the surface or at the inner surface of hay stems by immunohistochemical analyses using anti-EGF antibody. The finding that four of the five CBPs isolated and identified from sheep rumen contents were from F. succinogenes indicates that F. succinogenes is significantly involved in cellulose degradation in the rumen.

In vitro examination of DHA-edible micro algae : 1. Effect on rumen lipolysis and biohydrogenation of linoleic and linolenic acids

Effects of a docosahexaenoic acid (DHA)-edible algae product, Aquagrow-DHA, on lipolysis and biohydrogenation of linoleic acid (C18:2 n-6) was studied in 24 h in vitro incubations with buffer (20 ml), sheep rumen contents (5 ml), hay (0.4 g) and sunflower oil (20 mg). Four Aquagrow-DHA levels (0, 20.8, 41.6, 83.3 mg) were tested and addition of lard ensured that the total fat content was constant. Increasing Aquagrow-DHA proportionally inhibited hydrogenation of C18:2 n-6, provoking an accumulation of C18:1 trans fatty acids (mainly C18:1 t10 + t11). Analogous incubations for 6 and 24 h with linseed oil (20 mg) instead of sunflower oil, resulted in the accumulation of C18:2 t11c15 and, to a lower extent, C18:1 t10 + t11 and showed that Aquagrow-DHA reduced the rate of lipolysis of linolenic acid (C18:3 n-3). Comparison of these results with incubations with the individual constituents of Aquagrow-DHA and whole algae biomass revealed that the observed effects were related to the presence of DHA. Finally, incubations under a 50:50 H 2:CO 2 atmosphere suggested a direct inhibitory effect of unesterified DHA on hydrogenating bacteria involved in the conversion of C18:2 t11c15 and C18:1 trans isomers, rather than on H 2 availability.

Limited genetic variability inMegasphaera elsdenii strains

Levels of phenotypic and genotypic diversity among seven Megasphaera elsdenii strains recovered from rumen contents of cattle, sheep and lambs were determined by a combination of antibiotic-resistance analysis and PCR fingerprint techniques targeted both to the ribosomal RNA operon (ARDRA, RISA) and the whole genome (ERIC-PCR, RAPD-PCR). Despite exhibiting different antibiotic resistance profiles, the tested strains represent genetically nearly identical isolates. Close genetic relatedness was found among M. elsdenii isolates that originated from vastly different habitats worldwide, as revealed by the comparison of 16S rDNA sequences.

Production of indolic compounds by rumen bacteria isolated from grazing ruminants

To screen rumen bacterial cultures and fresh ruminal isolates for indole and skatole production. Culture collection strains and fresh bacterial isolates from rumen contents of sheep and dairy cows were screened for the production of indolic compounds. Clostridium aminophilum FT, Peptostreptococcus ssp. S1, Fusobacterium necrophorum D4 produced indole and Clostridium sticklandii SR produced indoleacetic acid. Fresh isolates from sheep (TrE9262 and TrE7262) and dairy cows (152R-1a, 152R-1b, 152R-3 and 152R-4) produced indole, indolepropionic acid, tryptophol and skatole from the fermentation of tryptophan and indoleacetic acid. Glucose altered the indolic compounds produced in some, but not all, isolates. TrE7262 and 152R-4 were identified as Clostridium sporogenes and 152R-1b as a new Cl. aminophilum strain. Isolates TrE9262, 152R-1a and 152R-3 were not closely related to any described species but belong to Megasphaera, Prevotella and Actinomyces genera, respectively. Rumen bacteria that produced a range of indolic compounds were identified. Some isolates are distinct from the previously described bacteria and may represent novel species. These observations will contribute to understanding skatole and indole formation in the rumen and will lead to methods that control the formation of indolic compounds in pasture-grazed ruminants.

A lack of predatory interaction between rumen ciliate protozoa and Shiga-toxin producing Escherichia coli

To investigate interactions between rumen protozoa and Shiga toxin-producing Escherichia coli (STEC) and to ascertain whether it is likely that rumen protozoa act as ruminant hosts for STEC. The presence of stx genes in different microbial fractions recovered from cattle and sheep rumen contents and faeces was examined using PCR. In animals shedding faecal STEC, stx genes were not detected in the rumen bacterial or rumen protozoal fractions. Direct interactions between ruminal protozoa and STEC were investigated by in vitro co-incubation. Rumen protozoa did not appear to ingest STEC, a STEC lysogen or non-STEC E. coli populations when co-incubated. The ruminal environment is unlikely to be a preferred habitat for STEC. Bacterial grazing by rumen protozoa appears to have little, if any, effect on STEC populations. This study indicates that ruminal protozoa are unlikely to be a major factor in the survival of STEC in ruminants. They appear as neither a host that protects STEC from the ruminal environment nor a predator that might reduce STEC numbers.

Effect of Yucca schidigera extract on the concentration of rumen microorganisms in sheep

The effects of Yucca schidigera extract (YSE) on pH and the concentration of protozoa, bacteria, and fungi in sheep rumen contents were investigated. In this study, 20 sheep were divided into four groups of five animals each and fed a basal diet for 3 weeks. Each group was then fed an experimental diet containing YSE at levels of 5, 10, 20 and 30 g/head/day, respectively. Samples of whole ruminal contents for measurement of protozoal, bacterial, and fungal concentrations and pH were obtained before feeding by rumenotomy after 3 weeks on the basal diet and by euthanasia after 3 weeks on the experimental diet. Animals fed YSE at a level of 30 g/head/day had higher rumen protozoal concentrations ( P < 0.015) and pH ( P < 0.01) than when fed the basal diet. Except for an increase in pH at the 10 g/head/day level, supplementation of YSE at levels of 5, 10 and 20 g/head/day to the basal diet had no effect on microbial concentrations or pH.

Effect of fish oil on in vitro rumen lipolysis, apparent biohydrogenation of linoleic and linolenic acid and accumulation of biohydrogenation intermediates

The effect of fish oil (FO) on lipolysis and apparent biohydrogenation of linoleic (C18:2n-6, LA), linolenic (C18:3n-3, LNA), eicosapentaenoic (C20:5n-3, EPA) and docosahexaenoic (C22:6n-3, DHA) acid was studied in 6 and 24 h in vitro incubations with diluted sheep rumen contents (50 ml) as inoculum and six substrates (0.50 g) containing compound feeds based on barley, sugar beet pulp and soybean meal. Feeds containing sunflower oil (SO, 80 g/kg DM) or linseed oil (LO, 80 g/kg DM), as C18:2n-6 and C18:3n-3 source, respectively, were further enriched with three levels of fish oil (0, 20 and 40 g/kg DM), whereas addition of lard (40, 20 and 0 g/kg DM) ensured equal amounts of added fat (120 g/kg DM) in all feeds. Lipolysis was determined by the difference in triacylglycerol before and after incubation, whereas apparent biohydrogenation was calculated by the decrease of free polyunsaturated fatty acids (PUFA). FO had no influence on the degree of lipolysis or apparent biohydrogenation of C18:2n-6 and C18:3n-3, or on lipolysis of EPA and DHA in the different incubations. Biohydrogenation of EPA and DHA, however, was reduced with increasing FO dose. Compared to C18:2n-6 and C18:3n-3, lipolysis as well as biohydrogenation of EPA and DHA were significantly lower. Although C18:2n-6 and C18:3n-3 disappeared to the same extent, the amount of stearic acid (C18:0), the end-product of their biohydrogenation, was significantly lower in substrates with FO supplementation. Higher amounts of t11C18:1 and t11c15C18:2 in incubations with these substrates suggest that FO mainly inhibits the final step of biohydrogenation of C18:2n-6 and C18:3n-3. Addition of FO to diets containing C18:2n-6 or C18:3n-3 could increase ruminal accumulation and, hence, duodenal flow of t11C18:1. This could result in a higher uptake by the tissues and more substrate for the endogenous synthesis of c9t11CLA.