Browsing by Subject "Rumen"

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    Effect of yeast, protected minerals and bismuth subsalicylate on in vitro fermentation by rumen microbes.
    (2012-04) Moreno, Martín Ruiz
    Three experiments were conducted using a dual flow continuous culture fermenter system. In Experiment I, two levels of active dry yeast at 0 or 2 mg/fermenter/day (NY and YS, respectively) were infused twice daily to fermenters in a completely randomized arrangement of treatments. Apparent and true OM digestion was not affected by yeast. No differences were obtained in NDF and ADF digestion. Total VFA concentrations were not affected by treatments. Addition of yeast did not affect VFA molar proportions or estimated CH4S production but resulted in a trend for a lower A:P ratio. Addition of yeast decreased NH3-N concentration and NH3-N daily flow, without affecting crude protein digestion and efficiency of microbial protein synthesis. Mean and minimum pH of fermenters did not differ between treatments but a trend for a lower maximum pH was obtained with yeast. In conclusion, a low dose of active dry yeast decreased NH3-N concentration and daily flow, without affecting any other of the in vitro rumen fermentation characteristics measured in this study. In Experiment II, effects of two levels of lignosulfonate and two sources of minerals (protected and unprotected) on rumen fermentation were evaluated using a 2 x 2 factorial arrangement of treatments. Addition of lignosulfonate tended to decrease daily flow of non NH3-N, efficiency of microbial protein synthesis, total VFA concentration and molar proportion of acetate, but increased molar proportion of propionate, valerate and caproate. Protected minerals decreased molar proportion of propionate. Addition of lignosulfonate increased ruminally soluble Cu and Mn, whereas protected minerals reduced ruminally soluble Cu. Concentrations of bacterial Cu and Zn increased with protected minerals in absence of lignosulfonate. Concentration of Mn was not affected by treatments. Addition of lignosulfonate resulted in higher enzymatic release of Zn from solids outflow but lower from bacterial pellets. Mean, minimum and maximum fermentation pH was higher with lignosulfonate, and not affected by mineral source. Addition of lignosulfonate induced major changes in ruminal fermentation. Protection of minerals decreased rumen soluble Cu and increased bacterial Cu and Zn without affecting postruminal release of minerals. In Experiment III, addition of bismuth subsalicylate (BSS) at 1% of DM and monensin (MON; 5 ppm) were used to assess their effects on rumen metabolism and H2S release by rumen microbes in a 2 x 2 factorial arrangement of treatments. Addition of BSS increased digestion of OM, NDF and ADF but decreased that of NFC and total VFA concentrations. Molar proportions of acetate and propionate increased with BSS in the diet, while that of butyrate decreased. Monensin decreased ADF digestion and A:P ratio, without affecting molar proportions of major VFA. Regarding nitrogen metabolism, MON increased non NH3-N outflow without affecting other measurements. Addition of BSS to the diet increased NH3-N concentration, NH3-N flow and dietary-N flow, while decreasing microbial-N outflow, CP digestion, and efficiency of microbial protein synthesis. Headspace H2S was reduced by 99% with BSS treatment but was not affected by MON. Only minor changes in fermentation pH were found with MON, but an increase in mean, minimum and maximum fermentation pH were found following addition of BSS. Results indicate that BSS can markedly reduce H2S production in short term and long term in vitro rumen incubations.
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    Effects of bismuth subsalicylate and beta extract of hops (Humulus lupulus) on in vitro fermentation with ruminal microbes
    (2013-08) Fessenden, Samuel William
    Symbiosis between microbes and ruminants gives the animal a unique ability to digest fiber and transform it into meat, milk, power and other useful products. Manipulation of rumen ecology with selective antimicrobial compounds can have beneficial effects by altering microbial output, allowing the animal to achieve greater levels of production per unit of input. Two experiments were conducted to determine effects of antimicrobial compounds on in vitro fermentation with ruminal microbes in continuous culture. Inclusion of bismuth subsalicylate decreased (P < 0.05) organic matter digestion, volatile fatty acid production and had negative influences on nitrogen and fatty acid metabolism. Results indicate that bismuth subsalicylate at 0.5% of diet dry matter was detrimental to overall fermentation with rumen microbes, and lower dosage levels should be investigated. In experiment 2, beta extract from the hop plant (Humulus lupulus) was administered to continuous culture fermenters at 0, 600, 1200 or 1800 mg of beta acids / kg of dry matter. Inclusion of beta extract did not affect (P > 0.05) ingredient digestion, volatile fatty acid production or nitrogen metabolism. Beta extract tended (P = 0.09) to increase culture pH, however effects were modest and lower than biologically relevant values. Further research investigating the adaptation of microbial populations to hop beta extract was recommended.
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    Effects of iso-alpha-acids on rumen fermentation and comparison of microbial populations between rumens and continuous culture fermenters
    (2015-08) Salfer, Isaac
    Two experiments were conducted using dual-flow continuous culture fermenters to study rumen fermentation in vitro. The first experiment examined the effects of iso-alpha-acids from Humulus lupulus (Hops) extract on rumen fermentation. Iso-alpha-acid extract (IE) was provided to continuous culture fermenters to supply 0 (CON), 600 (LOW), 1200 (MED) or 1800 mg of IE/kg of diet DM/day. There was no effect (P > 0.05) of IE inclusion on DM, OM, NDF or ADF digestion (%). Volatile fatty acid (VFA) metabolism was not affected by IE treatment (P > 0.05), with total VFA concentrations of 105.5, 93.4, 87.9 and 103.6 mM for the CON, LOW, MED and HIGH treatments, respectively. Nitrogen metabolism was also not affected (P > 0.05) by IE level, with the CON, LOW MED, and HIGH treatments resulting in nitrogen concentrations of 7.4, 5.3, 7.6 and 6.8 mg N/dL of rumen fluid, respectively. No effects (P > 0.05) of treatment on fermenter pH were observed. It was concluded that administration of IE had no impact on fermentation by ruminal microbes maintained in continuous culture fermenters. Experiment 2 used 16S amplicon sequencing to compare microbial populations between the rumen of dairy cattle and continuous culture fermenters and to determine the temporal changes in microbial community during fermenter operation. Redundancy analysis (RDA) was performed to determine correlations between fermentation measurements based on microbial community. Correlations were also conducted to determine associations between prominent microbial families and fermentation measures from the In vitro system. Differences in microbial community were assessed using UniFrac metrics, Analysis of molecular variance (AMOVA) and analysis of similarity (ANOSIM) based on Bray-Curtis dissimilarity matrices. Differences in taxonomic composition of different sample types were analyzed at kingdom, phylum, class, order and family taxonomic levels. Functional inferences were made by matching taxonomic data to KEGG Orthology terms using PICRUSt software, and analyzed based on sample type. Community profile did not differ (P > 0.10) between cows in either rumen or inoculum samples, but was different (P < 0.05) in fermenter samples. Microbial community within fermenters appeared to stabilize on day 7 of the experimental period according to AMOVA and ANOSIM analyses. Bacteroidetes and Firmicutes made up the two most abundant phyla in rumen, inoculum and fermenters and neither group was different (P > 0.10) based on sample type. Proteobacteria, Tenericutes, Spirochaetes and Verrucomicrobia were different (P < 0.05) between sample types. Rumen, inoculum and fermenters did not differ (P > 0.10) in relative abundance of Prevotellaceae, which was the most abundant family in all three samples. Abundant families that were different (P < 0.05) by sample type included Succinivibrionaceae, Lachnospiraceae and Paraprevotellaceae. PICRUSt predictions showed that amino acid metabolism, membrane transport, energy metabolism and cellular processes and signaling were different (P < 0.05) between sample types. Metabolism of carbohydrates, cofactors and vitamins, and lipids were not affected (P > 0.10) by sample type according to PICRUSt inferences.