Ruminants ( Shakira sulehri)

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Define Ruminant
Examine digestive system of cattle
Discuss the rumen microbes
Describe methods of manipulation
Explain how Infection occurs

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Ruminants ( Shakira sulehri)

  1. 1. RUMEN MICROBES AND THEIR MANIPULATION A Symbiotic Journey Inside The Cow By Shakira Ghazanfar SO, ASI, NARC
  2. 2. In the next 20 minutes, we’ll… Define Ruminant Examine digestive system of cattle Discuss the rumen microbes Describe methods of manipulation Explain how Infection occurs
  3. 3. What is a Ruminant? Ruminant: (n.) any of the various cud-chewing mammals having a stomach divided into four compartments. Cows, sheep, moose, goats, antelope, and camels
  4. 4. Ruminants.. • Has a stomach with 4 chambers: 1. rumen 2. reticulum 3. omasum 4. abomasum
  5. 5. What is RUMEN?  Digestive part in ruminants  150 L liquid  Natural fermentation tank and feed reservoir  Microorganisms adhere to feed particles and mucosal of rumen A Fermentation Vat Volume: 180-240L Temp: 38- 42º C pH: 6.4 to 7.2
  6. 6. The Rumen A Fermentation Vat Volume: 180-240L Temp: 38- 42º C pH: 6.4 to 7.2
  7. 7. Quantities of Microorganisms in Rumen 1. Bacteria/gm = 1010 (99.99 anaerobes)  Feed= mainly fibrous material (cellulose)  Cellulose is a lignified material (beta 1-4 bond) in feed  Animals cannot digest it without high quantities (60%) of cellulolytic bacteria  Cellulolytic bacteria= Break that beta-1,4- linkages of cellulose and release energy for milk formation 2. Protozoa/gm =109 3. Fungi/gm =105
  8. 8. Microbial Population • The rumen is home to billions and billions of microbes, including bacteria, protists, fungi, and viruses. • These many different rumen microbes form a complex community of organisms that interact with one another, helping the animal digest its food.
  9. 9. Establishment of rumen microorganisms 0 5 15 20 25 10 Days after birth Facultative anaerobes Microaerophilic Cellulolytic population Fungi Caecomyces Piromyces Neocallimastix Protozoa, Mycoplasma Entodinia Diplodinia Holotrichs 50
  10. 10. Ruminal microflora 1. BACTERIA • 107 – 1012/ ml rumen fluid • Cellulolytic bacteria • Bacteria producing VFA and lactic acid • Methane producing bacteria • Proteolytic bacteria • Lipolytic bacteria
  11. 11. Ruminal microflora 2. PROTOZOA • 105/ml rumen fluid • Utilize soluble sugars and polysaccharides • Utilize starch – prevent a decrease in pH
  12. 12. Ruminal microflora 3. FUNGI •High celullolytic and hemicellulolytic activity •Improve rumen fermentation •Increased body weight •Improved milk production •Improve overall animal production
  13. 13. Bacterial forms cocci rods Spirochete filamentous budding and appendaged
  14. 14. Cocci found in different arrangements single pairs groups chains
  15. 15. Groups of Bacteria in the Rumen  Free-living in the liquid phase  Loosely associated with feed particles  Attached to surface of protozoa and fungi
  16. 16. Adherence of mixed rumen bacteria to plant material. Protuberances from cells probably are binding factors.
  17. 17. Fibrobacter succinogenes • Gram - none motile rods but can become coccoid or oval on culture
  18. 18. Fibrobacter succinogenes • Reportedly most widespread cellulolytic bacteria; about 5 % of all rumen isolates • Most extensive lignocellulosic degradation in vitro; ferment cellobiose and glucose • Do not hydrolyse xylan and make limited use of pentoses liberated from fiber digestion
  19. 19.  Enhance beneficial processes  Minimize, alter or delete inefficient processes  Minimize, alter or delete processes harmful to the host • Aim of manipulating ruminal fermentation
  20. 20. ★ Dietary : Chemical & Physical treatment, Feeding frequency, Order, Additives, Plant genetics ★ Animal : Intake, Saliva flow, Digestive system ★ Microbial : Population, Activity, GMO • Methods for Manipulation
  21. 21. Effect of diet on the number & size of papillae A B C D Poor Quality Feed High Quality Feed
  22. 22. A well-fed ruminant A starving ruminant A young ruminant
  23. 23. Isolation of rumen bacteria • Usually total and cellulolytic bacteria – amylolytic, xylanolytic and saccharolytic e.t.c. • Sampling – Cannulated animals – Multi-site sampling – Minimize headspace • Homogenise under CO2; filter through cheese cloth into pre-warmed (ca 39oC) thermos
  24. 24. Viable cell count 1.dilute sample 1 ml 9 ml 107 106 105 104 1000 100 10 cell no/ml 2. plate out 0.1 ml
  25. 25. Isolation of bacteria – Solid associated microorganisms may be detached using methyl cellulose (or tween-80 followed by chilling for 6 - 8 h) • Dilute sample in a 10 fold dilution series using an anaerobic diluent • Role tube method employed for all but cellulolytic • Anaerobic and sterile procedures
  26. 26. Enumeration of bacteria • For cellulolytics: MPN procedure. – 1 ml from 10-6 to 10-8 dilutions inoculated in triplicate into 4 ml anaerobic growth media (39oC) in Hungate tubes, containing a strip of filter paper as sole C source. Incubate at 39oC for up to 2 weeks – Numbers determined statistically based on numbers of tubes containing digested filter paper at each dilution • For other groups, – Same procedure but inoculate (10-6 to 10-9) into media containing 1.8 % agar(47oC) and either a mixture of energy sources for total counts, or just the specific substrate for each sub group. Spin tubes in ice slurry to solidify agar – Incubate at 39oC for 2 to 3 days and count colonies (/ml rumen fluid)
  27. 27. Water + nutrients energy source;organic, inorganic or light carbon, nitrogen source Agar can be added to make the medium semi-solid and poured into Petri dishes Culture media 1. Biochemical requirements for growth
  28. 28. 2. Physical and environmental requirements for growth • oxygen concentration • pH (hydrogen ion concentration) • temperature
  29. 29. Growth media – Rumen fluid containing – Clarified autoclaved rumen fluid (10 to 20 %) – Mineral solution 1: KH2PO4 – Mineral solution 2: NaCl, (NH4)2SO4, CaCl2, MgSO4 and microelements – VFA and Vitamin solutions – Resazurin – Energy substrate(s) as required – Casein hydrolysate (amino acids and peptides) – pH adjusted to 6.5 • Boil; replace headspace with stream of CO2 – Reducing agent and bicarbonate – Dispense in to tubes, seal and autoclave
  30. 30. Growth media • Chemically defined media – No rumen fluid; nutrient requirements usually met by rumen fluid must be supplied e.g phenylpropanoic acid for R. albus and 1, 4- napthoquinone for S. dextrinosolvens.
  31. 31. Anaerobic glove box – Permits growth of anaerobes on Petri dishes, hence the use of techniques such as – replica plating – rapid identification systems such as strip tests • avoids exposure of bacteria to molten agar (47oC) – Sufficient CO2 in atmosphere to • maintain medium pH • for nutrition of microbes requiring CO2 – 95 % CO2/ 5% H2 ok for most rumen bacteria; for methanogens, 80% H2/20% CO2
  32. 32. An anaerobic glove box
  33. 33. Maintenance of cultures • Storage • at 4oC can retain viability for up to 1 month (storage usually for up to 1 week) • of 12 to 24 h cultures in 20 % glycerol for up to 1 year • under liquid nitrogen (-196oC); followed by rapid thawing in water at 32 to 35oC. Very successful. • Freeze drying. Reports of viability for up to 5 years
  34. 34. Conversion of carbohydrates to pyruvate
  35. 35. Methanogenesis – Three major catabolic pathways • CO2 reduction* – CO2 and H2 to form CH4; electrons mainly from free H2 but also formate • Methyltrophic pathway – reduce CH3 groups from compounds methanol, trimethylamine • Aceticlastic pathway – Split acetic acid and reduce CH3 to CH4
  36. 36. Cell Wall Structure of Bacteria Gram + Gram –
  37. 37. Microbiology of the Rumen 1: Role of Bacteria  Brings enzyme and substrate together in a poorly mixed system  Allows bacteria to colonize the digestible surface of feed particles  Reduces predatory activity of protozoa and help fungi function
  38. 38. Microbiology of the Rumen 2: Role of Protozoa  Digestion and fermentation carbohydrates and proteins  Ingest bacteria and feed particles  Engulf feed particles and digest CHOH, proteins and fats.
  39. 39. Microbiology of the Rumen 3: Role of fungi  Improved nutrient utilization  More feed intake  Increased body weight  Improved milk production
  40. 40. Rumen Microorganisms (Nutritional Requirements) • CO2 • Energy: End products from digestion of CHOH • Nitrogen: Ammonia (Majority of N needs) Amino acids (nonstructural CHOH digesters) • Minerals: Co, S, P, Na, K, Ca, Mg, Mn, Fe, Zn, Mo, Se • Vitamins: None required in mixed cultures
  41. 41. Rumen Digestion and Fermentation CO2 VFA Degradable Rumen Microbial cells Feed Microbes NH3, CH4 Heat Long-chain fatty acids H2S
  42. 42. ADP ATP NADP+ NADPH Sugars Catabolism Growth Maintenance Transport Microbial Metabolism VFA CO2 CH4 Heat
  43. 43. • Types of microorganisms in the rumen – Bacteria – Archea – Protozoa – Fungi – Mycoplasma – Bacteriophages • Considerable diversity in the population – Traditional culturing techniques • Bacteria: 22 Genera and 68 species • Protozoa: 6 Genera and 15 species • Fungi: 3 Genera and species – Molecular techniques • ?????
  44. 44. http://www.bacterialphylogeny.info/Reprints/Lecture-2%20Archaea-Eukaryote.pdf Domains of organisms ARCHEA
  45. 45. • Reasons for the diverse population – Wide range of substrates – Rapid environmental changes • Types and concentrations of nutrients • Frequency of feeding • pH • Presence of O2 – Range of environments and microenvironments • Digesta particles • Liquid • Rumen wall • Laminae of omasum • Surfaces or inside of other organisms – In terms of microbial growth, a group of microorganisms is more efficient than any single microorganism • Maximum biochemical work
  46. 46. • Properties of a true rumen microorganism – Anerobic or facultative anerobic – Produce endproducts found in the rumen or that are utilized by other microorganisms – Numbers needed • Bacterial species – >106/ml
  47. 47. • Quantities of microorganisms – Viable organisms • 1010 – 1011 bacteria/gm • 105 protozoa/gm • 105 fungi/gm • 109 bacteriophages/gm – Variability in counts • Total counts are 2 to 3 x greater than viable counts • Total counts decrease after feeding – Causes for reduction in bacteria » Lysis from O2 » Movement of bacteria from fluid to solid digesta » Washout with digesta flow » Dilution with water and saliva – Cause for reduction in protozoa » Chemotaxis – Problems with traditional techniques • Bacteria (Culture techniques) – Difficult to separate particulate-bound bacteria – Inability to count viable, but non-dividing cells – Colonies may be formed by clumps of cells – Inability to grow some species on lab media • Protozoa – Chemotaxis – Dilution of minor species
  48. 48. • Quantity of protozoa – Protozoa numbers < Bacteria numbers – Protozoa size are 500 to 1,000,000 x > Bacteria – Therefore normally, Protozoal volume = Bacterial volume
  49. 49. • Methods of classifying rumen bacteria – Traditional • Morphology – Shape – Size – Gram – or + – Groups • Energy source • Fermentation endproducts • Special nutritional requirements – Immunological – Molecular • RFLP (Restriction Fragment Length Polymorphisms) • 16s RNA sequencing • PCR (Polymerase Chain Reactions)
  50. 50. • Classifying rumen bacteria by energy source – Relationships • Few species specialize in metabolizing a single substrate, but many prefer certain substrates • Substrate concentration is important in controlling growth of specific species – General relationship u = umax / (1+ Ks/[S]) where u = growth rate umax = theoretical maximum growth rate Ks = Affinity coefficient for a substrate (Lower = more affinity) [S] = Substrate concentration Therefore, if the substrate concentration is very high relative to the affinity, the closer the growth rate will be to the maximum.
  51. 51. • Relationships – If species A has a higher affinity (ie. lower affinity coefficient) and equal umax to species B, then species A will always predominate except at very high concentrations – a – If species A has a higher affinity (lower Ks) and lower umax than species B, then species A will predominate at low concentrations and species B will predominate at high concentrations A B u [Substrate] u [Substrate] A B
  52. 52. • Classifying rumen bacteria by energy source – Cellulolytic bacteria • Cellulose – Primary constituent of plant cell walls – A chain of glucose units bound by beta-1,4-linkages – Can only be digested by microorganisms – Digestibility controlled by lignification • Common cellulolytic bacteria – Ruminococcus flavefaciens – Ruminococcus albus – Fibrobacter succinogenes – Butyrvibrio fibrisolvens – Clostridium lochheadii
  53. 53. • Growth requirements of cellulolytic bacteria – pH 6.0-7.0 » Will not grow at pH < 6.0 Reasons: Depletion of HCO3 VFAs are inhibitory Destruction of membrane potential – NH3* – Branched chain VFA* » Leucine > Isovaleric acid » Isoleucine > 2 methyl-butyric acid » Valine > Isobutyric acid – Phenolic acids* » Phenylalanine > Phenylacetic acid » Phenylalanine or Cinnamic acids > 3-Phenylpropionic acid – CO2 as HCO3* – S- as Cysteine or Sulfate
  54. 54. • Fermentation endproducts of cellulolytic bacteria – Cellobiose – Acetic acid* – Butyric acid – CO2* – H2* – Ethanol* – Succinic acid* – Formic acid – Lactic acid *Major endproducts Not normally found; Used by other bacteria
  55. 55. • Cellulose digestion – In reticulorumen • Approximately 90% of cellulose digestion – Requires two steps • Microbial attachment • Hydrolysis Miron et al. JDS 84:1294
  56. 56. – Attachment of cellulolytic bacteria on fiber • Results in a lag period in digestion • Phases – Transport of bacteria to fiber » Slow » Dependent on number of bacteria – Nonspecific adhesion of bacteria to sites on substrate » Binds with Glycocalyx Mixture of polysaccharide, glycoprotein and protein on outside of cell membrane of gram- bacteria Peptidoglycan of gram+ bacteria » Occurs mainly at cut or macerated sites of the plant – Specific adhesions of bacteria with digestible cellulose » Structures Cellulosome: Large, multienzyme complexes specialized for adhesion and hydrolysis of cellulose Fimbriae or Pili: Small (5-7 nm in width and 100-200 nm in length) structures in both gram + and – bacteria – Proliferation and colonization of bacteria
  57. 57. – Structure of the cellulosome – Cellulose hydrolysis • Cellulases are extracellular • Enzymes – Endo-B-1,4-glucanase > Cleaves cellulose chains – Exo-B-1,4-glucanase > Cleaves cellobiose units – Cellobiase > Cleaves cellobiose – Cellulose hydrolysis • Cellulases are extracellular • Enzymes – Endo-B-1,4-glucanase > Cleaves cellulose chains – Exo-B-1,4-glucanase > Cleaves cellobiose units – Cellobiase > Cleaves cellobiose
  58. 58. – Hemicellulolytic bacteria • Hemicellulose – A major component of plant cell walls – A chain of hexoses, pentoses, and uronic acids bound by beta-1,4-linkages – Digestibility controlled by lignification • Common hemicellulolytic bacteria – Most cellulolytic bacteria – Prevotella ruminicola • Growth requirements – Similar to cellulolytic bacteria • Fermentation endproducts – Similar to cellulolytic bacteria
  59. 59. – Pectinolytic bacteria • Pectin – Chains of uronic acids bound by alpha-1,4-linkages with pentose branch points – 2-6% forage DM – Highly digestible • Pectinolytic bacteria – Lachnospira multiparus – Succinovibrio dextrinosolvens – Fibrobacter succinogenes – Butyrvibrio fibrisolvens – Prevotella ruminicola – Streptococcus bovis • Fermentation endproducts – Acetic acid – Propionic acid – Butyric acid – Lactic acid – Succinic acid – Formic acid* Intermediates
  60. 60. – Amylolytic bacteria • Starch – Polymer of glucose units bound by alpha-1,4-linkages with varying numbers of alpha-1,6-branch points – Primary carbohydrate in grains • Amylolytic bacteria – Streptococcus bovis » Normally present in low numbers in cattle either fed forages or adapted to grain diets » Very high numbers in unadapted cattle that engorge on grain Reasons for increase High concentrations of glucose in rumen Low division time Loss of protozoa » Fermentation 85% of starch is fermented to lactic acid » Causes lactic acidosis
  61. 61. • Lactic acidosis Grain engorgement Increased [VFA] in rumen Decreased rumen pH and free glucose Increased S. bovis Increased rumen D,l-lactic acid pH 5.0 Increased lactobacilli species More D,L-lactic acid production Lactic acid absorbed through rumen wall D-lactic acid is not metabolized by the animal Increases blood [D-Lactic acid] Reduces blood pH Decreases the [CO3] in blood Hemoconcentration Coma
  62. 62. – More amylolytic bacterial species • Ruminobacter amylophilus • Prevotella ruminicola • Succinomonas amylolytica • Succinovibrio dextrinosolvens – Growth requirements • pH 5.0-6.0 • CO2 • NH3 • Peptides – Fermentation endproducts • Oligosaccharides (Intermediate) • Acetic acid* • Propionic acid* • Butyric acid • CO2 • Lactic acid • Succinic acid • Formic acid Intermediates
  63. 63. – Sugar fermenters • Free sugars rarely found in rumen • Few sugar utilizers – Streptococcus bovis – Lactobacillus species • Cellulodextrin utilizers – Treponema bryantii » Grows in co-culture with F. succinogenes
  64. 64. – Acid-utilizing bacteria • Acids that are usually intermediate metabolites – Lactic acid – Succinic acid – Formic acid • Acid-utilizing bacteria – Lactate utilizers » Megasphaera elsdenii » Veillonella alcalescens » Prevotella ruminicola » Fermentation endproducts Acetic acid Propionic acid* Valeric acid Caproic acid – Succinate utilizers » Selenomonas ruminantium » Veillonella alcalescens » Anerovibrio lipolytica » Fermentation endproducts Propionic acid* CO2 – Formate utilizer » Methanobrevibacter ruminantium
  65. 65. – Proteolytic bacteria • Few bacteria only use protein as their sole energy source • 38% of isolates are proteolytic • Most active proteolytic bacteria – Prevotella ruminicola – Ruminobacter amylophilus – Butyrvibrio fibrisolvens – Lipolytic bacteria • Hydrolyze triglycerides and phospholipids – Anerovibrio lipolytica • Hydrolyze galactolipids, phospholipids, and sulfolipids – Butyrvibrio fibrisolvens • Biohydrogenation
  66. 66. • Sulfur-reducing bacteria – Species • Desulfovibrio sapovorans – Metabolism • Low levels of sulfate – Butyrate + EtOH - Acetate + H2 – H2 cross-fed to Wolinella succinogenes in reaction H2 + Fumarate - succinate propionate • High levels of sulfate (depletion of fumarate) – Butyrate + sulfate - Acetate + H2S – Sulfur reduction is preferred use of H2 over CH4 H2_threshold Km Vmax – Sulfur reduction .0013 .1 .3 – Methane production .067 6.6 6.0
  67. 67. • Toxin-degrading bacteria – Degradation of mimosine • A goitrogen found in the tropical legume, Leucaena leucocephala • Caused toxicity in Australian ruminants, but not Hawaiian goats • Degraded by bacteria Synergistes jonesii – Now used as an inoculant for ruminants across the world – Degradation of oxalic acid • A toxin found in Halogeton plants – A noxious weed in the west – Toxic at intakes of .3 to .5% of intake for short periods – Mechanism » Primarily binds Ca – Degraded by bacteria Oxalobacter formigenes » Oxalate Formic acid + CO2
  68. 68. – Methanogenic archea • Classes – Free-living » Methanomicrobiales sp. » Methanosarcinales sp. – Associated with protozoa » Methanobrevibacter sp. » Methanococcales sp. • Methane production mechanisms – Acetate or methanol > CH4 + CO2 – CO2 + 4H2 > CH4 + H2O – Formic acid + 3H2 > CH4 + 2H2O • Effects – Energy waste (5-6% of GE) – Greenhouse gas – Requirement to increase ATP and microbial growth
  69. 69. • Rumen protozoa – Most are ciliated – Families • Isotrichidae (Holotrichs) – Cilia over entire body – Genuses » Isotricha » Dasytricha • Orphryscolidae (Oligotrichs) – Cilia in mouth region – Genuses » Entodinium » Eudiplodinium » Epidinium » Ophryoscolex Photos courtesy M. Rasmussen and S. Franklin, USDA-ARS http://www.rowett.ac.uk/ercule/html/rumen_protozoa.html
  70. 70. Protozoa motility Photos courtesy M. Rasmussen and S. Franklin, USDA-ARS
  71. 71. – Additional properties of protozoa • Much larger than bacteria • Count is normally 105/gm • Slow generation time • Closely associated with feed particles – Holotrichs exhibit chemotaxis moving to the back of the rumen when animals are eating before settling in ventral and cranial sacs – Do not readily pass from the rumen • Holotrichs near the rumen wall scavenge O2 • All protozoa store soluble carbohydrates as an amylopectin-like storage polysaccharide – Carbohydrate specificity » Holotrichs store sugars » Oligotrichs store starch – Benefits » To protozoa, it maintains a constant energy source » To animal, it stabilizes fermentation • Protozoa engulf and lyse bacteria – Contributes to rumen protein turnover reducing efficiency of protein use – Bacteria that resist lysing in the protozoa may have genes activated that result in resistant, more virulent pathogens • Protozoa have close relationships with methanogens
  72. 72. – Fermentation endproducts of protozoa • Holotrichs – Acetic acid – Butyric acid – Lactic acid – H2 • Oligotrichs – CO2 – H2 – Acetic acid – Butryric acid – N requirements of protozoa • Do not use NH3 • Actively proteolytic
  73. 73. – Factors affecting protozoa • Diet Feed CHO pH Protozoa Pasture Sugars, Cellulose 6-7 Total high Mod. Grain Sugars, Cellulose, 6.0-6.5 Total higher, Starch Inc % Oligotrichs High Grains Starch <5.5 No protozoa • Frequent feeding > Increases protozoa • High liquid dilution rate > Decreases protozoa • Defaunation – Early attempts » CuSO4 » Aeration » Detergents – Recent attempts » Lecithin or linoleic acid » Tannins (Quebracho or Yucca plants) » Saponins (Quillaja plants) » Coconut oil (Lauric acid) – Difficult to accomplish without affecting bacteria or host animal
  74. 74. The need for protozoa in the rumen Protozoa are not necessary for the animal (Commensalism) • Advantages of protozoa – Increased cellulose digestion • 25 – 33% of total cellulose digestion • Mechanisms – More active than bacteria? – Provide NH3 to bacteria – Remove O2 – Slower fermentation of starch and sugars – Greater VFA production – Increased transport on conjugated linoleic acid (CLA) and trans-11 (18:1) fatty acid to duodenum and meat and milk • Disadvantages of protozoa – Increased rumen protein turnover • Reduced efficiency of protein use • Increased rumen [NH3] – Increased CH4 production – Development of more virulent strains of pathogenic bacteria
  75. 75. • Net effects of defaunation – Increased daily gains – Improved feed efficiency – Decreased OM and cellulose digestion – Increased total and microbial protein flow to the duodenum – Decreased pH on high concentrate diets, but increased pH on high forage diets • pH response to defaunation = 0.31 – 0.006 x % concentrate in diet – Increased production of propionic acid and decreased production of butyric acid – Increased rumen volume and liquid outflow rate
  76. 76. Eugene et al. (2004)
  77. 77. Eugene et al. (2004)
  78. 78. • Rumen fungi – Species • Neocallismatix frontalis • Sphaeromonas communis • Piromonas communis • Orpinomyces joyonii – Occurrence • Appear 8 – 10 days after birth • More prevalent on grasses than legumes • May be related to sulfur supplementation • Function – Fiber digestion » Enzymes identified Cellulases Xylanases Lichenase Mannanase Feruloyl esterase* http://www.goatbiology.com/animations/funguslc.html
  79. 79. • Establishment of the rumen microbial population – At birth, rumen has no bacteria – Normal pattern of establishment Appear Peak Microorganisms 5-8 hours 4 days E. coli, Clostridium welchii, Streptococcus bovis ½ week 3 weeks Lactobacilli ½ week 5 weeks Lactic acid-utilizing bacteria ½ week 6 weeks Amylolytic bacteria Prevotella-wk 6 1 week 6-10 weeks Cellulolytic and Methanogenic bacteria Butyrvibrio-wk 1 Ruminococcus-wk 3 Fibrobacter-wk 1 1 week 12 weeks Proteolytic bacteria 3 weeks 5-9 weeks Protozoa - 9-13 weeks Normal population
  80. 80. • Factors affecting establishment of population – Presence of organisms • Normally population is established through animal-to-animal contact • Bacteria may establish without contact with mature ruminants – Establishment of protozoa requires contact with mature ruminants – Favorable environment • Substrates and intermediates • Increased rumen pH • Digesta turnover
  81. 81. • Altering the rumen population – Diet • High forage > High pH, cellulose, hemicellulose, sugars > High cellulolytic and hemicellulolytic bacteria > High methanogens > High protozoa • High concentrate> Low pH, high starch > Low cellulolytic and hemicellulolytic bacteria > High amylolytic bacteria > Low methanogens > Low protozoa, primarily oligotrichs – Buffers • Same as high forage – Antibiotics • Ionophores – Microbial inoculants
  82. 82. • Ionophore effects on the rumen microbial population – Ionophores • Monensin • Lasalocid • Laidlomycin – Actions • Create pores in membranes of gram + bacteria – Allows potassium to exit and hydrogen to enter cells • Bacteria affected Inhibits Effects Ruminococcus albus Decreased acetate, formate and Ruminococcus flavefaciens methane Butyrvibrio fibrisolvens Streptococci Decreased lactate Lactobacilli Increases Fibrobacter succinogenes Increased propionate Prevotella ruminicola Selenomonas ruminantium
  83. 83. – Net results of feeding ionophores • Increased propionate • Reduced protein degradation • Reduced deamination • Reduced methane production • Reduced lactate production
  84. 84. • Use of microbial inoculants – Dosing with lactate-utilizing bacteria can reduce lactic acid build up in rumen – Difficult to do long-term • Antagonistic environment • Difficult to get enough organisms • Considerable gene exchange – Mechanisms » Transformation » Conjugation » Transduction – Favorable conditions for gene transfer » High population » Intimate cell-to-cell contact » Supply of phages » Extrachromasomal plasmid DNA » Transient non-rumen bacteria

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