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Rumen GI- F&F > Microbes > Flashcards

Microbes Flashcards

1
Q

Microbiota

A

-community of many different types of microorganisms (bacteria, protozoa, fungi, bacteriophages)
-important for digestive efficiency/fermentation
-different species have different optimal conditions – need a balance

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2
Q

Ideal pH

A

-6-7
-relatively constant (no large fluctuations)

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3
Q

Ideal Temperature

A

38-39C

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4
Q

Importance of motility

A

-mixing contents
-prevents local build up of VFA

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5
Q

Importance of substrate and moisture

A

Important for:
-ingestion of new feed
-rumination

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6
Q

Removal of waste products

A

-absorbed through rumen epithelium (eg. VFA)
-passage to omasum

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7
Q

Anaerobic conditions

A
  • facultative anaerobes use of any O2 that make it inside to ensure environment remains anaerobic
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8
Q

Symbiotic relationship

A

-cows need microbes to break down feed because they cannot digest cellulose or hemicellulose
-microbes need cows to provide feed and environment

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9
Q

Different microbe types

A

-Amylolytic (starch fermenters)
-Cellulolytic (fiber fermenters)
-Methanogens

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10
Q

How do you alter microbial populations?

A

-directly adding microbes is not effective long-term as they cannot get established in a highly competitive environment
-most effective method would be to change the environment

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11
Q

Bacteria in rumen

A

-largest population of microbiome (50% of microbial mass in the rumen, 10^10 bacteria/gram many cells but small)
-mostly gram-negative
-obligate or facultative anaerobes

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12
Q

Bacteria locations

A

1.single cells or clumps- unattached, free floating in fluid (50% of total bacteria)
2.Attached to feed particles- stay in rumen longer (solid vs. fluid turnover)
3.Attached to rumen epithelium

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13
Q

Bacteria classification

A
  1. Primary bacteria
  2. Secondary bacteria
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14
Q

Primary bacteria

A

-directly ferment feed material
>amylolytic bacteria ferments starch
>cellulolytic bacteria ferments fiber

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15
Q

Secondary bacteria

A

-utilize products produced by primary bacteria
>methanogens use H+ to make CH4
>lactate-using bacteria (lactate is intermediate product of CHO fermentation; converts to VFAs)

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16
Q

Amylolytic starch fermenters

A

-optimal growth at lower pH (5.5-6)
-rapid proliferation, short life span (20-30mins)

17
Q

Cellulolytic fiber fermenters

A

-ferment cellulose and hemicellulose
-can also break down starch
-optimal growth at higher pH (6.2-7)
-longer lifespan (12-24hrs)

18
Q

Cellulolytic fiber fermenter method of breakdown

A

-excrete cellulase which can hydrolyse beta 1-4 linkage of cellulose and hemicellulose, and breaks starch into monosaccharides
-also use cellulosome (multi enzyme complex) which allows bacteria to adhere to and degrade cellulose

19
Q

Bacterial metabolism- protein

A

-can break down AA for energy
-transform one AA type into another
-can synthesize AA from non-protein N (eg.urea)

20
Q

Bacterial metabolism-lipids

A

-hydrolyze lipids
-biohydrogenate (saturate) fatty acids
-branched chain fatty acids
-odd-number chain fatty acids

21
Q

Bacterial metabolism- vitamins

A

-can synthesize B vitamins

22
Q

Protozoa

A

-smaller number than bacteria- 10^6/gram
>similar mass, larger cell size
-decrease with faster rumen turnover because they are in the fluid and can be washed away

23
Q

Where do protozoa acquire their nutrients from?

A

-they can eat bacteria
-can consume starch granules. Prevents formation of VFAs
-protein
-fat
-cellulose and hemicellulose (certain protozoa can produce enzymes that digest fiber; accounts for 35-30% of fiber digestion)

24
Q

Protozoa conditions

A

-population and species are more variable than bacteria
-more sensitive to changes in rumen conditions (pH, turnover, etc.)
-free floating in rumen liquid and mostly within the fibrous raft layer
-good indicator of general rumen health because they are very sensitive and would not be present in poor conditions

25
Q

Protozoa optimal pH

A

-optimal pH: 6.2-7.0 (same as cellulolytic bacteria)

26
Q

Protozoa consuming starch granules

A

-starch granules are unavailable to amylolytic bacteria
-prevents the rapid fermentation (VFAs) and drop in pH

27
Q

Protozoa as a source of protein

A

-Better AA profile than bacterial protein
-intracellular starch granules and fatty acids bypass rumen fermentation

28
Q

Protozoa cons

A

-use of AA that could be absorbed by the animal
-bacterial predator

29
Q

Fungi

A

-includes yeast
-low mass and low number (10^4/gram) BUT will be higher with high-fiber diets (up to 5-10% of microbial mass)
-anaerobic
-ferment starch, cellulose and hemicellulose, some protein

30
Q

Bacteriophages

A

-viruses that infect bacteria so are thought to be important in controlling bacterial populations
-do not ferment

31
Q

Bacteriophage current research

A

-looking at their impact on altering the rumen microbiome

32
Q

How can you test for issues in rumen microbiome?

A

-difficult to determine microbe populations
>limited information from microscopy
>expensive/impractical to DNA sequence

33
Q

How to treat rumen microbiome issues?

A

-Need to fix the underlying issue (eg. Diet)
-Can conduct transfaunation- transfer rumen fluid from donor healthy cow to a sick cow

34
Q

Antibiotics

A

-rumen infections generally do not occur because pathogens rarely out-compete normal rumen bacteria
-rumen microbes are susceptible to microbial antibiotics which is why ruminants should not be given oral antibiotics. Should give IV

35
Q

Exception to giving cows antibiotics orally

A

-Treating scours in calves
-Sulfonamide bolus

36
Q

Antimicrobials that can be given orally in feed to ruminants

A

-Ionophores
-Tylosin (eg. Tylan)

37
Q

Ionophores

A

-eg.Rumensin, monensin
-targets gram positive bacteria

38
Q

Tylosin

A

-used to prevent liver abscesses in finishing cattle

39
Q

Ionophores benefits

A

1.increases feed efficiency by increasing propionate proportions which means less methane produced and less energy loss

2.helps prevent acute lactic acidosis
>less Strep. Bovis prevents rapid pH drop
>does not prevent sub acute ruminal acidosis (reduces acid from lactate, not VFAs)

3.Helps prevent frothy bloat
>Strep bovis produces slime that can cause frothy bloat

4.helps prevent ketosis in dairy cows
>Less beta-hydroxybutyrate generated

5.reduces fecal shedding of M. paratuberculosis (Johnne’s disease)

6.Prevents coccidiosis

Rumen GI- F&F (10 decks)

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