Micro of Animals Flashcards
commensals
microorganisms found on the bodies of healthy animals/people
- residents ( skin, mouth, colon)
- can do no harm, be beneficial or be parasitism
disease vs infection
disease= damage or injury to the host that impairs host function infection= situation in which microorganism is established and growing in a host, causing damage
pathogenicity
the ability of a parasite to inflict damage to host
virulence
measure of pathogenicity
opportunist pathogen
causes disease only in the absence of normal host resistance
phylogenetic studies suggest that herbivory has evolved _____ in many different lineages
independently
GIT of herbivores
live on plants – cellulose and other insoluble polysaccharides
- lack the enzyme cellulase
- microorganisms degrade cellulose and other fiber to give host nutrients (mutualism) in either hind or fore gut
2 digestive stragegies have evolved in herbivorous animals
- foregut fermentation: fermentation chamber precedes (comes before) the acidic stomach
- Hindgut fermentation: uses cecum and large intestine as fermentation chambers
foregut fermentors
ruminants, monkeys
- fermentation chamber before stomach
handgun fermetors
rabbits, horses
- fermentation chamber after the small intestine
the rumen of ruminant animals
rumen- foregut fermentation chamber in ruminant animals
food is chewed minimally, swallowed and passes to rumen
rumen condition in cows
100-150L
39-40 degrees
5-7 pH
anaerobic environment (fermentation)
how is pH in rumen maintained
by saliva which contains sodium bicarbonate
only a small proportion of the microorganism in the rumen produce ______. and as such fermentation is mediated by?
cellulases.
mediated by cellulytic microbes which break down cellulose into glucose and cellobiose (then available to all other microbes)
sugars in gut get fermented by microbes and produce?
volatile FA: acetic acid, propionic acid, butyric acid
methane and CO2
where do the FA pass and what are they used for?
through the rumen wall and into the bloodstream and used as the animals main energy source
overall stiochiomentry of rumen fermentation
57 glucose–> [65 acetate, 20 propionate, 15 butyrate] + 60 CO2, 35 CH4 and 25 H2O
which ones are the rumen microorganisms?
Ciliated protozoa, bacteria, archaea, methanogens (300-400 species)
Methanogens
strict anaerobes that produce methane from H and CO2 or acetate (CH3COOH)
acetate used by methanogens is not available to the ___
host
up to ___ % of energy value of the feed can be lost as CH4
10%