nut 142 midterm 1

Feeding strategy relates to …

food eaten and method by which it is obtained

carnivore

meat eater
cats, sharks

omnivores

mixed, opportunistic feeders

Dogs, humans, pigs, chicken

insectivores

insect eaters
bats, swallows, ant eaters

granivore

seed and nut eaters
sparrows, quail

frugivores

fruit eaters
new world monkeys, fruit bats

herbivores

forage, foliage eaters

Many subtypes

Arboreal folivores

tree dwelling leaf eaters
primates (New World Monkeys), hoatzin, marsupials (koala)

terrestrial folivores

rock wallaby

terrestrial herbivores

Grazers, browsers, intermediate feeders

bulk and roughage eaters (grazers)

ruminants (cattle) and non-ruminants (horse, hippo, kangaroo)

concentrate selectors (browsers)

ruminants (deer, giraffes) and non-ruminants (rabbits)

intermediate feeders

ruminants (sheep, goats)

aquatic herbivores

manatee

avian graminivores

birds that eat the blades and rhizomes of grasses
geese

Types of terrestrial herbivores

concentrate selectors
intermediate feeders
grass/roughage eaters

autoenzymatic digesters

animals that have digestion carried out largely by enzymes produced by animal itself
mono-gastric

autoenzymatic digester (monogastric) example

chicken (pancreas produces amylase that digests grain starch)

alloenzymatic digesters

animals that have digestion carried out largely by enzymes produced by microbes in the gut

allo

other

auto

self

alloenzymatic digesters example

cow
microbes produce celluloses and hemicellulases that digest plant cell walls

autoenzymatic digesters

Mammalian species (pigs, human)

Avian species (chicken)

Foregut fermenters (alloenzymatic digesters)

ruminants (sheep, cattle, deer)

Non-ruminants (hyrax, peccary, hippo, kangaroo)

Hindgut fermenters

Hindgut fermenters (alloenzymatic digesters)

caecal fermenters:
mammalian species (rabbit)
avian species (ostrich)
colonic fermenter:
horse
caeco-colonic fermenters:
elephant

most alloenzymatic digesters are

herbivores

alloenzymatic digester exception

peccary (omnivore)

most autoenzymatic digesters are

non herbivores
carnivores, omnivores, granivores, insectivores

autoenzymatic digester exception

giant panda (herbivore)

GI Tract non-ruminants animals major features

esophagus
stomach
pancreas
duodenum
small intestine
cecum
large intestine
rectum

GI tract ruminant mammal major features

rumen
reticulum
omasum
abomasum
pylorus
duodenum
small intestine
caecum
colon
large intestine
rectum

GI tract birds major features

Esophagus
crop
proventriculus (true stomach)
gizzard
spleen
liver
pancreas
duodenal loop
small intestine
ceca
large intestine
vent
rectum

mouth/esophagus

grasping, chewing, swallowing of food

stomach/abomasum (ruminants)/ proventriculus (birds)

initiates digestion of proteins by action of pepsin and HCl

Small intestine

• digestive enzymes enter to break down non-structural carbohydrate, protein, and nucleic acids

• Nutrients absorbed in jejunum and ileum

• Bile released from liver to emulsify fat and create alkaline environment optimal for enzymatic digestion

cecum/colon

• fermentation of fiber and other components to volatile fatty acids (VFA)

• absorption of VFA and water

• minor importance in auto-enzymatic digesters/non-herbivores

reticulum and rumen (ruminants)

fermentation of fiber and other components to VFA

omasum (ruminants)

reduces feed particle size and absorbs water and VFA

crop (birds)

temporary storage of food and site of fermentation in some species

gizzard (birds)

reduction in feed particle size

GI tract of autoenzymatic/carnivores, insectivores, and frugivores

• glandular stomach

• Short hindgut

• Diet digested quickly → simple tract

autoenzymatic/omnivore GI tract

• simple stomach

• midgut and hindgut variable length
  ~midgut long in black bear
  ~hindgut long in opossum
  ~longer/better developed than in carnivores, frugivores

Longer and more complex tract reflects

more complex, difficult to digest diet

alloenzymatic/ruminant foregut fermenter: enlarged forestomach

• site of microbial fermentation

• controls flow of fluid and particles in digesta
  ~particles retained to maximize fermentation

alloenzymatic/ruminant foregut fermenter: Small to mid sized cecum

some additional fermentation

alloenzymatic/ruminant foregut fermenter: Four stomach compartments

• rumen

• reticulum

• omasum

• abomasum

Omasum absent for

chevrotain

alloenzymatic/non-ruminant foregut fermenter: enlarged forestomach

• can have pouches like rumen (hippo)

• can be tubular (kangaroo)

• last compartment is glandular stomach (like ruminant)

alloenzymatic/non-ruminant foregut fermenter: variable development of hindgut

• none for hippo

• some for kangaroo

alloenzymatic/cecal hindgut fermenter:

• simple stomach

• Retains fluid and fine particles (non fibrous and highly digestible)

• Excretes large particles (fibrous and poorly digestible)

• enlarged cecum

  • site of microbial fermentation

  • controls flow of fluid and particles in digesta

alloenzymatic/cecal hindgut fermenter: cecal fermentation permits small body size (<50kg)

• few other herbivores at small body size

• metabolic rate (energetic demands) is relatively high for small body sizes

• herbivores diet (grass and roughage) is generally poor quality

• retention of fluid and fine particles permits use of poor quality diet and makes herbivory possible

alloenzymatic/cecal hindgut fermenter: coprophragy

• eating of feces

• gives another chance to digest undigested material

• another strategy for small herbivores to cope with poor quality diets

alloenzymatic/colonic and caeca-colonic hindgut fermenter:

• simple stomach

• enlarged colon (site of microbial fermentation)

• variably sized caecum (additional fermentation)

• no selective retention of fluid
  (retention of fluid same or shorter than particles; unlike cecal fermenters)

• Tend to be large (>50kg)

foregut fermentation advantages

• high efficiency

• more extensive digestion

• longer retention of digesta particles in rumen vs. hindgut

• microbial products digested and absorbed in small intestine (microbial protein, vitamins)

hindgut fermentation advantages

• high throughout

• high feed intake

• in foregut fermenters, fore stomach is a bottleneck to intake bc of long digesta retention in that site

• Hindgut fermenters have no such bottleneck

Foregut fermenters outcompete hindgut fermenters when …

Food availability is limited and of high quality (high fiber low protein)

Foregut fermenters make more efficient use of …

Limited feed

Foregut fermenters do not need high intake food when …

Food is high quality

Hindgut fermenters outcompete foregut fermenters when ..

Food availability is high and of low quality (high fiber, low protein)

Hindgut fermenters do not need to be

Efficient

Hindgut fermenters high intake allows …

Energy and nutrient requirements to be met on even poorest diets

Fossil record shows competition between

Foregut and hindgut fermenters

Hindgut fermenters predominated before

Foregut fermenters evolved

Foregut fermenters evolved and later …

Largely displaced hindgut fermenters

Autoenzymatic digesters have …

Easily digested diet and simple GIT architecture

Alloenzymatic digesters have …

Difficult to digest diet (plant material) and complex GIT

Alloenzymatic digesters have different …

Digestive physiologies (e.g., foregut fermentation, hindgut fermentation), each w/ diff advantages

Microbes in ruminants grow in…

Rumen

Importance of microbes of ruminants:

• ferment fiber to compounds that can be used by host (short chain FA; VFA + lactate; make up to 75% of energy metabolized by host)

Microbes in ruminants pass to small intestine and …

Digested by host

• cells are protein rich (make up over 50% of protein metabolized by host)

5 major groups of microbes of ruminants

Bacteria
Protozoa
Fungi
Methanogens
Viruses

Bacteria makes up to ….

90% of microbial mass

Rumen fluid contains up to …

1010/mL of bacteria (more people on earth, # stars in Milky Way)

Bacteria size is

Small (0.3 to 50 micrometers)

Bacteria ferment many..

Substrates in feed
Diff bacteria ferment diff substrates

Bacteria

Role: digest feed
Domain: bacteria
Size (micrometer): 0.3 to 50
Density (#/mL): 10^9 to 10^10
Biomass (% of total): 60 to 90

Bacteria that ferment fiber (cellulose)

fiberobacter succinogenes S85

Ruminococcus albus 7

Ruminococcus flavefaciens FD1

Bacteria that ferment fiber (hemicellulose)

prevotella albensis M384

Butyrivibrio fibrisolvens D1

Prevotella bryantii B14

Bacteria that ferment fiber (pectin)

prevotella albensis M384

Treponema sp.

Lachnospira multipara

Butyrivibrio fibrisolvens D1

Prevotella bryantii B14

Bacteria that ferment starch

Prevotella bryantii B14

Succunivibrio dextrinosolvens 24

Succinimonas amyloltica B24

Megasphaera elsdenii T81

Ruminobacter amylophilus H-17

Prevotella albensis M384

Eubacterium ruminantium BC-23

Selenomonas ruminantium HD4

Butyrivibrio fibersolvens D1

Streptococcus bovis JB1

Bacteria that ferment sugar

Lachnospira multipara D32

lactobacillus ruminis RF1

treponema sp.

eubacterium ruminantium BC-23

Selenomonas ruminantium HD4

Butyrivibrio fibersolvens D1

streptococcus bovis JB1

Bacteria that ferment protein

Prevotella bryantii B14

streptococcus bovis JB1

prevotella albensis M384

selenomonas ruminantium HD4

Bacteria that ferment amino acids

Clostridium aminophilum F

Clostridium sticklandii SR

Bacteria that ferment lactate

Anaerovibrio lipolytica 5S

Megasphaera elsdenii T81

Selenomonas ruminantium HD4

Butyrivibrio fibrisolvens D1 ferments …

Hemicellulose, pectin, starch, sugar

Eubacterium ruminantium BC-23 ferments

Starch and sugar

Megasphaera elsdenii T81 ferments

Starch and lactate

Prevotella albensis M384 ferments

Hemicellulose, pectin, starch, protein

Selenomonas ruminantium HD4 ferments

Lactate, protein, sugar, starch

Prevotella bryantii B14 ferments

Hemicellulose, pectin, starch, protein

Streptococcus bovis JB1 ferments

Protein, starch, sugar

Treponema sp. ferments

Sugar and pectin

Protozoa

Roles: digest feed, act as predators

Domain: eukaryota

Size (micrometers): 20 to 200

Density (#/mL): 10^4 to 10^6

Biomass (% of total): 3 to 50

Ciliate Protozoa microbial mass is

3 to 50%

Ciliate Protozoa rumen fluid is

106/mL

Ciliate Protozoa size is

Large (20 to 200 micrometers)

Ciliate Protozoa acts as

Fermenter and predator of bacteria/other microbes