ANSC 3180 Lecture Notes - Lecture 14: Giant Panda, Chitinase, Food Composition Data
Carnivores and piscivores
○
Insectivores
○
Other microfaunivores
○
Carnivores:
•
Grazers, browsers, folivores
○
Nectarivores
○
Frugivores
○
Granivores
○
Herbivores:
•
Omnivores
•
Types of…
What is eaten
•
Major type of digestion
•
Protein, fat, EAAs
•
Minerals, vitamins
•
How indigestible components are delt with
•
'Summary'
Eat vertebrates, including fish
•
Autoenzymic digestion (by animals own enzymes)
•
Highly digestible
○
High in protein
○
Eat soft tissues:
•
20+ % fat pre-spawning, <1% fat post-spawning
!
E.g. salmon, mackerel, sardines, herring
!
Oily fish -store fat in muscles
○
<2% fat
!
E.g. cod, haddock, plaice, halibut
!
Non-oily/'white' fish -store fat in liver
○
Cold water fish are usually higher in fat content than warm water fish
○
Fat content available:
•
Balance of EAAs similar to requirements
•
Good source of minerals, vitamins
•
Low in calcium if prey is not eaten whole (no bones)
•
Bones
○
Fur (mammals), feathers (birds), scales (reptiles/fish)
○
Indigestible animal tissues:
•
Separated from soft tissues before ingestion1.
Separated in gizzard (birds) and then egested (usually as pellets)2.
Decrease digestibility of total diet
!
Some digestion of bones (Ca)
!
Not separated:3.
Indigestible animal tissues may be:
•
Carnivores & Piscivores
Eat insects
•
Autoenzymic digestion
•
Highly digestible
○
Adult insects: 50-75% CP
!
Caterpillars: 40-70% CP
!
High in protein
○
Adult insects: 10-40% EE
!
Fat content is variable
○
Soft tissues:
•
Balance of EAAs similar to requirements
•
Good source of P, trace minerals, vitamins
•
Bones, snail shells, egg shells may be eaten
○
Many exudates are high in calcium
!
Many insectivores are also gummivores, and eat exudates from trees
and shrubs
○
Low in calcium:
•
Chitin content is variable: 18-60%
○
Select insects with low chitin content1.
Remove high-chitin part of the exoskeleton before ingestion
( wings and tibia, 50% chitin, of grasshoppers are removed by
grasshopper sparrow)
2.
Crush insect (with beak or teeth), extract soft tissues and
discard exoskeleton
3.
Eat insects whole, then egest exoskeletons (kestrel, swallows,
flycatchers)
4.
Produce chitinase enzymes (at least partially digest chitin) -
energy value of chitin is usually low
5.
Animals/birds may:
○
Indigestible chitinous exoskeleton (carbohydrate):
•
Some adult/larval insects are in tree bark/ in ground during winter
○
Adult insects may be seasonal in temperatue areas
•
Have chitinous exoskeleton
○
3 part body (head, thorax, abdomen)
○
3 pairs of jointed legs
○
Compound eyes -2 antennae
○
Insect structure:
•
Insectivores
Microfaunivores eat other invertebrates (not insects)
•
Annelids (worms)
○
Molluscs (snails, mussels, oysters, clams) -calcareous shells
○
Molluscs (squid, octopus) -chitinous beak
○
Echinoderms (sea urchins, starfish) -calcareous exoskeleton
○
Arachnids (spiders)
○
Crustacea (crabs, lobsters, shrimp, crayfish, krill) -chitinous
exoskeleton (may be partly calcified)
○
Mammal and bird microfaunivores may eat:
•
Have autoenzymic digestion
•
Similar nutritional properties to insects
○
Soft tissues:
•
Remove shell (Ca) or exoskeleton (chitin) before ingestion1.
Eat squid whole, then egest beak (cormorant, albatross)2.
Eat molluscs whole, crush shell in gizzard (eider ducl)3.
Produce chitinase enzymes (at least partially digest chitin) although
energy value is low (king penguins -chitin digestibility is 85%)
4.
Indigestible shells, exoskeletons:
•
Other Microfaunivores
5B
Grasses (monocotyledons), broad-leaved plants (dicotyledons) -both
herbaceous (forbs), woody shrubs and trees
○
Eat vegetative parts of plants (leaves, stems)
•
Fore-gut (ruminants/ non-ruminant)
!
Hind-gut (in caecum/colon)
!
Microbial fermentation is essential for digestion of plant cell walls
(cellulose, hemicellulose)
○
Coprophagy and caecotrophy may occur
○
Alloenzymic digestion + microbial enzymes
•
Ex. Rhino -hind gut fermenter
•
Cell contents
○
Highly digestible -do not 'have/need' microbial fermentation
○
EXCEPTION: Giant panda -autoenzymic digestion
•
But LOW levels of methionine and lysine
!
Protein -fairly good balance of EAAs in young, green plant material
○
Sugars (non-structural carbohydrates)
○
Aquatic leaves and roots are a good Na source
!
Variable Na source (may need salt licks)
○
Poorly digestible
!
Hinders digestibility of cell contents
!
Chewing (rumination/merycism) in mammals
□
Muscular gizzard in birds
□
Requires physical breakdown
!
Requires microbial fermentation
!
Grazers -prefer long and green vs short and brown
vegetation
□
There is higher cell wall content in mature vegetation
!
Cell Wall (fibre)
○
Food composition:
•
Insects
○
Other invertebrates
○
Grains
○
Seeds
○
Young birds may supplement vegetation plant material to obtain extra
protein and energy with:
•
Grazers, Browsers, & Folivores
Eat nectar, honey, honeydew (produced by aphids -sap sucking insects)
•
Autoenzymic digestion
•
A very dilute sugar solution (sucrose, glucose, fructose)
•
Highly digestible
•
May contain very low levels of amino acids and lipis
•
Some insects and other invertebrates (soft-bodied for birds) must be
eaten to meet amino acid requirements
○
Poor amino acid balance
•
Young, growing mammals/birds must eat mainly insects/invertebrates to
meet protein requirements for growth
•
May also be eaten by nectarivores
○
High protein: 7-40% DM
○
Good source of vitamins, minerals
○
Pollen:
•
Nectarivores
Eat seeds, grains (seeds of grasses), nuts
•
Mainly autoenzymic digestion
•
High in starch
•
Low to moderate protein
•
Some seeds: low in methionine and lysine
○
Legumes (pea family): high in lysine
○
Balance of amino acids is variable and may be poor
•
Low in fibre (without seed coats/husked)
•
Good source of many vitamins and minerals
•
Low lipid in grass seeds
○
High lipids in oil seeds, sunflowers, safflowers
○
Variable oil content
•
Low in calcium
•
Gut microbes can break down phytate and release P (phytase
enzymes)
○
Moderate phosphorous but ~60-70% may be unavailable as phytate
•
Toxins and anti-nutrients may reduce digestibility in many wild seeds
•
May be cracked by teeth/beak, and discarded before ingestion1.
May be chewed by teeth, or ground in the gizzard, and then the seed
is digested
2.
Indigestible tough seed coat:
•
Some insects/other invertebrates may need to be eaten to meet amino acid
requirements
•
Young, growing mammals/birds may need to supplement diet with
insects/invertebrates to meet protein requirements for growth
•
Seeds, grains, and nuts are seasonal in temperate areas; available all year in
tropics
•
Granivores
Eat succulent, fleshy fruits
•
Mainly autoenzymic digestion
•
Variable energy, protein content
•
Low Ca -may ingest snails/grit
•
High water content, ~5% DM
!
High carbohydrates (fructose, glucose, sucrose)
!
Low amino acids
!
Low fibre
!
E.g. apples, blueberries
!
Nutrient-dilute fruits1)
Low water content
!
High lipid, 10-70% DM
!
Protein - 5-20% DM
!
Low carbohydrates
!
E.g. dates, avocados, mistletoe
!
May be discarded before ingestion
□
Seeds may be collected in the gizzard and regurgitated
□
Seeds may be chewed, cracked in the bill or ground in the
gizzard before the protein in the seed is digested
□
Indigestible tough fruit coat, seed:
!
Nutrient-dense fruits2)
Food:
•
Fruit is seasonal in temperate areas, available all year in tropics
•
Must eat mainly insects/invertebrates to meet protein requirements for
growth
○
Young, growing mammals/birds:
•
Frugivores
5C
If energy sufficient, nutrient deficiencies are unlikely
•
If flesh is only eaten (no bones) -low Ca
•
Carnivores:
If energy sufficient -low Ca
•
Insectivores:
If energy sufficient, nutrient deficiencies are unlikely
•
High diet variety
•
Omnivores:
Low/variable protein
•
Methionine and lysine may be low
○
Poor/variable AA balance
•
High fibre, decreases diet digestibility
•
Low/variable Na
•
Ca:P should be 1:1-2:1
○
Low Ca, Ca:P ratio poor
•
Diet variety is essential
•
Herbivores:
*see composition of coyote foods (do not to memorize specific
values)
○
Ex. Coyote -facultative carnivore (/omnivore)
•
White-tailed deer: 71.9%
!
Hare: 64.8%
!
Mice: 65.5%
!
All carcasses within 60-80% range
!
Water content (~60-70%)
○
%DM, Dry matter basis or 'as is', 'as fed', fresh weight basis
!
Nutrient content can be given as:
○
Dry Matter:
•
Low in white-tailed deer (4.3% cf 14.9%)
○
Assumed that coyotes would not eat the bones but they
usually do
□
Some predators will eat bone marrow
□
Bones:
!
Usually eaten although contents may be left
□
Adipose tissue around GIT may also be eaten
□
GIT:
!
White-tailed deer, bones, hide and GIT removed before analysis:
○
*Important to analyze food 'as eaten' -need to know how food is
eaten
Ash:
•
Bones contain some protein as collagen
○
Hair, feathers -high in protein but poorly digested
○
Laboratory mice -low at 53.8% cf to 80.5% and 70.1% in other prey
○
Crude Protein
•
Most variable component of animal food analysis
○
But predator will often kill young, or emaciated or ill animals -
the weakest
!
May have less fat, a different food analysis composition
!
Carcasses analyzed often from hunter's skill
○
No thermoregulation
□
No activity hunting for food
□
No activity escaping from predators
□
Often have higher fat
!
EE is high in laboratory mice, 32% cf 14.1% and 70.1% in other prey
○
Ether Extract (fat)
•
Plant cell walls
!
From GIT
!
GIT removed from white-tailed deer carcasses
□
Surprising that there is little difference between 3 prey species
!
May be given as ADF/NDF, herbivore diets
○
Crude Fibre
•
Not very useful value
○
Calculated by subtraction (not analyzed)
○
NFE reflected errors in all other values (may even be negative)
○
Animal tissues -glycogen
!
Plant tissues (GIT contents) -sugars, starch, pectin,
hemicellulose, cellulose
!
Includes carbohydrates:
○
Nitrogen-Free Extract
•
Analyzed by bomb calorimetry
○
4-6 kcal/g for both animal and plant foods
!
< 4 kcal/g --> usually with very high ash values
!
Pre-hibernation/torpor
□
Pre-migration
□
Laboratory animals
□
>6kcal/g (7-7.5) --> usually means obsese prey animals
!
Normal range for food analyses:
○
Usually highest in late summer-early fall
!
Seasonal changes in energy/g DM will affect predators
○
GE can be given as kcal/g Fresh weigh or kcal/g DM
○
Ash * 0 kcal/g = 0
!
CP * 5 kcal/g = 4.025
!
EE * 9 kcal/g = 1.269
!
CF * 4 kcal/g = 0.02
!
NFE * 4 kcal/g = 0.40
!
TOTAL = 5.354 kcal/g DM
!
GE is not always given with analysis:
○
Convert to DM basis
!
Moisture content = 73%
!
DM = 27%
!
1.48 x 100/27 = 5.4815 5.48 kcal/g DM
!
5.48 x 27/100 = 1.4796 1.48 kcal/g fresh weight
!
Ex. Deer carcass contain 1.48 kcal/g on fresh weight basis
○
Gross Energy (kcal/g)
•
Grey wolf
○
Red wolf
○
Ethiopian wolf
○
Golden jackal
○
Side-striped jackal
○
Black-backed jackal
○
Other canids:
•
Carnivores
5D
Birds: amount eaten -(amount in faeces + pellets)
○
Digestibility = amount eaten -amount in faeces
•
*faeces and urine cannot be separated in birds (except by
surgical modification)
□
Metabolizability (in birds) =Amount eaten -amount in faeces -amount in
urine
•
Amount of food eaten = amount provided -amount left
uneaten
▪
Measure:
□
If material left uneaten is different from what is eaten,
analyze both
▪
Analyze sample of food(s):
□
Collect total faeces (and pellets) produced/day and analyze
□
Captive animal/bird should eat normal diet (or diet to be tested) for
several days before testing
○
Determine amount and type of food eaten
□
Collect all faeces (and pellets) produced/day
□
Wild-ranging animal/bird:
○
Digestibility Studies (metabolizability, birds):
•
Digestibility of foods:
Grams of DM eaten/day -Grams of DM lost in faeces(/pellets)
○
White-tailed deer was analyzed with bones, hide and GIT
contents which are not well digested and reduce overall
digestibility of DM in diet
□
DM digestibility is high in white-tailed deer (96.7% cf 81.5%, 83.2%)
○
Dry Matter:
•
Grams of CP eaten/day -grams of CP lost in faeces(/pellets)
○
White-tailed deer analyzed without bones, hide
□
Protein in bones (collagen), protein in hair (keratin) -not well
digested and reduce overall digestibility of CP in diet
□
CP digestibility high in white-tailed deer (98.3% cf 90.5%, 87.9%)
○
Crude Protein:
•
EE digestibility high in all prey (95.7-97.3%)
○
Little or no indigestible lipids in bone, hide, or GIT
○
Ether Extract:
•
Energy digestibility high in white-tailed deer (98.8% cf 88.2, 90.5%)
○
Therefore, prey should all have same energy (kcal/g)
□
White-tailed deer analyzed without bones, hide and GIT which reduce
overall digestibility of energy in diet
○
Energy
•
Carnivore -Coyote
Crude Protein: 39% (lower than coyote prey)
•
Ether Extract: 52% (higher than coyote prey)
•
Crude Protein + Ether Extract: 91% (similar to coyote prey)
•
Ash + Crude Fat + NFE: 9% (higher than deer but smaller than other prey)
•
Energy: 5.7 kcal/g (similar to coyote prey)
•
CP has low digestibility -84.2% (lower than coyote prey)
○
EE digestibility -97.7% (same as mouse)
○
Energy digestibility -92% (same as mouse)
○
Ringed seal carcasses digestibility:
•
Carnivore -Polar Bear (prey: ringed seal)
Component Complete carcass Carcass without bones/hide
DM 75-85% >95%
CP 80-90% ~98%
EE 97-98% 97-98%
Energy ~90% 98-99%
Lean (muscle) tissue and adipose tissue -highly digestible
•
Digestibility decreases with indigestible components present in whole
carcass (but Ca is supplied by bones)
•
Energy digestibility in intact carcass is ~90%: DE = GE * 0.9
•
Digestibility in Carnivores (vertebrate prey):
At least 24 species of small cats
•
Few large cats
•
Obligate Carnivores -Felids
Red-tailed hawk
Swainson's hawk
Peregrine falcon
Gyrfalcon
Bald Eagle
Great horned owl
Snowy owl
Gastric pH (before meal) 1.6 (1.3-1.8) 2.35 (2.2-2.5)
% food appearing as pellet 5.2 12.5
% bones in pellet 6.5 45.8
More often tear flesh of prey
▪
Less often eat prey whole
▪
But eat at least some of the bones
▪
Hawks, falcons, eagles
□
Often ingest prey whole
▪
Owls
□
Two groups:
○
Gastric digestion in raptors
•
Hawks, falcons, eagles: 1.6
○
Owls: 2.35
○
pH is a log scale -1 unit difference = difference of 10x
○
pH is an important difference between groups:
•
Hawks, falcons, eagles: 5.2 -6.5
○
Owls: 12.5 -48.5
○
Decreased bone digestion
□
Decreased Ca available
□
Bone in pellets from hawk/falcon/eagle are less
representative of diet due to greater digestion
▪
Their pellets are less useful for food habit studies
▪
BUT: owl pellets are more useful for food habit studies
□
Less acidic gastric pH in owls:
○
% food appearing as pellet -% bones in pellets
•
DE -urine (& gas) = ME
□
GE -faeces = DE
○
Measured as DE (digestibility) in mammals (usually)
□
Digestive efficiency is measured as ME (metabolizability) in birds -
faeces and urine mixed in cloaca
○
Not because digestive efficiency is lower
□
ME in birds is ~75% of GE (68-82%)
▪
DE in birds is usually similar to DE in mammals
□
ME in mammals (~91% of DE) is 82% of GE (79-85%)
▪
DE in mammals is ~90% of GE (intact carcasses)
□
ME in birds is lower than DE in mammals
○
Digestive efficiency (energy)
•
Avian Carnivores
Eat only dead prey, killed by accident or by other carnivores
○
Carnivores who cannot kill their own prey
○
Includes vultures and their close relatives (condor)
○
Only 23 obligate scavengers (all birds)
•
Obligate Scavengers
DM -31.9%
□
EE -6% (12.0 in hare)
□
CP -75.5% (70.1 in hare)
□
Ash -3.8% (14.9 in hare)
□
GE -5.02 kcal/g DM (4.97 in hare)
□
Ca -0.31%
□
Ca:P, ~1:4
▪
Ca:P in bones, ~2:1
▪
Ca:P in diet should be 1:1 -2:1
▪
Therefore, grasshopper in low in Ca
▪
P -1.27%
□
Grasshopper
○
EE -10-40%
□
CP -50-75%
□
Adult insects
○
CP -40-70%
□
Caterpillars
○
Example Prey:
•
Ca (% DM) P (% DM) Ca:P
earthworm 0.95 0.95 1 : 1
mealworm 0.038 0.57 .06 : 1
Wax moth larva 0.030 0.39 .08 : 1
Cricket 0.10 0.79 .13 : 1
Ca:P lower than 1:1 (except earthworm)
○
Ca is low (except earthworm) -soil in gut
○
Most animals need ~0.5% DM Ca in diet
○
Ca:P content of invertebrates
•
BUT, Ca is usually low (Ca:P is usually below 1:1)
○
Food composition and digestibility is very similar to vertebrate prey
•
Decreases CP and EE digestibility by physically blocking
access of digestive enzymes to protein and lipid
□
35-85% digestibility of chitin
▪
Some mammals/birds produce chitinase enzyme which at least
partially digests chitin
□
Chitin….
○
Chitin exoskeletons -relatively indigestible
•
Ca exoskeletons/shells decrease DM digestibility but provide Ca in the diet
•
Insectivores & Microfaunivores
5E
May be called forage or browse (eaten by grazers, browsers, and
folivores)
○
Does not include fruits, seeds, plant exudates, pollen
○
Does not usually include fungi
○
May include algae (for marine mammals)
○
Ex. Reindeer lichen
□
May include lichens -a symbiotic relationship between a fungus and
algae
○
Eat leaves, stems and vegetative parts of plants
•
Algae are autotrophs and manufacture organic compounds from
water, CO2 and minerals, using solar radiation -photosynthesis
○
Algae then pass organic compounds to the fungi (heterotrophs, need
organic compounds in food)
○
Fungi provide 'shelter' for algae which are otherwise aquatic
○
Lichens (algae + fungus):
•
In quality, composition, energy content and digestibility
□
In quantity
□
With time (seasonally)
□
Very variable ….
○
Species of plant1.
leaves usually higher quality than stems
▪
Part of plant 2.
young plants have higher quality
▪
Age of plant 3.
when grasses start to produce seeds, leaf and stem quality
decreases
▪
Stage of growth of plant 4.
Low rainfall may reduce growth, quality may decrease
more quickly
▪
High temperatures -quality may decrease quickly
▪
Effect of climate 5.
N, P, K -needed for growth (added as artificial fertilizer)
▪
Effects of soil fertility and soil minerals6.
Toxins, anti-nutrients -protect plants from predation
▪
Plant defense chemicals7.
Factors which affect variability:
○
Forage and browse:
•
Pectin (soluble) -digested by microbial enzymes
!
Hemicellulose (insoluble) -digested by microbial enzymes
!
Cellulose (insoluble) -digested by microbial enzymes
!
Lignin (insoluble) -indigestible
!
Cell walls:
○
Soluble carbohydrates (~NFE)
!
Protein (~CP)
!
Cell contents:
○
Immature -37%
▪
Mature -85%
▪
Grasses:
!
Immature: 44%
▪
Mature: 75%
▪
Growing: 31%
!
Fallen, weathered: 49%
!
Leaves:
▪
Forbs:
!
Immature: 36%
▪
Mature: 62%
▪
Woody twigs:
!
Acorns: 40%
▪
Fleshy fruits: 41%
▪
Mushrooms: 39%
▪
Compare to…
!
More cell wall material is deposited with time
▪
Lignin may be deposited after pectin, cellulose and
hemicellulose
▪
*see diagram of cell wall composition
▪
*cell wall content increases with maturity
!
Cell wall contents (%DM):
○
Forage and browse composition:
•
Component (%DM) Summer Early Winter Late Winter
CP 18 7 5
Cell wall constituents 38 47 54
ADF cellulose 16 24 38
ADF lignin 916 13
~7% DM from late summer -early spring
▪
~17% DM in summer
▪
Biomass is low when quality is high (high CP, low
CWC) -from spring to summer
▪
CP:
!
>50% DM in late winter
▪
~30% DM in mid-summer
▪
Decreases from midsummer to late winter
▪
Fibre: hemicellulose, cellulose, lignin
!
~42-43% DM through year
▪
Soluble carbohydrates (NFE)
!
~5% DM through year
▪
Ash:
!
~5% DM through year
▪
EE:
!
Seasonal changes in food composition
○
Drops by ~20% at end of summer (associated with increase in
cellulose and lignin)
!
Hemicellulose, cellulose and lignin
▪
A measure of 'plant cell wall'
▪
Neutral detergent fibre (NDF; van Soest)
!
Cellulose, lignin
▪
Correlates with digestibility
▪
Acid detergent fibre (ADF; van Soest)
!
DM digestibility:
○
Accessibility changes with season
!
As snow depth increases, smaller browsers may gain access to
browse normally (too high to reach)
!
Some large herbivores are too heavy to walk across
surface of snow (takes more energy to walk through
trees)
▪
May 'breast' trees -walking over them and pushing it
down to gain access to higher browse
▪
Depends on snow compactness/ice crust
!
Caribou 'crater' -digging down to forage (an extra energy
expense)
▪
Some herbivores need to access forage below the snow
!
Forage and browse accessibility:
○
Na, K, Na:K, Ca, P, Ca:P
▪
Na, Ca, and P may be low
▪
K is high in most plant material
▪
Na:K and Ca:P -may be unbalanced
▪
Minerals are important in herbivore foods
!
Winter: 81 ppm
!
Spring: 48 ppm
!
Summer: 49 ppm
!
Fall: 41 ppm
!
Na:
▪
Winter: 11,134 ppm
!
Spring: 20,214 ppm
!
Summer: 14, 959 ppm
!
Fall: 12,355 ppm
!
K:
▪
Winter -1:137
!
Spring -1:421
!
Summer -1:305
!
Fall -1:301
!
Na:K
▪
Na and K in white-tailed deer diets:
!
Most herbivores need ~0.15% DM Na in diet (1500 ppm) -
approx. 1:4 Na:K
!
K is highest in spring and decreases through winter
!
Need to conserve Na
▪
Use of salt licks helps to redress imbalance (high levels
of K)
▪
K is high -Na is low
!
Required amount is ~1500 ppm
▪
Rodents may 'girdle' trees under snow to get bark
!
Bark: 547 ppm (300-1700)
▪
Twigs: 76 ppm (10-300)
▪
Leaves: 58 ppm (<10-600)
▪
Horsetails: 1574 ppm
▪
Aquatic plants: 2850-8048 ppm
▪
Algae: 14,600 ppm
▪
Na in herbivore food:
!
White-tailed deer
▪
Moose
▪
Reindeer
▪
Groundhogs
▪
Meadow voles
▪
Fox squirrels
▪
Prairie dogs
▪
Elephants -mine for salt in caves at night
▪
Na may be limiting for:
!
%Ca %P Ca:P
Willow leaves 0.82 0.41 2:1
Willow twigs -summer 0.51 0.12 4.3:1
Willow twigs - ? 0.39 0.13 3:1
Pond lily -leaves 0.63 0.31 2:1
Pond lily -stems 0.74 0.19 3.9:1
Fireweed 0.95 0.39 2.4:1
Lichen 0.31 0.36 0.9:1
Need Ca at ~0.5% DM in diet -lichen is low in Ca
▪
Willow twigs and pond lily stems -too little P
!
Lichen is around adequate ratio but Ca is low
!
Need Ca:P at 1:1-2:1
▪
Osteophagia: bone eating -supplies Ca, P and Na
!
Some rodents may chew shed antlers
!
Snails may be eaten
!
Higher calcium requirements for birds laying
eggs -may eat grit, broken egg shells
!
Higher calcium requirements for lactating
mammals
!
If Ca is low in diet:
▪
Ca and P in browse and forage plants:
!
Ash:
○
Composition of mule/white-tailed deer foods:
•
DM CP EE CF NFE DE
balsam 48 11.3 57 22 63 2.62
Red maple 31 11 51 18 42 1.39
Striped
maple
40 46 44 21 58 1.52
Mountain
maple
37 51 47 26 48 1.80
hobblebush 55 47 39 44 55 2.54
hazelnut 32 44 54 12 47 1.54
Ruminant
s
Non-ruminant
Herbivores
Carnivore
s
%DM 31-55 "75-85
%CP 1-51 69-74 80-90
%EE 39-57 "97-98
%CF 12-44 16-35 "
%NFE 42-63 69-72 "
DE (kcal/g
DM)
1.39-2.62 "~4.0
%DE "52-59 ~90
DM, CP and EE -all lower in herbivores compared to
carnivores
!
Rate of passage through GIT is slower
!
Digestion is more efficient
!
Less materials eaten
!
Ruminants:
▪
Rate of passage through GIT is faster
!
Passage is not restricted by omasum
!
CF digestion is less efficient, bacteria have less
time (caecum fermenters may be at low end of
range)
!
More material may be eaten (colon fermenters), or
food is chosen more selectively (caecum
fermenters)
!
Non-ruminants:
▪
CF is similar in ruminants and non-ruminants:
!
Cell contents may be digested by pre-gastric bacteria in
ruminants (less efficient anaerobic fermentation
compared to gastric digestion)
▪
NFE is somewhat higher in non-ruminants
!
Also, energy density (GE) of vegetative plant food is less
than that of animal flesh and adipose tissue
▪
DE is lower in ruminants and non-ruminants compared to
carnivores
!
Digestive Efficiencies: comparison
○
Browse Digestibility (% kcal/g DM) -white tailed deer
•
Herbivores
5F
Eat seeds and grain
•
See table
○
Slightly higher in weed seeds compared to cultivated grains
!
CP -good source
○
Some seed eaters remove husk/seed coat before eating
(takes time)
▪
Higher food quality (increased digestibility) VS. less time
available for foraging
▪
Moderately high in weed seeds
!
Cultivated grains are bred for thinner husk and for larger
size (less seed coat/g)
▪
Low in cultivated grains
!
CF
○
Good in weed seeds in germination
!
Bred for larger size, larger endosperm (less germ/g)
▪
*see diagram
▪
Lower in cultivated grains, except oil seeds
!
Fats in plants are either mono-or polyunsaturated
▪
If 1-2% EE is in diet of seed eaters, EFA needs should be met
!
EE
○
'soluble' carbohydrates/sugars -mostly non-structural
carbohydrates (e.g. starch)
!
Good in weed seeds
!
High in cultivated grains
!
NFE
○
Eater of weed seeds must eat a variety
▪
Weed seeds are variable in ash -partly due to Ca levels
!
Cultivated grains -ash and Ca are low
!
Need 0.5% DM Ca, need at least 1:1 Ca:P
!
Weed seeds -good Ca (except buckwheat), P is adequate
▪
Cultivated grains -Ca is low and therefore, Ca:P is poor
▪
Ca, P
!
Some P in seeds and grains is present as phytate -poorly
digested
▪
Phytic acid = inositol hexaphosphate
▪
Phytases in the seed release P for germenation
▪
P in phytate will be unavailable
!
Ruminants/foregut fermenters: microbes have
phytases to make P availble
!
Animals/birds have little phytase
▪
P availability
!
Not given analysis -may be low
▪
Na
!
Ash
○
Profile not given
!
Methionine, and lysine may be low in some species -must eat
variety
!
Amino Acids
○
Weed seeds: 4.17-4.68 --> good energy source
!
GE
○
Cultivated grains: NFE, CP and EE are well digested (~80%)
!
Higher fibre levels, smaller seeds
▪
Higher levels of tannins, trypsin inhibitors, other
toxins/antimetabolites
▪
If seeds are eaten, plants reproduction has failed -unless
some seeds pass through GIT undigested
▪
Weed seeds may be less digestible:
!
Digestibility
○
Composition of weed seeds, and cultivated grains (%DM)
•
Seeds and grains are seasonal in temperate areas -must combine with other
food sources
•
Not a balanced feed
○
Monoculture agriculture, makes grains available but may present a
problem to wildlife (e.g. migrating birds)
○
Fewer hedges with weed seeds is also a problem
○
*highway medians and verges are now being planted with wild
species and left unmowed
Grains are excellent energy source, but:
•
See table on slide
○
High digestibility compared to ~90% in carnivores (eating complete
carcass)
○
Both vole and mouse remove shell/husk before eating nuts
○
Digestibility of nuts by small rodents
•
Granivores
See table on slide
○
CP: high (25.7-33.3%)
!
CF: moderate (12.5-12.9%)
!
NFE: moderate (31.2-44.5%)
!
EE: moderate (1.4-3.1%)
!
Ca is low (.03-.16%)
!
P is high (0.52-0.61%)
!
Ca:P is poor
!
Ca & P:
▪
Ash: high (7.9-12.2) -usually ~5% (not due to high Ca levels)
!
Vegetative plant material:
○
CP: low (1.9-5.8%)
!
CF: moderate (8-19.3%)
!
NFE: high (56.7-73.2%)
!
Except gallberries (high; 10.8%)
▪
EE: moderate for plant material (1-4.9%)
!
Ca is low-high (0.13-0.71%)
!
P is low (0.06-0.10%)
!
Ca:P is poor
!
Ca & P:
▪
Ca and P are usually low in fleshy fruits (apples,
blueberries, cherries, grapes, prickly pear)
▪
Ash: moderate (1-7.6%)
!
Fruit:
○
Composition is variable --> must eat variety
○
Composition of black bear foods:
•
Frugivores
5G
Very low %DM -bulky; ~73.5% water
○
60-79% of CP is either unavailable in cell walls or indigestible
spores, or present as non-protein N
!
High CP, 21.5%
○
Low Ca, 0.09%
○
Low Na, 0.03%
○
GE -5.0 kcal/g
○
Composition of fungi:
•
Long-nosed potoroo (marsupial) -foregut fermenter
!
Red-backed vole (eutherian) -caecum fermenter
!
Eaten by:
○
CP digestibility is quite low
!
DM: GE digestibility higher in fore-gut fermenters
!
NDF: vole may grind food better when eating
!
Digestibility:
○
Hypogeous fungi (underground fungi; e.g. truffle)
•
Seasonal availability
•
Fungal cell walls contain hemicellulose, cellulose, and may contain chitin
•
Mycophages (eat fungi)
Mountain goats
○
Black-tailed deer
○
Yunnan snub-nosed monkey
○
Flying squirrel
○
Caribou/reindeer
○
Includes:
•
2-3% CP -low
○
0.31% Ca -low
○
0.36% P
○
Ca:P = 0.9:1 -adequate (just okay)
○
Lichen composition:
•
--> good energy, low protein
•
Lichenophages (eat lichens)
Salt licks
○
Possible reasons for use
○
Composition
○
Sodium
•
Toxins, antinutrients, antimetabolites
•
Metabolism and conservation
○
Protein
•
Foraging theory
•
Limiting Factors:
High levels of Na and Mg in salt licks
▪
Low P and K
▪
Moderate Ca
▪
pH = 7.0
▪
Composition of natural salt licks:
!
Only Na and Mg significantly higher in salt lick areas
▪
'natural salt lick' areas -where animals are observed to lick the
ground and ingest 'soil/minerals'
!
Used water containing Na salts to soak wooden stakes
▪
NaCl, NaI, NaHCO3
!
MgCl2, CaCl2
!
KHCO3, KI, KCl
!
Salts used:
▪
Were observed drinking the dilute Na solutions
!
Ignored stakes soaked in Mg, Ca, and K salts
◊
Were observed chewing/licking the wooden stakes
soaked in NaCl, NaI, and NaHCO3
!
Rabbits, fox squirrels, groundhogs, and white-tailed deer:
▪
Study to investigate reasons for salt lick use:
!
Porcupines have been observed damaging wooden
buildings when the wood had bee soaked with urine
(containing salt Na)
▪
Mountain goats in Olympic National Park have been
observed eagerly eating table salt offered by visitors
▪
In winter, food is the most effective bait
!
NaCl has been used as a very effective bait in trapping
white-tailed deer in Adriondack Mountains, in spring and
summer
▪
Other observations:
!
Acquisition of mineral nutrients1.
Healthy rumen/reticulum (reticulorumen) -pH = 5.5-7.0
!
pH may decrease to 4.0 with high starch in diet
!
Buffer pH
▪
Physically protect epithelium
▪
Salt licks can be used to:
!
Counter-balance rumen acidosis 2.
Adsorption of toxins, onto soil particles
!
Epithelium protection
!
Protection against plant toxins in GIT3.
E.g. pangolin (anteater without teeth) -ingest sand to abrade
ant exoskeletons
!
Comminution (grinding, triturating) of food particles 4.
E.g. young ruminants, fore-gut fermenters
!
Microbial inoculation5.
To fill stomach to dispel hunger during starvation6.
I.e. eating a non-food item
!
May be difficult to tell when substance eaten has valid
nutritional use
!
'Depraved' appetite, pica7.
Possible reasons for salt lick use by herbivorous mammals (and potentially
by birds): involves soil ingestion (geophagia)
•
Salt Licks:
5H
E.g. lignin, suberin, cutin, silica
○
*see diagram on slide
○
Not in algae, fungi, mosses, lichens
▪
Found only in 'higher plants' (monocotyledons 'grasses',
dicotyledons 'flowering plants')
!
Added rigidity to plant cell walls
!
Increases as plant matures
!
Up to 15-20% of cell wall
!
End walls disintegrate leaving hollow tubes
▪
Side walls strengthened with rings or spirals of lignin
▪
Transport water/minerals from soil
▪
Support the plant/tree
▪
Xylem cells are dead
!
Lignin is main protector of digestible cell wall
carbohydates
▪
E.g. bracket fungi on trees
!
Lignin can be broken down by certain fungi
▪
Lignin is not digested by animal/bird/bacterial enzymes, or by
acid hydrolysis in the gastric stomach (abomasum,
proventriculus)
!
Lignin:
○
Cutin is found as the structural compoenent of the plant cuticle
(at plant surface)
!
Reduces water loss
!
Prevents entry by microbes
!
Cutin:
○
Suberin is found between cell wall and cell contents
!
Cork cells/ outer layer of tree back, wound repair, around some
roots
!
Suberin:
○
*cutin and suberin are very poorly digested
Usually not in dictoyledons
▪
Si: 3-5% DM in grasses
▪
Found in grasses, sedges, ferns, horsetails
!
Hard, gritty material
!
Reduces cell wall digestibility
!
Increase tooth abrasion
!
May result in formation of urinary calculi
!
Silica/quartz
○
Substances that physically prevent digestive enzymes from reaching the
digestible carbohydrates, proteins and lipids (physical protection)
1.
E.g. soluble phenolics, alkaloids, terpenoids
○
Important as anti-herbivory compounds
!
Against mammals, birds, reptiles, amphibians, fish,
invertebrates
▪
Most act against all consumers -'broad spectrum'
!
E.g. pyrethrins (from chysanthemum flowers) -highly
toxic to insects, low toxicity to mammals
▪
Few are selective
!
Have no (few) primary metabolic functions within the plant
○
Must either be isolated within plant OR be stored in an inactive
form that becomes active when the plant material is consumed
!
Secondary plant compounds are usually also toxic to plants which
produce them
○
Plant consumers (primary consumers) continually evolve new
biochemical detoxification pathways SO plants constantly evolve new
defense compounds
○
Avoid
!
Fore-gut bacteria (detoxify most compounds)
!
Metabolic breakdown
!
Options for herbivores:
○
Ruminants and other foregut fermenters have advantage over
hind-gut fermenters, detoxification early in passage through
GIT
!
Many secondary plant compounds can be detoxified by GIT bacteria
○
Tannins may bind to viral/bacterial/fungal pathogens in GIT
and reduce infection
!
Most secondary plant compounds are antinutrients/antimetabolites
BUT some are beneficial (under certain circumstances)
○
Substances that interfere with digestions, nervous system function, growth,
reproduction and/or taste bitter (or smell bad)
2.
Toxins, Antinutrients & Antimetabolites -plant protective and defensive agents
Food Composition & Digestion
Friday,*March*24,*2017
12:27*PM
Carnivores and piscivores
○
Insectivores
○
Other microfaunivores
○
Carnivores:
•
Grazers, browsers, folivores
○
Nectarivores
○
Frugivores
○
Granivores
○
Herbivores:
•
Omnivores
•
Types of…
What is eaten
•
Major type of digestion
•
Protein, fat, EAAs
•
Minerals, vitamins
•
How indigestible components are delt with
•
'Summary'
Eat vertebrates, including fish
•
Autoenzymic digestion (by animals own enzymes)
•
Highly digestible
○
High in protein
○
Eat soft tissues:
•
20+ % fat pre-spawning, <1% fat post-spawning
!
E.g. salmon, mackerel, sardines, herring
!
Oily fish -store fat in muscles
○
<2% fat
!
E.g. cod, haddock, plaice, halibut
!
Non-oily/'white' fish -store fat in liver
○
Cold water fish are usually higher in fat content than warm water fish
○
Fat content available:
•
Balance of EAAs similar to requirements
•
Good source of minerals, vitamins
•
Low in calcium if prey is not eaten whole (no bones)
•
Bones
○
Fur (mammals), feathers (birds), scales (reptiles/fish)
○
Indigestible animal tissues:
•
Separated from soft tissues before ingestion
1.
Separated in gizzard (birds) and then egested (usually as pellets)
2.
Decrease digestibility of total diet
!
Some digestion of bones (Ca)
!
Not separated:
3.
Indigestible animal tissues may be:
•
Carnivores & Piscivores
Eat insects
•
Autoenzymic digestion
•
Highly digestible
○
Adult insects: 50-75% CP
!
Caterpillars: 40-70% CP
!
High in protein
○
Adult insects: 10-40% EE
!
Fat content is variable
○
Soft tissues:
•
Balance of EAAs similar to requirements
•
Good source of P, trace minerals, vitamins
•
Bones, snail shells, egg shells may be eaten
○
Many exudates are high in calcium
!
Many insectivores are also gummivores, and eat exudates from trees
and shrubs
○
Low in calcium:
•
Chitin content is variable: 18-60%
○
Select insects with low chitin content
1.
Remove high-chitin part of the exoskeleton before ingestion
( wings and tibia, 50% chitin, of grasshoppers are removed by
grasshopper sparrow)
2.
Crush insect (with beak or teeth), extract soft tissues and
discard exoskeleton
3.
Eat insects whole, then egest exoskeletons (kestrel, swallows,
flycatchers)
4.
Produce chitinase enzymes (at least partially digest chitin) -
energy value of chitin is usually low
5.
Animals/birds may:
○
Indigestible chitinous exoskeleton (carbohydrate):
•
Some adult/larval insects are in tree bark/ in ground during winter
○
Adult insects may be seasonal in temperatue areas
•
Have chitinous exoskeleton
○
3 part body (head, thorax, abdomen)
○
3 pairs of jointed legs
○
Compound eyes -2 antennae
○
Insect structure:
•
Insectivores
Microfaunivores eat other invertebrates (not insects)
•
Annelids (worms)
○
Molluscs (snails, mussels, oysters, clams) -calcareous shells
○
Molluscs (squid, octopus) -chitinous beak
○
Echinoderms (sea urchins, starfish) -calcareous exoskeleton
○
Arachnids (spiders)
○
Crustacea (crabs, lobsters, shrimp, crayfish, krill) -chitinous
exoskeleton (may be partly calcified)
○
Mammal and bird microfaunivores may eat:
•
Have autoenzymic digestion
•
Similar nutritional properties to insects
○
Soft tissues:
•
Remove shell (Ca) or exoskeleton (chitin) before ingestion1.
Eat squid whole, then egest beak (cormorant, albatross)2.
Eat molluscs whole, crush shell in gizzard (eider ducl)3.
Produce chitinase enzymes (at least partially digest chitin) although
energy value is low (king penguins -chitin digestibility is 85%)
4.
Indigestible shells, exoskeletons:
•
Other Microfaunivores
5B
Grasses (monocotyledons), broad-leaved plants (dicotyledons) -both
herbaceous (forbs), woody shrubs and trees
○
Eat vegetative parts of plants (leaves, stems)
•
Fore-gut (ruminants/ non-ruminant)
!
Hind-gut (in caecum/colon)
!
Microbial fermentation is essential for digestion of plant cell walls
(cellulose, hemicellulose)
○
Coprophagy and caecotrophy may occur
○
Alloenzymic digestion + microbial enzymes
•
Ex. Rhino -hind gut fermenter
•
Cell contents
○
Highly digestible -do not 'have/need' microbial fermentation
○
EXCEPTION: Giant panda -autoenzymic digestion
•
But LOW levels of methionine and lysine
!
Protein -fairly good balance of EAAs in young, green plant material
○
Sugars (non-structural carbohydrates)
○
Aquatic leaves and roots are a good Na source
!
Variable Na source (may need salt licks)
○
Poorly digestible
!
Hinders digestibility of cell contents
!
Chewing (rumination/merycism) in mammals
□
Muscular gizzard in birds
□
Requires physical breakdown
!
Requires microbial fermentation
!
Grazers -prefer long and green vs short and brown
vegetation
□
There is higher cell wall content in mature vegetation
!
Cell Wall (fibre)
○
Food composition:
•
Insects
○
Other invertebrates
○
Grains
○
Seeds
○
Young birds may supplement vegetation plant material to obtain extra
protein and energy with:
•
Grazers, Browsers, & Folivores
Eat nectar, honey, honeydew (produced by aphids -sap sucking insects)
•
Autoenzymic digestion
•
A very dilute sugar solution (sucrose, glucose, fructose)
•
Highly digestible
•
May contain very low levels of amino acids and lipis
•
Some insects and other invertebrates (soft-bodied for birds) must be
eaten to meet amino acid requirements
○
Poor amino acid balance
•
Young, growing mammals/birds must eat mainly insects/invertebrates to
meet protein requirements for growth
•
May also be eaten by nectarivores
○
High protein: 7-40% DM
○
Good source of vitamins, minerals
○
Pollen:
•
Nectarivores
Eat seeds, grains (seeds of grasses), nuts
•
Mainly autoenzymic digestion
•
High in starch
•
Low to moderate protein
•
Some seeds: low in methionine and lysine
○
Legumes (pea family): high in lysine
○
Balance of amino acids is variable and may be poor
•
Low in fibre (without seed coats/husked)
•
Good source of many vitamins and minerals
•
Low lipid in grass seeds
○
High lipids in oil seeds, sunflowers, safflowers
○
Variable oil content
•
Low in calcium
•
Gut microbes can break down phytate and release P (phytase
enzymes)
○
Moderate phosphorous but ~60-70% may be unavailable as phytate
•
Toxins and anti-nutrients may reduce digestibility in many wild seeds
•
May be cracked by teeth/beak, and discarded before ingestion1.
May be chewed by teeth, or ground in the gizzard, and then the seed
is digested
2.
Indigestible tough seed coat:
•
Some insects/other invertebrates may need to be eaten to meet amino acid
requirements
•
Young, growing mammals/birds may need to supplement diet with
insects/invertebrates to meet protein requirements for growth
•
Seeds, grains, and nuts are seasonal in temperate areas; available all year in
tropics
•
Granivores
Eat succulent, fleshy fruits
•
Mainly autoenzymic digestion
•
Variable energy, protein content
•
Low Ca -may ingest snails/grit
•
High water content, ~5% DM
!
High carbohydrates (fructose, glucose, sucrose)
!
Low amino acids
!
Low fibre
!
E.g. apples, blueberries
!
Nutrient-dilute fruits1)
Low water content
!
High lipid, 10-70% DM
!
Protein - 5-20% DM
!
Low carbohydrates
!
E.g. dates, avocados, mistletoe
!
May be discarded before ingestion
□
Seeds may be collected in the gizzard and regurgitated
□
Seeds may be chewed, cracked in the bill or ground in the
gizzard before the protein in the seed is digested
□
Indigestible tough fruit coat, seed:
!
Nutrient-dense fruits2)
Food:
•
Fruit is seasonal in temperate areas, available all year in tropics
•
Must eat mainly insects/invertebrates to meet protein requirements for
growth
○
Young, growing mammals/birds:
•
Frugivores
5C
If energy sufficient, nutrient deficiencies are unlikely
•
If flesh is only eaten (no bones) -low Ca
•
Carnivores:
If energy sufficient -low Ca
•
Insectivores:
If energy sufficient, nutrient deficiencies are unlikely
•
High diet variety
•
Omnivores:
Low/variable protein
•
Methionine and lysine may be low
○
Poor/variable AA balance
•
High fibre, decreases diet digestibility
•
Low/variable Na
•
Ca:P should be 1:1-2:1
○
Low Ca, Ca:P ratio poor
•
Diet variety is essential
•
Herbivores:
*see composition of coyote foods (do not to memorize specific
values)
○
Ex. Coyote -facultative carnivore (/omnivore)
•
White-tailed deer: 71.9%
!
Hare: 64.8%
!
Mice: 65.5%
!
All carcasses within 60-80% range
!
Water content (~60-70%)
○
%DM, Dry matter basis or 'as is', 'as fed', fresh weight basis
!
Nutrient content can be given as:
○
Dry Matter:
•
Low in white-tailed deer (4.3% cf 14.9%)
○
Assumed that coyotes would not eat the bones but they
usually do
□
Some predators will eat bone marrow
□
Bones:
!
Usually eaten although contents may be left
□
Adipose tissue around GIT may also be eaten
□
GIT:
!
White-tailed deer, bones, hide and GIT removed before analysis:
○
*Important to analyze food 'as eaten' -need to know how food is
eaten
Ash:
•
Bones contain some protein as collagen
○
Hair, feathers -high in protein but poorly digested
○
Laboratory mice -low at 53.8% cf to 80.5% and 70.1% in other prey
○
Crude Protein
•
Most variable component of animal food analysis
○
But predator will often kill young, or emaciated or ill animals -
the weakest
!
May have less fat, a different food analysis composition
!
Carcasses analyzed often from hunter's skill
○
No thermoregulation
□
No activity hunting for food
□
No activity escaping from predators
□
Often have higher fat
!
EE is high in laboratory mice, 32% cf 14.1% and 70.1% in other prey
○
Ether Extract (fat)
•
Plant cell walls
!
From GIT
!
GIT removed from white-tailed deer carcasses
□
Surprising that there is little difference between 3 prey species
!
May be given as ADF/NDF, herbivore diets
○
Crude Fibre
•
Not very useful value
○
Calculated by subtraction (not analyzed)
○
NFE reflected errors in all other values (may even be negative)
○
Animal tissues -glycogen
!
Plant tissues (GIT contents) -sugars, starch, pectin,
hemicellulose, cellulose
!
Includes carbohydrates:
○
Nitrogen-Free Extract
•
Analyzed by bomb calorimetry
○
4-6 kcal/g for both animal and plant foods
!
< 4 kcal/g --> usually with very high ash values
!
Pre-hibernation/torpor
□
Pre-migration
□
Laboratory animals
□
>6kcal/g (7-7.5) --> usually means obsese prey animals
!
Normal range for food analyses:
○
Usually highest in late summer-early fall
!
Seasonal changes in energy/g DM will affect predators
○
GE can be given as kcal/g Fresh weigh or kcal/g DM
○
Ash * 0 kcal/g = 0
!
CP * 5 kcal/g = 4.025
!
EE * 9 kcal/g = 1.269
!
CF * 4 kcal/g = 0.02
!
NFE * 4 kcal/g = 0.40
!
TOTAL = 5.354 kcal/g DM
!
GE is not always given with analysis:
○
Convert to DM basis
!
Moisture content = 73%
!
DM = 27%
!
1.48 x 100/27 = 5.4815 5.48 kcal/g DM
!
5.48 x 27/100 = 1.4796 1.48 kcal/g fresh weight
!
Ex. Deer carcass contain 1.48 kcal/g on fresh weight basis
○
Gross Energy (kcal/g)
•
Grey wolf
○
Red wolf
○
Ethiopian wolf
○
Golden jackal
○
Side-striped jackal
○
Black-backed jackal
○
Other canids:
•
Carnivores
5D
Birds: amount eaten -(amount in faeces + pellets)
○
Digestibility = amount eaten -amount in faeces
•
*faeces and urine cannot be separated in birds (except by
surgical modification)
□
Metabolizability (in birds) =Amount eaten -amount in faeces -amount in
urine
•
Amount of food eaten = amount provided -amount left
uneaten
▪
Measure:
□
If material left uneaten is different from what is eaten,
analyze both
▪
Analyze sample of food(s):
□
Collect total faeces (and pellets) produced/day and analyze
□
Captive animal/bird should eat normal diet (or diet to be tested) for
several days before testing
○
Determine amount and type of food eaten
□
Collect all faeces (and pellets) produced/day
□
Wild-ranging animal/bird:
○
Digestibility Studies (metabolizability, birds):
•
Digestibility of foods:
Grams of DM eaten/day -Grams of DM lost in faeces(/pellets)
○
White-tailed deer was analyzed with bones, hide and GIT
contents which are not well digested and reduce overall
digestibility of DM in diet
□
DM digestibility is high in white-tailed deer (96.7% cf 81.5%, 83.2%)
○
Dry Matter:
•
Grams of CP eaten/day -grams of CP lost in faeces(/pellets)
○
White-tailed deer analyzed without bones, hide
□
Protein in bones (collagen), protein in hair (keratin) -not well
digested and reduce overall digestibility of CP in diet
□
CP digestibility high in white-tailed deer (98.3% cf 90.5%, 87.9%)
○
Crude Protein:
•
EE digestibility high in all prey (95.7-97.3%)
○
Little or no indigestible lipids in bone, hide, or GIT
○
Ether Extract:
•
Energy digestibility high in white-tailed deer (98.8% cf 88.2, 90.5%)
○
Therefore, prey should all have same energy (kcal/g)
□
White-tailed deer analyzed without bones, hide and GIT which reduce
overall digestibility of energy in diet
○
Energy
•
Carnivore -Coyote
Crude Protein: 39% (lower than coyote prey)
•
Ether Extract: 52% (higher than coyote prey)
•
Crude Protein + Ether Extract: 91% (similar to coyote prey)
•
Ash + Crude Fat + NFE: 9% (higher than deer but smaller than other prey)
•
Energy: 5.7 kcal/g (similar to coyote prey)
•
CP has low digestibility -84.2% (lower than coyote prey)
○
EE digestibility -97.7% (same as mouse)
○
Energy digestibility -92% (same as mouse)
○
Ringed seal carcasses digestibility:
•
Carnivore -Polar Bear (prey: ringed seal)
Component Complete carcass Carcass without bones/hide
DM 75-85% >95%
CP 80-90% ~98%
EE 97-98% 97-98%
Energy ~90% 98-99%
Lean (muscle) tissue and adipose tissue -highly digestible
•
Digestibility decreases with indigestible components present in whole
carcass (but Ca is supplied by bones)
•
Energy digestibility in intact carcass is ~90%: DE = GE * 0.9
•
Digestibility in Carnivores (vertebrate prey):
At least 24 species of small cats
•
Few large cats
•
Obligate Carnivores -Felids
Red-tailed hawk
Swainson's hawk
Peregrine falcon
Gyrfalcon
Bald Eagle
Great horned owl
Snowy owl
Gastric pH (before meal) 1.6 (1.3-1.8) 2.35 (2.2-2.5)
% food appearing as pellet 5.2 12.5
% bones in pellet 6.5 45.8
More often tear flesh of prey
▪
Less often eat prey whole
▪
But eat at least some of the bones
▪
Hawks, falcons, eagles
□
Often ingest prey whole
▪
Owls
□
Two groups:
○
Gastric digestion in raptors
•
Hawks, falcons, eagles: 1.6
○
Owls: 2.35
○
pH is a log scale -1 unit difference = difference of 10x
○
pH is an important difference between groups:
•
Hawks, falcons, eagles: 5.2 -6.5
○
Owls: 12.5 -48.5
○
Decreased bone digestion
□
Decreased Ca available
□
Bone in pellets from hawk/falcon/eagle are less
representative of diet due to greater digestion
▪
Their pellets are less useful for food habit studies
▪
BUT: owl pellets are more useful for food habit studies
□
Less acidic gastric pH in owls:
○
% food appearing as pellet -% bones in pellets
•
DE -urine (& gas) = ME
□
GE -faeces = DE
○
Measured as DE (digestibility) in mammals (usually)
□
Digestive efficiency is measured as ME (metabolizability) in birds -
faeces and urine mixed in cloaca
○
Not because digestive efficiency is lower
□
ME in birds is ~75% of GE (68-82%)
▪
DE in birds is usually similar to DE in mammals
□
ME in mammals (~91% of DE) is 82% of GE (79-85%)
▪
DE in mammals is ~90% of GE (intact carcasses)
□
ME in birds is lower than DE in mammals
○
Digestive efficiency (energy)
•
Avian Carnivores
Eat only dead prey, killed by accident or by other carnivores
○
Carnivores who cannot kill their own prey
○
Includes vultures and their close relatives (condor)
○
Only 23 obligate scavengers (all birds)
•
Obligate Scavengers
DM -31.9%
□
EE -6% (12.0 in hare)
□
CP -75.5% (70.1 in hare)
□
Ash -3.8% (14.9 in hare)
□
GE -5.02 kcal/g DM (4.97 in hare)
□
Ca -0.31%
□
Ca:P, ~1:4
▪
Ca:P in bones, ~2:1
▪
Ca:P in diet should be 1:1 -2:1
▪
Therefore, grasshopper in low in Ca
▪
P -1.27%
□
Grasshopper
○
EE -10-40%
□
CP -50-75%
□
Adult insects
○
CP -40-70%
□
Caterpillars
○
Example Prey:
•
Ca (% DM) P (% DM) Ca:P
earthworm 0.95 0.95 1 : 1
mealworm 0.038 0.57 .06 : 1
Wax moth larva 0.030 0.39 .08 : 1
Cricket 0.10 0.79 .13 : 1
Ca:P lower than 1:1 (except earthworm)
○
Ca is low (except earthworm) -soil in gut
○
Most animals need ~0.5% DM Ca in diet
○
Ca:P content of invertebrates
•
BUT, Ca is usually low (Ca:P is usually below 1:1)
○
Food composition and digestibility is very similar to vertebrate prey
•
Decreases CP and EE digestibility by physically blocking
access of digestive enzymes to protein and lipid
□
35-85% digestibility of chitin
▪
Some mammals/birds produce chitinase enzyme which at least
partially digests chitin
□
Chitin….
○
Chitin exoskeletons -relatively indigestible
•
Ca exoskeletons/shells decrease DM digestibility but provide Ca in the diet
•
Insectivores & Microfaunivores
5E
May be called forage or browse (eaten by grazers, browsers, and
folivores)
○
Does not include fruits, seeds, plant exudates, pollen
○
Does not usually include fungi
○
May include algae (for marine mammals)
○
Ex. Reindeer lichen
□
May include lichens -a symbiotic relationship between a fungus and
algae
○
Eat leaves, stems and vegetative parts of plants
•
Algae are autotrophs and manufacture organic compounds from
water, CO2 and minerals, using solar radiation -photosynthesis
○
Algae then pass organic compounds to the fungi (heterotrophs, need
organic compounds in food)
○
Fungi provide 'shelter' for algae which are otherwise aquatic
○
Lichens (algae + fungus):
•
In quality, composition, energy content and digestibility
□
In quantity
□
With time (seasonally)
□
Very variable ….
○
Species of plant1.
leaves usually higher quality than stems
▪
Part of plant 2.
young plants have higher quality
▪
Age of plant 3.
when grasses start to produce seeds, leaf and stem quality
decreases
▪
Stage of growth of plant 4.
Low rainfall may reduce growth, quality may decrease
more quickly
▪
High temperatures -quality may decrease quickly
▪
Effect of climate 5.
N, P, K -needed for growth (added as artificial fertilizer)
▪
Effects of soil fertility and soil minerals6.
Toxins, anti-nutrients -protect plants from predation
▪
Plant defense chemicals7.
Factors which affect variability:
○
Forage and browse:
•
Pectin (soluble) -digested by microbial enzymes
!
Hemicellulose (insoluble) -digested by microbial enzymes
!
Cellulose (insoluble) -digested by microbial enzymes
!
Lignin (insoluble) -indigestible
!
Cell walls:
○
Soluble carbohydrates (~NFE)
!
Protein (~CP)
!
Cell contents:
○
Immature -37%
▪
Mature -85%
▪
Grasses:
!
Immature: 44%
▪
Mature: 75%
▪
Growing: 31%
!
Fallen, weathered: 49%
!
Leaves:
▪
Forbs:
!
Immature: 36%
▪
Mature: 62%
▪
Woody twigs:
!
Acorns: 40%
▪
Fleshy fruits: 41%
▪
Mushrooms: 39%
▪
Compare to…
!
More cell wall material is deposited with time
▪
Lignin may be deposited after pectin, cellulose and
hemicellulose
▪
*see diagram of cell wall composition
▪
*cell wall content increases with maturity
!
Cell wall contents (%DM):
○
Forage and browse composition:
•
Component (%DM) Summer Early Winter Late Winter
CP 18 7 5
Cell wall constituents 38 47 54
ADF cellulose 16 24 38
ADF lignin 916 13
~7% DM from late summer -early spring
▪
~17% DM in summer
▪
Biomass is low when quality is high (high CP, low
CWC) -from spring to summer
▪
CP:
!
>50% DM in late winter
▪
~30% DM in mid-summer
▪
Decreases from midsummer to late winter
▪
Fibre: hemicellulose, cellulose, lignin
!
~42-43% DM through year
▪
Soluble carbohydrates (NFE)
!
~5% DM through year
▪
Ash:
!
~5% DM through year
▪
EE:
!
Seasonal changes in food composition
○
Drops by ~20% at end of summer (associated with increase in
cellulose and lignin)
!
Hemicellulose, cellulose and lignin
▪
A measure of 'plant cell wall'
▪
Neutral detergent fibre (NDF; van Soest)
!
Cellulose, lignin
▪
Correlates with digestibility
▪
Acid detergent fibre (ADF; van Soest)
!
DM digestibility:
○
Accessibility changes with season
!
As snow depth increases, smaller browsers may gain access to
browse normally (too high to reach)
!
Some large herbivores are too heavy to walk across
surface of snow (takes more energy to walk through
trees)
▪
May 'breast' trees -walking over them and pushing it
down to gain access to higher browse
▪
Depends on snow compactness/ice crust
!
Caribou 'crater' -digging down to forage (an extra energy
expense)
▪
Some herbivores need to access forage below the snow
!
Forage and browse accessibility:
○
Na, K, Na:K, Ca, P, Ca:P
▪
Na, Ca, and P may be low
▪
K is high in most plant material
▪
Na:K and Ca:P -may be unbalanced
▪
Minerals are important in herbivore foods
!
Winter: 81 ppm
!
Spring: 48 ppm
!
Summer: 49 ppm
!
Fall: 41 ppm
!
Na:
▪
Winter: 11,134 ppm
!
Spring: 20,214 ppm
!
Summer: 14, 959 ppm
!
Fall: 12,355 ppm
!
K:
▪
Winter -1:137
!
Spring -1:421
!
Summer -1:305
!
Fall -1:301
!
Na:K
▪
Na and K in white-tailed deer diets:
!
Most herbivores need ~0.15% DM Na in diet (1500 ppm) -
approx. 1:4 Na:K
!
K is highest in spring and decreases through winter
!
Need to conserve Na
▪
Use of salt licks helps to redress imbalance (high levels
of K)
▪
K is high -Na is low
!
Required amount is ~1500 ppm
▪
Rodents may 'girdle' trees under snow to get bark
!
Bark: 547 ppm (300-1700)
▪
Twigs: 76 ppm (10-300)
▪
Leaves: 58 ppm (<10-600)
▪
Horsetails: 1574 ppm
▪
Aquatic plants: 2850-8048 ppm
▪
Algae: 14,600 ppm
▪
Na in herbivore food:
!
White-tailed deer
▪
Moose
▪
Reindeer
▪
Groundhogs
▪
Meadow voles
▪
Fox squirrels
▪
Prairie dogs
▪
Elephants -mine for salt in caves at night
▪
Na may be limiting for:
!
%Ca %P Ca:P
Willow leaves 0.82 0.41 2:1
Willow twigs -summer 0.51 0.12 4.3:1
Willow twigs - ? 0.39 0.13 3:1
Pond lily -leaves 0.63 0.31 2:1
Pond lily -stems 0.74 0.19 3.9:1
Fireweed 0.95 0.39 2.4:1
Lichen 0.31 0.36 0.9:1
Need Ca at ~0.5% DM in diet -lichen is low in Ca
▪
Willow twigs and pond lily stems -too little P
!
Lichen is around adequate ratio but Ca is low
!
Need Ca:P at 1:1-2:1
▪
Osteophagia: bone eating -supplies Ca, P and Na
!
Some rodents may chew shed antlers
!
Snails may be eaten
!
Higher calcium requirements for birds laying
eggs -may eat grit, broken egg shells
!
Higher calcium requirements for lactating
mammals
!
If Ca is low in diet:
▪
Ca and P in browse and forage plants:
!
Ash:
○
Composition of mule/white-tailed deer foods:
•
DM CP EE CF NFE DE
balsam 48 11.3 57 22 63 2.62
Red maple 31 11 51 18 42 1.39
Striped
maple
40 46 44 21 58 1.52
Mountain
maple
37 51 47 26 48 1.80
hobblebush 55 47 39 44 55 2.54
hazelnut 32 44 54 12 47 1.54
Ruminant
s
Non-ruminant
Herbivores
Carnivore
s
%DM 31-55 "75-85
%CP 1-51 69-74 80-90
%EE 39-57 "97-98
%CF 12-44 16-35 "
%NFE 42-63 69-72 "
DE (kcal/g
DM)
1.39-2.62 "~4.0
%DE "52-59 ~90
DM, CP and EE -all lower in herbivores compared to
carnivores
!
Rate of passage through GIT is slower
!
Digestion is more efficient
!
Less materials eaten
!
Ruminants:
▪
Rate of passage through GIT is faster
!
Passage is not restricted by omasum
!
CF digestion is less efficient, bacteria have less
time (caecum fermenters may be at low end of
range)
!
More material may be eaten (colon fermenters), or
food is chosen more selectively (caecum
fermenters)
!
Non-ruminants:
▪
CF is similar in ruminants and non-ruminants:
!
Cell contents may be digested by pre-gastric bacteria in
ruminants (less efficient anaerobic fermentation
compared to gastric digestion)
▪
NFE is somewhat higher in non-ruminants
!
Also, energy density (GE) of vegetative plant food is less
than that of animal flesh and adipose tissue
▪
DE is lower in ruminants and non-ruminants compared to
carnivores
!
Digestive Efficiencies: comparison
○
Browse Digestibility (% kcal/g DM) -white tailed deer
•
Herbivores
5F
Eat seeds and grain
•
See table
○
Slightly higher in weed seeds compared to cultivated grains
!
CP -good source
○
Some seed eaters remove husk/seed coat before eating
(takes time)
▪
Higher food quality (increased digestibility) VS. less time
available for foraging
▪
Moderately high in weed seeds
!
Cultivated grains are bred for thinner husk and for larger
size (less seed coat/g)
▪
Low in cultivated grains
!
CF
○
Good in weed seeds in germination
!
Bred for larger size, larger endosperm (less germ/g)
▪
*see diagram
▪
Lower in cultivated grains, except oil seeds
!
Fats in plants are either mono-or polyunsaturated
▪
If 1-2% EE is in diet of seed eaters, EFA needs should be met
!
EE
○
'soluble' carbohydrates/sugars -mostly non-structural
carbohydrates (e.g. starch)
!
Good in weed seeds
!
High in cultivated grains
!
NFE
○
Eater of weed seeds must eat a variety
▪
Weed seeds are variable in ash -partly due to Ca levels
!
Cultivated grains -ash and Ca are low
!
Need 0.5% DM Ca, need at least 1:1 Ca:P
!
Weed seeds -good Ca (except buckwheat), P is adequate
▪
Cultivated grains -Ca is low and therefore, Ca:P is poor
▪
Ca, P
!
Some P in seeds and grains is present as phytate -poorly
digested
▪
Phytic acid = inositol hexaphosphate
▪
Phytases in the seed release P for germenation
▪
P in phytate will be unavailable
!
Ruminants/foregut fermenters: microbes have
phytases to make P availble
!
Animals/birds have little phytase
▪
P availability
!
Not given analysis -may be low
▪
Na
!
Ash
○
Profile not given
!
Methionine, and lysine may be low in some species -must eat
variety
!
Amino Acids
○
Weed seeds: 4.17-4.68 --> good energy source
!
GE
○
Cultivated grains: NFE, CP and EE are well digested (~80%)
!
Higher fibre levels, smaller seeds
▪
Higher levels of tannins, trypsin inhibitors, other
toxins/antimetabolites
▪
If seeds are eaten, plants reproduction has failed -unless
some seeds pass through GIT undigested
▪
Weed seeds may be less digestible:
!
Digestibility
○
Composition of weed seeds, and cultivated grains (%DM)
•
Seeds and grains are seasonal in temperate areas -must combine with other
food sources
•
Not a balanced feed
○
Monoculture agriculture, makes grains available but may present a
problem to wildlife (e.g. migrating birds)
○
Fewer hedges with weed seeds is also a problem
○
*highway medians and verges are now being planted with wild
species and left unmowed
Grains are excellent energy source, but:
•
See table on slide
○
High digestibility compared to ~90% in carnivores (eating complete
carcass)
○
Both vole and mouse remove shell/husk before eating nuts
○
Digestibility of nuts by small rodents
•
Granivores
See table on slide
○
CP: high (25.7-33.3%)
!
CF: moderate (12.5-12.9%)
!
NFE: moderate (31.2-44.5%)
!
EE: moderate (1.4-3.1%)
!
Ca is low (.03-.16%)
!
P is high (0.52-0.61%)
!
Ca:P is poor
!
Ca & P:
▪
Ash: high (7.9-12.2) -usually ~5% (not due to high Ca levels)
!
Vegetative plant material:
○
CP: low (1.9-5.8%)
!
CF: moderate (8-19.3%)
!
NFE: high (56.7-73.2%)
!
Except gallberries (high; 10.8%)
▪
EE: moderate for plant material (1-4.9%)
!
Ca is low-high (0.13-0.71%)
!
P is low (0.06-0.10%)
!
Ca:P is poor
!
Ca & P:
▪
Ca and P are usually low in fleshy fruits (apples,
blueberries, cherries, grapes, prickly pear)
▪
Ash: moderate (1-7.6%)
!
Fruit:
○
Composition is variable --> must eat variety
○
Composition of black bear foods:
•
Frugivores
5G
Very low %DM -bulky; ~73.5% water
○
60-79% of CP is either unavailable in cell walls or indigestible
spores, or present as non-protein N
!
High CP, 21.5%
○
Low Ca, 0.09%
○
Low Na, 0.03%
○
GE -5.0 kcal/g
○
Composition of fungi:
•
Long-nosed potoroo (marsupial) -foregut fermenter
!
Red-backed vole (eutherian) -caecum fermenter
!
Eaten by:
○
CP digestibility is quite low
!
DM: GE digestibility higher in fore-gut fermenters
!
NDF: vole may grind food better when eating
!
Digestibility:
○
Hypogeous fungi (underground fungi; e.g. truffle)
•
Seasonal availability
•
Fungal cell walls contain hemicellulose, cellulose, and may contain chitin
•
Mycophages (eat fungi)
Mountain goats
○
Black-tailed deer
○
Yunnan snub-nosed monkey
○
Flying squirrel
○
Caribou/reindeer
○
Includes:
•
2-3% CP -low
○
0.31% Ca -low
○
0.36% P
○
Ca:P = 0.9:1 -adequate (just okay)
○
Lichen composition:
•
--> good energy, low protein
•
Lichenophages (eat lichens)
Salt licks
○
Possible reasons for use
○
Composition
○
Sodium
•
Toxins, antinutrients, antimetabolites
•
Metabolism and conservation
○
Protein
•
Foraging theory
•
Limiting Factors:
High levels of Na and Mg in salt licks
▪
Low P and K
▪
Moderate Ca
▪
pH = 7.0
▪
Composition of natural salt licks:
!
Only Na and Mg significantly higher in salt lick areas
▪
'natural salt lick' areas -where animals are observed to lick the
ground and ingest 'soil/minerals'
!
Used water containing Na salts to soak wooden stakes
▪
NaCl, NaI, NaHCO3
!
MgCl2, CaCl2
!
KHCO3, KI, KCl
!
Salts used:
▪
Were observed drinking the dilute Na solutions
!
Ignored stakes soaked in Mg, Ca, and K salts
◊
Were observed chewing/licking the wooden stakes
soaked in NaCl, NaI, and NaHCO3
!
Rabbits, fox squirrels, groundhogs, and white-tailed deer:
▪
Study to investigate reasons for salt lick use:
!
Porcupines have been observed damaging wooden
buildings when the wood had bee soaked with urine
(containing salt Na)
▪
Mountain goats in Olympic National Park have been
observed eagerly eating table salt offered by visitors
▪
In winter, food is the most effective bait
!
NaCl has been used as a very effective bait in trapping
white-tailed deer in Adriondack Mountains, in spring and
summer
▪
Other observations:
!
Acquisition of mineral nutrients1.
Healthy rumen/reticulum (reticulorumen) -pH = 5.5-7.0
!
pH may decrease to 4.0 with high starch in diet
!
Buffer pH
▪
Physically protect epithelium
▪
Salt licks can be used to:
!
Counter-balance rumen acidosis 2.
Adsorption of toxins, onto soil particles
!
Epithelium protection
!
Protection against plant toxins in GIT3.
E.g. pangolin (anteater without teeth) -ingest sand to abrade
ant exoskeletons
!
Comminution (grinding, triturating) of food particles 4.
E.g. young ruminants, fore-gut fermenters
!
Microbial inoculation5.
To fill stomach to dispel hunger during starvation6.
I.e. eating a non-food item
!
May be difficult to tell when substance eaten has valid
nutritional use
!
'Depraved' appetite, pica7.
Possible reasons for salt lick use by herbivorous mammals (and potentially
by birds): involves soil ingestion (geophagia)
•
Salt Licks:
5H
E.g. lignin, suberin, cutin, silica
○
*see diagram on slide
○
Not in algae, fungi, mosses, lichens
▪
Found only in 'higher plants' (monocotyledons 'grasses',
dicotyledons 'flowering plants')
!
Added rigidity to plant cell walls
!
Increases as plant matures
!
Up to 15-20% of cell wall
!
End walls disintegrate leaving hollow tubes
▪
Side walls strengthened with rings or spirals of lignin
▪
Transport water/minerals from soil
▪
Support the plant/tree
▪
Xylem cells are dead
!
Lignin is main protector of digestible cell wall
carbohydates
▪
E.g. bracket fungi on trees
!
Lignin can be broken down by certain fungi
▪
Lignin is not digested by animal/bird/bacterial enzymes, or by
acid hydrolysis in the gastric stomach (abomasum,
proventriculus)
!
Lignin:
○
Cutin is found as the structural compoenent of the plant cuticle
(at plant surface)
!
Reduces water loss
!
Prevents entry by microbes
!
Cutin:
○
Suberin is found between cell wall and cell contents
!
Cork cells/ outer layer of tree back, wound repair, around some
roots
!
Suberin:
○
*cutin and suberin are very poorly digested
Usually not in dictoyledons
▪
Si: 3-5% DM in grasses
▪
Found in grasses, sedges, ferns, horsetails
!
Hard, gritty material
!
Reduces cell wall digestibility
!
Increase tooth abrasion
!
May result in formation of urinary calculi
!
Silica/quartz
○
Substances that physically prevent digestive enzymes from reaching the
digestible carbohydrates, proteins and lipids (physical protection)
1.
E.g. soluble phenolics, alkaloids, terpenoids
○
Important as anti-herbivory compounds
!
Against mammals, birds, reptiles, amphibians, fish,
invertebrates
▪
Most act against all consumers -'broad spectrum'
!
E.g. pyrethrins (from chysanthemum flowers) -highly
toxic to insects, low toxicity to mammals
▪
Few are selective
!
Have no (few) primary metabolic functions within the plant
○
Must either be isolated within plant OR be stored in an inactive
form that becomes active when the plant material is consumed
!
Secondary plant compounds are usually also toxic to plants which
produce them
○
Plant consumers (primary consumers) continually evolve new
biochemical detoxification pathways SO plants constantly evolve new
defense compounds
○
Avoid
!
Fore-gut bacteria (detoxify most compounds)
!
Metabolic breakdown
!
Options for herbivores:
○
Ruminants and other foregut fermenters have advantage over
hind-gut fermenters, detoxification early in passage through
GIT
!
Many secondary plant compounds can be detoxified by GIT bacteria
○
Tannins may bind to viral/bacterial/fungal pathogens in GIT
and reduce infection
!
Most secondary plant compounds are antinutrients/antimetabolites
BUT some are beneficial (under certain circumstances)
○
Substances that interfere with digestions, nervous system function, growth,
reproduction and/or taste bitter (or smell bad)
2.
Toxins, Antinutrients & Antimetabolites -plant protective and defensive agents
Food Composition & Digestion
Friday,*March*24,*2017 12:27*PM
Carnivores and piscivores
○
Insectivores
○
Other microfaunivores
○
Carnivores:
•
Grazers, browsers, folivores
○
Nectarivores
○
Frugivores
○
Granivores
○
Herbivores:
•
Omnivores
•
Types of…
What is eaten
•
Major type of digestion
•
Protein, fat, EAAs
•
Minerals, vitamins
•
How indigestible components are delt with
•
'Summary'
Eat vertebrates, including fish
•
Autoenzymic digestion (by animals own enzymes)
•
Highly digestible
○
High in protein
○
Eat soft tissues:
•
20+ % fat pre-spawning, <1% fat post-spawning
!
E.g. salmon, mackerel, sardines, herring
!
Oily fish -store fat in muscles
○
<2% fat
!
E.g. cod, haddock, plaice, halibut
!
Non-oily/'white' fish -store fat in liver
○
Cold water fish are usually higher in fat content than warm water fish
○
Fat content available:
•
Balance of EAAs similar to requirements
•
Good source of minerals, vitamins
•
Low in calcium if prey is not eaten whole (no bones)
•
Bones
○
Fur (mammals), feathers (birds), scales (reptiles/fish)
○
Indigestible animal tissues:
•
Separated from soft tissues before ingestion1.
Separated in gizzard (birds) and then egested (usually as pellets)2.
Decrease digestibility of total diet
!
Some digestion of bones (Ca)
!
Not separated:3.
Indigestible animal tissues may be:
•
Carnivores & Piscivores
Eat insects
•
Autoenzymic digestion
•
Highly digestible
○
Adult insects: 50-75% CP
!
Caterpillars: 40-70% CP
!
High in protein
○
Adult insects: 10-40% EE
!
Fat content is variable
○
Soft tissues:
•
Balance of EAAs similar to requirements
•
Good source of P, trace minerals, vitamins
•
Bones, snail shells, egg shells may be eaten
○
Many exudates are high in calcium
!
Many insectivores are also gummivores, and eat exudates from trees
and shrubs
○
Low in calcium:
•
Chitin content is variable: 18-60%
○
Select insects with low chitin content1.
Remove high-chitin part of the exoskeleton before ingestion
( wings and tibia, 50% chitin, of grasshoppers are removed by
grasshopper sparrow)
2.
Crush insect (with beak or teeth), extract soft tissues and
discard exoskeleton
3.
Eat insects whole, then egest exoskeletons (kestrel, swallows,
flycatchers)
4.
Produce chitinase enzymes (at least partially digest chitin) -
energy value of chitin is usually low
5.
Animals/birds may:
○
Indigestible chitinous exoskeleton (carbohydrate):
•
Some adult/larval insects are in tree bark/ in ground during winter
○
Adult insects may be seasonal in temperatue areas
•
Have chitinous exoskeleton
○
3 part body (head, thorax, abdomen)
○
3 pairs of jointed legs
○
Compound eyes -2 antennae
○
Insect structure:
•
Insectivores
Microfaunivores eat other invertebrates (not insects)
•
Annelids (worms)
○
Molluscs (snails, mussels, oysters, clams) -calcareous shells
○
Molluscs (squid, octopus) -chitinous beak
○
Echinoderms (sea urchins, starfish) -calcareous exoskeleton
○
Arachnids (spiders)
○
Crustacea (crabs, lobsters, shrimp, crayfish, krill) -chitinous
exoskeleton (may be partly calcified)
○
Mammal and bird microfaunivores may eat:
•
Have autoenzymic digestion
•
Similar nutritional properties to insects
○
Soft tissues:
•
Remove shell (Ca) or exoskeleton (chitin) before ingestion
1.
Eat squid whole, then egest beak (cormorant, albatross)
2.
Eat molluscs whole, crush shell in gizzard (eider ducl)
3.
Produce chitinase enzymes (at least partially digest chitin) although
energy value is low (king penguins -chitin digestibility is 85%)
4.
Indigestible shells, exoskeletons:
•
Other Microfaunivores
5B
Grasses (monocotyledons), broad-leaved plants (dicotyledons) -both
herbaceous (forbs), woody shrubs and trees
○
Eat vegetative parts of plants (leaves, stems)
•
Fore-gut (ruminants/ non-ruminant)
!
Hind-gut (in caecum/colon)
!
Microbial fermentation is essential for digestion of plant cell walls
(cellulose, hemicellulose)
○
Coprophagy and caecotrophy may occur
○
Alloenzymic digestion + microbial enzymes
•
Ex. Rhino -hind gut fermenter
•
Cell contents
○
Highly digestible -do not 'have/need' microbial fermentation
○
EXCEPTION: Giant panda -autoenzymic digestion
•
But LOW levels of methionine and lysine
!
Protein -fairly good balance of EAAs in young, green plant material
○
Sugars (non-structural carbohydrates)
○
Aquatic leaves and roots are a good Na source
!
Variable Na source (may need salt licks)
○
Poorly digestible
!
Hinders digestibility of cell contents
!
Chewing (rumination/merycism) in mammals
□
Muscular gizzard in birds
□
Requires physical breakdown
!
Requires microbial fermentation
!
Grazers -prefer long and green vs short and brown
vegetation
□
There is higher cell wall content in mature vegetation
!
Cell Wall (fibre)
○
Food composition:
•
Insects
○
Other invertebrates
○
Grains
○
Seeds
○
Young birds may supplement vegetation plant material to obtain extra
protein and energy with:
•
Grazers, Browsers, & Folivores
Eat nectar, honey, honeydew (produced by aphids -sap sucking insects)
•
Autoenzymic digestion
•
A very dilute sugar solution (sucrose, glucose, fructose)
•
Highly digestible
•
May contain very low levels of amino acids and lipis
•
Some insects and other invertebrates (soft-bodied for birds) must be
eaten to meet amino acid requirements
○
Poor amino acid balance
•
Young, growing mammals/birds must eat mainly insects/invertebrates to
meet protein requirements for growth
•
May also be eaten by nectarivores
○
High protein: 7-40% DM
○
Good source of vitamins, minerals
○
Pollen:
•
Nectarivores
Eat seeds, grains (seeds of grasses), nuts
•
Mainly autoenzymic digestion
•
High in starch
•
Low to moderate protein
•
Some seeds: low in methionine and lysine
○
Legumes (pea family): high in lysine
○
Balance of amino acids is variable and may be poor
•
Low in fibre (without seed coats/husked)
•
Good source of many vitamins and minerals
•
Low lipid in grass seeds
○
High lipids in oil seeds, sunflowers, safflowers
○
Variable oil content
•
Low in calcium
•
Gut microbes can break down phytate and release P (phytase
enzymes)
○
Moderate phosphorous but ~60-70% may be unavailable as phytate
•
Toxins and anti-nutrients may reduce digestibility in many wild seeds
•
May be cracked by teeth/beak, and discarded before ingestion1.
May be chewed by teeth, or ground in the gizzard, and then the seed
is digested
2.
Indigestible tough seed coat:
•
Some insects/other invertebrates may need to be eaten to meet amino acid
requirements
•
Young, growing mammals/birds may need to supplement diet with
insects/invertebrates to meet protein requirements for growth
•
Seeds, grains, and nuts are seasonal in temperate areas; available all year in
tropics
•
Granivores
Eat succulent, fleshy fruits
•
Mainly autoenzymic digestion
•
Variable energy, protein content
•
Low Ca -may ingest snails/grit
•
High water content, ~5% DM
!
High carbohydrates (fructose, glucose, sucrose)
!
Low amino acids
!
Low fibre
!
E.g. apples, blueberries
!
Nutrient-dilute fruits1)
Low water content
!
High lipid, 10-70% DM
!
Protein - 5-20% DM
!
Low carbohydrates
!
E.g. dates, avocados, mistletoe
!
May be discarded before ingestion
□
Seeds may be collected in the gizzard and regurgitated
□
Seeds may be chewed, cracked in the bill or ground in the
gizzard before the protein in the seed is digested
□
Indigestible tough fruit coat, seed:
!
Nutrient-dense fruits2)
Food:
•
Fruit is seasonal in temperate areas, available all year in tropics
•
Must eat mainly insects/invertebrates to meet protein requirements for
growth
○
Young, growing mammals/birds:
•
Frugivores
5C
If energy sufficient, nutrient deficiencies are unlikely
•
If flesh is only eaten (no bones) -low Ca
•
Carnivores:
If energy sufficient -low Ca
•
Insectivores:
If energy sufficient, nutrient deficiencies are unlikely
•
High diet variety
•
Omnivores:
Low/variable protein
•
Methionine and lysine may be low
○
Poor/variable AA balance
•
High fibre, decreases diet digestibility
•
Low/variable Na
•
Ca:P should be 1:1-2:1
○
Low Ca, Ca:P ratio poor
•
Diet variety is essential
•
Herbivores:
*see composition of coyote foods (do not to memorize specific
values)
○
Ex. Coyote -facultative carnivore (/omnivore)
•
White-tailed deer: 71.9%
!
Hare: 64.8%
!
Mice: 65.5%
!
All carcasses within 60-80% range
!
Water content (~60-70%)
○
%DM, Dry matter basis or 'as is', 'as fed', fresh weight basis
!
Nutrient content can be given as:
○
Dry Matter:
•
Low in white-tailed deer (4.3% cf 14.9%)
○
Assumed that coyotes would not eat the bones but they
usually do
□
Some predators will eat bone marrow
□
Bones:
!
Usually eaten although contents may be left
□
Adipose tissue around GIT may also be eaten
□
GIT:
!
White-tailed deer, bones, hide and GIT removed before analysis:
○
*Important to analyze food 'as eaten' -need to know how food is
eaten
Ash:
•
Bones contain some protein as collagen
○
Hair, feathers -high in protein but poorly digested
○
Laboratory mice -low at 53.8% cf to 80.5% and 70.1% in other prey
○
Crude Protein
•
Most variable component of animal food analysis
○
But predator will often kill young, or emaciated or ill animals -
the weakest
!
May have less fat, a different food analysis composition
!
Carcasses analyzed often from hunter's skill
○
No thermoregulation
□
No activity hunting for food
□
No activity escaping from predators
□
Often have higher fat
!
EE is high in laboratory mice, 32% cf 14.1% and 70.1% in other prey
○
Ether Extract (fat)
•
Plant cell walls
!
From GIT
!
GIT removed from white-tailed deer carcasses
□
Surprising that there is little difference between 3 prey species
!
May be given as ADF/NDF, herbivore diets
○
Crude Fibre
•
Not very useful value
○
Calculated by subtraction (not analyzed)
○
NFE reflected errors in all other values (may even be negative)
○
Animal tissues -glycogen
!
Plant tissues (GIT contents) -sugars, starch, pectin,
hemicellulose, cellulose
!
Includes carbohydrates:
○
Nitrogen-Free Extract
•
Analyzed by bomb calorimetry
○
4-6 kcal/g for both animal and plant foods
!
< 4 kcal/g --> usually with very high ash values
!
Pre-hibernation/torpor
□
Pre-migration
□
Laboratory animals
□
>6kcal/g (7-7.5) --> usually means obsese prey animals
!
Normal range for food analyses:
○
Usually highest in late summer-early fall
!
Seasonal changes in energy/g DM will affect predators
○
GE can be given as kcal/g Fresh weigh or kcal/g DM
○
Ash * 0 kcal/g = 0
!
CP * 5 kcal/g = 4.025
!
EE * 9 kcal/g = 1.269
!
CF * 4 kcal/g = 0.02
!
NFE * 4 kcal/g = 0.40
!
TOTAL = 5.354 kcal/g DM
!
GE is not always given with analysis:
○
Convert to DM basis
!
Moisture content = 73%
!
DM = 27%
!
1.48 x 100/27 = 5.4815 5.48 kcal/g DM
!
5.48 x 27/100 = 1.4796 1.48 kcal/g fresh weight
!
Ex. Deer carcass contain 1.48 kcal/g on fresh weight basis
○
Gross Energy (kcal/g)
•
Grey wolf
○
Red wolf
○
Ethiopian wolf
○
Golden jackal
○
Side-striped jackal
○
Black-backed jackal
○
Other canids:
•
Carnivores
5D
Birds: amount eaten -(amount in faeces + pellets)
○
Digestibility = amount eaten -amount in faeces
•
*faeces and urine cannot be separated in birds (except by
surgical modification)
□
Metabolizability (in birds) =Amount eaten -amount in faeces -amount in
urine
•
Amount of food eaten = amount provided -amount left
uneaten
▪
Measure:
□
If material left uneaten is different from what is eaten,
analyze both
▪
Analyze sample of food(s):
□
Collect total faeces (and pellets) produced/day and analyze
□
Captive animal/bird should eat normal diet (or diet to be tested) for
several days before testing
○
Determine amount and type of food eaten
□
Collect all faeces (and pellets) produced/day
□
Wild-ranging animal/bird:
○
Digestibility Studies (metabolizability, birds):
•
Digestibility of foods:
Grams of DM eaten/day -Grams of DM lost in faeces(/pellets)
○
White-tailed deer was analyzed with bones, hide and GIT
contents which are not well digested and reduce overall
digestibility of DM in diet
□
DM digestibility is high in white-tailed deer (96.7% cf 81.5%, 83.2%)
○
Dry Matter:
•
Grams of CP eaten/day -grams of CP lost in faeces(/pellets)
○
White-tailed deer analyzed without bones, hide
□
Protein in bones (collagen), protein in hair (keratin) -not well
digested and reduce overall digestibility of CP in diet
□
CP digestibility high in white-tailed deer (98.3% cf 90.5%, 87.9%)
○
Crude Protein:
•
EE digestibility high in all prey (95.7-97.3%)
○
Little or no indigestible lipids in bone, hide, or GIT
○
Ether Extract:
•
Energy digestibility high in white-tailed deer (98.8% cf 88.2, 90.5%)
○
Therefore, prey should all have same energy (kcal/g)
□
White-tailed deer analyzed without bones, hide and GIT which reduce
overall digestibility of energy in diet
○
Energy
•
Carnivore -Coyote
Crude Protein: 39% (lower than coyote prey)
•
Ether Extract: 52% (higher than coyote prey)
•
Crude Protein + Ether Extract: 91% (similar to coyote prey)
•
Ash + Crude Fat + NFE: 9% (higher than deer but smaller than other prey)
•
Energy: 5.7 kcal/g (similar to coyote prey)
•
CP has low digestibility -84.2% (lower than coyote prey)
○
EE digestibility -97.7% (same as mouse)
○
Energy digestibility -92% (same as mouse)
○
Ringed seal carcasses digestibility:
•
Carnivore -Polar Bear (prey: ringed seal)
Component Complete carcass Carcass without bones/hide
DM 75-85% >95%
CP 80-90% ~98%
EE 97-98% 97-98%
Energy ~90% 98-99%
Lean (muscle) tissue and adipose tissue -highly digestible
•
Digestibility decreases with indigestible components present in whole
carcass (but Ca is supplied by bones)
•
Energy digestibility in intact carcass is ~90%: DE = GE * 0.9
•
Digestibility in Carnivores (vertebrate prey):
At least 24 species of small cats
•
Few large cats
•
Obligate Carnivores -Felids
Red-tailed hawk
Swainson's hawk
Peregrine falcon
Gyrfalcon
Bald Eagle
Great horned owl
Snowy owl
Gastric pH (before meal) 1.6 (1.3-1.8) 2.35 (2.2-2.5)
% food appearing as pellet 5.2 12.5
% bones in pellet 6.5 45.8
More often tear flesh of prey
▪
Less often eat prey whole
▪
But eat at least some of the bones
▪
Hawks, falcons, eagles
□
Often ingest prey whole
▪
Owls
□
Two groups:
○
Gastric digestion in raptors
•
Hawks, falcons, eagles: 1.6
○
Owls: 2.35
○
pH is a log scale -1 unit difference = difference of 10x
○
pH is an important difference between groups:
•
Hawks, falcons, eagles: 5.2 -6.5
○
Owls: 12.5 -48.5
○
Decreased bone digestion
□
Decreased Ca available
□
Bone in pellets from hawk/falcon/eagle are less
representative of diet due to greater digestion
▪
Their pellets are less useful for food habit studies
▪
BUT: owl pellets are more useful for food habit studies
□
Less acidic gastric pH in owls:
○
% food appearing as pellet -% bones in pellets
•
DE -urine (& gas) = ME
□
GE -faeces = DE
○
Measured as DE (digestibility) in mammals (usually)
□
Digestive efficiency is measured as ME (metabolizability) in birds -
faeces and urine mixed in cloaca
○
Not because digestive efficiency is lower
□
ME in birds is ~75% of GE (68-82%)
▪
DE in birds is usually similar to DE in mammals
□
ME in mammals (~91% of DE) is 82% of GE (79-85%)
▪
DE in mammals is ~90% of GE (intact carcasses)
□
ME in birds is lower than DE in mammals
○
Digestive efficiency (energy)
•
Avian Carnivores
Eat only dead prey, killed by accident or by other carnivores
○
Carnivores who cannot kill their own prey
○
Includes vultures and their close relatives (condor)
○
Only 23 obligate scavengers (all birds)
•
Obligate Scavengers
DM -31.9%
□
EE -6% (12.0 in hare)
□
CP -75.5% (70.1 in hare)
□
Ash -3.8% (14.9 in hare)
□
GE -5.02 kcal/g DM (4.97 in hare)
□
Ca -0.31%
□
Ca:P, ~1:4
▪
Ca:P in bones, ~2:1
▪
Ca:P in diet should be 1:1 -2:1
▪
Therefore, grasshopper in low in Ca
▪
P -1.27%
□
Grasshopper
○
EE -10-40%
□
CP -50-75%
□
Adult insects
○
CP -40-70%
□
Caterpillars
○
Example Prey:
•
Ca (% DM) P (% DM) Ca:P
earthworm 0.95 0.95 1 : 1
mealworm 0.038 0.57 .06 : 1
Wax moth larva 0.030 0.39 .08 : 1
Cricket 0.10 0.79 .13 : 1
Ca:P lower than 1:1 (except earthworm)
○
Ca is low (except earthworm) -soil in gut
○
Most animals need ~0.5% DM Ca in diet
○
Ca:P content of invertebrates
•
BUT, Ca is usually low (Ca:P is usually below 1:1)
○
Food composition and digestibility is very similar to vertebrate prey
•
Decreases CP and EE digestibility by physically blocking
access of digestive enzymes to protein and lipid
□
35-85% digestibility of chitin
▪
Some mammals/birds produce chitinase enzyme which at least
partially digests chitin
□
Chitin….
○
Chitin exoskeletons -relatively indigestible
•
Ca exoskeletons/shells decrease DM digestibility but provide Ca in the diet
•
Insectivores & Microfaunivores
5E
May be called forage or browse (eaten by grazers, browsers, and
folivores)
○
Does not include fruits, seeds, plant exudates, pollen
○
Does not usually include fungi
○
May include algae (for marine mammals)
○
Ex. Reindeer lichen
□
May include lichens -a symbiotic relationship between a fungus and
algae
○
Eat leaves, stems and vegetative parts of plants
•
Algae are autotrophs and manufacture organic compounds from
water, CO2 and minerals, using solar radiation -photosynthesis
○
Algae then pass organic compounds to the fungi (heterotrophs, need
organic compounds in food)
○
Fungi provide 'shelter' for algae which are otherwise aquatic
○
Lichens (algae + fungus):
•
In quality, composition, energy content and digestibility
□
In quantity
□
With time (seasonally)
□
Very variable ….
○
Species of plant1.
leaves usually higher quality than stems
▪
Part of plant 2.
young plants have higher quality
▪
Age of plant 3.
when grasses start to produce seeds, leaf and stem quality
decreases
▪
Stage of growth of plant 4.
Low rainfall may reduce growth, quality may decrease
more quickly
▪
High temperatures -quality may decrease quickly
▪
Effect of climate 5.
N, P, K -needed for growth (added as artificial fertilizer)
▪
Effects of soil fertility and soil minerals6.
Toxins, anti-nutrients -protect plants from predation
▪
Plant defense chemicals7.
Factors which affect variability:
○
Forage and browse:
•
Pectin (soluble) -digested by microbial enzymes
!
Hemicellulose (insoluble) -digested by microbial enzymes
!
Cellulose (insoluble) -digested by microbial enzymes
!
Lignin (insoluble) -indigestible
!
Cell walls:
○
Soluble carbohydrates (~NFE)
!
Protein (~CP)
!
Cell contents:
○
Immature -37%
▪
Mature -85%
▪
Grasses:
!
Immature: 44%
▪
Mature: 75%
▪
Growing: 31%
!
Fallen, weathered: 49%
!
Leaves:
▪
Forbs:
!
Immature: 36%
▪
Mature: 62%
▪
Woody twigs:
!
Acorns: 40%
▪
Fleshy fruits: 41%
▪
Mushrooms: 39%
▪
Compare to…
!
More cell wall material is deposited with time
▪
Lignin may be deposited after pectin, cellulose and
hemicellulose
▪
*see diagram of cell wall composition
▪
*cell wall content increases with maturity
!
Cell wall contents (%DM):
○
Forage and browse composition:
•
Component (%DM) Summer Early Winter Late Winter
CP 18 7 5
Cell wall constituents 38 47 54
ADF cellulose 16 24 38
ADF lignin 916 13
~7% DM from late summer -early spring
▪
~17% DM in summer
▪
Biomass is low when quality is high (high CP, low
CWC) -from spring to summer
▪
CP:
!
>50% DM in late winter
▪
~30% DM in mid-summer
▪
Decreases from midsummer to late winter
▪
Fibre: hemicellulose, cellulose, lignin
!
~42-43% DM through year
▪
Soluble carbohydrates (NFE)
!
~5% DM through year
▪
Ash:
!
~5% DM through year
▪
EE:
!
Seasonal changes in food composition
○
Drops by ~20% at end of summer (associated with increase in
cellulose and lignin)
!
Hemicellulose, cellulose and lignin
▪
A measure of 'plant cell wall'
▪
Neutral detergent fibre (NDF; van Soest)
!
Cellulose, lignin
▪
Correlates with digestibility
▪
Acid detergent fibre (ADF; van Soest)
!
DM digestibility:
○
Accessibility changes with season
!
As snow depth increases, smaller browsers may gain access to
browse normally (too high to reach)
!
Some large herbivores are too heavy to walk across
surface of snow (takes more energy to walk through
trees)
▪
May 'breast' trees -walking over them and pushing it
down to gain access to higher browse
▪
Depends on snow compactness/ice crust
!
Caribou 'crater' -digging down to forage (an extra energy
expense)
▪
Some herbivores need to access forage below the snow
!
Forage and browse accessibility:
○
Na, K, Na:K, Ca, P, Ca:P
▪
Na, Ca, and P may be low
▪
K is high in most plant material
▪
Na:K and Ca:P -may be unbalanced
▪
Minerals are important in herbivore foods
!
Winter: 81 ppm
!
Spring: 48 ppm
!
Summer: 49 ppm
!
Fall: 41 ppm
!
Na:
▪
Winter: 11,134 ppm
!
Spring: 20,214 ppm
!
Summer: 14, 959 ppm
!
Fall: 12,355 ppm
!
K:
▪
Winter -1:137
!
Spring -1:421
!
Summer -1:305
!
Fall -1:301
!
Na:K
▪
Na and K in white-tailed deer diets:
!
Most herbivores need ~0.15% DM Na in diet (1500 ppm) -
approx. 1:4 Na:K
!
K is highest in spring and decreases through winter
!
Need to conserve Na
▪
Use of salt licks helps to redress imbalance (high levels
of K)
▪
K is high -Na is low
!
Required amount is ~1500 ppm
▪
Rodents may 'girdle' trees under snow to get bark
!
Bark: 547 ppm (300-1700)
▪
Twigs: 76 ppm (10-300)
▪
Leaves: 58 ppm (<10-600)
▪
Horsetails: 1574 ppm
▪
Aquatic plants: 2850-8048 ppm
▪
Algae: 14,600 ppm
▪
Na in herbivore food:
!
White-tailed deer
▪
Moose
▪
Reindeer
▪
Groundhogs
▪
Meadow voles
▪
Fox squirrels
▪
Prairie dogs
▪
Elephants -mine for salt in caves at night
▪
Na may be limiting for:
!
%Ca %P Ca:P
Willow leaves 0.82 0.41 2:1
Willow twigs -summer 0.51 0.12 4.3:1
Willow twigs - ? 0.39 0.13 3:1
Pond lily -leaves 0.63 0.31 2:1
Pond lily -stems 0.74 0.19 3.9:1
Fireweed 0.95 0.39 2.4:1
Lichen 0.31 0.36 0.9:1
Need Ca at ~0.5% DM in diet -lichen is low in Ca
▪
Willow twigs and pond lily stems -too little P
!
Lichen is around adequate ratio but Ca is low
!
Need Ca:P at 1:1-2:1
▪
Osteophagia: bone eating -supplies Ca, P and Na
!
Some rodents may chew shed antlers
!
Snails may be eaten
!
Higher calcium requirements for birds laying
eggs -may eat grit, broken egg shells
!
Higher calcium requirements for lactating
mammals
!
If Ca is low in diet:
▪
Ca and P in browse and forage plants:
!
Ash:
○
Composition of mule/white-tailed deer foods:
•
DM CP EE CF NFE DE
balsam 48 11.3 57 22 63 2.62
Red maple 31 11 51 18 42 1.39
Striped
maple
40 46 44 21 58 1.52
Mountain
maple
37 51 47 26 48 1.80
hobblebush 55 47 39 44 55 2.54
hazelnut 32 44 54 12 47 1.54
Ruminant
s
Non-ruminant
Herbivores
Carnivore
s
%DM 31-55 "75-85
%CP 1-51 69-74 80-90
%EE 39-57 "97-98
%CF 12-44 16-35 "
%NFE 42-63 69-72 "
DE (kcal/g
DM)
1.39-2.62 "~4.0
%DE "52-59 ~90
DM, CP and EE -all lower in herbivores compared to
carnivores
!
Rate of passage through GIT is slower
!
Digestion is more efficient
!
Less materials eaten
!
Ruminants:
▪
Rate of passage through GIT is faster
!
Passage is not restricted by omasum
!
CF digestion is less efficient, bacteria have less
time (caecum fermenters may be at low end of
range)
!
More material may be eaten (colon fermenters), or
food is chosen more selectively (caecum
fermenters)
!
Non-ruminants:
▪
CF is similar in ruminants and non-ruminants:
!
Cell contents may be digested by pre-gastric bacteria in
ruminants (less efficient anaerobic fermentation
compared to gastric digestion)
▪
NFE is somewhat higher in non-ruminants
!
Also, energy density (GE) of vegetative plant food is less
than that of animal flesh and adipose tissue
▪
DE is lower in ruminants and non-ruminants compared to
carnivores
!
Digestive Efficiencies: comparison
○
Browse Digestibility (% kcal/g DM) -white tailed deer
•
Herbivores
5F
Eat seeds and grain
•
See table
○
Slightly higher in weed seeds compared to cultivated grains
!
CP -good source
○
Some seed eaters remove husk/seed coat before eating
(takes time)
▪
Higher food quality (increased digestibility) VS. less time
available for foraging
▪
Moderately high in weed seeds
!
Cultivated grains are bred for thinner husk and for larger
size (less seed coat/g)
▪
Low in cultivated grains
!
CF
○
Good in weed seeds in germination
!
Bred for larger size, larger endosperm (less germ/g)
▪
*see diagram
▪
Lower in cultivated grains, except oil seeds
!
Fats in plants are either mono-or polyunsaturated
▪
If 1-2% EE is in diet of seed eaters, EFA needs should be met
!
EE
○
'soluble' carbohydrates/sugars -mostly non-structural
carbohydrates (e.g. starch)
!
Good in weed seeds
!
High in cultivated grains
!
NFE
○
Eater of weed seeds must eat a variety
▪
Weed seeds are variable in ash -partly due to Ca levels
!
Cultivated grains -ash and Ca are low
!
Need 0.5% DM Ca, need at least 1:1 Ca:P
!
Weed seeds -good Ca (except buckwheat), P is adequate
▪
Cultivated grains -Ca is low and therefore, Ca:P is poor
▪
Ca, P
!
Some P in seeds and grains is present as phytate -poorly
digested
▪
Phytic acid = inositol hexaphosphate
▪
Phytases in the seed release P for germenation
▪
P in phytate will be unavailable
!
Ruminants/foregut fermenters: microbes have
phytases to make P availble
!
Animals/birds have little phytase
▪
P availability
!
Not given analysis -may be low
▪
Na
!
Ash
○
Profile not given
!
Methionine, and lysine may be low in some species -must eat
variety
!
Amino Acids
○
Weed seeds: 4.17-4.68 --> good energy source
!
GE
○
Cultivated grains: NFE, CP and EE are well digested (~80%)
!
Higher fibre levels, smaller seeds
▪
Higher levels of tannins, trypsin inhibitors, other
toxins/antimetabolites
▪
If seeds are eaten, plants reproduction has failed -unless
some seeds pass through GIT undigested
▪
Weed seeds may be less digestible:
!
Digestibility
○
Composition of weed seeds, and cultivated grains (%DM)
•
Seeds and grains are seasonal in temperate areas -must combine with other
food sources
•
Not a balanced feed
○
Monoculture agriculture, makes grains available but may present a
problem to wildlife (e.g. migrating birds)
○
Fewer hedges with weed seeds is also a problem
○
*highway medians and verges are now being planted with wild
species and left unmowed
Grains are excellent energy source, but:
•
See table on slide
○
High digestibility compared to ~90% in carnivores (eating complete
carcass)
○
Both vole and mouse remove shell/husk before eating nuts
○
Digestibility of nuts by small rodents
•
Granivores
See table on slide
○
CP: high (25.7-33.3%)
!
CF: moderate (12.5-12.9%)
!
NFE: moderate (31.2-44.5%)
!
EE: moderate (1.4-3.1%)
!
Ca is low (.03-.16%)
!
P is high (0.52-0.61%)
!
Ca:P is poor
!
Ca & P:
▪
Ash: high (7.9-12.2) -usually ~5% (not due to high Ca levels)
!
Vegetative plant material:
○
CP: low (1.9-5.8%)
!
CF: moderate (8-19.3%)
!
NFE: high (56.7-73.2%)
!
Except gallberries (high; 10.8%)
▪
EE: moderate for plant material (1-4.9%)
!
Ca is low-high (0.13-0.71%)
!
P is low (0.06-0.10%)
!
Ca:P is poor
!
Ca & P:
▪
Ca and P are usually low in fleshy fruits (apples,
blueberries, cherries, grapes, prickly pear)
▪
Ash: moderate (1-7.6%)
!
Fruit:
○
Composition is variable --> must eat variety
○
Composition of black bear foods:
•
Frugivores
5G
Very low %DM -bulky; ~73.5% water
○
60-79% of CP is either unavailable in cell walls or indigestible
spores, or present as non-protein N
!
High CP, 21.5%
○
Low Ca, 0.09%
○
Low Na, 0.03%
○
GE -5.0 kcal/g
○
Composition of fungi:
•
Long-nosed potoroo (marsupial) -foregut fermenter
!
Red-backed vole (eutherian) -caecum fermenter
!
Eaten by:
○
CP digestibility is quite low
!
DM: GE digestibility higher in fore-gut fermenters
!
NDF: vole may grind food better when eating
!
Digestibility:
○
Hypogeous fungi (underground fungi; e.g. truffle)
•
Seasonal availability
•
Fungal cell walls contain hemicellulose, cellulose, and may contain chitin
•
Mycophages (eat fungi)
Mountain goats
○
Black-tailed deer
○
Yunnan snub-nosed monkey
○
Flying squirrel
○
Caribou/reindeer
○
Includes:
•
2-3% CP -low
○
0.31% Ca -low
○
0.36% P
○
Ca:P = 0.9:1 -adequate (just okay)
○
Lichen composition:
•
--> good energy, low protein
•
Lichenophages (eat lichens)
Salt licks
○
Possible reasons for use
○
Composition
○
Sodium
•
Toxins, antinutrients, antimetabolites
•
Metabolism and conservation
○
Protein
•
Foraging theory
•
Limiting Factors:
High levels of Na and Mg in salt licks
▪
Low P and K
▪
Moderate Ca
▪
pH = 7.0
▪
Composition of natural salt licks:
!
Only Na and Mg significantly higher in salt lick areas
▪
'natural salt lick' areas -where animals are observed to lick the
ground and ingest 'soil/minerals'
!
Used water containing Na salts to soak wooden stakes
▪
NaCl, NaI, NaHCO3
!
MgCl2, CaCl2
!
KHCO3, KI, KCl
!
Salts used:
▪
Were observed drinking the dilute Na solutions
!
Ignored stakes soaked in Mg, Ca, and K salts
◊
Were observed chewing/licking the wooden stakes
soaked in NaCl, NaI, and NaHCO3
!
Rabbits, fox squirrels, groundhogs, and white-tailed deer:
▪
Study to investigate reasons for salt lick use:
!
Porcupines have been observed damaging wooden
buildings when the wood had bee soaked with urine
(containing salt Na)
▪
Mountain goats in Olympic National Park have been
observed eagerly eating table salt offered by visitors
▪
In winter, food is the most effective bait
!
NaCl has been used as a very effective bait in trapping
white-tailed deer in Adriondack Mountains, in spring and
summer
▪
Other observations:
!
Acquisition of mineral nutrients1.
Healthy rumen/reticulum (reticulorumen) -pH = 5.5-7.0
!
pH may decrease to 4.0 with high starch in diet
!
Buffer pH
▪
Physically protect epithelium
▪
Salt licks can be used to:
!
Counter-balance rumen acidosis 2.
Adsorption of toxins, onto soil particles
!
Epithelium protection
!
Protection against plant toxins in GIT3.
E.g. pangolin (anteater without teeth) -ingest sand to abrade
ant exoskeletons
!
Comminution (grinding, triturating) of food particles 4.
E.g. young ruminants, fore-gut fermenters
!
Microbial inoculation5.
To fill stomach to dispel hunger during starvation6.
I.e. eating a non-food item
!
May be difficult to tell when substance eaten has valid
nutritional use
!
'Depraved' appetite, pica7.
Possible reasons for salt lick use by herbivorous mammals (and potentially
by birds): involves soil ingestion (geophagia)
•
Salt Licks:
5H
E.g. lignin, suberin, cutin, silica
○
*see diagram on slide
○
Not in algae, fungi, mosses, lichens
▪
Found only in 'higher plants' (monocotyledons 'grasses',
dicotyledons 'flowering plants')
!
Added rigidity to plant cell walls
!
Increases as plant matures
!
Up to 15-20% of cell wall
!
End walls disintegrate leaving hollow tubes
▪
Side walls strengthened with rings or spirals of lignin
▪
Transport water/minerals from soil
▪
Support the plant/tree
▪
Xylem cells are dead
!
Lignin is main protector of digestible cell wall
carbohydates
▪
E.g. bracket fungi on trees
!
Lignin can be broken down by certain fungi
▪
Lignin is not digested by animal/bird/bacterial enzymes, or by
acid hydrolysis in the gastric stomach (abomasum,
proventriculus)
!
Lignin:
○
Cutin is found as the structural compoenent of the plant cuticle
(at plant surface)
!
Reduces water loss
!
Prevents entry by microbes
!
Cutin:
○
Suberin is found between cell wall and cell contents
!
Cork cells/ outer layer of tree back, wound repair, around some
roots
!
Suberin:
○
*cutin and suberin are very poorly digested
Usually not in dictoyledons
▪
Si: 3-5% DM in grasses
▪
Found in grasses, sedges, ferns, horsetails
!
Hard, gritty material
!
Reduces cell wall digestibility
!
Increase tooth abrasion
!
May result in formation of urinary calculi
!
Silica/quartz
○
Substances that physically prevent digestive enzymes from reaching the
digestible carbohydrates, proteins and lipids (physical protection)
1.
E.g. soluble phenolics, alkaloids, terpenoids
○
Important as anti-herbivory compounds
!
Against mammals, birds, reptiles, amphibians, fish,
invertebrates
▪
Most act against all consumers -'broad spectrum'
!
E.g. pyrethrins (from chysanthemum flowers) -highly
toxic to insects, low toxicity to mammals
▪
Few are selective
!
Have no (few) primary metabolic functions within the plant
○
Must either be isolated within plant OR be stored in an inactive
form that becomes active when the plant material is consumed
!
Secondary plant compounds are usually also toxic to plants which
produce them
○
Plant consumers (primary consumers) continually evolve new
biochemical detoxification pathways SO plants constantly evolve new
defense compounds
○
Avoid
!
Fore-gut bacteria (detoxify most compounds)
!
Metabolic breakdown
!
Options for herbivores:
○
Ruminants and other foregut fermenters have advantage over
hind-gut fermenters, detoxification early in passage through
GIT
!
Many secondary plant compounds can be detoxified by GIT bacteria
○
Tannins may bind to viral/bacterial/fungal pathogens in GIT
and reduce infection
!
Most secondary plant compounds are antinutrients/antimetabolites
BUT some are beneficial (under certain circumstances)
○
Substances that interfere with digestions, nervous system function, growth,
reproduction and/or taste bitter (or smell bad)
2.
Toxins, Antinutrients & Antimetabolites -plant protective and defensive agents
Food Composition & Digestion
Friday,*March*24,*2017 12:27*PM
Document Summary
Cold water fish are usually higher in fat content than warm water fish. Low in calcium if prey is not eaten whole (no bones) Separated in gizzard (birds) and then egested (usually as pellets) Bones, snail shells, egg shells may be eaten. Many insectivores are also gummivores, and eat exudates from trees and shrubs. Remove high-chitin part of the exoskeleton before ingestion ( wings and tibia, 50% chitin, of grasshoppers are removed by grasshopper sparrow) Crush insect (with beak or teeth), extract soft tissues and discard exoskeleton. Eat insects whole, then egest exoskeletons (kestrel, swallows, flycatchers) Produce chitinase enzymes (at least partially digest chitin) - Produce chitinase enzymes (at least partially digest chitin) - energy value of chitin is usually low. Adult insects may be seasonal in temperatue areas. Some adult/larval insects are in tree bark/ in ground during winter. Molluscs (snails, mussels, oysters, clams) - calcareous shells.