Wildlife Nutrition Exam 1

Describe and compare the different (general) nutritional niches of wild animals.

1. Herbivores

2. Carnivores

3. Omnivores

4. Scavengers/detritivores

Herbivore vs. omnivore vs. carnivore

Herbivores: Animals that only consume plant matter (leaves, twigs, seeds, fruits, and nectar), elongated digestive tracts and rely on symbiotic gut microbes to break down their food.

Carnivores: Animals whose diet consist of primarily or exclusively of animal tissue (Meat) Highly digestible and nutrient-dense, they have relatively short, simple digestive tracts.

Omnivores: Opportunistic feeder that consume both plant and animal matter, shift diet based on season

Scavengers: organisms that consume dead organic matter, dead animals, while detritivores consume decomposing organic debris and waste/

What does it mean when a species is an (dietary) opportunist?

Animal eats a wide variety of foods based on availability and change its diet based on what is easy to find to its environment.

Evolutionary and nutritional advantages and disadvantages of carnivory

Meat-eating

Advantages:

• High nutrient density

• easily absorbable protein, fats, + chemical energy,

• need smaller meal sizes + less continuous feeding time

• simple digestion

Disadvantages:

• High energy cost

• Unreliable food supply

• inflexible diet

Evolutionary and nutritional advantages and disadvantages of

herbivory

Advantages:

• Abundant food source

• Lower risk of injury

Disadvantages:

• Low nutrient density, lower concentration of protein and usable energy than meat

• Constant feeding required, large portion of each day grazing or chewing

• complex digestion needed, hard to digest, multi-chambered stomachs needed to extract nutrients

Explain why animals require nutrients, not food items

Animals bodies only recognize chemical building blocks.

(biochemical and physical characteristics of food items matter)

What is Nutrition?

The series of processes by which an animal acquires, processes, digests, absorbs, metabolizes and excretes portions of its external chemical environment for the function of internal metabolism

What is a nutrient?

Any chemical element or compounds in the diet that supports normal reproduction, growth, lactation, or maintenance of life processes

What is the relationship between food items and nutrients?

Food items acts as the physical vehicles or matrices that deliver essential nutrients (such as carbohydrates, proteins, fats, vitamins, and minerals)

Discuss the different strategies available to know what animals consume in the wild?

• Direct observation

• feeding site surveys

• post-ingestion sampling

• Biological indicators (stable isotopes, signatures of specific nutrients (Fatty acids, etc.))

What are factors that may influence what animals consume in the wild?

• food abundance

• food quality

• nutrient requirements

What is Direct observation advantages and disadvantages

Advantages

• real time, recorded media

Disadvantages

• time-consuming

• limited/biased observations

Feeding site survey advantages and disadvantages?

advantages:

• clip patches of randomly selected areas (Like grass from a certain spot)

disadvantages

• must mimic animal selectively

What is post-ingestion sampling?

• analyzing food resources or markers after they have been consumed by an animal

• more accurate window into true nutrient intake and digestibility

• for fecal analysis, only most resistant items are present (digestible components are digested)

• morphological ID or molecular techniques (profiling prey DNA)

• DNA metabarcoding

• Fistula, gavage, fecal, post-mortem

• INVASIVE

• requires reference collection ☹ and ID keys

What are the Biological Indicators?

• Stable isotopes

  • S13C (13C/ 12C)

  • C3 plants tend to have lower 13C while C4 plants tend to have higher

  • S14N (14N/15N

  • Indicates position on food chain

  • 15N tends to become enriched in consumers over their diets

  • S17O (18O,17O,16O)

  • metabolic water vs. preformed water

• Nutrient signatures

  • fatty acids

What are the six main classes of nutrients? (Is energy a nutrient?)

• Carbohydrate

• Protein

• Lipid

• Vitamins

• Minerals

  • these are micronutrients

• Water

Nutrient Requirement

The defined level of a particular nutrient required to support the maintenance of life processes (growth, reproduction, lactation, if applicable)

What are nutrients used for?

Used to produce energy, build and repair tissues, and regulate life-sustaining functions

What may be some consequences of malnutrition (toxicities or deficiencies)?

• Lethargy

• Failure to maintain BW

  • emaciation

• Signs of nutrition-related disorders

• DEATH

• stunted growth

• Failure to reproduce

What does it mean when a nutrient is dietary essential?

• It is required

• cannot be synthesized by the body in sufficient amounts (or at all) to satisfy metabolic needs

What impacts nutrient requirements?

• Genotype (population wise)

  • species/breeds = differences in GIT

  • Sex

• Genotype (individual wise)

  • genetic variations

• Environment-ish

  • housing condition

  • Age/life stages

  • exercise level

  • BW and body condition

How do we know nutrient requirements of a given species?

• empirical dose-response/titration studies

Explain how natural history influences species’ nutritional ecology

• natural selection in nutrition ecology

• similar structure on overall GIT

• species specific adaptations reflecting their unique dietary niche

  • ex: Galapagos finches with different types of beaks (woodpecker, ground, warbler for insects, seeds ,etc.)

Describe the general structure of the gastrointestinal tract (

• Headgut

• foregut

• midgut

• hindgut

  *Liver, gallbladder, bile duct, and pancreas are not considered apart of digestive tract

What organs are included in the headgut?

• Buccal cavity and Pharynx (lips, cheeks, teeth, hard + soft palates, tongue, and salivary glands)

What organs included in foregut?

Esophagus and stomach

What organs included in Midgut?

• Small intestine

• Pancreas and biliary system

What are the small intestine parts?

• Duodenum

• Jejunum

• Ileum

What organs included in Hindgut?

• Large intestine

  • cecum/ceca, colon, and rectum

Nutritional Processes include what?

• prehension (picking up things to put in mouth)

• Ingestion

• Mastication (chewing)

• Deglutition (Swallowing)

• Digestion (mechanical, chemical, enzymatic)

• Absorption

• Metabolism

• Excretion

What are the liver, gallbladder, and pancreas?

They are accessory organs

• but technically foregut

Foregut vs. hindgut fermenters including their nutritional functions and

significances.

Foregut: (ruminants)

• herbivores that digest plant fibers

• chambered stomach

• microbial breakdown that takes a long time

• larger SI than LI

• animal eats first then the microbes do to actually gain the nutrients

• regurgitate then chew again their food (Cud) to digest nutrients

• digestion takes place in an enlarged stomach or specialized pouch (like the rumen) before food reaches the true stomach and small intestine.

Hindgut:

• monogastric herbivores that digest plant fiber using symbiotic microorganisms

• simple stomach, one chambered

• undigested fiber like cellulose digest in cecum/ceca and large colon

• faster time to digest than foregut fermenters

• symbiotic bacteria + microbes create VFAs (volatile fatty acids)

• fermentation happens AFTER the small intestine

What materials/nutrients are the main target of fermentation here? And why do

they need to be fermented (and by what)?

Fibrous carbohydrates (plants)

• cellulose, pectin, hemicellulose

Fermentation breaks down complex polymers down into volatile fatty acids (VFA), uses as a major energy source

• nutrient release (it degrades the plant cell walls, releasing trapped intracellular nutrients like sugar, protein, and starches) so animals can use them

Auto-enzymatic vs. allo-enzymatic digestion

Auto-enzymatic: digestive enzymes come FROM the host animal (they secrete it themselves)

• auto = self

• humans, pigs, dogs ,cat, monogastrics

Allo-enzymatic: Host cannot digest on their own, enzymes produced from symbiotic microorganisms/microbes like bacteria, protozoa and fungi inhabiting the gut.

• ruminants and hindgut fermenters

Where is the fermentation site for foregut vs. hindgut fermenters?

• Foregut: occurs BEFORE the small intestine, specialized multi-chambered stomach or pre-gastric pouch (Rumen, reticulum in ruminants)

• Hindgut: occurs AFTER the stomach and small intestine, localized in enlarged sections of lower digestive tract, (cecum/ceca or colon, horses, rabbits, elephants)

What are the advantages and disadvantages of foregut vs. hindgut fermenters?

foregut

advantages:

• protein recycling, animals digest microbes themselves when they pass into true stomach, gaining rich microbial protein

• fiber efficiency: excellent at extracting max. energy and nutrients from poor-quality, highly fibrous food

• toxic breakdown: microbes

Carnivores vs. omnivores vs. herbivores (foregut vs. hindgut fermenters); can

you justify your classification?

• Carnivore: eat meat, simple short digest tracts, sharp canines to tear flesh, highly acidic stomachs to break down proteins quickly

• Omnivores: eat both plant and animal. unspecialized teeth, moderately long digestive tract able to process mixed diet

• Herbivore: eat primarily plants, plant cellulose hard to digest, required specialized fermentation chambers and long digestive tracts. Herbivores split into two distinct digestive ways

  • Foregut fermenters (ruminant, pregastric): cows, sheep, etc, ferment plant fiber BEFORE the true stomach and intestine. feed microbes first. microbes break down cellulose early, and animal later absorbs both nutrients and microbial protein in SI, highly effective but slower

  • Hindgut (post gastric): feed animals first. horses, rabbits, rhinos, use simple stomach + digest food enzymatically first, leaving fiber fermentation for enlarged cecum and LI, processes food faster but extracts LESS overall nutrition unless animal coprophagy (ingesting feces) to recover microbial proteins (rabbits).

• Justifying: evolutionary functional anatomy, diet dictates length and complexity of GIT.

What is comparative nutrition? What is nutritional wisdom?

• Comparative: cross-species study (comparing) of adaptions and utilization of diff nutrient sources.

• Nutritional wisdom: Unfounded concept that animals have innate ability to select from best of foods to satisfy their nutrient requirements

From a comparative nutrition perspective, how to find a good model if we don’t

have much information on our species of interest?

Use data of a well-researched animal with a close relationship as a model.

Describe the important functions of teeth

• Upper (maxillary) jaw

• Lower (mandibular) jaw

• Incisors: small teeth at front, nip, gnaw

• Canines: long pointed teeth, tear, puncture, hold

• Premolars: puncture and slice

• Molars: Large flat teeth, crush or grind

What are the important functions of the tongue?

• prehensile organ during digestion

• mixing food in mouth

• transport food posteriorly to esophagus

• sensory: touch, temp, taste (sweet, sour, bitter, salt, umami)

• Papillae (buds)

What are the importion functions of salivary glands?

• lubricate food making it easier to mash and digest

• buffering capacity (pH)

• nutrients (for microbes)

• enzymatic capacity

• membrane protection

Homodont vs. Heterodont

• homodont (same): teeth have same shape and size (shark, crocodile, dolphin, most non-mammalian vertebrates)

• heterodont: teeth are differentiated into distinct types w/ specialized functions (most mammals)

Deciduous vs. permanent teeth

• Deciduous: baby teeth (temporary that fall out)

• Permanent: final adult set that replaces baby teeth

What species have the zygomatic glands?

• only carnivores

Special adaptations of ruminants, how having no upper incisor can be

advantageous for them?

• continuous and large volume of saliva production

• grip, press, tear tough grass and forage against hard upper gum line called dental pad

Why do ruminants produce a large volume of saliva daily?

• neutralizes acid (buffering) bc contains bicarbonate, keep rumen pH stable

• Feeding microbes

• Moistening food to swallow easily and to regurgitate cud for re-chewing

• 
  

Identify and compare the numbers and forms of incisors, canines, premolars, molars (and carnassial) among mammalian species.

Incisors: located at front of mouth, single-rooted, biting, nipping, grooming sharp-edged

canines: sharp pointed teeth, puncture, grab, tear food, or serve as weapon/defense

Premolars: found behind canines, cheek teeth have one or more cusps and deciduous, crush, grind, slice food

Molars: very back jaw, multi-cusped, no baby predecessors, crush or grind food in final stages of chewing

• Carnassial: specialized shearing teeth found in carnivores (cats, wolves) act like scissors to slice flesh and cut tough animal tissue, last upper premolar (p4) and first lower molar (M1)

How could we tell the differences between herbivores’ and carnivores’ teeth? (hint: what is the occlusal surface?)

Occlusal surface: specific chewing or biting surface where upper and lower teeth meet

• carnivores: sharp, blade like, or serrated, triangle or jagged knives

• Herbivores: Broad, flat, and heavily ridged, works like millstone to pulverize tough, fibrous plant walls.

What are carnassial teeth? What species have carnassial teeth?

shearing teeth found in carnivores (cats, wolves) act like scissors to slice flesh and cut tough animal tissue, last upper premolar (p4) and first lower molar (M1)

What is the dental formula. Can you write down the dental formula if given a skull image?

2 (I U/L C U/L P U/L M U/L)

What is the composition of saliva?

• Water

• Mucin

• Bicarbonate salts

• Enzymes (species-specific)

  • amylase (not in ruminants, carnivores, birds…)

  • Lipase

What enzymes are present in the saliva? (and hence what nutrient(s) are first

digested in the oral cavity?)

• Enzymes:

  • Amylase

  • lipase

  • Lysozyme(protective enzymes)

• carbohydrates (starch + complex sugars) first digested

Does it make sense for some species to have low to no amylase activity in their headgut?

Yes, depending on what they eat.

• strict carnivores: natural diet contains no starch, producing salivary amylase would be waste of energy

• Herb and Omnivores: high-starch diets (humans, rodents, pigs), high level of headgut amylase, begin breaking down food after chewing

What does the esophagus connect?

• Mouth to stomach (pharynx to stomach)

What is peristalsis?

• alternating contractions + relaxations of muscles layers squeezing and layers pushing

• moves material through digestive track

Why are the upper and lower esophageal sphincters important?

UES: prevent reflux of ingesta from esophagus back into throat

LES: prevent gastric content from re-entering into esophagus

What are the four major anatomical parts of the stomach?

• Cardia

• Fundus

• Body

• Pylorus (pyloric sphincter)

What are the regions of epithelial lining in the stomach?

• Non-glandular stratified squamous

• Cardiac gland region

• Proper gastric glands

• Pyloric gland

nonglandular vs. glandular regions of epithelial lining in stomach?

• Non-glandular: stratified squamous epithelium

• Glandular: simple columnar epithelium, forms gastric pits and tubular glands

What are the functions of each epithelial lining in stomach?

• Non-glandular stratified squamous:

  • stomach protection (mucus)

  • storage and holding

  • mechanical mixing

  • fermentation site

• Cardiac glandular: Mucus, HCO3

• Proper (fundic) gastric glandular: HCL and pepsinogen

• Pyloric glandular (sphincter): mucus, HCO3 (bicarbonate)

What are the five major components that are secreted in the stomach and what

are their respective functions?

• Mucin

  • protects mucosa from chemical and mechanical damage, and a lubricant

• Hydrochloric acid (HCL)

  • highly acidic (~pH 2)

  • made by gastric parietal cells

  • denatures (unfolds) protein

  • activates digestive enzymes, pepsinogen → pepsin

  • kills bacteria

• Pepsinogen

  • inactive proteolytic enzyme

  • active enzyme form → pepsin

  • starts protein digestion into polypeptides

• Rennin (chymosin)

  • proteolytic enzyme

  • only in young mammals

  • coagulate milk to reduce rate of passage

• Gastrin (hormone)

  • hormone released from pyloric cells (G cell)

  • Due to stomach distention and/or presences of proteins

  • stimulates HCl and pepsinogen secretion and gastric motility

What happen to food (or technically, ingesta at this stage) when it is in the

stomach?

• when swallowed food mass called bolus enters stomach, mechanical churning and chemical digestion

• stomach transforms ingesta into thick, semi-liquid mixture called chyme

where in the stomach does that happen?

• cardia

• fundus and body (corpus)

• Antrum

• The pylorus

What nutrient(s) is being digested in the stomach and by what?

• proteins primary nutrient digested,

• broken down by pepsin and gastric acid

Why is the stomach highly acidic and why is that important?

Presence of hydrochloric acid (HCl), drops gastric pH to highly acidic 1.5-3.5

Adaptations in Avians

• Crop

• proventriculus

• ventriculus

Adaptations in ruminants

• Rumen

• Reticulum

• Omasum

• Abomasum

What are crop, proventriculus, and ventriculus in an avian species and what are

their functions?

• crop: some avian species (not all)

  • many shapes

  • thin-walled, expanded, muscular pouch of esophagus

  • Mucous, no enzymes

  • Functions

    • temp food storage

    • moistening and softening

    • “crop milk”

    • Fermentation - Hoatzin

• Proventriculus (gastric stomach)

  • tubular gland: mucous

  • gastric gland: HCl and pepsin

• Ventriculus (muscular stomach_

  • “gizzard”

  • smooth muscle

  • cuticle/koilin

    • protective CHO/Protein membrane from HCl, digestive enzymes + grinding

  • For grinding and crushing

What are the four components of a ruminant’s stomach and what are their

functions respectively?

• Rumen: 80% of a ruminant stomach by volume

  • primary site of fiber digestion by anaerobic microbial fermentation

  • wide, flat papillae

    • absorption by increasing surface area

      • blind sacs

      • end products of fermentation: VFA and NH3

    • Help push food back to esophagus (regurgitation)

    • No enzyme secretion

    • Mucous secretion

    • Esophageal groove (young ruminants)

• Reticulum: 5% of a ruminant stomach by volume

  • honeycome-like lining

    • help trap large food particles or foreign objects “hardware disease”

    • ingesta movement

      • rumination → oral cavity

      • Mixing → rumen

      • Passage → Omasum

• Omasum: 7-8% of ruminant stomach by volume

  • leaf-like folds

    • further reduce food particle size before moving to abomasum

    • large surface area to absorb water, volatile, fatty acid (VFA) and minerals (sodium and potassium)

    • Reticulo-omasal orifice (ROO)

• Abomasum: 7-8% ruminant stomach by volume

  • functions as monogastric animal’s stomach

    • “true stomach”

    • has glands and secretes enzymes

What is ruminal acidosis and how does that inform dietary managements?

• rumen pH drops significantly and rapidly (5.5-5.0) when consumes easily and highly fermentable feed

  • ex. grains, high-sugar forages (large amount of VFA)

• shifts from fiber-digesting microbes to lactic acid producing bacteria

  • further lowing the pH

• Clinical signs: anorexia, bloat, diarrhea, bloat, death if severe

• normal rumen pH: 6.2-7.0

• require sufficient amount of “low-quality” fiber to maintain healthy rumen

• diet high in fermentable CHO and low in fiber

label number 1

Mouth (oral cavity)

what is number 2?

Salivary glands

What is number 3?

Pharynx

What is number 4?

Esophagus

What is number 5?

Stomach

What is Number 6?

Liver

What is number 7?

Duodenum (mostly digestion) SI

What is number 8?

Pancreas

What is number 9?

Jejunum (digestion and absorption) SI

What is number 10?

Illeum (absorption) SI

What is number 11?

Cecum

What is number 12?

Colon

What is number 13?

Rectum

What is number 14?

Anus

Why do liver/gallbladder (and the bile ducts) as well as pancreas all cluster

around at the very beginning of the duodenum?

All share common embryonic origin from embryonic gut tube and must release digestive juice (secretions) where food first exits stomach

• major duodenal papilla

Gastrin vs. Secretin, cholecystokinin (CCK), and gastric inhibitory peptide

What are their functions respectively and at what stage(s) of the

eating/digestion are they released?

• Gastrin: stimulates stomach acid production also release of HCL hydrochloric acid and pepsinogen from parietal and chief cells, increases stomach contractions (motility) helps promote mucosal growth, released during cephalic and gastric stages (STOMACH G CELL)

• Secretin: originates in duodenum wall cells SI

  • release cuz of chyme and acid

  • stimulates production of pancreatic juice for buffering

  • stimulates decreased stomach motility and acid

• Cholecystokinin (CCK): duodenum wall cells SI

  • release cuz of lipid and protein in duo.

  • slows stomach acid

  • stimulates pancreatic and bile secretions

• Gastric inhibitory peptide (GIP): SI

  • Duodenum wall cells

  • release cuz of lipid + protein in duodenum

  • inhibits stomach acid and enzymes

  • decrease stomach motility

Where is bile produced vs. stored? What are functions of bile?

• produced by liver

• stored in gallbladder, enters duodenum from bile duct

• 98% of bile recycled

• fat emulsification

• pancreatic lipase activation

• (DOES NOT contain digestive enzymes)

What are the accessory organs?

• Pancreas

• Gallbladder

• Salivary glands

• Liver

Pancreatic alpha cells vs. beta cells (what hormones do they produce

respectively)?

• Endocrine portion of pancreas

  • alpha cells: produce glucagon

  • Beta cells: produce insulin

in protein digestion, why is it important to have a precursor

form?

• enzymes involved

• stomach → pepsin (pepsinogen)

• SI/pancreas → trypsin (trypsinogen), chymotrypsin, elastase

precursor: inactive enzyme form (zymogen or proenzyme) that safely travels to where it’s needed before turning into active protein-digesting tool

What enzymes are in Starch digestion

• headgut/salivary glands

  • salivary amylase

• Small intestine/pancreas

  • pancreatic amylase

  • Brush border enzymes

    • dextrinase

    • glucoamylase

    • lactase (young mammals)

    • maltase

    • sucrase

Lipid digestion

• headgut/salivary glands

  • lingual lipase (minimal)

• Stomach

  • gastric lipase (minimal)

• SI/pancreas

  • pancreatic lipase

  • colipase

  • not enzymes but bile salts and micelles

Why is it important to have increased surface area in the intestine?

• maximizes the rate and efficiency of nutrient absorption into bloodstream.

Identify key physiological adaptations that increase absorption efficiency.

Three levels:

• macro - extreme surface area expansion

  • strategic vascularization

• cellular level (micro)

  • villi and microvilli

  • abundant mitochondria

• molecular level (subcellular)

  • specialized transporter proteins

  • electrochemical gradients

Can you label the ceca/cecum, colon, and rectum on a GIT illustration?

What are the main functions of the large intestine?

• absorb remaining water + electrolytes, house beneficial gut bacteria, form and eliminate solid waste

Fermentation is a symbiotic relationship between the hosts and the microbials.

What do the host and microbials provide respectively?

• both parties help eachother

• both exchange vital resources to survive and thrive

What is animal fiber?

• natural materials made mostly of proteins that come from animal hair, fur, skin, insect secretions

• ex: wool, silk, fur, feathers, leather

What enzymes are secreted in each section and what nutrients do they digest?

• digestive enzymes are released in specific parts of digest tract to break down carbs, proteins, and fats into smaller parts your body can absorb

  • mouth → salivary amylase, lingual lipase

  • stomach → pepsin, gastric lipase

  • Pancreas → pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, pancreatic lipase, nucleases (DNA and RNA)