animal nutrition exam 2

Why do we care about animal nutrition

• Animals reach their genetic potential

• Health

• $$$

Order of nutrient utilization

1. Ingest feed

2. Digest feed → nutrients (GIT)

3. Absorb nutrients → blood

4. Assimilate (use) nutrients to do work

Name the monomers of each nutrient class

• proteins → AAs

• carbohydrates → monosaccharides

• fats → N/A? Fatty acids/glycerol

• minerals → inorganic elements

Which of the nutrient classes is unnecessary?

Carbohydrates

Essential monomers are needed…

BECAUSE the animal cannot make enough of it, even if they have adequate SUBSTRATE

Enterocytes

absorb things in SI

What are some reasons an animal may not be able to produce essential monomers?

• high number of enzymes

• Lots of compartmentalization

Fat composition

No water in fat

Water

most important, body is about 75% water

Sources of water

• free water

• Water in feedstuffs (AF)

• Metabolic water

Oxygen…

Is the terminal (final) electron acceptor

Traits of water

• biological solvent, transport

• Dietary source of minerals

• Heat dissipation

Urea

Not too bad but needs to be eliminated, water gets rid of it (urine)

CHO formula

CxH2xOx

Types of Carbohydrates

• Disaccharides (sugars)

• Polysaccharides (starches)

• Fibers

Amylose

Starch, alpha linkage (connected by a little O in the middle), more easily digestible

• animal enzymes, amylase

Cellulose

Fiber, B-linkage → affects digestability

• microbial enzymes

Functions of carbs

• short term energy storage (Glucose → glycogen)

Where is glycogen stored

Liver and skeletal muscle

Protein composition

• CHON-S

• 10 essential AAs

Protein functions

structure

• energy

• enzymes and hormones

Structure of an AA

How we make our proteins

Utilize translation to disassemble proteins and then make our own from the AAs

Types of lipids

• simple lipids: fats, oils, waxes

• Compound lipids

• Sterols → cholesterols

Types of protein

• lipoprotein: animal

• glycoprotein: plant

How many Cs do fatty acids have

18

Fatty acid structure

• end in carboxyl, COOH

Types of fatty acids

• linoleic acid: polyunsaturated (multiple C=C), liquid at room temp, C18:2

• Linolenic acid: C18:3

• arachidonic acid C20:4 (carnivores)

Types of Minerals

• macro → %

• Ca, P, Na, Cl, S, K, Mg

• Micro (trace) → ppm or ppb

• Fe, Se, Co, Cu, Zn

Vitamins structure

Contain C (organic)

Fat soluble: ADEK → store extra

Water soluble: B complex + C → urinate extra

Lumen is…

On the outside of the body

GIT organs

GIT:

• mouth

• Esophagus

• Stomach

• SI

• LI

• anus

Accessory organs

• liver

• Gall bladder

• Pancreas

• Kidneys

• Salivary glands

• Brain

Where are the foregut, midgut, and hindgut?

Foregut: stomach

Midgut: small intestine

Hindgut: large intestine

Birds are most similar to

Monogastrics

Avian monogastric differences & components

• have a cloaca → urine and feces go together

• 2 cecums (ceca)

• Stomach = proventriculus, takes contents to gizzard

• “Crop is the first stop”

• Gizzard serves to decrease particle size

“Ensacculated”

Ridges within hindgut

What does RRO stand for?

Rumen, reticulum, omasum

→ abomasum

Where does the esophagus connect?

Reticulorumen (reticulum)

Benefits of fermentation for microbes (specific)

• metabolize things that contain C → carbon skeleton of AAs and carbohydrates

• Done to gain ATP for themselves

Benefits of fermentation for host

• source of CP once microbes die

• VFAs

VFAs are used to…

Produce:

• glucose

• ATP

Dietary contribution of fermentation to ruminants, simple monogastrics, avians, and hindgut fermenters

Ruminants: provide energy

Simple monogastrics: minimal to a lot of energy (species dependent)

Avians: low, species dependent

Hindgut fermenters: diet dependent, forage provides lots of energy, grain provides moderate energy

Horse GIT

• higher and faster passage rate

• “Hayburners” → eat way more

• Smaller GIT than cattle

• Have one chance at fermentation while cattle have 2

SI absorbs…

• AAs

• Monoglycerides

• Fatty acids

• Glucose

• Minerals

• Vitamins

LI absorbs…

• VFAs (provided by microbes)

• water

Types of salivary glands

• Parotid → largest

• Mandibular/submandibular → along jawline

• Sublingual/buccal → near teeth

Amylase

Digests starch

Saliva

• antibacterial, antimicrobial, antifungal

• Buffer

• Lubricant

• Remineralizes

Esophagus

• connects to reticulum

• Epiglottis covers trachea

• 2 layers of muscle running opposite to one another

• Delivers bolus

Gastric stomach components

• “gastric” → HCl

• Omental fat: holds stomach in place

• Serosa: “inside” of the stomach, touches organs

• Lumen: touches digesta, technically outside

Purpose of HCl

• kills pathogens and microbes

• Denatures proteins so they can be rebuilt

• Minimal digestion of proteins, carbs, and fats

Pepsin

Initial protein digestion

• breaks them into peptides

• Protease

Gastrin

Hormone that regulates gastric secretions, especially HCl

Parietal cells

secrete H+ and Cl- ions

Cardiac tissue

Sphincter between esophagus and stomach, opens to vomit

zymogen

Inactive enzyme that’s activated AFTER secretion to protect cells

Phases of eating/gastric

• cephalic

• Gastric

• Intestinal

Small intestine

• enzymatic digestion

• Immune and barrier function

Nutrient sink, “first dibs”

Structure of SI

Duodenum → Jejunum → Ileum

Digestion → absorption → immune

Plicae folds

Mucosa folds in SI, allow for Villi to bunch up like carpet

Crypts

• stem cells

• At the base

• Diet adaptability → are where new cells are made and can change what they’re making

Bile

• emulsifies fats

• Stored in gallbladder

Benefit of emulsifying fat

Allows little globules to be in water so lipase can break it down

Where do SI enzymes come from?

Pancreas secretes bicarbonate into the duodenum.

Purpose of bicarbonate in SI

• buffer fluid, increases pH that’s been decreased by HCl

Enterocytes

• cells that absorb in SI

Extrusion zone

Where villi are shed

Protein degradation

Pepsin → pancreatic proteases → SI pepsidases

Large intestine function

• create and absorb VFAs from microbes

• Absorb water gradually

Large intestine components

• cecum: “blind sac” increases time for fermentation

• Large and small colon

Pancreas

• produces digestive enzymes

• Produces bicarbonate, which prevents ulcers

• Makes LOTS of enzymes because they get used up

• 2-20% of pancreatic action is making metabolic hormones

Liver

• produces bile

• Gets access to all blood nutrients first (portal vein)

• Site for metabolic pathways

• Metabolizes hormones

Gallbladder

• stores bile

• Sits on the back of the liver

Kidneys

• no direct connection to GIT

• Communicate through blood

• Urea cycle, excrete waste N

Brain

• satiety

• Produces metabolic and gastrointestinal hormones

• Target of hormones

Eructation

Belching, gets rid of bloat gases

Ruminant differences

• stomach complex is very large, 60-80% of digesta is there

• High retention time in rro

Reticulorumen composition of digesta

Gas cap → fiber mat → digesta

= stratified

Reticulorumen

• site of microbial fermentation

• Honeycomb

• Pillar cinches

• Papillae

Papillae

Tongue like projections in reticulorumen that help absorb VFAs and ammonia in particular

Omasum

“Many plies”

• traps particles to further ferment

• Increases absorption

• Controls passage to abomasum

Methane

Produced by methanogens, waste of carbon

Biohydrogenation

Saturating fatty acids by adding hydrogen, saturates the bonds

Required fatty acids

Linoleic acid and linolenic acid

What kinds of lipids can microbes ferment?

Hydrolize/ferment glycerol, triglycerides, and phospholipids. DO NOT FERMENT FATTY ACIDS (individual monomers!!)

Microbe degradation of protein

release proteases, peptidases, and deaminases

Deaminase

Released by microbe protein degradation, take away the amine group in a protein, so that the microbes can make their own proteins (MCP) microbe crude protein

Microbes are the only organisms that can make ________

Amino acids, amino acid synthesis/reamination

Importance of urea in ruminant diet

Allows the microbes to get NH3 (nitrogen is the important part) (NPN in feed) to make the new amino acids they need

Pie-crust metaphor

Microbes need to have amino acids. The question is: will they make their own amino acids, or will they take them from another source?

Starch and Fiber effects on the gut microbiome, and why

Fiber: slowly decreases pH

Starch: decreases pH

The microbes ferment the monosaccharides to make VFAs, which are acids. The starches are fermented quicker, so they’ll lower the pH faster

What do we feed to rumen microbes?

• soluble (digestible) carbs

• RDP

• NPN (urea)

• Fatty acids (the microbes get no energy from them, so they change them to VFA’s by BIOHYDROGENATING them)… C=C → C-C

How does NASEM define a requirement?

The minimum amount of nutrients needed by a similar group of animals at the same physiological state, based on production level

1st law of thermodynamics

Energy cannot be created nor destroyed

2nd law of thermodynamics

Universe tends towards maximum disorder

Exergonic vs. endergonic reactions, & which is more favored?

• exergonic: energy releasing ← more favored

• endergonic: energy requiring

Because we use our ATP before making more

Conventional energy scheme

Gross energy → Digestible energy → Metabolizable energy → Net energy

HIF

Heat increment of feeding

• fermentation

• digestion and absorption

• waste removal

• product formation

Loss of carbon

What part of the conventional energy structure do nutritionists care most about?

Net energy: describes what the animal actually uses for maintenance or product formation, best for DIET FORMULATION AND REQUIREMENTS