UCM Animal Nutrition Exam 1

diet

a specific mixture of feedstuffs used to supply nutrients to an animal

ration

The daily allocation of the diet that has been formulated for the animal

Monogastric

an animal with a monogastric GI tract has a stomach with one compartment

ex) swine, poultry, horses (enlarged cecum = hindgut fermenter), dogs, cats

ruminant

an animal with a ruminant GI track, has a stomach with four compartments

ex) cattle, sheep, goats

plant products consumed by animals

• seeds (grain)

  • high energy density due to highly digestible carbs and lipids

• leaves and stems

  • low energy density due to lowly digestible carbs and lack of lipids

farm animal diets are formulated primarily on the amount of ….

energy and protein required by the animal

digestion

the process by which feedstuffs are broken down into microscopic nutrient molecules

digestion via mechanical action

breakdown of feedstuffs by mastication and gastrointestinal muscular contractions

digestion via chemical action

breakdown of feedstuffs by acids in the gastrointestinal tract

digestion via enzymatic action

breakdown of feedstuff by enzymes in the gastrointestinal tract

absorption

process by which nutrients are absorbed from the GI tract through villi along the wall of the small intestines and into the bloodstream of the body

three classes of nutrients that provide energy to the animal

• carbohydrates

• lipids

• proteins

three nutrient classes that do not provide energy to the animal

• water

• vitamins

• minerals

enzymes

special proteins that catalyze reactions in the body

growth and production

condition is which animal is producing muscle tissue, milk, eggs, offspring to power

maintenance

condition in which the animal is maintaining, neither gaining or losing body condition

why is the animal’s stage of production so important?

• young animal require high levels of energy and protein in the diet to grow

• mature animals require low levels of energy and protein in the diet because they are no longer growing

what is the overall goal of an animal nutrition feeding program?

to feed a balanced diet in a ration containing feedstuffs that meet the daily nutrient requirements of the animal, which is based on the stage of production for that animal

hindgut fermenter VS monogastrics

hindgut fermenter has an enlarged cecum (horse)

why can ruminants and hindgut fermenters thrive on forages whereas monogastrics can not?

forages can only be digested by microbes, hangout fermenters and ruminants have microbial digestion

cellulase

enzyme produced by microbes to break down forages

where does microbial digestion occur in ruminants?

rumen and cecum

where does microbial digestion occur in hindgut fermenters?

cecum

order the GI tracts from most forage consumed and digested to least

1. ruminants - 44%

2. hindgut fermenter - 39%

3. monogastics = 22%

prehension of monogastics

bring food to the mouth, tongue is used

mastication of the monogastrics

means to chew, top and bottom incisors and molars

feed bolus

a soft mass of masticated feed, saliva produced in the salivary glands moistens and lubricates the feed, swallowing this is called deglution

what type of digestion occurs in the mouth?

mechanical and enzymatic digestion

amylase

enzyme present in the saliva to begin starch digestion

peristalsis

the contraction of the smooth muscles in the esophagus to move the feed bolus

sphincter

muscular structure that constricts to restrict the movement of body fluids in the body

ex) the sphincter at the entrance to the stomach keeps hydrochloric acid from refluxing into the esophagus but relaxes to allow the feed bolus to enter the stomach

what kind of digestion occurs in the stomach?

• chemical : hydrochloric acid

• enzymatic : pepsin

• mechanical : muscular contraction

NOT the major site of digestion and NO absorption occurs

pepsin

enzyme secreted into the stomach to digest protein

what keeps the stomach from digesting itself?

to avoid being digested by hydrochloric acid and pepsin, mucous is produced by special cells lining the inside of the stomach coating the stomach in protection

chyme

partially-digested feed

food bolus → chyme (after it passes out of the stomach)

order the three sections of the small intestine of monogastrics

1. duodenum, beginning section, connects to the stomach, MAJOR SITE OF DIGESTION

2. jejunum, middle section

3. ileum, end section, connects to the large intestine

what makes the duodenum the major site of digestion in monogastrics?

because the duodenum receives secretions from the gall bladder of the liver and the pancreas

job of gall bladder secretions

• bile is stored in the gall bladder from the liver

• this bile is then secreted when chyme is released from the stomach to help digest fat

• the process of bile preparing the lipids for digestion is a process called emulsification

* this is all happening in the duodenum of the small intestine *

job of pancreas secretions

• secretes buffers to increase the pH of the chyme to avoid damage to the epithelial cells that line the duodenum

  • pH is originally low after coming out of the hydrochloric acid from the stomach

• secretes enzymes to aid in digestion

  • protease = proteins

  • amylase = starch

  • lipase = lipids

* this is all happening in the duodenum of the small intestine *

what causes the secretion of buffers and enzymes from the pancreas?

two hormones are released in response to nutrients in the chyme and the low pH

1. secretin = causes release of buffers fro pancreas to raise the pH

2. cholecystokinin = causes release of enzymes and bile

job of the jejunum and ileum

MAJOR SITES OF ABSORPTION because of the villi that line the inside and increase the surface area of the small intestine

what happens if the villi of the jejunum and ileum regions of the small intestine are destroyed?

• diarrhea !

• absence of villi means the nutrients in the chyme are not being absorbed and instead the chyme passes straight through the small intestine

where is the cecum loacted in monogastrics?

between the small intestine and the large intestine

• not a major site of microbial digestion in monogastric (swine, poultry)

• instead some microbial digestion occurs in the colon

job of the large intestine in monogastrics

water absorption

job of the rectum

temporary storage of feces

four compartments of the ruminant stomach

1. rumen

2. reticulum

   • “reticulorumen”

3. omasum

4. abomasum

ruminant teeth

• bottom incisors with hard “dental pad” on top

• molars on top and bottom

bicarbonate

chemical buffer produced in saliva that helps maintain the correct pH in the rumen

• microbes needs a pH of 6-6.5 for microbial digestion

job of the esophagus in ruminants

transport the feed bolus from the mouth to the retculorumen

what is rumination?

• the process that ruminants use to get more nutrients from the food

• microbial digestion

• especially important to digest forages

reticulorumen

• consists of both the reticulum and rumen

  • rumen is lined with finger-like projections called papillae

  • reticulum is lined with ridges that form honeycomb pattern

rumen

• primary location of microbes and site of microbial digestion

• largest compartments of the stomach

  • mature bovine can hold 40-50 gallons of fluid

why is microbial digestion so effective in the rumen?

• the rumen is the site of a mutualistic symbiotic relationship (both organisms benefit)

forages are consumed but cellulose can not digest → microbes in the rumen consume the cellulose (this benefits the microbes) and produce volatile fatty acids → the volatile fatty acids are absorbed and used as energy, microbes can be digested and used as a protein source (this benefits the ruminant)

why do microbes like the rumen?

because it is warm, moist, and low in oxygen which allows anaerobic microbial digestion to occur (anaerobic = little or no oxygen)

what three volatile fatty acids are produced during microbial digestion?

1. acetate

2. propionate

3. butyrate

how does the ruminant animal get protein is the microbes consume protein to create volatile fatty acids?

after some time in the rumen, the microbes make their way through the digestive system with the digest and are killed in the abomasum.

they are then digested in the duodenum and the amino acids from the digested protein from the microbes is absorbed in the jejunum and the ileum to provide the protein for the ruminant.

how/where are the volatile fatty acids absorbed?

through the papillae in the rumen wall

reticulum job

main function: regurgitate partially digested feed back to the mouth for rumination

• also helps to catch foreign objects in feed to protect the digestive tract

omasum job

not understood completely, mainly responsible for moving digesta into the abomasum, absorbing excess fluid from the rumen, absorbing VFAs and grinding of the digest from the rumen

abomasum job

TRUE STOMACH OF THE RUMINANT (all three types of digestion occur; mechanical, chemical, and enzymatic)

• mixes the feed bolus with hydrochloric acid (chemical) and pepsin (enzymatic) by muscular contractions (mechanical)

compare and contrast the ruminant small intestine to the monogastric small intestine

comparisons:

• the pancreas and the gall bladder secrete enzymes, buffers, and bile into the duodenum

• protein and lipid digestion and absorption occurs

contrasts:

• is not the major site of carbohydrate digestion and absorption because the majority of carbohydrates have already been digested and absorbed as VFAs in the rumen

cecum job in ruminants

• second opportunity for microbial digestion of forage, nothing compared to the microbial digestion happening in the rumen

• VFAs produced here are absorbed through the cecum wall

newborn ruminant rumen

• nonfunctional and nonexistent

  • milk flows from the mouth → esophagus → omasum → abomasum

reticular groove

important in young ruminants

• prevents milk from flowing into the undeveloped rumen

• forms in response to the sucking reflex

development of the rumen

• rumen will begin developing over a six week period after birth

• development is dependent on the consumption of solid food

  • as forage is consumed this allows for microbial digestion to occur which produced VFAs and causes the development of papillae

when is the rumen developed enough for weening?

1-5 month of age the rumen is developed enough to survive on forages

• sheep/goats = 1 month

• cattle = 3.5-5 months

rumen size percentage change during development

1. reticulorumen = 30% of the stomach

   abomasum = 60% of the stomach

2. reticulorumen = 85% of the stomach

   abomasum = 8% of the stomach

distribution of feedstuffs in the rumen

• forages are on top of the rumen fluid (raft)

• grains sinks to bottom of the rumen fluid

define hindgut fermentation

microbial digestion takes place in the cecum located between the small intestine after the feed has passed through the stomach

why are the microbes not a source of protein in hindgut fermentation?

since microbial digestion takes places after the stomach it is impossible for the microbes the be killed in the stomach (by protease related from the pancreas) and digested as proteins and absorbed in the small intestine

horse teeth

top and bottom incisors and molars

esophagus in hindgut fermenters

feed only travels down the esophagus

• hindgut fermenters CANNOT vomit

  • this is an issue if something poisonous is eaten because the horse cannot throw up to alleviate the problem

hindgut fermenter stomach

• main site of digestion bc all three forms of digestion occur (mechanical, chemical, and enzymatic)

• hydrochloric acids kills most microbes but some survive and live in the cecum to perform microbial digestion

hindgut fermenter small intestine

• normal three sections and functions

• horses do not have a gallbladder

  • liver continuously releases bile instead

  • no gall bladder because horses do no consume a high lipid diet so the bile does not need to be stored to emulsify the lipids

hindgut fermenter cecum

SITE OF MICROBIAL DIGESTION

• chyme flows in the cecum → digested by microbes → flows out the cecum the way it came in

• no enzymes to buffered are secreted

• VFAs are produced from microbial digestion

  • absorbed in the cecum and colon (large intestine)

  • main source of energy for the horse

• horse cecum = 4ft long and hold 8 gallons

  • swine cecum is only 10in long and holds 0.5 gallons

colic

pained caused by the sharp turn of the horses’ large intestine which lead to compaction of feces and blockages, can lead to death if not treated

compare and contrast the microbial digestion of the hindgut fermenters and ruminants

compare:

• both used forages for energy by microbial digestion

contrasts:

• hindgut fermenters use microbial digestion in the cecum

• ruminants use microbial digestion mainly in the rumen but also in the cecum

compare and contrast microbial digestion of the hindgut fermenter and other monogatsrics

compare:

• both have a cecum

contrast:

• only hindgut fermenters can utilize forages due to microbial digestion in the cecum, other monogastrics cannot do this as efficiently

chicken teeth

no teeth, beak is used to peck food and break it apart (mechanical digestion)

poultry esophagus

food enters the mouth then travels down the esophagus to the crop

crop

modification of the esophagus where food can be temporarily stored, secretions (saliva) in the crop soften the feed

proventriculus

TRUE STOMACH IN POULTRY (all three forms of digestion are present)

• mechanical = muscular contraction s

• chemical = hydrochloric acid

• enzymatic = pepsin

gizzard

MAIN SITE OF MECHANICAL DIGESTION

• purpose is to grind up the chyme from the proventriculus via muscular contractions and grit

• tough tissue lining

• mostly unnecessary with modern poultry bc food is already processed

poultry cecum

• two ceca present

• some microbial digestion but VFAs produced have little effect on energy intake

cloaca

• chamber for the digestive, urinary, and reproductive passages

• opens externally at the vent

digestion in the body

breaking feed particles into microscopic nutrient molecules by mechanical, chemical, and enzymatic digestion

absorption into the body

absorbing the microscopic nutrient molecules into the blood stream from the GI tract

metabolism by the body

using the microscopic nutrient molecules in the body’s cells

difference between carbohydrates and protein?

nitrogen !

• carbohydrates do not contain N

• proteins do contain N in the amino acid

how is protein used for structure in animal bodies

• muscle

• connective tissue

• bones

• hair/wool

how is protein used for physiological purposes in animal bodies

• enzymes

• blood proteins

• hormones

• antibodies

how are proteins used as a source of energy in animal bodies

if starving, the muscle tissue can be broken down and used for energy

what is a protein

a specific group of amino acids that can connected in a long chain (polypeptide chain)

what are amino acids

amino group

• NH2 chemical group

carboxylic acid group

• COOH chemical group

side chain

• R, what makes each AA unique

draw an amino acid real quick go

how are amino acids connected to form a protein

peptide bonds

• COOH group and NH2 group release H2O, allowing the C and N to create a covalent bond (peptide bond)

define essential amino acid

amino acids that the animal’s body cannot make on its own and must be consumed in the diet to be present in the body

what are the 10 essential amino acids

PVT TIM HALL

1. phenylalanine

2. valine

3. tryptophan

4. threonine

5. isoleucine

6. methionine

7. histidine

8. arginine

9. leucine

10. lysine

what are limiting amino acids

essential amino acids that are present in the lowest amount in the diet

• most common in animal livestock = lysine, methionine, threonine

draw lysine