UCM Animal Nutrition Quiz 2

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

draw methionine

draw threonine

swine limiting amino acids

1. lysine

2. threonine

3. tryptophan

beef cattle limiting amino acids - high forage diet

1. methionine

2. arginine

3. lysine

beef cattle limiting amino acids - high grain diet

1. arginine

2. lysine

3. methionine

poultry limiting amino acids

1. methinine

2. lysine

3. threonine

why are lysine, methionine, and threonine usually the most limiting amino acids in farm animal diets

they are sound in the lowest amounts in plants, have to be supplemented in most livestock diets

what does protein requirement refer to

the requirement of the body for the essential amino acids and especially the limiting amino acids

why do protein requirements differ per species

• the microbes are the source of protein for the ruminant (but do not prevent limiting AAs)

• monogastrics cannot used microbes as a source of protein

what does protein quality mean

refers to the digestibility of the protein and contains a proportion of essential amino acids relative to the animal’s diet

what can damage protein quality

exposure to high temperatures

protein from animals sources has ________ quality then protein from plant sources

better

• meaning some amino acids need to be supplemented, but this is expensive and cows cannot be fed animal protein due to risk of Mad Cow Disease

what protease enzymes are released from the stomach into the stomach

1. pepsin

what protease enzymes are released from the pancreas into the duodenum

1. trypsin

2. chymotrypsin

3. carboxypeptidase

what protease enzymes are released by the villi and act at the surface of the vili

1. aminopeptidase

2. dipeptidase

how does protein digestion happen in the stomach of monogastrics + hindgut fermenters

pepsin begins breaking down the proteins into shorter chains of amino acids

• pepsin only works at a low pH so it works in the stomach but not in the duodenum because the pH is too high

how does protein digestion happen in the small intestine of monogastrics + higdgut fermenters

proteins digestion occurs primarily in the duodenum but also in the jejunum and ileum

• pancreas releases 3 protease enzymes (trypsin, chymotrypsin, carboxypeptidae) into the duodenum that cut the the long protein chains into short polypeptide chains or dipeptides

• villi of the jejunum and ileum release 2 protease enzymes (aminopeptidase, dipeptidase) that act at the surface of the villi and cut the short polypeptide chains or dipeptides into individual amino acids

amino acids then travel to the liver for further processing

how does protein digestion happen in the rumen

no protease enzymes, all protein digestion is performed by microbial digestion

• microbes can produce all 20 amino acids and use their own protease enzymes to break down proteins

how does protein digestion happen in the abomasum

pepsin begins breaking down the proteins into shorter chains of amino acids

• the protein being used here is coming from the microbes

how are amino acids absorbed into the cell

absorbed directly into the cell from the blood, are used to build new proteins in the cell

define protein turnover

proteins are constantly being built and broken down within the cell

• anabolism = building proteins from amino acids

• catabolism = breaking down proteins into amino acids to produce energy for the cell

how do proteins provide energy for the cell

after a protein is broken down (catabolism) into amino acids, the amino group is removed leaving two carbon structures, these combine together to form glucose which can then be used to produce ATP

protein→amino acid→2 carbon structures→glucose→ATP

what is urea

as a result of removing nitrogen from amino acids for energy production, the let go nitrogens combine with oxygen and carbon to form a molecule (urea) that is used to remove excess nitrogen from the body

• high levels of nitrogen is toxic to animals and humans

• urea is filtered from the blood by the kidneys and released in urine