Livestock Nutrition

1
Livestock Nutrition

• Ch. 2
• Digestion in Animals

2
Objectives

• 1- Describe the nonruminant (monogastric),
  ruminant, and avian digestive systems.
• 2- Describe the process of digestion in animals.
• 3- Describe the absorption of nutrients in
  animals.

3
Digestive Systems

• Digestion is a process that breaks feed down into
  simple substances that can be absorbed by the
  body.
• This usually involves mechanical, chemical and
  enzymes.
• The compounds are then absorbed into the blood
  stream.

4
Digestive tract

• Also known as the gastrointestinal tract or the
  alimentary tract.
• Begins at the mouth and ends at the anus.

5
Three kinds of digestive systems.

• Non-ruminant (monogastric).
• Ruminant (polygastric).
• Avian

6
Non-ruminant digestive systems.

• Swine, horses humans.
• Single compartment stomach.
• Includes, mouth, teeth, tongue, salivary glands,
  esophagus, stomach, small intestine, liver,
  pancreas, cecum, large intestine, rectum and anus.

7
Parts of Swine Digestive Tract

• Parts of the swine digestive system.
• Know location and function of each part.

8
Parts of Horse Digestive System

• Know the location and function of each part.
• Pay particular attention to the highly adapted
  cecum.

9
Mouth, part of digestive system.

• The mouth contains the teeth, tongue, and
  salivary glands.
• Chewing action (mechanical part of digestion).
• Food is cut and torn in the mouth, then mixed
  with saliva, which is produced in three different
  places.
• Three paired sets of salivary glands, located
  under the lower jaw and under the ears.

10
Mouth

• Saliva contains water, mucin, bicarbonate salts
  and enzymes.
• Horse saliva does not contain enzymes.
• In swine, saliva contains the enzymes salivary
  amylase and salivary maltase.

11
Enzymes

• Enzymes work in the whole digestive process, form
  mouth to anus.
• Enzymes are organic catalysts that cause and/or
  speed up digestive action.
• However, enzymes remain unchanged in this
  process.
• A weak acid solution will halt enzyme action.

12
Digestion in the Mouth

• Saliva stimulates the taste nerves.
• Water moistens the feed for chewing and
  swallowing.
• Mucin lubricates the feed for swallowing.
• Bicarbonate salts buffer the pH in the stomach.

13
The Tongue

• The tongue gathers feed in the mouth.
• Directs the feed in the throat for swallowing.
• Mixes feed.

14
Esophagus

• A tube like passage which leads from the mouth to
  the stomach.
• Peristaltic waves send feed down the esophagus,
  (muscle contractions).
• The cardia, located at the end of the esophagus
  prevents feed in the stomach from coming back
  into the esophagus. ( non-ruminants)

15
Stomach

• Pear shaped, muscular organ, receives feed, where
  it is further broken down by muscle in the
  stomach wall.
• Gastric juices, secreted by the glands in the
  stomach wall, start to flow the moment masticated
  feed enter the stomach.
• Gastric juices have about 0.2 to 0.5 percent HCl.

16
Stomach

• The wall of the stomach is lined with muscle,
  this muscle churns and squeezes the feed.
• This action forces the liquid portion on into the
  small intestine.
• The stomach of the horse has less muscular
  activity than that of other species, causing an
  increased tendency toward digestive disorders.

17
Horse Stomach

• The stomach of a horse is smaller, compared to
  other species, in relation to the size of the
  animal.
• Therefore, it is more desirable to feed horses in
  smaller amounts at one time but provide more
  frequent feedings.

18
Small Intestine

• Duodenum, the first part of the small intestine.
• This is where secretions from the pancreas, liver
  and intestinal walls occur.
• Active digestion takes place here.
• Bile, secreted in the liver is stored in the
  gallbladder where it is secreted into the
  duodenum.
• Horses do not have a gallbladder, therefore, bile
  is secreted continuously from the liver to the
  duodenum.

19
Small Intestine

• The middle part of the Small Intestine is called
  the Jejunum.
• The last part of the small intestine is called
  the ileum.
• Nutrient absorption occurs in these two section
  of the small intestine.

20
Small Intestine

• Chyme is partially digested feed in the stomach.
• Chyme is an acid, semi fluid, gray, pulpy mass.
• Pancreatic juice is secreted by the pancreas, a
  small gland located between the folds of the
  small intestine.
• Pancreatic juice contains enzymes.

21
Small Intestine, Proteins

• Proteins are further broken down into
  polypeptides oligopeptides, dipeptides and amino
  acids, eventually broken down into simple amino
  acids.
• Starch is changed to maltose.
• Fats in the feed are broken down into fatty acids
  glycerol and monoglycerides.
• Bile helps emulsify fats.

22
Large Intestine in Swine

• The small intestine does the majority of
  absorption.
• Cecum in swine has little or no function.
• The cecum is the first part of the large
  intestine.
• The colon is the middle and largest part of the
  large intestine.

23
Large Intestine, Horses

• Cecum is an important organ in horses.
• The large intestine makes up approximately 60 of
  the total digestive tract.
• Divided into cecum, large colon, small colon and
  rectum.
• Horses can use large amounts of roughage because
  of the presence of bacteria in the cecum and
  colon.
• These bacteria digest hemicelluloses and
  cellulose and ferment carbohydrates.

24
Large Intestine, Horses

• IMPORTANT- because the large intestine of the
  horse usually contains substantial quantities of
  ingested material, impaction occurs easily.
• This impaction is the start of what horse
  ailment?

25
Large Intestine

• In all species, undigested, unabsorbed and
  indigestible material passes from the small
  intestine to the large.
• The main function of the L intestine is to absorb
  water from the material passing through.
• In the Horse, the small colon is the site of most
  of the water resorption.
• Feces, material that is not absorbed or digested.
• Anus, the external opening at the end of the
  digestive tract.

26
Ruminant Digestive SystemMouth

• Saliva of ruminants does not contain enzymes to
  help digest the starches.
• It contains buffers which neutralize the fatty
  acid produced in the rumen.
• The rumen contents are maintained at
  approximately a pH of 6-6.5.
• This pH level promotes microbial growth in the
  rumen.
• Mature cows produce about 12 gallons of saliva
  per day while sheep produce 2 gal.

27
Ruminant Digestion Stomach.

• The stomach of the ruminant contains four
  compartments the rumen, reticulum, omasum and
  the abomasum.
• The rumen or paunch is the first.
• The reticulum or honey comb is second.
• There is not a clear partition between these two
  compartments.
• The cardia, (lower part of the esophagus is
  common to both compartments.
• No enzymes are secreted in these tow parts.

28
Ruminant Digestion Stomach

• The third compartment is the omasum or many
  plies.
• It constitutes 8 of the stomach.
• The omasum contains strong muscles in the walls.
• The fourth and last part of the ruminant stomach
  is the abomasum or true stomach.
• The Abomasum makes up 7 of the stomach.

29
Ruminant Digestion

• Ruminants eat rapidly swallowing much of their
  feed without chewing.
• Solid feed goes to the rumen.
• The liquid part also goes into the rumen. But
  passes quickly to the reticulum, then through the
  omasum and on into the abomasum.

30
Esophageal Groove

• These two muscular folds for a passage way from
  the cardia, ( the end of the esophagus), to the
  omasum.
• When closed this passage way directs feed from
  the esophagus directly to the omasum and when it
  is open the material goes into the rumen and the
  reticulum.
• Its major function appears to be to allow milk
  ingest by a nursing animal to bypass fermentation
  in the rumen. Serves no purpose in adult
  ruminants.

31
Bovine Digestive system

• Identify location and function of each of the
  parts of the Bovine digestive system.

32
Rumination

• After the ruminant animal has filled the rumen
  with feed it lies down to ruminate, (chew its
  cud).
• Cattle spend from 5-7 hours ruminating, broken up
  into 6-8 rumination periods.
• Regurgitation is the process of forcing the feed
  back into the mouth for chewing.
• This is done through series of muscular
  contractions and pressure in the rumen and
  reticulum.

33
Rumination

• The animal breathes in with a closed glottis.
• This causes a drop in pressure in the thorax and
  esophagus.
• The pressure in the rumen is now greater, forcing
  the cud into the esophagus where it is carried to
  the mouth, with muscular contractions.
• More saliva is then mixed with the feed and it
  passes into the reticulum, if sufficient chewing
  has been done.

34
Rumen Microorganisms

• Rumen and reticulum contain millions of
  microorganisms called bacteria and protozoa.
• Together, these tiny organisms feed on the
  fibrous material in the rumen.
• They digest cellulose and compiles starch,
  synthesize protein and synthesize vitamins.

35
Microorganisms

• The three types of rumen bacteria are
  streptococci, lactobacilli and celluloytic
  bacteria.
• 50-65 of the starch is digested in the rumen.
• Protein in the rumen is converted to ammonia,
  organic acids and amino acids.
• Most amino acids synthesized by the rumen,
  therefore, it is not necessary to supply large
  quantities of amino acids in the ration.

36
Functions of the Rumen

• There is continual flow of feed materials into
  and out of the rumen.
• It acts like a large fermentation vat and account
  for about 50-85 of the total utilization of the
  digestible dry matter in the ration.
• Saliva which is mixed with feed helps control the
  pH of the rumen.
• A shift of microorganisms can result from the
  types of feed fed.

37
Function of the Rumen

• Feed material stays in the rumen and reticulum
  area from about two hours to several days.
• The kind of feed influences time. Concentrates
  pass quicker than roughages.
• Papillae line the interior wall of the rumen,
  they increase surface area therefore increasing
  the absorption ability of the rumen wall.

38
Function of the Rumen

• Bacterial action in the rumen produces large
  quantities (30-50 quarts per hour) of gas, mainly
  CO2 and CH4.
• This gas must be removed or the animal will
  bloat.
• The gas is released through eructation,
  (belching).
• Small amounts are absorbed by the bloodstream and
  then eliminated through the lungs.

39
Function of the Reticulum

• Contains the same bacteria and protozoa as the
  rumen.
• Lined with intersecting ridges that form
  honeycomblike projections.
• Hardware that is ingest are trapped in this area
  and generally do not move further through the
  digestive system.
• Feed is moved back and forth between the rumen
  and reticulum by regular contractions originating
  in the reticulum.

40
Function of the Omasum

• The omasum grinds and squeezes the feed.
• Little or no digestive action.
• The material leaving the omasum is 60-70 percent
  drier than the material entering it.

41
Function of the Abomasum

• Digestion here is much the same as it is in a
  monogastric animal.
• Digestive juices are added to the feed and it is
  moistened.
• There is little or no digestion of fat, cellulose
  or starch.
• pH level of 3.5-4.0.
• The feed becomes highly fluid as it passes into
  the small intestine.

42
Avian Digestive Systems

• Different from nonruminant and ruminant.
• Feed in proventriculus are secreted by the
  glandular stomach and mixed with feed. The feed
  next moves to the gizzard.
• Epithelium breaks the feed into smaller
  particles, further mixing of proventricular
  digestive juices with the feed in the gizzard.The
  end of the digestive system is the vent.

43
Absorption of Nutrients

• Absorption is the process of taking nutrients
  from the digested feed into the blood and lymph
  systems.
• In nonruminants most absorption takes place from
  the small intestine with a lesser amount being
  absorbed from the large intestine.
• In ruminants there is some absorption of
  nutrients through the wall of the rumen.

44
Absorption of Nutrients

• Villi are small cone-shaped projection on the
  wall of the small intestine. Each villi contains
  a network of blood capillaries through which
  nutrients enter the blood stream.
• Protein is converted to amino acids.
• Starches and sugars are converted to glucose,
  fructose and galactose.
• Crude fiber is converted to short chained fatty
  acids or glucose by digestion.
• These nutrients pass into the blood capillaries
  by osmosis through the semi permeable membranes.

45
Absorption of Nutrients

• The two methods of absorption are diffusion and
  active transport.
• Diffusion is the movement of molecules from an
  area of high concentration to one of low
  concentration.
• Active transport is the movement of molecules
  from one area to another requiring the
  expenditure of energy.
• Amino acids and glucose move by active transport.

46
Metabolism

• Metabolism is the sum of the chemical and
  physical changes continually occurring in living
  organisms and cells utilizing nutrients.
• Anabolism is the formation and repair of body
  tissues.
• Catabolism is the breakdown of body tissue into
  simpler substances.

47
Nutrient Transport

• Nutrients in the water soluble form, are
  primarily carried by the blood in the animals
  body from where they are absorbed to where they
  are utilized.
• Nutrients are used for maintenance, oxidation
  provides hear for body temperature and movement.
• Nutrients are also used fro growth and fattening,
  fetal development, production of milk and eggs,
  wool and mohair and work.

48
Summary

• Digestion is breaking feed down into simple
  substances that can be absorbed by the body.
• Digestion occurs when feeds are broken up
  mechanically and acted upon by enzymes and other
  digestive juices.
• Most absorption of nutrients after digestion
  takes place in the small intestine, although some
  absorption occurs in the rumen.

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52
Review Questions

• 1- Define digestion and digestive system.
• 2- Name the three major kinds of digestive
  systems and give examples of animals with each
  type.
• 3- Name the parts of the monogastric digestive
  system and briefly describe the function of each.

53
Review Questions

• 4- Devine and give examples of enzymes.
• 6- Define chyme.
• 7- Describe the function of the liver.
• 9- Name the four major compartments of the
  stomach of a ruminant.
• 10- Describe the function of each compartment.

54
Review Questions

• 13- Name the major microorganisms found in the
  rumen and describe their function.
• 15- Describe how absorption of nutrients occurs.
• 16- Define and briefly describe metabolism.

55
Review Answers

• 1- Digestion mechanical, chemical, and enzymic
  actions that break feed down into simple
  substances that can be absorbed by the body.
  Digestive system the passage through the body
  that begins at the mouth and ends with the anus
  through which feed passes as it is digested.

56
Review Answers

• 2- Non ruminant Swine and horses.
• Ruminant Cattle, sheep and goats.
• Avian Poultry.
• 3- Mouth Teeth tongue and salivary glands.
  Chewing action mechanical digestion. Esophagus,
  passageway to the stomach. Small Intestine, the
  duodenum, jejunum and ileum, the site of most of
  the absorption. Gallbladder and liver production
  of bile, storage of wastes. Villi, moves food
  through the stomach, aids in absorption. Cecum,
  non-functional in swine, aids in roughage
  digestion in horses. Colon, with the help of
  bacteria breaks down roughages. Rectum????

57
Review Answers

• 4- Organic catalysts that cause and/or speed up
  digestive action but remain unchanged in the
  process. Examples amylase, maltase, lipase,
  carboxypeptidase, peptidase, sucrase, lactase,
  nucleotidase and cellulase.
• 6- Partially digested feed in the stomach.
• 7- Secretes bile.
• 9- Rumen, Reticulum, omasum and abomasum.

58
Review Answers

• 10- Rumen and Reticulum Fat to form fatty
  acids and glycerol glycerol to form propionic
  acid site of microorganisms that act on
  protein/nonprotein nitrogen to form essential
  amino acids starch/sucrose/cellulose. Omasum
  Grinds and squeezes feed, removes some liquid
  little digestive action in the omasum. Abomasum
  true stomach, acts on proteins stops action of
  salivary amylase contains HCl.

59
Review Answers

• 13- Streptococci Lactobacilli -Digests
  starches and sugars rations of high concentrates
  and young tender forages will increase
  Streptococci and Lactobacilli.
• Bacteriodes succinogenes and Ruminococcus
  flavefaciens Digest cellulose and hemicellulose.
• Protozoa digest polysaccharides, ferment
  cellulose.

60
Review Answers

• 15- Most absorption is done by diffusion and
  active transport. Most in the non-ruminant
  stomach is done in the small intestine, in
  ruminant animals they use the small intestine and
  to a small degree through the rumen.

61
Review Answers

• 16- Metabolism refers to the chemical and
  physical changes occurring after the feed
  nutrients are absorbed into the bloodstream.

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63
Livestock Nutrition

• Ch. 2
• Digestion in Animals

64
Objectives

• 1- Describe the nonruminant (monogastric),
  ruminant, and avian digestive systems.
• 2- Describe the process of digestion in animals.
• 3- Describe the absorption of nutrients in
  animals.

65
Digestive Systems

• Digestion is a process that breaks feed down into
  simple substances that can be absorbed by the
  body.
• This usually involves mechanical, chemical and
  enzymes.
• The compounds are then absorbed into the blood
  stream.

66
Digestive tract

• Also known as the gastrointestinal tract or the
  alimentary tract.
• Begins at the mouth and ends at the anus.

67
Three kinds of digestive systems.

• Non-ruminant (monogastric).
• Ruminant (polygastric).
• Avian

68
Non-ruminant digestive systems.

• Swine, horses humans.
• Single compartment stomach.
• Includes, mouth, teeth, tongue, salivary glands,
  esophagus, stomach, small intestine, liver,
  pancreas, cecum, large intestine, rectum and anus.

69
Parts of Swine Digestive Tract

• Parts of the swine digestive system.
• Know location and function of each part.

70
Parts of Horse Digestive System

• Know the location and function of each part.
• Pay particular attention to the highly adapted
  cecum.

71
Mouth, part of digestive system.

• The mouth contains the teeth, tongue, and
  salivary glands.
• Chewing action (mechanical part of digestion).
• Food is cut and torn in the mouth, then mixed
  with saliva, which is produced in three different
  places.
• Three paired sets of salivary glands, located
  under the lower jaw and under the ears.

72
Mouth

• Saliva contains water, mucin, bicarbonate salts
  and enzymes.
• Horse saliva does not contain enzymes.
• In swine, saliva contains the enzymes salivary
  amylase and salivary maltase.

73
Enzymes

• Enzymes work in the whole digestive process, form
  mouth to anus.
• Enzymes are organic catalysts that cause and/or
  speed up digestive action.
• However, enzymes remain unchanged in this
  process.
• A weak acid solution will halt enzyme action.

74
Digestion in the Mouth

• Saliva stimulates the taste nerves.
• Water moistens the feed for chewing and
  swallowing.
• Mucin lubricates the feed for swallowing.
• Bicarbonate salts buffer the pH in the stomach.

75
The Tongue

• The tongue gathers feed in the mouth.
• Directs the feed in the throat for swallowing.
• Mixes feed.

76
Esophagus

• A tube like passage which leads from the mouth to
  the stomach.
• Peristaltic waves send feed down the esophagus,
  (muscle contractions).
• The cardia, located at the end of the esophagus
  prevents feed in the stomach from coming back
  into the esophagus. ( non-ruminants)

77
Stomach

• Pear shaped, muscular organ, receives feed, where
  it is further broken down by muscle in the
  stomach wall.
• Gastric juices, secreted by the glands in the
  stomach wall, start to flow the moment masticated
  feed enter the stomach.
• Gastric juices have about 0.2 to 0.5 percent HCl.

78
Stomach

• The wall of the stomach is lined with muscle,
  this muscle churns and squeezes the feed.
• This action forces the liquid portion on into the
  small intestine.
• The stomach of the horse has less muscular
  activity than that of other species, causing an
  increased tendency toward digestive disorders.

79
Horse Stomach

• The stomach of a horse is smaller, compared to
  other species, in relation to the size of the
  animal.
• Therefore, it is more desirable to feed horses in
  smaller amounts at one time but provide more
  frequent feedings.

80
Small Intestine

• Duodenum, the first part of the small intestine.
• This is where secretions from the pancreas, liver
  and intestinal walls occur.
• Active digestion takes place here.
• Bile, secreted in the liver is stored in the
  gallbladder where it is secreted into the
  duodenum.
• Horses do not have a gallbladder, therefore, bile
  is secreted continuously from the liver to the
  duodenum.

81
Small Intestine

• The middle part of the Small Intestine is called
  the Jejunum.
• The last part of the small intestine is called
  the ileum.
• Nutrient absorption occurs in these two section
  of the small intestine.

82
Small Intestine

• Chyme is partially digested feed in the stomach.
• Chyme is an acid, semi fluid, gray, pulpy mass.
• Pancreatic juice is secreted by the pancreas, a
  small gland located between the folds of the
  small intestine.
• Pancreatic juice contains enzymes.

83
Small Intestine, Proteins

• Proteins are further broken down into
  polypeptides oligopeptides, dipeptides and amino
  acids, eventually broken down into simple amino
  acids.
• Starch is changed to maltose.
• Fats in the feed are broken down into fatty acids
  glycerol and monoglycerides.
• Bile helps emulsify fats.

84
Large Intestine in Swine

• The small intestine does the majority of
  absorption.
• Cecum in swine has little or no function.
• The cecum is the first part of the large
  intestine.
• The colon is the middle and largest part of the
  large intestine.

85
Large Intestine, Horses

• Cecum is an important organ in horses.
• The large intestine makes up approximately 60 of
  the total digestive tract.
• Divided into cecum, large colon, small colon and
  rectum.
• Horses can use large amounts of roughage because
  of the presence of bacteria in the cecum and
  colon.
• These bacteria digest hemicelluloses and
  cellulose and ferment carbohydrates.

86
Large Intestine, Horses

• IMPORTANT- because the large intestine of the
  horse usually contains substantial quantities of
  ingested material, impaction occurs easily.
• This impaction is the start of what horse
  ailment?

87
Large Intestine

• In all species, undigested, unabsorbed and
  indigestible material passes from the small
  intestine to the large.
• The main function of the L intestine is to absorb
  water from the material passing through.
• In the Horse, the small colon is the site of most
  of the water resorption.
• Feces, material that is not absorbed or digested.
• Anus, the external opening at the end of the
  digestive tract.

88
Ruminant Digestive SystemMouth

• Saliva of ruminants does not contain enzymes to
  help digest the starches.
• It contains buffers which neutralize the fatty
  acid produced in the rumen.
• The rumen contents are maintained at
  approximately a pH of 6-6.5.
• This pH level promotes microbial growth in the
  rumen.
• Mature cows produce about 12 gallons of saliva
  per day while sheep produce 2 gal.

89
Ruminant Digestion Stomach.

• The stomach of the ruminant contains four
  compartments the rumen, reticulum, omasum and
  the abomasum.
• The rumen or paunch is the first.
• The reticulum or honey comb is second.
• There is not a clear partition between these two
  compartments.
• The cardia, (lower part of the esophagus is
  common to both compartments.
• No enzymes are secreted in these tow parts.

90
Ruminant Digestion Stomach

• The third compartment is the omasum or many
  plies.
• It constitutes 8 of the stomach.
• The omasum contains strong muscles in the walls.
• The fourth and last part of the ruminant stomach
  is the abomasum or true stomach.
• The Abomasum makes up 7 of the stomach.

91
Ruminant Digestion

• Ruminants eat rapidly swallowing much of their
  feed without chewing.
• Solid feed goes to the rumen.
• The liquid part also goes into the rumen. But
  passes quickly to the reticulum, then through the
  omasum and on into the abomasum.

92
Esophageal Groove

• These two muscular folds for a passage way from
  the cardia, ( the end of the esophagus), to the
  omasum.
• When closed this passage way directs feed from
  the esophagus directly to the omasum and when it
  is open the material goes into the rumen and the
  reticulum.
• Its major function appears to be to allow milk
  ingest by a nursing animal to bypass fermentation
  in the rumen. Serves no purpose in adult
  ruminants.

93
Bovine Digestive system

• Identify location and function of each of the
  parts of the Bovine digestive system.

94
Rumination

• After the ruminant animal has filled the rumen
  with feed it lies down to ruminate, (chew its
  cud).
• Cattle spend from 5-7 hours ruminating, broken up
  into 6-8 rumination periods.
• Regurgitation is the process of forcing the feed
  back into the mouth for chewing.
• This is done through series of muscular
  contractions and pressure in the rumen and
  reticulum.

95
Rumination

• The animal breathes in with a closed glottis.
• This causes a drop in pressure in the thorax and
  esophagus.
• The pressure in the rumen is now greater, forcing
  the cud into the esophagus where it is carried to
  the mouth, with muscular contractions.
• More saliva is then mixed with the feed and it
  passes into the reticulum, if sufficient chewing
  has been done.

96
Rumen Microorganisms

• Rumen and reticulum contain millions of
  microorganisms called bacteria and protozoa.
• Together, these tiny organisms feed on the
  fibrous material in the rumen.
• They digest cellulose and compiles starch,
  synthesize protein and synthesize vitamins.

97
Microorganisms

• The three types of rumen bacteria are
  streptococci, lactobacilli and celluloytic
  bacteria.
• 50-65 of the starch is digested in the rumen.
• Protein in the rumen is converted to ammonia,
  organic acids and amino acids.
• Most amino acids synthesized by the rumen,
  therefore, it is not necessary to supply large
  quantities of amino acids in the ration.

98
Functions of the Rumen

• There is continual flow of feed materials into
  and out of the rumen.
• It acts like a large fermentation vat and account
  for about 50-85 of the total utilization of the
  digestible dry matter in the ration.
• Saliva which is mixed with feed helps control the
  pH of the rumen.
• A shift of microorganisms can result from the
  types of feed fed.

99
Function of the Rumen

• Feed material stays in the rumen and reticulum
  area from about two hours to several days.
• The kind of feed influences time. Concentrates
  pass quicker than roughages.
• Papillae line the interior wall of the rumen,
  they increase surface area therefore increasing
  the absorption ability of the rumen wall.

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Function of the Rumen

• Bacterial action in the rumen produces large
  quantities (30-50 quarts per hour) of gas, mainly
  CO2 and CH4.
• This gas must be removed or the animal will
  bloat.
• The gas is released through eructation,
  (belching).
• Small amounts are absorbed by the bloodstream and
  then eliminated through the lungs.

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Function of the Reticulum

• Contains the same bacteria and protozoa as the
  rumen.
• Lined with intersecting ridges that form
  honeycomblike projections.
• Hardware that is ingest are trapped in this area
  and generally do not move further through the
  digestive system.
• Feed is moved back and forth between the rumen
  and reticulum by regular contractions originating
  in the reticulum.

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Function of the Omasum

• The omasum grinds and squeezes the feed.
• Little or no digestive action.
• The material leaving the omasum is 60-70 percent
  drier than the material entering it.

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Function of the Abomasum

• Digestion here is much the same as it is in a
  monogastric animal.
• Digestive juices are added to the feed and it is
  moistened.
• There is little or no digestion of fat, cellulose
  or starch.
• pH level of 3.5-4.0.
• The feed becomes highly fluid as it passes into
  the small intestine.

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Avian Digestive Systems

• Different from nonruminant and ruminant.
• Feed in proventriculus are secreted by the
  glandular stomach and mixed with feed. The feed
  next moves to the gizzard.
• Epithelium breaks the feed into smaller
  particles, further mixing of proventricular
  digestive juices with the feed in the gizzard.The
  end of the digestive system is the vent.

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Absorption of Nutrients

• Absorption is the process of taking nutrients
  from the digested feed into the blood and lymph
  systems.
• In nonruminants most absorption takes place from
  the small intestine with a lesser amount being
  absorbed from the large intestine.
• In ruminants there is some absorption of
  nutrients through the wall of the rumen.

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Absorption of Nutrients

• Villi are small cone-shaped projection on the
  wall of the small intestine. Each villi contains
  a network of blood capillaries through which
  nutrients enter the blood stream.
• Protein is converted to amino acids.
• Starches and sugars are converted to glucose,
  fructose and galactose.
• Crude fiber is converted to short chained fatty
  acids or glucose by digestion.
• These nutrients pass into the blood capillaries
  by osmosis through the semi permeable membranes.

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Absorption of Nutrients

• The two methods of absorption are diffusion and
  active transport.
• Diffusion is the movement of molecules from an
  area of high concentration to one of low
  concentration.
• Active transport is the movement of molecules
  from one area to another requiring the
  expenditure of energy.
• Amino acids and glucose move by active transport.

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Metabolism

• Metabolism is the sum of the chemical and
  physical changes continually occurring in living
  organisms and cells utilizing nutrients.
• Anabolism is the formation and repair of body
  tissues.
• Catabolism is the breakdown of body tissue into
  simpler substances.

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Nutrient Transport

• Nutrients in the water soluble form, are
  primarily carried by the blood in the animals
  body from where they are absorbed to where they
  are utilized.
• Nutrients are used for maintenance, oxidation
  provides hear for body temperature and movement.
• Nutrients are also used fro growth and fattening,
  fetal development, production of milk and eggs,
  wool and mohair and work.

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Summary

• Digestion is breaking feed down into simple
  substances that can be absorbed by the body.
• Digestion occurs when feeds are broken up
  mechanically and acted upon by enzymes and other
  digestive juices.
• Most absorption of nutrients after digestion
  takes place in the small intestine, although some
  absorption occurs in the rumen.

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114
Review Questions

• 1- Define digestion and digestive system.
• 2- Name the three major kinds of digestive
  systems and give examples of animals with each
  type.
• 3- Name the parts of the monogastric digestive
  system and briefly describe the function of each.

115
Review Questions

• 4- Devine and give examples of enzymes.
• 6- Define chyme.
• 7- Describe the function of the liver.
• 9- Name the four major compartments of the
  stomach of a ruminant.
• 10- Describe the function of each compartment.

116
Review Questions

• 13- Name the major microorganisms found in the
  rumen and describe their function.
• 15- Describe how absorption of nutrients occurs.
• 16- Define and briefly describe metabolism.

117
Review Answers

• 1- Digestion mechanical, chemical, and enzymic
  actions that break feed down into simple
  substances that can be absorbed by the body.
  Digestive system the passage through the body
  that begins at the mouth and ends with the anus
  through which feed passes as it is digested.

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Review Answers

• 2- Non ruminant Swine and horses.
• Ruminant Cattle, sheep and goats.
• Avian Poultry.
• 3- Mouth Teeth tongue and salivary glands.
  Chewing action mechanical digestion. Esophagus,
  passageway to the stomach. Small Intestine, the
  duodenum, jejunum and ileum, the site of most of
  the absorption. Gallbladder and liver production
  of bile, storage of wastes. Villi, moves food
  through the stomach, aids in absorption. Cecum,
  non-functional in swine, aids in roughage
  digestion in horses. Colon, with the help of
  bacteria breaks down roughages. Rectum????

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Review Answers

• 4- Organic catalysts that cause and/or speed up
  digestive action but remain unchanged in the
  process. Examples amylase, maltase, lipase,
  carboxypeptidase, peptidase, sucrase, lactase,
  nucleotidase and cellulase.
• 6- Partially digested feed in the stomach.
• 7- Secretes bile.
• 9- Rumen, Reticulum, omasum and abomasum.

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Review Answers

• 10- Rumen and Reticulum Fat to form fatty
  acids and glycerol glycerol to form propionic
  acid site of microorganisms that act on
  protein/nonprotein nitrogen to form essential
  amino acids starch/sucrose/cellulose. Omasum
  Grinds and squeezes feed, removes some liquid
  little digestive action in the omasum. Abomasum
  true stomach, acts on proteins stops action of
  salivary amylase contains HCl.

121
Review Answers

• 13- Streptococci Lactobacilli -Digests
  starches and sugars rations of high concentrates
  and young tender forages will increase
  Streptococci and Lactobacilli.
• Bacteriodes succinogenes and Ruminococcus
  flavefaciens Digest cellulose and hemicellulose.
• Protozoa digest polysaccharides, ferment
  cellulose.

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Review Answers

• 15- Most absorption is done by diffusion and
  active transport. Most in the non-ruminant
  stomach is done in the small intestine, in
  ruminant animals they use the small intestine and
  to a small degree through the rumen.

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Review Answers

• 16- Metabolism refers to the chemical and
  physical changes occurring after the feed
  nutrients are absorbed into the bloodstream.