1. RUMINATION, DEGLUTITION AND
SALIVARY SECRETION IN
RUMINANTS
By
Dr. Allah Bux Kachiwal
Professor
Department of Veterinary Physiology and Biochemistry
https://www.facebook.com/ABKachiwal/
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Email: kachiwal2003@gmail.com
abkachiwal@sau.edu.com
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2. Digestive system
• Comprises on alimentary canal/ Gastrointestinal
tract and accessory glands (Salivary, pancreas, Liver)
• portal for nutrients to gain access to the
circulatory system
• Foodstuffs (CHO, proteins, fats) are broken
down to very simple molecules.
• Resulting sugars, aminoacids, fatty acids, etc are
then transported across the GI tract lining into
blood.
• The specific foodstuffs animals are able to utilize
is dependent on the type of digestive system they
possess.
3. Functions of digestive system
Digestion
Conversion of complex food material
in diet into simpler diffusible form.
Absorption
• The digested food enters the blood
circulation through GIT wall.
Digestive system
4. Classification of domestic animals based on
type of digestive system they posses:
►Monogastric – simple stomach.
►Ruminant (cranial fermentor) – multi-
compartmented stomach.
►Hind gut (caudal) fermentor – simple stomach,
but very large and complex large intestine
Digestive system
5. Types of Digestive Systems
Cats
Chickens Pigs
Dogs
Turkeys
Monogastrics
Ruminants/
Cranial fermentors
Hind Gut
Fermentors
Beef
Cattle
Dairy
Cattle
Deer
Sheep
Goats
Horses
Rabbits
Ostrich
6. Classification of domestic animals based on
feeding habit:
1. Herbivores Eat plants only
• E.g. cattle, horse, sheep etc
2. Carnivores Eat flesh of other animals
• E.g. Dog, cat, loin
3. Omnivores Eat both plants and animals
• E.g. cattle, buffaloes, sheep and goat etc
Digestive system
7. The process of digestion
1. Prehension: Act of bringing food into mouth
2. Ingestion: Taking in the food
a. Mastication (Chewing)
b. Deglutition (Swallowing)
c. Regurgitation (Chewing the cud, In
ruminants).
3. Digestion: Conversion of food from non-
diffusible into diffusible form
Digestive system
8. The process of digestion
4. Absorption: Digested food enters the
circulation thru GIT wall
5. Assimilation: In cell food is either used for
energy purpose or construct body tissue
6. Egestion (Defecation): Removal of waste
Digestive system
9. Types of digestion:
1. Mechanical Digestion:
Physical breakdown of food during
mastication, GIT wall contraction
2. Chemical/Enzymatic digestion
- With the help of chemicals e.g. HCl in
stomach
- With the help of animals
Digestive system
10. Types of digestion:
1. Incomplete (Partial) Digestion:
Breakdown of food into intermediates but
not final products. Starch----Maltose
2. Complete digestion
Complex molecules split up into final units
E.g. Protein---amino acids
Digestive system
11. Types of digestion:
1. Intracellular Digestion:
Takes place inside the cell
2. Extracellular digestion
Takes place out side the cell
Digestive system
12. Organs of Digestion
SIMPLE STOMACH
1. Mouth
2. Esophagus
3. Stomach
4. Small Intestine i. Duodenum
ii. Jejunum
iii. Illeum
5. Large intestine i.Cecum
ii. Colon
iii.Rectum
6. Anus
13. Digestive Tract - Horse
Esophagus
Stomach
Duodenum
Small
intestine
Cecum
Large
colon
Small colon
Rectum
15. Organs of Digestion
COMPOUND STOMACH
1. Mouth
2. Esophagus
3. Stomach (Rumen, Reticulum,
Omasum, Abomasum)
4. Small Intestine i. Duodenum
ii. Jejunum
iii. Illeum
5. Large intestine i.Cecum
ii. Colon
iii.Rectum
6. Anus
16. Digestive Tract – Cattle
Esophagus
Rumen
Omasum
Reticulum
Abomasum
Pancreas
Liver
Gall
bladder
Cecum
Small intestine
Large
intestine
Rectum
18. PREHENSION
• The seizing and conveying of food to
the mouth or oral cavity.
• Methods vary in different animals, but
in all domestic animals lips, teeth and
tongue are principle organs of this
function.
• Forelimbs and hands are main
prehensile organs in case of pet
animals and human.
20. MASTICATION
• Mechanical breakdown of food in
the mouth.
• Mouth is the sac or cavity having
different parts.
• Many vertebrates have teeth used
for chewing or mastication.
• Birds
– Lack teeth
– Break up food in a two-chambered
stomach
– Gizzard – muscular chamber that uses
ingested pebbles to grind food
20
21. TEETH
• Mechanically reduce the size of ingested food
particles by girding
• Increase the surface area for chemical and
microbiological degradation.
• Four types of teeth:
• 1.Incissors(I). Also called nippers.
• 2.Canines(C).also called fangs ,eye teeth or tusks.
• 3.Premolars(P).
• 4.Molars(M). Cheek teeth
NOTE: IN RUMINANTS THE INCISSORS AND CANNINES
OF MAXILLA ARE REPLACED BY THE DENTAL PAD.
23. • Carnivores – pointed teeth that lack flat grinding
surfaces_ less chewing_ less time.
• Herbivores – large flat teeth suited for grinding
cellulose cell walls of plant tissues_high chewing.
• Humans have carnivore-like teeth in the front
and herbivore-like teeth in the back
23
24.
25.
26.
27. TONGUE
• Long rough and
mobile drawn
between the incisors
and dental pad in
herbivores.
• Between the upper
and lower jaw in
others animals.
• Inside the mouth,
the tongue mixes
food with saliva
• Manipulatory organ
27
28. Role of Mastication (Act of chewing)
• Jaw movements (Reflex)
• Physical break down of food.
• Provides larger surface area of enzymatic
reactions.
• Stimulates saliva secretion.
• Less chewing in carnivores.
• More chewing in herbivores.
• Proper mastication results in bolus
formation.
• In carnivores and herbivores jaw movement
is vertical.
• In herbivores the lateral movement.
• Upper jaw is wider than lower jaw.
29. Role of Salivary glands and saliva
• Parotid Mandibular Sublingual Zygomatic
• Exocrine
• Secret serous, mucus or mixed secretion
• Facilitates mastication and deglutition
30. Role of Salivary glands and saliva
• Contains salivary amylase- an enzyme that
breaks down starch.
• Alkaline in nature, reduce PH in stomach.
• The volume of saliva varies but greatest in
herbivores.
• In cow 25 to 50 gal/d (100 to 200 L/D).
• Additional function neutralization of large
amounts of acids that are produced as a
result of fermentation.
• To meet the buffering demand ruminant
saliva contains bicarbonate and phosphate
buffers( particular for bacterial growth).
31. Role of Salivary glands and saliva
• Salivation is controlled by the
nervous system
• Tasting, smelling, and even thinking
or talking about food stimulate
increased salivation
32. Deglutition = Act of swallowing
• Convey of food mass (bolus) from the
mouth to the stomach.
• Suitable area of swallowing generally
midline between the tongue and hard
palate for swallowing.
Three stages of swallowing:
• Through the mouth (Voluntary)
• Through the pharynx (Reflex)
• Through the oesphagus (Reflex)
33. DEGLUITATION
• The food is in contact with the receptors of
mucous membrane of posterior part of mouth
and with the posterior wall of pharynx.
• Impulses from the receptors pass along the
glossopharyngeal , the superior laryngeal
branch of vagus nerve and the maxillary
division of the trigeminal nerve to the
swallowing center in the medulla. Collection of
nerves are located in the 4th ventricle of brain.
• Whole process is completed in 0.5 to 0.7 secs.
34. The Esophagus
• Extending tube from the pharynx to
stomach, crosses the thorax and
perforates the diaphragm.
• Actively moves a bolus through
peristalsis
• Swallowing center in brain stimulates
successive one-directional waves of
contraction
• Sphincter opens to allow food to enter
stomach
– Humans lack a true sphincter here.
34
41. Esophagus
• Gastrointestinal tract is multi-layered
– Mucosa – innermost
• Epithelium that lines the interior, or lumen, of
the tract
– Submucosa
• Connective tissue
– Muscularis
• Circular and longitudinal smooth muscle layers
– Serosa – outermost
• Epithelium covering external surface of tract
NOTE: CAUDAL PART OF THE ESOPHAGUS
IS COMPOSED OF SMOOTH MUSCLES.
41
47. The Stomach
• Low pH in the stomach helps denature food
proteins
– Activates pepsin and keeps it functioning
• No significant digestion of carbohydrates or fats
occurs
• Absorption of some water (aspirin and alcohol)
• Mixture of partially digested food and gastric
juice is called chyme
• Peptic ulcer – commonly caused by bacteria
• Leaves the stomach through the pyloric sphincter
to enter the small intestine
47
48. GASTRIC GLANDS
• Three types of glands are present
• 1. Cardia gland 2. fundic gland. 3. pyloric gland
Mucus 1. HCL 1. mucus
2. pepsinogen 2. gastrin
.Gastric acid secretion is stimulated by
Acetylcholine( parasympathic), gastrin and
histamine( an amino acid derivatives present in
most of the body tissue.
.Normal PH 3.5 to 5 , below the PH of 2 the
inhibition of gastric secretion occurs.
49. The Small Intestine
• Consists of duodenum, jejunum, and
ileum
• Receives
– Chyme from stomach
– Digestive enzymes and bicarbonate from
pancreas
– Bile from liver and gallbladder.
– Most digestion and absorption occurs in
intestine expect those animals which
may prolong fermentation process.
49
50. • Epithelial wall is covered with villi
– Villi are covered by microvilli
– Greatly increase surface area
• Microvilli participate in digestion and absorption
– Brush border enzymes
• Many adults lack the enzyme lactase
– Have lactose intolerance
50
52. Digestive Systems
• Accessory organs
– Liver
• Produces bile( greenish yellow solution of bile salts bilirubin,
cholesterol, lecithin and electrolytes are continuously synthesized by
the hepatic cells of liver.
– Gallbladder
• Stores and concentrates bile, concentration is low in ruminants because
they eat frequently.
• Absent in horse so bile is directly entered in the duodenum.
– Pancreas
• Produces pancreatic juice
• Digestive enzymes and bicarbonate buffer
52
53. Accessory Organs
• Pancreas
– Pancreatic fluid is secreted into the duodenum through
the pancreatic duct
– Enzymes
• Trypsin and chymotrypsin – proteins into smaller
polypeptides
• Pancreatic amylase – polysaccharides into shorter
sugars
• Lipase – fats into free fatty acids and
monoglycerides
– Bicarbonate neutralizes acidic chyme
– Exocrine and endocrine gland
53
54. The Large Intestine
(colon)
• Much shorter than small intestine, but has
larger diameter
• Small intestine empties directly into the
large intestine at a junction where two
vestigial structures, cecum and appendix,
remain
• No digestion occurs
• Function to reabsorb water, remaining
electrolytes, and vitamin K
• Prepare waste for expulsion 54
56. The Large Intestine
• Many bacteria live and reproduce
within the large intestine
• Feces compacted and passed to
rectum
• Feces exit anus (defecation).
– Smooth muscle sphincter (involuntary)
– Striated muscle sphincter (voluntary)
56
57. Variations in Digestive
Systems
• Digestive tracts of some animals contain
bacteria and protists that convert cellulose
into substances the host can absorb
– Minor in humans
– Essential to some animals
• Herbivores have longer digestive tracts
– Greater time for digestion of cellulose
– Modifications to enhance digestion of plant
material
57
58. Variations in Digestive
Systems
• Rodents, horses, deer, and rabbits
digest cellulose in the cecum
– Regurgitation of contents is not possible
• However, some such animals practice
coprophagy
– Eat their feces to absorb nutrients on the
second passage of food
– Cannot remain healthy if prevented from
eating feces
58
59. Variations in Digestive
Systems
• All mammals rely on intestinal
bacteria to synthesize vitamin K,
which is required for blood clotting
• Birds, which lack these bacteria,
must consume the required quantities
of vitamin K in their diet
59
62. 62
What is a ruminant?
• Specialized
digestive system
capable of
digesting cellulose.
• Has a stomach with
4 distinct
compartments
• Cattle, sheep,
goats, deer & elk.
63. • Ruminants have a four-
chambered stomach
– Rumen, reticulum,
omasum
– True stomach –
abomasum
– Rumen has cellulose-
degrading microbes
– Contents can be
regurgitated and
rechewed
• Rumination
– Evolved only once 63
64. 64
Compartment Capacity
• Reticulum(honeycomb) 5% of capacity
• Rumen (pouch) 80% of
capacity
• Omasum (manyplies) 7% of capacity
• Abomasum(truestomach) 8% of capacity
• First three are also called forestomach
65. 65
FUNCTIONS
Abomasum Site of chemical digestion in a
polygastric digestive system.
Reticulum “hardware stomach” holding area for
foreign materials in a polygastric system.
Rumen Largest compartment of the
polygastric system, serves as a
storage area.
Omasum Muscular portion of the polygastric
system that squeezes excess
water from digested food products.
66. Accessory Organ
Function
• Liver
– Chemically modifies the substances absorbed
from the digestive tract before they reach the
rest of the body
– Ingested alcohol and other drugs are taken
into liver cells and metabolized
– Removes toxins, pesticides, and carcinogens,
converting them to less toxic forms
– Regulates levels of steroid hormones
– Produces most proteins found in plasma
66
67. 67
Vocabulary Review
Monogastric A digestive system with one
stomach compartment
Polygastric A digestive system capable of breaking
down cellulose into digestible protein
and carbohydrates. The
stomach is divided into
compartments each with a specialized
function.
Ruminant An animal with a polygastric digestive
system.
Rumination Part of the process of digestion in a
polygastric system where a bolus is
regurgitated, re- chewed and
swallowed.
68. Regulation of Food
Intake
• Control mechanism links food intake
to energy balance
– Leptin – peptide hormone
• Key to appetite control
• Produced by adipose tissue
• Leptin receptor located in hypothalamus
• Reduced leptin signals brain to intake food
• Research on leptin in humans ongoing
68
69. Regulation of Food
Intake
• Other hormones involved in the
control of feeding and energy include
– Insulin, GIP, and CCK, which signal
satiety
– Ghrelin which stimulates food intake
– Efferent control of feeding
• Neuropeptide Y (NPY) induces feeding
activity
69
70. 70
Vocabulary Review
Mastication The act of chewing where salivary
enzymes are added to food
products.
Bacterial digestion The bacterial and protozoa
action in the rumen of a
polygastric digestive system that breaks
down cellulose into digestible
carbohydrate and protein products and
synthesizes B vitamins.
Bolus Partially chewed food held in the
reticulum that is regurgitated,
chewed completely and re- swallowed.
