Digestion in monogastric animal and hormonal control

1. DR.SOURABH KANT , I.V.R.I. ,- IZATNAGAR, INDIA

2. What is Digestion
 Digestion is the breakdown of food into smaller components that can be
more easily absorbed and assimilated by the body
 These smaller substances are absorbed through the small intestine into
the blood stream
 Digestion is a form of catabolism that is often divided into two processes
based on how food is broken down:
1. Mechanical digestion
2. Chemical digestion
 Mechanical digestion refers to the physical breakdown of large pieces of
food into smaller pieces which can subsequently be accessed by digestive
enzymes.
 chemical digestion, enzymes break down food into the small molecules the
body can use

4. Monogastric animal different from Ruminant animal
I. A monogastric organism has a simple single-chambered stomach
II. In ruminantorganism, like a cow, goat, or sheep, which has a four-chambered complex
stomach
III. Monogastrics cannot digest the fiber molecule cellulose as efficiently as ruminants
IV. No rumination like ruminant animal
V. A monogastric digestive system works as soon as the food enters the mouth
VI. Saliva moistens the food and begins the digestive process.
VII. After being swallowed, the food passes from the esophagus into the stomach, where
stomach acid and enzymes help to break down the food
VIII. While in ruminant,it undergo degradation by means of microbe like
protozoa,bacteria,fungus
IX. Bile salts stored in the gall bladder empty the contents of the stomach into the small
intestines where most fats are broken down. The pancreas secretes enzymes and alkali to

5. Consist of 6-main parts:
1. Mouth
2. Esophagus
3. Stomach
4. Small Intestine (SI)
5. Large Intestine (LI)
6. Supportive organs
a. Liver
b. Pancreas
c. gall bladder

6. Digestion in Mouth
1-Receive feed with the help of Lips,
teeth and tongue help in prehension
2-Saliva secretion
3-paired saliva glands in the mouth
i. Parotids gland
ii. Submandibular (submaxillary) gland
iii. Sublingual gland
4-Digestion
- Mechanical (chewing)
- Enzymatic (α-amylase → starch digestion)
Food taste
5- tasted buds

7. Composition and Function of saliva(mouth)
Composition-
99% water
Mucus → lubrication aid for swallowing
Bicarbonate salts (Na) → buffer to regulate pH of stomach
Amylase enzyme in some species
Human-strong activity
Pigs- limited
Horses- not exist
Function of Saliva
1.Lubricant
2. Protection of membranes in mouth
3. Digestion (amylase)
4. Thermoregulations (dogs-panting; cats-grooming

8. Factors affecting saliva production
1. Feed intake
as intake increase → saliva flow ↑
2. Feed moisture content
wet feed → ↓saliva
3. Diet composition (fiber)
fiber increase chewing → saliva flow ↑
4. Health
5.Healing power

11. Esophagus
Hollow muscular tube lined with mucosal cells that transport ingesta from the mouth to
stomach
Peristaltic muscular contractions
Cardiac valve (sphincter) at the end of esophagus prevent ingesta from moving back

13. Size and various enzyme in stomach
Size vary between species
Human: 1.5 L (20% of human GI relative capacity)
Pigs: 7.9 L (30% of pigs GI relative capacity)
Horses: 18.2 L (9% of horses GI relative capacity)
Secretions in the stomach (gastric Juices)
1.Hydrochloric acid (HCL)
2. Pepsinogen
3. Mucus
1.Hydrochloric acid (HCL)
Lowers stomach pH = 1-3
Low pH cause:
a. Initiate protein digestion (denaturation)
b. Activate a protein digestive enzyme (pepsin)
c. Kill pathogenic bacteria in ingested feeds

15. Contd….
2.Pepsinogen
-inactive proteolytic enzyme
- conversion to pepsin (active proteolytic enzyme) requires HCL (low pH condition)
3.Mucus
- Protecting stomach wall from acid and pepsin
- Malfunction → Ulcer
- No absorption of nutrients in the stomach
- Materials leaving the stomach called Chyme
Functions of Stomach
1. Storage of ingested feed (control flow)
2. Reduce feed particle size through its muscular movements
3. Initiate protein digestion
4. Secretions of gastirc juices

16. Liver
1.Bile synthesis
2. Site for urea formation
3. Detoxification of harmful compounds
4. Storage of CHO (glycogen) and vitamins
5. Synthesis of glucose
6. Synthesis of cholesterol and triglycerides
7. Synthesis and degradation of amino acids

17. Bile
Bile Synthesis(Liver Function)
-Made in the liver
- Stored in gallbladder
-Secreted bile enters duodenum
(small intestine)
via duct (bile duct)
Bile Function(Liver Function)
a.Emulsification of fats to facilitate lipids
b.digestion and absorption in small intestine
Activate pancreatic lipase enzyme

19. Contd….
Assist in CHO, proteins and lipids digestion in small intestine
Pancreatic secretions enter duodenum (small intestine) via duct
Pancreatic secretions:
1.Digestive enzymes:
2. Bicarbonate (buffer)
3. Hormones
Digestive enzymes
a. Amylase → digest starch
b. Trypsin
c. Chymotrypsin
d. Carboxypeptidase
e. Neuclease
b - e → involve in proteins digestion
f. Lipase → digest lipids
g. cholesterol esterase → digest cholesterol

20. Contd…
Bicarbonate (buffer)
- Neutralize small intestine pH
- Enzymes require pH > 6.5 to function in small intestine (duodenum)
- Pancreatic enzymes and bicarbonate are made in pancreas → released into duodenum (small
intestine) via duct.
Hormones
a. Insulin
b. Glucagon
- Released into blood
- Regulate (maintain) blood glucose level
High blood glucose → insulin release →↑ glucose uptake by cells and also increase glycogen
synthesis
Low blood glucose → ↑ glucagon release →
a. breakdown glycogen to glucose
b. increase synthesis of glucose from AA

23. Contd…
Different part of Small Intestine (SI)
1. Duodenum
2. Jejunum
3. ileum
Duodenum
- First section of SI ,Shortest section
- Main site for CHO, protein and lipid digestion
- pH = 6.0-6.5
- Digestion accomplished by secretions from:
a. Pancreas (enzymes and buffer)
b. Duodenal wall (enzymes)
c. Liver (bile)
Duodenal wall secretions
-Enzymes
1. Maltase 2. Sucrase 3. Lactase 4. Aminopeptidase
5. Dipeptidase help in protein digestin

24. Contd….
Jejunum and ileum
Jejunum = Middle section
Ileum = Last section
Jejunum & ileum are the main site for nutrients absorption (AA, glucose, FA, vit & minerals)
Walls of lower intestine are folded and lined with villi (fingerlike projections) → help in ↑ing
surface area
Each villi has minute projections called microvilli → more ↑ in surface area
Absorption in SI
1. Passive diffusion
2. Facilitated diffusion
3. Active absorption

25. Passive diffusion
from high to low concentration
eg. minerals, water
Facilitated diffusion
-from high to low concentration
but use carrier proteins in intestinal
surface
- eg. Vitamins
Active absorption:
-from low to high concentration
- requires energy and specific
carrier proteins
eg. Glucose and amino acids

27. Contd….
Sections of LI
1.Cecum
2. Colon:
3. Rectum
Cecum
-first section of LI
- Contain active bacteria similar to rumen bacteria
- Fermentation site
Monogastric animals however, don't benefit from these vitamins and bacterial protein
Colon:
Storage site
water absorption (also some minerals absorption)
No absorption of amino acids and sugars

28. Contd…..
Rectum
last section of LI functions
1. Fiber digestion
- Digestion by bacteria inhabiting the cecum
(very limited in monogastric animals except in horses)
- End-products of fermentation
(VFA, B-vits, bactereial protein) have little use.
2. Absorption
- water (mainly)
- very limited absorption of nutrients
(feedstuff or microbial origin)
- No AA or glucose absorption

31. Thanks