Download Livestock Digestion

Livestock Digestion
Objective 12.01-12.02: Describe the
functions of the major parts of the
digestive system for ruminants and
non-ruminants.
Accessory Organs
• What is an accessory organ?
– An organ that helps with digestion but is not
part of the digestive tract. The accessory
digestive organs are the tongue, salivary
glands, pancreas, liver, and gallbladder.
Definition care of MedicineNet.com
http://www.medterms.com/script/main/art.asp?articlekey=25962
Accessory Digestive Organs
• An accessory organ of the digestive
system is the salivary glands
– Secrete Saliva
– Help soften food
– Make food easier to swallow
– Start the digestion process
Accessory Digestive Organs
• The pancreas is an elongated, lobedshaped organ.
– Made of two parts
• Exocrine
– Largest part
– Produces digestive juices
• Endocrine
– Produces insulin that goes into the blood
Accessory Digestive Organs
• The liver is another lobed-shaped organ
that is responsible for purifying blood.
– Assists in the formation of blood
– Destroys exhausted red blood cells
• Remember: red blood cells deliver oxygen
Accessory Digestive Organs
• Gall Bladder
– Empties waste
– Secretes bile
• Bile- yellow liquid that aids in digestion of lipids
– Horses don’t have a gall bladder
• Bile is mainly to breakdown fats and horses
typically ingest less fat than other animals
Digestive Organs
The Philosophy of Digestion
(partial digestion review)
• What is digestion??
– Conversion of “feedstuffs” into nutrients
• Last stage of digestion?
– Excreting unused food residues
– Fecal matter
The Philosophy of Digestion
• Digestive Processes
– Mechanical
– Chemical
– Microbial
The Philosophy of Digestion
• Mechanical Actions of Digestion
– Mastication
– Deglutition
– Regurgitation
– Motility
– Defecation
The Philosophy of Digestion
• Mastication
– The chewing of food
• Deglutition
– The act of swallowing
• Regurgitation
– Casting up undigested food from the stomach for chewing again
(cud)
• Motility
– Process of contracting or shrinking (squeezing food through
intestines etc)
• Defecation
– The elimination of fecal material from the rectum
The Philosophy of Digestion
• Microorganisms exist in the digestive
compartments of ruminants
– They break down the cellulose of plant cell
walls
– Also called roughages
The Philosophy of Digestion
• Roughages
– Cellulose of plant walls
– What makes up the majority of a ruminant’s
diet
– Gives ruminants 60%-80% of their energy
– About 60%-90% of the digestion occurs in the
rumen
The Philosophy of Digestion
• The hypothalamus glad is the gland that
controls the animal’s appetite
– Three things that affect appetite
• Level of glucose in the blood
• Amount of feed in the stomach
• Environmental temperature
The Philosophy of Digestion
• Chewing food is also called…
mastication/masticating
– This aids in the digestion process
– Breaks down and reduces the particle size of
food
– Mixes food with saliva
The Philosophy of Digestion
• What is chewing “cud?”
– Occurs in ruminants
– A cow will chew it’s regurgitated food
• Why?
– This aids in digestion
– Roughages held in the rumen can be
regurgitated and “re-chewed” to help digest
The Philosophy of Digestion
• Do poultry have teeth?
– NO!
• How do they grind their food with no
teeth?
– The gizzard, an organ used to grind and crush
food in chickens, turkeys, etc
The Philosophy of Digestion
The Philosophy of Digestion
• Enzymes are responsible for most
chemical changes in the digestive process
because they speed up the biochemical
reactions of digestion
• A few enzymes to know
– Ptyalin
– Amylopsin
– Sucrase
The Philosophy of Digestion
• Enzymes
– Ptyalin
• Breaks down carbohydrates
– Amylopsin
• In the pancreas, breaks down starches
– Sucrase
• Another enzyme to help breakdown carbs
The Philosophy of Digestion
• Which compartment was called the “true
stomach” of a ruminant?
– Abomasum
• Two enzymes in the Abomasum
Ruminant!
– Pepsin
– Rennin
» Both are activated by hydrochloric acids and help
break down proteins
The Philosophy of Digestion
Ruminant!
The Philosophy of Digestion
• More Enzymes…
– Trypsin
– Chymotrypsin
– Carboxypeptidase
• Help break down proteins into amino acids, which
are the final product in digestion
The Philosophy of Digestion
• …and More Enzymes…
– Lipase
• Breaks down fats
– Bile
• Secreted by the liver, breaks fats up
– Steapsin
• Secreted from the pancreas, finishes the break
down of fats
The Philosophy of Digestion
• In animals, minerals are dissolved in the
stomach
– The stomach contains hydrochloric acid
• Through absorption, digested nutrients
can pass from the walls of the digestive
tract into the blood
The Philosophy of Digestion
• Most absorption occurs
– Carnivores and Omnivores
• Small intestine
– Absorbed by villi in the small intestines
– Herbivores
• Large intestine
The Philosophy of Digestion
• More about Absorbing
– Lymph
• Absorbs fats
– Blood
• Absorbs carbs, proteins, water, and inorganic salts
• Digestion is complete only after absorption
has made the nutrients available for other
parts to use
Assignment
• Complete the rest of the notes by
reviewing what you already know and
using the packet that was passed out
• Most of these notes will serve as a review