Animal Nutrition Flashcards
Ingestion
is the process whereby food is taken into the mouth.
Digestion
is the process whereby food molecules are broken down into small particles
Two types of digestion
Mechanical digestion and Chemical digestion.
Absorption
is the process whereby the digested food is taken up by the blood streams
Assimilation
is the movement of food to different cells of the body.
Secretion
is the process whereby digestive juices are released by different organs of the body
Egestion/excretion
is the elimination of waste out of the body.
Examples of ruminant animals
➢ Cattle
➢ Sheep
➢ Goats
Examples of non-ruminant animals
➢ Fowl
➢ Pig
➢ Donkey
➢ Horses
Comparison of external structure of the alimentary canal of ruminants and non-ruminants
Ruminants:
➢ Polygastric
➢ Complex stomach
➢ Digest food with high quality fibre and cellulose
➢ Chew their food partially, regurgitate later and re-chew.
Non-ruminants
➢ Monogastric
➢ Simple stomach
➢ Cannot digest food with high quality fibre and cellulose
➢ Chew their food properly and swallow it once
Functions and adaptations of various structures of the alimentary canal
Alimentary canal(digestive tract or gut) :
is a long tube, divided into several regions which are specialised for; Ingestion, Digestion, Absorption and Egestion (Excretion/Elimination).
Mouth
Functions of the Mouth:
➢ Intake of food (ingestion)
➢ Grinding and chewing by teeth
➢ Secretion of saliva by salivary glands
➢ Moistening and softening by saliva
➢ Rolling, mixing and swallowing by tongue
Tongue
Functions of the tongue:
➢ rolls the food into bolus
➢ mixes the food with saliva
➢ It is a taste organ
Peristalsis
is the involuntary contraction and relaxation of muscles that pushes food through the alimentary canal
Functions of peristalsis
➢ Peristalsis occur in the oesophagus, stomach and intestines ➢ If the rate of peristalsis increases, food will move faster along the alimentary canal and less fluid will be absorbed leading to Diarrhoea
➢ If the rate of peristalsis decreases, food will move slower along the alimentary canal and more fluid will be absorbed leading to Constipation
Retro-peristalsis
Retro-peristalsis is the involuntary contraction and relaxation of muscles that pushes food back to the mouth in the alimentary canal
Pharynx
is the funnel-shaped muscular tube connecting the mouth cavity to the digestive and respiratory systems. It is enclosed by the epiglottis to prevent food from entering the trachea during swallowing.
Functions of the pharynx
➢ Exchange of gases
➢ Allows for the passage of food from the mouth to the oesophagus ➢ Connects the mouth to the oesophagus
Oesophagus (gullet)
There is no absorption of nutrients
Oesophagus is a tube-like structure that extends from the back of the throat (pharynx) to the stomach.
Functions of the oesophagus
➢ Connects the mouth to the stomach
➢ Allows the passage of food to the stomach
➢ Contain mucous membranes that secrete mucus which lubricates the food for easy passage.
Crop
There is no absorption of nutrients
is the enlarged extension of the oesophagus where food is stored, moistened and softened in fowls.
Functions of the crop
➢ Stores the food
➢ Moistens and softens the food
Stomach
Stomach is a pear-shaped, sac-like structure that store and chemically digest the food
Functions of the stomach (stomach of a pig)
Stores food temporarily
➢ Chemically digest the food
➢ Secretes mucus that protects it from acidity
(Stomach of the fowl)
Functions of the Proventriculus
➢ Secrete digestive juices
➢ Chemically digest the food
Functions of the Ventriculus(gizzard)
➢ Store food
➢ Grinds the food by small stones (mechanical digestion)
Forestomachs
Rumen, Reticulum and Omasum
Reticulorumen
Rumen and Reticulum functioning as a unit
Rumen
~Rumen is the largest compartment of the forestomach.
~Found on the left half of the abdominal cavity.
~The rumen contains large amounts of microbes; Bacteria, Fungi and Protozoa.
~The walls of the rumen is covered with finger-like projections called Papillae that increase the absorption area and act as heating rods for fermentation of crude fibre.
~No digestive juices or enzymes are secreted in the rumen.
Papillae
Finger-like projections that increase the absorption area and act as heating rods for fermentation of crude fibre.
Functions of the rumen
➢ Stores food temporarily for digestion
➢ Contains micro-organisms to break down high fibre and cellulose
➢ Provides suitable PH for functioning of rumen micro-organisms
➢ Microbial fermentation
Reticulum
~Reticulum is the smallest compartment of the forestomach.
~ It has a honeycomb shaped pattern.
~Reticulum is also called a “hardware stomach” because it is where hard objects such as nails, wires and foreign objects settle.
~No digestive juices or enzymes are secreted in the reticulum.
Functions of the reticulum
➢ Traps foreign objects such as wires, nails and stones
➢ Forms boluses for regurgitation and rumination
➢ Acts as a filter
Omasum
~The omasum has leaf-like folds (like the pages of a book).
~ The folds increase the surface area for absorption of moisture from the ingested feed.
~The inner wall of the omasum is covered with Papillae that increase the surface area
Functions of the omasum
➢ Acts as a temporary storage site and filter
➢ Break down large food particles into smaller particles
Abomasum
~Abomasum is a true or glandular stomach.
~Abomasum is the compartment of the ruminant stomach that corresponds to the simple stomach of a pig.
~Enzymatic digestion starts in the abomasum.
~Secrete hydrochloric acid which makes it to be more acidic.
Abomasum
~Abomasum is a true or glandular stomach.
~Abomasum is the compartment of the ruminant stomach that corresponds to the simple stomach of a pig.
~Enzymatic digestion starts in the abomasum.
~Secrete hydrochloric acid which makes it to be more acidic.
Functions of the abomasum
➢ Secretes digestive juices, hydrochloric acid and digestive enzymes
➢ Sends chyme to small intestines ➢ Break down food particles into simple molecules, by chemical digestion
Small intestines
is a long coiled tube that is divided into 3 parts; Duodenum, Jejunum and Ileum.
Properties of the small intestines
~Small intestines is the longest section of the alimentary canal.
~Its length increases the surface area for absorption of digested feed. ~Small intestines are also folded to increase the surface area for absorption.
~Finger-like projections called villi increase the surface area for absorption.
~Contraction and relaxation of the walls of the small intestines by peristalsis forces food to move across the small intestines
Lacteal
Absorbs digested fats
Blood capillaries
Absorb digested proteins and carbohydrates
Mocro-villi
Increase surface area
Villi
Villi are small finger-like projections of the small intestines It consists of; Blood capillaries, Lacteal, Gland of lieberkuhn, lymph vessel and micro villi
Functions of villi
(main function) absorption of digested nutrients
➢ Blood capillaries absorbs digested proteins and carbohydrates
➢ Lacteal absorbs digested fats
Suitability of villi for its function
➢ Contains blood capillaries and lacteal for absorption of digested nutrients
➢ It has finger-like projections that increase the surface area for absorption
Duodenum
Duodenum is the first section of the small intestines.
Further digestion takes place in the duodenum.
Secretions received by duodenum are; Bile, Pancreatic juice, and Intestinal juice.
The ducts that open in the duodenum are bile ducts and pancreatic ducts
Jejunum
Jejunum is located between the duodenum and ileum The villi in the jejunum are much longer than those in duodenum and ileum The small intestines also have many folds which further increase the surface area for absorption
Illeum
~Ileum is the last and longest part of the small intestines.
~It is connected to the large intestines by ileo-caecal valve Ileum
~ allows for the passage of undigested nutrients to the large intestines
Illeum
~Ileum is the last and longest part of the small intestines.
~It is connected to the large intestines by ileo-caecal valve Ileum
~ allows for the passage of undigested nutrients to the large intestines
Functions of the small intestines
➢ Absorption of water-soluble vitamins (B&C) and minerals
➢ Absorption of water and nutrients
➢ Digestion of food in the duodenum
Adaptation of small intestines to the absorption of most digested food
➢ It is long enough
➢ It has many folds
➢ It has more villi
➢ Constant peristalsis
Large intestines
Large intestine is the final part of the digestive system. Large intestines are divided into 3 parts namely; Caeca, Colon and Rectum
Functions of the large intestines
➢ Reabsorption of water in the faecal material by the caeca
➢ Dehydration of ingested matter by the caeca
➢ Fermentation of remaining available nutrients, by colon
➢ Provision of a suitable environment for bacteria to grow and reproduce by the colon
➢ Storage of undigested food by rectum
➢ Secretion of mucus to lubricate and make the passage of waste easier
Anus
Anus eliminates waste in the form of faeces
Cloaca/vent
➢ Cloaca/vent is a common opening for both digestive and urinary systems in fowls
Mechanical and Chemical digestion
There are two types of digestion namely; Mechanical and Chemical digestion
➢ Mechanical digestion is the physical breakdown of large food molecules into smaller molecules, e.g. Chewing, grinding, and churning ➢ Chemical digestion is the breakdown of food by chemical reactions such as hydrochloric acid and digestive juices
Saliva
Saliva is a thin, colourless, watery and slightly alkaline liquid.
Saliva contains enzyme salivary emylase.
Saliva is secreted by salivary glands in the mouth
Three parts of salivary glands
➢ Sublingual glands found underneath the tongue and lower jaws
➢ Submandibular glands located at the angle of the lower jaw
➢ Parotid glands found below the ears
Functions of saliva
➢ Moistening of the food and mouth
➢ Secretes ptyalin containing enzyme salivary emylase
➢ Solvent for dry food
➢ Neutralises acidity
Functions of hydrochloric acid
➢ It is anticeptic
➢ Break down food into simple soluble substances
➢ Neutralises alkaline reaction of saliva
➢ Changes the PH of the stomach into acid medium
Functions of enzymes
➢ Pepsin converts proteins to peptides
➢ Rennin converts soluble caseinogen into insoluble casein. This means it curdles milk
➢ Gastric lipase converts fats into glycerol and fatty acids
Accessory digestive organs
- Liver
- Pancreas
- Intestinal glands
Liver
Liver is the largest gland in the body It is an exocrine gland that is located above the stomach
Functions of the liver
➢ Secretes bile to the small intestines
➢ Synthesises glucose
➢ Converts glucose to glycogen
➢ Temporary storage organ for excess nutrients taken in
Bile
Bile is a bitter, yellow-green, alkaline liquid, rich in organic salts It is stored in the Gall bladder until it is required for digestion. Bile contains no enzymes but salts
Functions of Bile
➢ Digests and absorbs fats
➢ Emulsify fats
➢ Neutralise acidity
➢ It is anticeptic
Pancreas
Pancreas is a gland located between the stomach and small intestines
Which tissues does the pancreas contain
It contains both endocrine and exocrine tissues
What do the tissues exocrine pancreas and endocrine pancreas excrete
➢ Exocrine pancreas secretes pancreatic juice
➢ Endocrine pancreas is also known as islets of Langerhans, and secretes hormones
Endocrine pancreas/Islets of Langerhans
➢ Secrete hormone insulin and glucagon directly to the blood stream ➢ Insulin stimulates the conversion of glucose to glycogen
➢ Insulin promotes the movement of glucose and other nutrients out of the blood into the cells to be used as energy
➢ Glucagon promotes the movement of glucose into the blood into the blood when glucose levels are low
➢ Glucagon breaks down glycogen to glucose
Functions of the pancreas
➢ Secretes pancreatic juice
➢ Secrete hormone insulin and glucagon
Intestinal glands:
Glands of Lieberkuhn
The Glands of Lieberkuhn are found throughout the small intestines between the villi
Function of Glands of Lieberkuhn
➢ Secretes duodenal juice (succus intericus)
Brunner’s glands/Duodenal glands
Brunner’s glands are located in the Duodenum
Functions of Brunner’s glands/Duodenal glands
➢ Produce alkaline secretion rich in mucus
➢ Protects the duodenum from acidic chyme
➢ Lubricates the walls of the small intestines
Digestion in ruminants:
Ruminantion
Rumination is when food is chewed, swallowed, brought back to the mouth (regurgitation) and chewed again.
What does rumination stimulate
Rumination stimulates the secretion of saliva which is necessary for fermentation in the reticulorumen
Property of the saliva of ruminants
does not contain the enzyme salivary emylase
Rumination consists of which four processes
Regurgitation, Remastication, Reswallowing and Eructation.
The process of rumination
➢ Ruminants chew their food partially, roll it into bolus and swallow
➢ The food moves via the oesophagus by the process of peristalsis and stored in the rumen (and reticulum)
➢ In the reticulum, the food is separated into digestible material and nondigestible material (such as stones and nails)
➢ The undigested food in the reticulorumen is regurgitated back to the mouth by retro-peristalsis to be remasticated, re-chewed thoroughly and re-swallowed
➢ Very fine particles pass into the omasum and ends up in the abomasum
Regurgitation
Regurgitation is the process whereby food is brought back to the mouth by retroperistalsis to be rechewed
Regurgitation
Regurgitation is the process whereby food is brought back to the mouth by retroperistalsis to be rechewed
Eructation/Belching
is the removal of gases through the mouth
Trocar and cannula
is an instrument used to treat bloating in cattle
Young ruminants properties
➢ Young calves are NOT really ruminants when they are born
➢ The forestomachs (rumen, reticulum, and omasum) are formed but NOT fully developed ➢ During this time there are no micro-organisms in the rumen
➢ The milk provides all the necessary nutrition to the calve
➢ The milk therefore moves directly to the abomasum via the oesophageal groove
➢ Abomasum secretes rennin which curdles milk and slow it down to allow time for digestion
➢ Immature ruminants should not be fed non-protein nitrogen feeds such as urea
➢ The calve will only become a real ruminant when it is three to four months old
➢ Microorganisms only become established in the rumen when the young ruminant starts to eat solid food
➢ The development of rumen and reticulum is triggered by volatile fatty acids produced during fermentation of hay or grain
➢ Rumen microorganisms are obtained from the mother or environment
➢ The rumen gradually increases in size and starts to function its digestive processes
➢ The oesophageal groove disappears and the animal become a fully functional ruminant
REQUIREMENTS FOR NORMAL FUCTIONING OF RUMEN MICROBES
➢ Oxygen-free environment
➢ The presence of carbon dioxide
➢ Neutral PH
➢ Regular intake of feed
➢ Osmotic condition
➢ Sufficient nutrients
FUCTIONS OF RUMEN MICROBES
➢ Digestion of cellulose and hemicellulose
➢ Hydrolysis of protein
➢ Synthesis of vitamins
➢ Synthesis of amino
Which substances are found in the rumen
➢ Gases (mainly carbon dioxide and methane)
➢ The grain and roughage of the previous day
➢ The new roughage
THE END PRODUCTS OF MICROBIAL FERMENTATION
➢ Volatile fatty acids such as acetic acid, propionic acid and butyric acid ➢ Ammonia
➢ Gases (mainly carbon dioxide and methane)
ABSORPTION OF FOOD IN THE RUMEN INTO THE BLOODSTREAM
Active transport:
is the movement of nutrients against the concentration gradient.
Properties of active transport
➢ During active transport, molecules move from an area of lower concentration to an area of higher concentration.
➢ Energy is needed for active transport
➢ Energy is supplied by ATP (adenosine triphosphate).
Passive transport
is the movement of nutrients along the concentration gradient.
Property of passive transport
➢ During passive transport, molecules move from an area of higher concentration to an area of lower concentration.
