Agricultural Science Grade 12

• Animal nutrition


  The foods consumed by animals and how it is digested to help to keep the body of an animal healthy and warm
• Differences between Ruminants and non-ruminants

  • Ruminant: has a complex stomach with four compartments
  • Non-ruminant: has a simple stomach with less than four compartments
• Differences in feed utilized

  • Ruminant: can feed on roughages and utilize urea
  • Non-ruminant: cannot feed on roughage and cannot utilize urea
• Alimentary canal of a pig (non-ruminant)
• Digestive glands and digestive juices

  • Salivary gland (3 pairs) - Saliva
  • Gastric glands - Gastric juice and Hydrochloric acid
  • Gland of Lieberkuhn - Succus entericus
  • Liver - Bile
  • Pancreas - Pancreatic juice
• Cardiac region


  Secretes mucus to protect stomach linings against Hydrochloric Acid
• Pyloric region


  Controls the exits of foods
• Fundic region


  Secretes Hydrochloric Acid, renin and pepsin
• Digestive enzymes and pH content of a pig

  • Salivary amylase - Alkaline pH
  • Renin & pepsin - Acidic pH
  • Sucrase, maltase, lipase, trypsin - Small intestine
• Functioning of parts of alimentary canal of a pig

  • Mouth - Intake of food
  • Oesophagus - Transport food
  • Stomach - Temporal storage
  • Small intestine - Absorption
  • Large intestine - Absorption of water
  • Anus - Expel waste
• Processes taking place in the alimentary canal of a pig

  • Mouth - Ingestion, mechanical digestion, chemical digestion, mastication
  • Stomach - Chemical digestion
  • Small intestine - Absorption, assimilation, chemical digestion
  • Large intestine - Microbial fermentation
  • Anus - Egestion/excretion
• Adaptation of different parts of the alimentary canal of a pig

  • Mouth - 3 pairs of salivary glands
  • Oesophagus - Muscles, cardiac sphincter
  • Stomach - Pear shape, pyloric sphincter
  • Small intestine - Long, folded, villi
• Alimentary canal of a fowl (non-ruminant)
• Functioning of different parts of alimentary canal of a fowl

  • Beak - Collect food
  • Crop - Moistening, soaking, softening, storage
  • Gizzard - Grinding
  • Small intestine - Absorption
  • Liver - Secrete bile, store glucose and fat soluble vitamins, detoxify
  • Large intestine - Absorption of water
  • Cloaca - Expel urine and faeces
• Processes occurring in different parts of alimentary canal of fowl

  • Beak - Ingestion
  • Oesophagus - Peristalsis
  • Crop - Moistening
  • Proventriculus - Chemical digestion
  • Ventriculus - Mechanical digestion
• Adaptation of different parts of the alimentary canal of a fowl

  • Ventriculus - Muscular, contains stones for grinding
  • Proventriculus - Secretes renin and pepsin
  • Cloaca - Urogenital
• Alimentary canal of a ruminant
• Pathway of food in the alimentary canal of a ruminant

  • Food moves from oesophagus to rumen

  2. Food regurgitates from reticulo-rumen to mouth for re-chewing

  3. After re-chewing, food moves back through retro-peristalsis into omasum and abomasum
• Functioning of different parts of alimentary canal of ruminants

  • Mouth - Intake of food

  Oesophagus - Transport food

  Stomach - Temporary storage, 4 compartments (rumen, reticulum, omasum, abomasum)

  Small intestine - Absorption

  Large intestine - Absorption of water

  Anus - Expel waste
• Processes taking place in different parts of alimentary canal of ruminants

  • Mouth - Ingestion, mechanical digestion

  Oesophagus - Peristalsis

  Rumen - Microbial digestion, heat production

  Reticulum - Storage of foreign objects

  Omasum - Water absorption, grinding

  Abomasum - Chemical digestion
• Adaptation in different parts of alimentary canal of ruminant

  • Mouth - 3 pairs of salivary glands, acidic pH, no enzyme

  Oesophagus - Cardiac sphincter, muscles

  Rumen - Largest compartment, papillae for heat production, microorganisms
• Functions of rumen microorganisms

  • Digestion of cellulose/roughage

  Digestion of starch

  Digestion of protein

  Synthesis of microbial protein

  Production of volatile fatty acids
• Population of bacteria in the rumen

  • Cellulolytic bacteria
  • Amylolytic bacteria
  • Proteolytic bacteria
• Cellulolytic bacteria


  Digest cellulose
• Population of cellulolytic bacteria


  Increases with increase in cellulose intake
• Cellulase


  Enzyme secreted by cellulolytic bacteria
• Amylolytic bacteria


  Digest starch
• Population of amylolytic bacteria

  Increases with increase in starch intake
• Maltase


  Enzyme secreted by amylolytic bacteria
• Proteolytic bacteria


  Digest protein
• Population of proteolytic bacteria

  Increases with increase in protein intake
• Rumen bacteria are very sensitive to feed changes, therefore frequent and sudden changes in diet may disturb rumen functions
• Digestion of cellulose/roughage by rumen micro-organisms

  1. Digest cellulose to form fatty acids, carbon dioxide and methane

  2. Over accumulation of methane can cause animal to bloat
• Synthesis of vitamin by rumen micro-organisms

  Can make vitamin B and K
• It is not important to include vitamin B Complex and vitamin K in the feed of ruminant
• Synthesis of protein by rumen micro-organisms

  Break large protein molecule into amino acids (smaller compound)
• Digestion of starch by rumen micro-organisms

  Digest starch into maltose (simpler substance)
• Requirements for rumen micro-organisms / Ideal conditions for rumen micro-organisms

  • Suitable pH (pH 6.4)
  • Suitable temperature (warm temperature between 39°C and 40°C)
  • Sufficient nitrogen (micro-organisms need nitrogen from urea to form protein)
  • Regular intake of food
  • Oxygen-free environment
• Reticulum


  Honeycomb stomach or hardware stomach, where foreign objects are stored
• Omasum


  Leaf stomach, has many folds that help in water absorption and grinding of food