5A. Digestion Flashcards
What is the role of the mouth in pig digestion?
- Grabbing of feed:
- Slurry of fluid taken up by suction - Fine materials taken up by tongue - Tongue and teeth help to shear off parts from larger pieces - Grinding action of the teeth: This action helps break food particles into smaller pieces.
- Saliva addition: secrete a combination of serous (thin fluid) and mucous (viscous) saliva
Describe the regions and functions (5) of a pig’s stomach.
- oesophageal
- cardiac
- fundic
- pyloric regions.
- The stomach is a glandular organ that performs these functions:
- Produces HCl to lower stomach pH to 2-3
- Produces mucus
- Produces the enzyme, pepsinogen
- Storage: This allows for opportunistic eating and ranges from 30 ml in newborns to 5 liters in adult pigs.
- Mechanical reduction of feed particles: The stomach continuously contracts and churns feed, breaking it into smaller particles for release into the duodenum.
- Secretion: The stomach secretes mucus, which has a protective function.
What is the function of hydrochloric acid in the stomach?
lowers the pH of the stomach to 2–3
1. Denaturing proteins, which exposes the peptide body to proteolytic enzymes
2. Destroying microorganisms ingested with the feed
3. Activating the proenzyme pepsinogen to pepsin
Describe the small intestine of a pig.
- A complex tube that lies in a spiral, allowing it to fit in a small space.
- Primary site for the digestion and absorption of nutrients.
- 3 parts:
- Duodenum (5%): This is the mixing site of digesta from the stomach with intestinal, pancreatic, and liver secretions.
- Jejunum (90%)
- Ileum (5%)
What are the roles of the liver, gallbladder and bile in digestion?
- Liver: The liver secretes bile.
- Gall bladder: The gall bladder stores bile.
- Bile: Bile enters the duodenum and aids in the digestion and absorption of fat by emulsifying fat globules. This emulsification increases the surface area of fat exposed to enzymes.
What disease can cattle get in their liver
Liver Fluke
- wet conditions where they ingest mud snail
What are the functions of the pancreas in digestion?
The pancreas produces pancreatic juice, which contains:
1. Alkaline buffer:
2. Exocrine secretions: An array of enzymes for digesting carbohydrates, fats, and proteins.
3. Endocrine secretions: These secretions include hormones like insulin and glucagon and releases hormones into the bloodstream
What are the main functions of the large intestine in pigs?
- Absorption of water: This is the primary role of the large intestine.
- Digestion: A small amount of digestion occurs in the large intestine.
- Compaction of indigestible materials: The large intestine compacts indigestible materials in preparation for elimination.
- Microbial growth: The sacculated structure of the colon allows microbes to dwell in sacs, avoiding being washed away with digesta. This leads to limited VFA production and some B vitamin synthesis.
Describe the digestion of proteins, fats, and starch in pigs.
Proteins:
* Stomach: Protein is broken down into peptides by the enzyme pepsin.
* Small intestine: Peptides are further broken down into amino acids by peptidases. The small intestine is the main site of amino acid absorption.
Fats:
* Small intestine: Fats are broken down into fatty acids by pancreatic lipases, aided by bile salts.
Starch:
* Mouth: Starch is initially broken down into maltose by amylase in saliva. Starch is the highest energy source in pigs
* Small intestine: Maltose is further broken down into glucose by pancreatic amylase and maltase. The small intestine is the main site of glucose absorption.
What are some metabolic disorders associated with pigs?
- Protein deficiency: This occurs due to suboptimal intake of specific amino acids.
-
Fat deficiency:
1. linoleic acid - essential fatty acid - lead to hair loss, dermatitis, and an unthrifty appearance. -
Mineral deficiency: Examples include:
1. Calcium and/or phosphorus = in rickets
2.. Iodine = hairless, weak, or stillborn pigs
3. Iron and copper deficiency = anemia -
Vitamin deficiency:
1. Vitamin E = poor immunity and reproduction
2. Vitamin D = rickets, stiffness, and weak and bent bones
3. Vitamin K = reduced blood clotting
4. Niacin deficiency = digestive disturbances and scours
What are gastric ulcers, and what factors contribute to their development in pigs?
Gastric ulcers are lesions in the stomach lining, specifically in the area surrounding the esophageal opening. They typically occur in pigs from weaning onwards, with the highest prevalence observed from 55 kg to market weight. Factors contributing to gastric ulcers in pigs include:
* Feed particle size: Feeding finely ground feed (particle size < 400 µm) is associated with a higher risk of ulcers.
* Pelleted rations: Pelleted feed, potentially due to the finely ground ingredients used, may contribute to ulcer development.
* Diet composition: Concentrated, nutrient-dense diets that are low in fiber
* Stress: Various stress factors like anxiety, fear, pain, fatigue, crowding, fasting, prolonged transportation, social stress from mixing with unfamiliar pigs, poor air quality, etc., are frequently suggested as contributing factors to gastric ulcer development.
* Seasonal effects: A greater occurrence of ulcers in hot, summer months may be related to inconsistent feeding behavior or stress associated with access to water.
Describe the digestive system of a horse - stomach
Stomach:
1. 9-15 liters
2. Performs both mechanical churning and enzymatic digestion.
3. Enzymes: ¤ Pepsin for protein digestion ¤ Amylase for starch digestion
4. Diet and environment play a role in stomach health: High grain, low meal frequency, and environmental stress (e.g., stall vs. pasture) can increase the risk of gastric ulcers.
Describe the digestive system of a horse - small intestine
Small Intestine:
1. Muscular tube, 15-22m long, with a capacity of 55-70 liters.
2. Comprises the duodenum, jejunum, and ileum.
3. Performs enzymatic digestion.
4. Primary site of protein digestion and amino acid absorption.
Describe the digestive system of a horse - hindgut.
Hindgut:
1. Includes the cecum, large colon, small colon, rectum, and anus.
2. Represents 62% of the digestive tract, 7m long, with a capacity of ~150 liters.
3. Digestion is largely microbial.
4. Functions: ¤ Bacterial fermentation of fiber and undigested starches ¤ Absorption of water and electrolytes.
What is coprophagia in horses?
Coprophagia is the consumption of feces. While it might seem unusual, it’s a normal behavior observed in:
* Foals: Most common in the first two months of life
* Adults: Can occur in adults deficient in protein or minerals
* Harmful effects: While coprophagia can be a source of certain nutrients, it can also introduce harmful infections with parasites
Outline the digestion process of proteins, fats, and starch in horses, including the role of the cecum and colon.
Proteins:
* Stomach: Protein is broken down into peptides by the enzyme pepsin.
* Small Intestine: Peptides are further broken down into amino acids by peptidases.
Fats:
* Small Intestine: Fats are broken down into fatty acids and BMG (beta-monoglycerides) by pancreatic lipases, aided by bile salts.
Starch:
* Small Intestine: Starch is broken down into glucose by pancreatic amylase and maltase.
Fiber (Cellulose, Hemicellulose):
* Cecum and Colon: Fibrous residues are fermented by microbial enzymes, producing: ¤ VFAs (acetate, propionate, and butyrate) ¤ Microbial protein
Explain the structure and functions of the esophagus and crop in the avian digestive system.
Esophagus:
* Structure: The upper esophagus contains many mucous glands.
Crop:
* Structure: The crop is an enlargement of the esophagus forming a ‘sac’.
* Functions: ¤ Storage of food ¤ A small amount of microbial fermentation occurs in the crop.
