Animal Nutrition Exam 3

What is Ptyalin?

Salivary amylase, only found in pigs.

What is the purpose of Ptyalin?

Starts breakdown of starch, of little value due to minimal time food spends in mouth.

Swine Saliva

• pH of 7.4 moistens feed and helps in chewing and swallowing

• Produced by 3 pairs of glands (parotid, mandibular, and submaxillary)

• Ptyalin

What is the source of the three parts of gastric juices?

Neck cells, parietal cells, and chief cells.

Where are the three gastric juices produced?

Mucin - Neck Cells

HCl - Parietal Cells

Pepsin - Chief Cells

What is the function of the three parts of gastric juices?

Mucus - protection

HCl - protein digestion

Pepsin - protein digestion

Where does protein digestion start?

Stomach

Where does protein digestion finish?

SI

What is the function of the small intestine?

Continue process of digestion and start absorption

Swine Stomach Facts

Capacity is about 2 gallons and it requires about 24hrs to empty

Swine Small Intestine Facts

About 60ft in length and 2.5 gallons.

How does the small intestine complete its funciton?

By using pancreatic juices, bile, duodenal juice, and movement of intestinal wall.

What juices, etc are chemical, mechanical, or enzymatic?

Enzymatic - Pancreatic juice, duodenal juice

Chemical - Bile

Mechanical - Movement of intestinal wall

What is the function of the pancreas?

Produce juices, buffers, and insulin.

What is the function of pancreatic juices?

Enzymes for proteins, fats, and CHO

Buffers

Insulin for CHO metabolism

Protease enzymes in protein digestion produced from the pancreas.

Trypsin, chymotrypsin, carboxypeptidase, and aminopeptidases (this one is brush border of SI).

Trypsin

• Not used for first 24hrs

• Initially secreted as trypsinogen activated by Ca ions and enzyme enterokinase from brush border

• Breakdown proteins into amino acids and peptides

Why is trypsin not used for the first 24 hours?

Cholostrum has trypsin inhibitors.

Chymotrypsin

• Secreted as chymotrypsinogen, activated by trypsin

• Breakdown proteins to petides and amino acids

Carboxypeptidase

• Secreted as procarboxypeptidase, activated by trypsin

• Acts on peptides, breakdown to amino acids

Aminopeptidases

Acts on small peptides, breakdown to amino acids

What is the role of bile in fat digestion?

• Emulsifies fat

• Digestion and absorption of fat

• Aids in absorption of fat soluble vitamins

• Activates lipase

What is the role of pancreatic lipase in fat digestion?

• Converts fats into fatty acids and glycerol

• Action most effective after fats have been emulsified by the bile

How are carbs digested in swine?

Pancreatic amylase and brush border enzymes.

What does pancreatic amylase do with starch?

Converts starch to maltose.

What are brush border enzymes?

Maltase, sucrase, and lactase.

Maltase

Converts maltose to glucose.

Sucrase

Converts sucrose to glucose and fructose

Lactase

Converts lactose to glucose and galactose

Large Intestine Facts

16ft in length and a capacity of 2.5 gallons. Cecum is about 10ft long and a capacity of 0.5 gallons. Colon is about 16ft long and a capacity of 2 gallons.

How is protein digested in swine?

By using protease enzymes.

What makes up the large intestine?

Colon and cecum that terminates as rectum and at the anus.

What is the function of the large intestine?

Absorb water, VFA, and act as reservoir for waste materials.

Describe prehension in the carnivore.

Canine teeth - ripping/tearing

Molars - mastication

What is the role of the salivary glands?

Lubrication of food.

How does the stomach differ for canines?

High pH, no salivary amylase, and a small cecum.

How do the intestines differ for canines?

Contains aminopeptidase in SI. Electrolyte and water absorption in LI. Has an ascending and descending colon.

How does the physical and chemical digestion function in the stomach, SI, and LI in carnivores?

Stomach has HCl and pepsin. Performs chemical, enzymatic, physical, and mechanical digestion.

SI has enterokinase, aminopeptidase, lactase, sucrase, and maltase.

LI does water and electrolyte absorption.

How does the cecum differ in carnivores v ruminants?

It is not well developed.

How does the digestive tract of avians differ from mammalian species?

They have a crop, gizzard, two ceca, vent, proventriculus, and ventriculus.

How does the mouth differ in avian than mammalian species?

They have no teeth, no soft palate, small and poorly developed salivary glands, salivary amylase, and no digestion here.

What type of digestion occurs in the mouth of avians?

None.

The esophagus and avians.

Connects mouth to proventriculus. Dilation = crop.

What is the role and function of the crop?

Primary: Food storage

Others: Dilation of esophagus, moistens food, fermentation in some species, and varies in size with eating habits

Proventriculus aka what?

Glandular stomach.

What is the role and function of the proventriculus?

• Comparable to glandular stomach in mammals or abomasums in ruminants

• Varies in size (fish-eating = large)

• Site of gastric juice production (HCl, pepsin, mucin)

• Low pH

• Ingesta passes through rapidly

Ventriculus aka what?

Gizzard

What is the role and function of the ventriculus?

• Grinding organ, very muscular

• Varies in size and muscularity by species

• Grit for grinding feed particles (rocks and oyster shells)

• No enzymes secreted; but enzymes from PV work here

Variety in size and muscularity by species of ventriculus.

• Large and well developed in wild species

• Small and less developed in species consuming pre-ground diets

How does the SI in avians differ from mammalian species?

Generally same enzymes, but no lactase.

Longer in herbivorous than carnivorous birds.

How is the SI in avians similar to mammalian species?

Same fxns in digestion and absorption.

How many ceca are present in avians?

Two

What is the function of the cecum/ceca in avians?

Water absorption, fiber digestion, and water soluble vitamin synthesis.

Cecum/ceca facts for avians.

Size influenced by diet (larger for high fiber diets)

Modern chickens do not need this/these

How does the LI in avians differ from mammalian species?

Relatively short, no distinct rectum or colon, and vitamin K synthesis

How is the LI in avians similar to mammalian species?

Water absorption

What is the cloaca?

Orifice in avians.

What is the function of the cloaca?

Orifice for feces and urine, copulation, and egg laying in females.

What is the main function of the ruminant stomach?

Utilize the largest CHO source in the world as an energy source. Produce food and other products.

How does the dentition of cattle vary from swine?

No upper incisors but they contain a dental pad.

What is the role of saliva in ruminants?

Moistens food, more importantly provides buffer, and microorganisms produce Volatile Fatty Acids.

What are the four compartments of the ruminant stomach?

Rumen, reticulum, omasum, and abomasum.

What is the contents of the rumen?

Contents are about 20% of the body weight.

Volume: 60 gallons of liquid and 50lbs of dry material.

What is the true glandular stomach?

Abomasum. It’s lined with mucous membrane and gastric juice is secreted.

What are collectively termed as the forestomachs?

Rumen/reticulum and omasum.

What is the lining of the forestomachs?

Stratified squamous epithelium. Not glandular and no secretions.

Rumen Function

Main function: Act as site for anaerobic bacterial fermentation

Undeveloped at birth (sterile), partially developed at 4-6 weeks of age, 1st place food goes in adult.

Some nutrients bypass anaerobic fermentation.

Rumen Anatomy

Wall covered with papillae.

Rumen + Storage of Food

Consume large amounts to digest later.

• Regurgitation, mastication, etc.

• Forage processing machines.

What is the microbial population of the rumen at birth?

None - sterile.

What is the role of papillae?

Small finger-like projections, increase surface area, influence by diet and season.

Where is papillae found?

Rumen.

What is the esophageal groove?

Aka reticular groove

Groove which can contract and form tube to bypass rumen/reticulum

Empties into omasum

What is the function of the esophageal grove?

Allow milk to pass directly to omasum and abomasum. Keeps milk out of young ruminant’s undeveloped rumen.

What is the function of the reticulum?

Site of microbial action and absorption of VFAs.

Pacemaker for rumen contractions.

• Contractions start in reticulum spread to rumen and mixes rumen contents

Reticulum Anatomy

Honey Comb

Heavy particles move to bottom, light ones float.

Lighter ones subject to rumination.

What is rumination?

Regurgitation, remastication, resalivation, reglutition.

What is the function of the omasum?

Unclear

Some water and VFA absorption, some mechanical digestion from lamina, and regulates particle size flowing to abomasum/SI.

Omasum Anatomy

“Many plies”

lamnia propia

What is the function of the abomasum?

Secretions

• HCl - denatures protein, but also kills MCO

• Mucin, pepsin, etc.

The abomasum is also called what?

True stomach

Describe post gastric fermentation.

• 5-15% of cellulytic digestion can occur in colon and cecum

• MCO here as well but lost in feces, lose MCO protein

• VFAs produced and can be absorbed through LI

• Water absorption

Where are VFA’s produced?

LI

Where are VFA’s absorbed?

LI

What are the impacts of heat produced during the fermentation process?

Useful in winter and detrimental in summer.

What gases are produced during fermentation?

65% CO₂

25% CH₄

7% N₂

Some O₂, H₂, H₂S

Explain lipid fermentation.

• MOs saturate otherwise unsaturated fatty acids

• Reason ruminants deposit saturated fat

• Excessive fat levels decrease fiber digestion (>10% diet and coats feed which hinders microbial attachment and degradation of cellulose)

Rumination Process

Set of steps that reduce particle size of digesta for passage to lower tract.

Define the four steps of rumination.

1. Regurgitation - Bolus moved by reverse contraction of esophagus from rumen to mouth

2. Remastication - Reduce particle size

3. Resalivation - Buffer and nitrogen recycling

4. Reglutition

How many steps of rumination are there?

Four

What is produced during eructation and at what volumes?

Gases

Hydrogen, carbon dioxide, methane (CH4), and hydrogen sulfide (H2S)

What problems can occur during eructation?

Bloat and rumen acidosis.

What causes bloat?

Primarily cuased by inability to erucate (froth and foam)

Secondarily cuased by something wrong anatomically

Commonly seen distention of left side

Legumes, barn door left open

What are the impacts of bloat?

Tx & preventin: Trochar and lonophores

What is rumen acidosis?

Lactic acidosis due to high levels of concentrate (corn) in diet.

What causes rumen acidosis?

• Rapid increase in grain in diet

• Rapid change from forage to concentrate

• “Barn door left open”

• Grazing residue crop

• Improper ration balancing and/or management

Changes in lactic acid producing bacteria due to rumen acidosis.

• Due to increase in reality available CHO source

• pH decreases to 4.5 to 5

• pH decrease kills of good MOs

• Lower pH goes sicker the animal gets

What is the impact of rumen acidosis?

Decrease intake, abdominal pain, dehydration (sunken eyes, staggers, coma, death) and laminitis.

Rumen Acidosis - Physiology

• Acid absorbed lowers blood pH

• Keratinization of rumen wall

• Osmotic changes - influx of water into rumen

• Dehydration and damage to rumen wall

Rumen Acidosis - Management

• Have adequate roughage in diet

• Adapt animals to new diets slowly

• Feed buffer

• Liver abscesses - abx (tylan and chlortetracycline)