Young Ruminants: Essentially monogastric – only abomasum is functional

3 weeks: Rumen begins to become fumctional

3 months: (4 mo.) fully functional

Esophageal Groove: muscle, during first 3-4 months of life active. Nursing stimulates it closing – milk by-passes rumen and goes into abomasum.

Terms

Regurgitate: to cast up "digested" feed to the mouth

Ruminate: Regurgitation, chewing, reswallowing

Eructate: Elimination of gas via belching

Gas produced by bacteria and protozoa

CO₂ and CH₄

Bloat = inability to expell gas

Swallow

Regurgitate

Chew bolus

Swallow

Another bolus regurgitated

Nonruminant Herbivore Digestion/Absorption

Mouth (see monogastric)

1. Food acquisition

2. Mechanical breakdown - mastication

3. Saliva

Esophagus - transportation

Stomach (see monogastric)

Small Intestine (enzymes from SI and Pancreas) – See Monogastric

Large Intestine

Cecum ~same as rumen, a pocket off of the LI

CP – already digested and Absorbed

Starch - already digested and Absorbed

Cellulose – VFA produced and some absorbed

B vitamins synthesized, but not absorbed in cecum

L.I. = H₂O absorption (minor mineral and H₂O soluble vitamins)

Pre-gastric VS. Post-gastric digestion of cellulose

Poultry Digestion/Absorption

Mouth (beak)

1. Food acquisition – no teeth

2. Poorly developed salivary gland

Esophagus - transportation

Crop – part of esophagus – ingesta holding and moistening, some species have a little fermentation

Proventriculus – ingesta passes through quickly

Gastric juice produced - HCl & pepsinogen

Ventriculus = Gizzard – very muscular to contract for physical ¯ particle size

Contains stones (grit) to assist in this physical breakdown

No enzymes, but HCl and pepsin from Proventriculus

Small Intestine – see monogastric

Enzymes ?? Lactase??

Ceca – 2 "cecums" – same as in horse, but not as extensively used

Large Intestine – see monogastric

Feces and urine (uric acid) are both excreted through same opening (vent)

The Pancreas

Two types of tissue

Acini = secrete the various digestive enzymes

Islets of Langerhans = secrete hormones – two types of islet cells

a = secrete glucagon

b = secrete insulin

glucagon and insulin are antagonistic, play key roles in blood glucose concentration

The Liver

Gland: largest and probably the most important gland in the body

Functions:

Bile synthesis = emulsifies fat – allows for digestion and absorption

Glucose regulation (blood)

Glycogen – storage and release (animal starch)

Gluconeogenesis – synthesis of glucose

Deamination of AA = remove amino group from aa, be used for energy – N goes to Urea cycle

Fatty Acid synthesis – from CHO and protein

Formation of ketones

Formation of lipoproteins, phospholipids, & cholesterol

Storage = Vit. A, ~D, B12 , Fe

Detoxification = first place nutrients from SI go to via blood, toxins detoxified (hopefully)

Formation of plasma proteins = fibrinogen, prothrombin, (blood clot formation)

Degradation and Excretion of Hormones = steroid hormones, cholesterol

Bile

Produced = continuously by the liver

Stored = gall bladder

Secreted = into SI as ingesta enters from the stomach (cholecystokinin)

Functions

Fat Emulsification = detergent action (break down particles (globules)

Fat Absorption = fat and fat soluble vitamin absorption

**Increase fat solubility in water