Lecture 8 - Avian digestion Flashcards
Major proponents of the chicken digestive tract
Crop -> proventriculus -> gizzard -> pancreas -> SI -> LI (ceca) -> cloaca
Oral/pharyngeal differences in birds
No teeth
Beak
Lots of saliva
No epiglottis
Few tastebuds
How is the esophagus distinct?
Large in diameter
What is the crop? Fxn
Esophageal pouch NOT stomach
Storage
Can have none, one, or two
What is the proventriculus
Glandular stomach
Secrete mucus, pepsinogen, acid
Storage in some species
What is the gizzard
Muscular stomach
Mechanical digestion
Use grit
How is the gizzard protected
Lined with thick cuticle (koilin)
What is koilin
CHO protein complex
Mucosal secretions solidify on surface when exposed to low pH
Protect against acid
Left vs right hepatic (liver) ducts
Left drains into duodenum
Right leads to gallbladder, then bile duct and duodenum (not all have gallbladder)
How does the SI differ
No lymphatic system; fat absorbed to blood capillaries (to liver)
Meckel’s diverticulum (yolk sac vestige)
Ileocaecal junction is circular muscle (not same as sphincter)
Describe the LI
Paired ceca (small amount feed digested here 10%)
No separation among LI, colon, rectum
SHORT
Cloacal bursa
How is glucose absorbed
Mostly in duodenum/jejunum, facilitated diffusion
How are TG packed once absorbed
Portomicrons
What happens in the cecum
Active absorption of glucose
Amino acids absorbed
What fills first after eating food
Ventriculus
What happens once the ventriculus is filled
Tonic contraction of crop relaxes
Contractions in ventriculus send back into proventriculus and into duodenum
How do birds contraction cycles work
- thin muscles of gizzard contract (2-3 peristaltic waves through duodenum)
- thick muscles of gizzard contract (1 peristaltic wave passes through proventriculus)
What is orad movement
Reflux of duodenal contents into the gizzard
Egest a pellet of bones and feather
Migrating motor complex occur in what state
Fed and fasted (pig = just fasted)
Anti-peristaltic contractions in birds
Arise from the cloaca 10-14 times/min
Not during defecation
Move urine from cloaca into colon and ceca to absorb water
When do birds stop feeding
Response to distention of gizzard
Glucose receptors in crop/intestine
Amino acid receptors in intestine
What can birds detect with regards to aa
Subtle differences in protein content and composition
e.g. methionine adequate vs excess/deficient
Birds have mucous glands in
Esophagu
Found in crop…
Bacterial fermentation
Free glucose
