ch. 13 & 14: carnivore & avian digestion

describe prehension in the carnivore

use canine teeth for ripping and tearing

what is the role of salivary glands in carnivores

they lubricate food for swallowing, but true carnivores eat wet feed (carcasses) so they don’t really salivate too crazy much

what are the 3 salivary glands and where are they

1) parotid: underneath the ear

2) submandibular/submaxillary: either side of jaw

3) sublingual: under tongue

how does the digestive tract of an avian differ from a mammalian species?

no teeth, crop and gizzard, 2 ceca

how does the avian mouth differ from mammal

no teeth, no soft palate, small & poorly developed salivary glands, salivary amylase (little value)

what kind of digestion occurs in the mouth of an avian?

no digestion occurs

what is the crop in the avian digestive system?

the crop is a dilation of the esophagus that functions to store and moisten food

fermentation can occur here in some species (NOT DIGESTION), and it varies in size with eating habits

what is the function of the proventriculus

• the true glandular stomach

• varies in size depending on diet (eat seeds = small, eat fish = big)

• site of gastric juice production (HCl, pepsin, mucin) and a low pH

• food passes through quickly just to mix with the gastric juices

what is the function of the gizzard (ventriculus)?

• a very muscular grinding organ that holds grit (rocks and oyster shells) to grind down feed particles

• no need to excrete its own enzymes - uses those mixed into ingesta from PV

• varies in size and muscularity

  • wild species: large & well developed

  • domesticated (fed pre-ground diets): small & less developed

how does the diet of a bird impact the length of its small intestine

longer in herbivores than carnivorous

what enzyme do avians lack that mammals have

lactase

how many ceca are present in avians and what is their function?

• 2 are present a the jxn bw SI and LI

• function: some water absorption, some fiber digestion, water soluble vitamin synthesis (B vitamins)

• modern chickens do not need ceca

how does the large intestine in avians differ from mammalian species

it’s relatively short, there is no distinct rectum or colon, and there is vitamin K synthesis

what is the cloaca

common orifice for feces and urine, copulation, and egg laying