Lecture 13 - Avian and Hindgut Digestive Systems
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How is the Avian Digestive System Different from other systems?
• birds don’t have teeth • have poorly developed salivary glands (traces of salivary amylase, minimal carbohydrate digestion before small intestine)
What is the crop?
The holding site for ingested feed • created crop milk • in birds that eat high fiber diets : microbial digestion
How is chemical and mechanical digestion separated in birds?
It is separated into the proventriculus and the ventriculus
What is the ventriculus?
Area specialized on mechanical digestion • thick, muscular wall: physical reduction of particle size (muscular contraction) • no enzymes secreted (chemical digestion here is a product of gastric secretions from the proventriculus
Compare pancreatic enzymes in the avian digestive system
• they are released into the duodenum similar to other nonruminants • no lactase
What is the function of the small intestine?
Major site of absorption - relatively faster passage relate than other nonruminants
Describe the rate of passage from the small intestine
Digesta passes to the paired cecum • microbial fermentation • no substantial contribution to the bird nutrient needs
What is the function of the ceca?
Water absorption, synthesis of water soluble vitamins, vitamin K (Very limited vitamin absorption)
How are hindgut fermenters different from other systems?
Most microbial fermentation in large intestine
The stomach and small intestine functions in hindgut fermenters And horse exceptions
Similar functions to other nonruminants • Exception of the horse 1) limited stomach muscular contractility which leads to stratification of ingesta 2) no gallbladder; continuous release of bile from liver to duodenum