Lecture 1 Flashcards
What type of digestive animals are horses
Non-ruminant herbivores
Digestive tract is divided into?
Foregut
- monogastric like
Hindgut
- ruminant like
What is a rumen?
- positives? negatives?
large liquid sack
- less agile
- high microbial activity (nutritionally efficient)
Major location of microbial activity
cecum and colon
- posterior to the small intestine
Primary nutrient uptake location?
Small intestine
- duodenum and jejunum
- less in ilium
Nutrient utilization is between
monogastrics (pigs) and ruminants (cows)
Time for feed to move through digestive tract
65-75hrs (fast compared to some ruminants)
Shape of jaw
lower is narrower than upper
- lateral grinding motion is limited (inefficient)
Feature of teeth
both upper and lower incisors
- permits close grazing
Features of lips
strong
mobile
prehensile (capable of grasping)
Salivary glands
Parotid (90% of saliva)
Sublingual
Submaxillary glands
Saliva functional components
Bicarbonate Buffers
- optimizes pH
Amylase
- begins carbohydrate digestion
Stomach in contrast to bovine
- size
- time of emptying
10x smaller than bovine
1/3 the time to empty
Stomach functional compounds
Small microbial population
- fermentation
Gastric HCl
- denatures dietary protein, allows for hydrolysis by pepsin
Gastric Lipase
- hydrolysis of fat
2 main regions of stomach
- main structural difference?
glandular region
- protective layer from enzyme acids
esophageal region
- no protective layer
- surceptible to problems
Small intestine proportional size
30% of digestive tract
Pancreas secretes
Bile
- no gallbladder
- constantly secreted into small intestine
Significant enzymatic hydrolysis in SI due to
Pancreatic Secreations
Major site of nutrient absorption
duodenum and jejunum
- less in ilium
Large intestine proportion of digestive tract
60% length of digestive tract
Parts of large intestine
cecum
large colon
small colon
rectum
Reason for high fermentation compared to monogastrics
Cecum larger than a cow
- replaces rumen
Cecum
- role
- functional components
active population of bacteria and protozoa
- for fermentation of undigested feedstuffs including forage fibers
Cecum efficiency
66% efficiency of cow
- for converting fiber to nutrients
Microbial action
synthesizes
- vitamins
- volatile fatty acids (VFAs)
- amino acids
Main site of water absorption in intestinal tract
Cecum
Synthesized in large intestine that provides energy
- what %
volatile fatty acids
- 25% energy needs
what happens to undigested dietary protein
- implications?
degraded to ammonia in large intestine
- amino acids from this little significance
- little active transport of amino’s in large intestine
- less able to improve amino acid profile of low quality protein than ruminants
- high quality required
Microbial synthesis of vitamins
not adequate to meet requirements
- particularly during training
When does cecum start functioning
15-24 months old
- limit ability to use forages
- acts like monogastric
Initial location of protein digestion
- what enzyme
stomach
- pepsin
Major site of protein digestion
small intestine
- liberated peptides and amino acids absorbed by “active transport”
amino acids synthesized by microbial activity absorbed?
Cecum and large intestine
- by diffusion
Young horses and protein
Requires dietary protein
- lacks cecal protein synthesis
- cecum doesnt function until 15-24months
Amino acid that promotes growth of young horses
lysine
- connective tissue
Protein in hay digestion
large intestine
- hay high in cellulose + hemicellulose
- limit protein release for young horses
Major site of starch and other soluble carbohydrate digestion and absorption
small intestine
- actively absorbed
- as simple sugars
Soluble carbs that reach cecum and large intestine
metabolized to volatile fatty acids
- acetate
- propionate
- butyrate
Carbohydrate overload
excess reaches LI
- can upset GI tract
insoluble fiber fate
metabolized to VFAs in large intestine
- cellulolytic bacteria numbers same as bovine
- protozoa differ greatly
dietary fatty acid composition similar to?
fatty acid composition of body fat
- little microbial alteration
fatty acid absorption
small intestine
high fat diet tollerance
very good
- no gallbladder
- bile constantly released
Phosphorus and calcium absorption
phosphorous = large intestine calcium = proximal small intestine
excess dietary phosphorus reduces calcium but calcium has no effect on phosphorus
