hind gut fermenters, the equine digestive tract

Question 1

what is fermentation

Answer 1

the process in which an organic substance is broke down into a simper substance by microorganisms

Question 2

what is hind gut fermentation

Answer 2

the majority of GIT microbial fermentation occurring after the small intestine: the caecum and colon

Question 3

what are caecotrophs

Answer 3

animals that consume ‘soft pellet’ of food which are produced by means of caecal digestion and expelled out through the anus

Question 4

what are examples of hind gut fermenters

Answer 4

small (<50kg) hindgut fermenters: rabbits
reverse peristalsis within the proximal colon back to caecum
tend to be ceacotrophs
large: (>50kg) hindgut fermenters: horse

Question 5

the feral horse

Answer 5

perissodactyl ungulates

evolved to live on low quality roughage diet eaten in large amounts

Question 6

the mouth

Answer 6

prehension and mastication

Question 7

teeth

Answer 7

hypsodont teeth
incisors, pre molars and molars
intensive mastication but slow ingestion rate
constant and rapid wear down of teeth due to high silica content of plants

Question 8

saliva

Answer 8

produced by: 
parotid
mandibular 
sublingual 
10-12 litres a day

Question 9

oesophagus

Answer 9

approx 1.5m long
buccal cavity -> cardiac sphincter
smooth(and some striated) muscle

Question 10

equine stomach

Answer 10

9-15 litre capacity
non glandular vs. glandular region
cardiac and pyloric sphincters

Question 11

stomach regions

Answer 11

saccus caecum
cardiac region
fundic region
pyloric region

Question 12

stomach secretions

Answer 12

gastric glands in fundic region
3 cell types:
mucous cells 
parietal cells 
chief cells

Question 13

small intestine of the horse

Answer 13

22m long, 64 litre capacity
rapid transit of digesta 
external secretion into the duodenum:
pancreatic juice
bile

Question 14

accessory organs

Answer 14

liver: bile production
pancreas: digestive enzymes, pancreatic juice- neutralisation of food bolus pH

Question 15

small intestine- digestion and absorption

Answer 15

enzymatic digestion and absorption of:
simple sugars and starch- e.g amylase, glucosidase, sucrase
fats- e.g pancreatic lipase, phospholipase
protein- e.g. aminopeptidase, trypsin
vitamins (e.g. vit A,D,E)
minerals (e.g. Na,P,Ca,Mg)

Question 16

the equine large intestine

Answer 16

7m long, volume- 130 Litres
microbial fermentation using bacteria, fungi and protozoa
4 sections: caecum, large colon, small colon, rectuum

Question 17

caecum

Answer 17

blind-ended comma shaped sac, 1m long
30-34L capacity
fermentation vat

Question 18

large colon

Answer 18

3.5m long, average capacity= 80L
4 compartments: 
right ventral 
left ventral
left dorsal 
right dorsal 
flexures

Question 19

small colon

Answer 19

between the transverse colon and the rectum
3m long, 10cm wide
rectum- anus

Question 20

GIT microbes

Answer 20

fibrotic microbes located in Ll 
fermentation of fibre producing:
volatile fatty acids (VFA's)
vitamins (B complex and K)
consistent environment required for optimal function

Question 21

insufficient dietary fibre

Answer 21

fibre degrading microbes lose food source
|
less beneficial microbes proliferate 
|
death of beneficial fibre- degrading microbes 
|
acidic hindgut, production of poisonous endotoxins and other substances including amines
|
Ll lining damage and "leaky" GIT
/                                 \
appetite                  colic/
loss                        laminitis/
                                   death