ch. 16: horse digestion

what percent of the total digestive tract does the stomach take up?

8.5%

what percent of the horse digestive tract is classified as foregut or hindgut?

fore gut: 38.5%

hind gut: 61.5%

allows for more cellulose digestion

describe a horse’s mouth

1) upper and lower incisors (no dental pad)

2) upper and lower molars

3) mobile lip

4) 3 salivary glands (parotid, sublingual, submaxillary) with NO ENZYMES

how does the stomach of a horse differ from other species?

1) smaller in relation to the total tract (8-10%)

2) not as muscular

these tend to lead to greater digestive disturbances

how should you feed a horse?

fed in small meals throughout the day because of their small and not-as-muscular stomach

what digestive issue is common in horses (esp. performance horses)?

ULCERS

how is bile secreted and where is it stored?

secreted by liver continuously & directly into small intestine because HORSES DO NOT HAVE GALL BLADDERS

where do microbes live in the horse?

cecum and large colon

what VFAs are produced by microbes in the cecum and large colon

acetate, propionate, butyrate

what is and isn’t absorbed in the colon

absorbed: VFAs

NOT absorbed: MCO protein, B protein, vitamin K

this is because they’re past the primary site of absorption (small intestine)

how are soluble CHOs digested in the horse

in small intestine with pancreatic amylase and brush border disaccharidases

how are fibrous CHOs digested in the horse

in large intestine via MCO fermentation

converted into VFAs that are then absorbed & used for energy

less efficient than ruminants due to the faster passage rate (no rumination)

how are fats digested in the horse

digested and absorbed in the small intestine from a constant secretion of bile

how are proteins digested in the horse

digested in stomach and SI

MCO protein is produced in the hindgut and cannot be digested nor absorbed

what is colic

a potentially fatal syndrome that is manifested by mild to severe abdominal pain & depression

what causes colic

1) gut compaction and/or dehydration

i.e. too much/too rapid grain consumption and stoppage of intestinal flow (layering of ingesta in the stomach and S.I.)

2) parasites, gas production (distention in GI tract) & improper husbandry

what are symptoms of colic

pawing, kicking at belly, abnormal postures

what is the treatment of colic

can require extensive surgery

what is founder disease

problem with too much or too fast eating and can cause acidosis & the production of endotoxins (by microbes)

what causes founder?

excess soluble CHO in grain or lush pastures

(too much CHO pouring over into the cecum where MCO digest it quickly and produce too much lactic acid)

what can founder disease cause?

laminitis

microbes produce endotoxins that get into the bloodstream and flow to the hoof to cause inflammation in the lamina

can lead to lameness