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227 .205 (15)

Ruminant gut anatomy

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Massey University
227 .205
Peter Davie

Ruminant abdomen 1)small thorax. 2) Large abdomen. 3) Forestomach -Left side of abdomen -only 3 separate chambers are known as the forestomach. 4)Liver- pushed towards the right as it is displaced by the forestomach 5)Diaphragm between thorax and abdomen 6)Midgut: Small and large intestine – right side 7) esophagus runs into forestomach(rumen) Esophagus-Rumenduodenumjejunum ileum cecum ascending colon transverse colon descending colon  rectum 8) All structures are nearly the same for ruminant except for the a) forestomach b) ascending colon 9) ascending colon: double spiral 10) stomachs a)rumen – is 80% of the forestomach of the animals - in calf is very small b)Reticulum – is a separate pouch - about 5% c)omasum- 8% d)abomasum- is the true stomach - glandular stomach for digestive - is significant until calf starts eating grass. - 7% adult - calf -60% . As it is drinking milk. And rumen is very small 11) ruminant stomach a) 3 “forestomachs”: rumen, reticulum, omasum -some food from esophagus enters the reticulum and some into the rumen - maybe known as the ruminoreticulum as the functions are quiet similar but are histologically quiet different. Passes from the reticulum the omasum( a nonglandular outpouching of the rumen  abomasums for acid digestion of food compounds that aren’t dealt with by the rumen. b)1 true stomach : abomasum - it is similar in form and function to monogastric stomach Food goes through chambers in that order c) rumen: -microbial fermentation chamber - anaerobic environment -mechanical mixing- quiet muscular - some absorption of digestion products, some passed along 12) Horse: digestion of carbohydrates by cecum and ascending colon 13)Left side projection a) most surface projection is rumen b)reticulum - close to heart and spleen - outpouch cranially -pressed onto diaphragm - in contact with liver - spleen is retroperitoneal and sits tightly up against the rumen c) longitudinal grooves separate the dorsal sac of rumen from ventral sac of rumen - corresponds to muscular grooves inside - form D, V and CR and CA blind ended sacs 14) From right side a) omasum only seen on right side b) abomasum - visible right side and also ventrally. -sitting on abdominal floor, roughly midline or pushed slightly right on ventral floor -Has greater ventrally and lesser curvature dorsally c) greater omentum attaches to grater curvature just like horse and dog - greater omentum also attaches to part of the rumen 15) Duodenum- is retroperitoneal - covered only by parietal peritoneum jejunum is intraperitoneal and is covered by mesoduodenum 16) passage of food Esophagus rumen reticulumomasum abomasums Calf: rumen is undeveloped Bypass the reticulum and rumen by the groove because milk doesn’t need to be fermented eophagus--> reticular groove omasum abomasums SI 17)HARDWARE DISEASE - if cows picks up wire/ nail eats it a)It falls into reticulum, the contraction of the reticulum causes the wire to poke into the pericardium of the heart b) can puncture the liver from reticulum get abscesses -c)puncture of spleen – get vasculare damage - farmer: feeds the cows magnet either as a preventive or as a treatment. - the wire adheres to the magnet and can be passed out with the magnet. 18)external grooves are visible -left and right longitudinal groove - cranial groove - caudal groove -dorsal coronary groove -ventral coronary groove - ruminoreticular groove a) the grooves visible externally map onto ‘pillars’ internally -ruminoreticular groove acts as a barrier between reticulum and rumen. - grooves just subdivides the rumen in blind ended pouches 19) ruminoreticular groove/gastric groove a) closes in the calf when the calf is suckling as a vagal reaction - the milk is channelled to the omasum and abomasums -b)also influenced by the ADH – to allow water to go directly into omasum and abomasums if the animal is dehydrated 20) Ruminal lining – histologically similar to esophagus -rumen , reticulum and omasum all stratified squamous epithelium a)two main parts of the rumen i) ruminal pillar- different covering but still stratified squamous epithelium ii) ruminal papillae- is the other part b) stratified, keratinised, squamous epithelium - just like esophagus - so rumen can absorb somethings example: water, by products of microbial fermentation c) absorptive d) non-glandular- does no
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