Ruminant digestion 10

BY4055

Ruminant digestion

multi-stage process adapted for fibre digestion

Rumination

regurgitation, re-chewing, and re-swallowing of feed

Key digestion steps

intake, chewing, swallowing, fermentation, absorption, eructation

Ruminant mouth function

prehension and initial mastication

Ruminant dental formula (cattle/sheep)

upper 0 incisors, lower 4 incisors, no canines, 3 premolars, 3 molars

Chewing motion in ruminants

lateral grinding to increase surface area

Tongue function

feed grasping, bolus formation, taste

Papillae on tongue

rough structures aiding forage prehension

Taste role in grazers

food avoidance rather than selection

Pharynx function

swallowing, rumination, eructation

Gas production in rumen

30–50 L/hour in cattle

Oesophagus in ruminants

bidirectional for cud chewing

Oesophageal muscle type

entirely striated muscle

Oesophageal absorption

negligible

Rumen location

left side of abdominal cavity

Rumen function

storage and microbial fermentation vat

Rumen capacity

cattle 100–200 L, sheep 10–25 L

Rumen microbes

bacteria, protozoa, fungi

Main rumen end products

volatile fatty acids (VFAs)

Rumen papillae function

increase surface area for VFA absorption

Reticulum structure

honeycomb lining

Reticulorumen

combined rumen and reticulum function

Reticulum role

sorting digesta and aiding regurgitation

Omasum nickname

manyplies

Omasum main function

water absorption

Water absorbed in omasum

50–70%

Omasum additional role

VFA absorption and particle filtration

Abomasum definition

true stomach

Abomasum pH

about 2

Abomasum secretions

hydrochloric acid and pepsin

Rennin function

coagulates milk in young animals

Oesophageal groove function

directs milk to abomasum in young animals

Rumen development trigger

intake of forage and concentrates

Age rumen becomes functional

6–9 months

Small intestine regions

duodenum, jejunum, ileum

Small intestine function

enzymatic digestion and nutrient absorption

Pancreatic enzymes

amylase, lipase, proteases

Bile function

emulsification and digestion of fats

Large intestine role

secondary fermentation and water absorption

Large intestine contribution

additional VFA and mineral absorption

Main structures of large intestine

caecum, colon, rectum