Lecture 14 - Rumen (Grosche) Flashcards Preview

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list animals with a ruminant digestive system that are known as ruminantia

cattle, sheep, goat, bison, water buffalo, yak, antelope, deer, wildebeest, nilgai, pronghorn, giraffe, etc.


define ruminantia

Ruminantia includes many of the well-known large grazing or browsing mammals: among them cattle, goats, sheep, deer, and antelope.

All members of the Ruminantia are ruminants: they digest food in two steps, chewing and swallowing in the normal way to begin with, and then regurgitating the semi-digested cud to re-chew it and thus extract the maximum possible food value.


define tylopods

an even-toed ungulate mammal of a group that comprises the camels, llamas, and their extinct relatives. They are distinguished by bearing their weight on the sole-pads of the feet rather than on the hoofs, and they do not chew the cud.


list animals with a ruminant digestive system that are known as tylopods

camel, dromedary, llama, guanaco, alpaca, vicuna


what is a special feature of the ruminant digestive system

it allows them to gain nutrition from forages (grass) and other roughages (high fiber food)


which animals have one stomach with 3 compartments?

alpacas, camels, llamas


what are 3 characteristics of ruminant teeth?

1. no upper incisors
2. dental pad: fibrous connective tissue with cornified epithelium
3. mobile lower teeth
4. canine tooth referred to as the 4th incisor


how many baby teeth does a ruminant typically have



how many permanent teeth does a ruminant typically have?



what are 4 characteristics of alpaca teeth?

1. one upper incisor
2. dental pad
3. fighting teeth: modified incisor and canine teeth
4. two fighting teeth on upper jaw and one on lower jaw


how many baby teeth does an alpaca have?

18 - 22


how many permanent teeth does an alpaca have?

28 - 32


what are two characteristics of a ruminant tongue?

1. transverse lingual fossa
2. covered with lingual papillae (has mechanical and sensory functions)


4 characteristics of nasolabial glands in the ruminant

1. small glands in the muzzle
2. produce a watery secretion which keep the muzzle moist
3. chemical properties are similar to saliva
4. cattle mix nasolabial gland secretion with feed during chewing and lick their muzzle during rumination


how much mastication is done before first swallowing?

very little to provide significant volume of food in the rumen


what are some characteristics of rumination?

1. regurgitation of portions of ingested food
2. thorough mastication
3. rumination takes up to 8 - 12 hours/day
4. lubrication for swallowing
5. mixing with saliva to buffer rumen
6. exposure to digestive enzymes


what is the significance of spitting in camelids?

its a special kind of regurgitation

- an expression of displeasure, esablishment of social order in herd, response to serious threat
- true acid stomach content spit is highest level of serious and vile aggression with several prior behavioral warnings
- sometimes its just air and saliva spit without prior warnings


what is the pH of ruminant saliva?

8.1 , isotonic and is 99 - 99.5% water


what are the anorganic components of saliva in ruminants?

Na = 136-201 mEq/L
bicarb = 108
P = 26
Cl = 14 - 15
K = 14-15


what are the organic components of saliva in ruminants

70% of dry matter
albumin, globulin, glucoprotein, mucin


alkaligenic glands are high in what compound? and found in which glands?

high in bicarb - particularly in the parotid and mandibular glands


mucogenic glands are high in what compound? and found in which glands?

mucoprotein; found in submaxillary, sublingual, labial, pharyngeal and buccal


which gland has continous production of alkaline saliva?

parotid glands


what are the functions of saliva?

1. moistens and lubricates food, aids in bolus formation and swallowing
2. anti-foaming properties to prevent bloating
3. adds water and nutrients (urea, P, Mg, Cl)
4. recycling of nitrogen via rumeno-hepatic circulation (absorption of ammonia, secretion of urea)


what are some characteristics shared by the rumen, reticulum and omasum?

1. lined with non-glandular mucous membranes
2. absorption but no secretion
3. sites of anaerobic microbial fermentation


what are some characteristics of the abomasum?

lined with glandular mucosa

secretion of digestive enzymes


what is the muscularture of the cardia used for?

rumiantion and formation of esophageal (reticular) groove


what is the function of the esophageal groove

for bypassing the rumen, reticulum and omasum in young animals


the rumen comprises up to how much of the stomach capacity?



what is the principle site of microbial fermentation and absorption of short-chain volatile fatty acids (VFAs)?

the rumen


where are VFA's absorbed in ruminants?

through rumen papillae


what are 2 characteristics of rumen papillae

1. covered with stratified squamous epithelium
2. supplied by 1 or 2 arterioles


how do molecules pass through rumen papillae?

molecules pass through the epithelium by diffusion, reach the venules and are transported via ruminal veins to the hepatic portal vein into the liver


how does the reticulum interact with the rumen

via mixing activity and forming the food bolus


how would you describe the reticulum?

a pouch-like structure in the forward area of the stomach


hardware disease

heavy or dense feed or foreign objects eaten by the animal fall into the reticulum


characteristics of the omasum

stratified squamous epithelium, muscular folds, highly vascularized and absorptive

aids in grinding of the food

20 - 25% of the absorptive capacity of the rumen (water, VFA)


what cells are located in the fundic region of the abomasum

parietal cells - secrete HCl
chief cells - secrete pepsin
mucus secreting cells


what cells are located in the pyloric region of the abomasum

mucus secreting cells


which digestive organs grow at the fastest rates in the growing young ruminant?

the rumen, reticulum, omasum and small intestines


what is the primary stimulus to development of eptihelum and papillae?

the presences of VFAs


what substrate is available in the rumen?

hay and long fiber: development of rumen wall muscle and volume

concentrates: stimulate microbial fermentation and the production of butryate and propionate; for quick development of rumen epithelium and papillae


what is a major function of the ruminant foregut?

physical breakdown of feed


physical breakdown process is continous and is composed of:

1. chewing during eating and rumination
2. microbial fermentation


contractions of the reticulo-rumen are essential for:

1. mixing rumen contents
2. eructation (belching) of gasses
3. rumination


contractions in the reticulo-rumen can be classified as:

primary - mixing cycle

secondary - eructative contractions


define primary reticulo-ruminal contractions and its process

definition: during a normal mixing cycle, contractions are first initiated in the reticulum and the reticulo-rumen fold

1. the reticulum contracts to about half of its resting size.
2. a second, more powerful contraction in the reticulum passes caudally over the rumen, resulting in a lifting of the cranial sac due to contraction of ruminal pillars and compression of the dorsal sac
3. the contraction wave continues over the caudodorsal blind sac, ventral sac and caudoventral blind sac


where does the secondary reticulo-ruminal contraction typically orginate

in the ventral blind sac either independently or immediately following a primary contraction


describe the process of the secondary reticulo-ruminal contraction

a wave of contraction passes in a circular manner to the dorsal blind sac, dorsal sac and ventral sac and back to the ventral blind sac

eructation typically occurs at the end of contraction of the dorsal sac


list promoting factors of the reticulo-ruminal motility

- feeding (during chewing)
- increased intra-ruminal pressure (mild distension)
- hypoglycemia


list inhibiting factors affecting the reticulo-ruminal motility

- water deficiency
- recumbency
- increased intra-abomasal pressure
- rumen acidosis
- hyperglycemia
- severe ruminal distension
- pain (abdominal)


what microbes are found in the rumen?

bacteria, protozoa, anaerobic fungi


what are some positive effects of ruminal microbes

- they digest cellulose and hemicellulose via cellulases
- provide high quality protein
- provide B-vitamins
- detoxification of toxic compounds


what compounds do microbes produce?

VFA, methane, CO2, and ammonia


what makes up VFAs?

- its the main energy source for ruminants
- acetate, proprionate, butryate


describe the microbiology of ruminal microbes

bacteria: mostly obligate anerobes
protozoa: large, unicellular, prety on bacteria, numbers affected by diet
fungi: low numbers, digest recalcitrant fiber


microbes occur in 3 main locations:

1. adhered tightly to the rumen wall (minor contribution)
2. associated with and attached to feed particles (major contribution)
3. floating freely in the rumen liquid phase (major contribution)


rsult of physical and microbial activities convert diet to:

useful products: VFA, microbial prtoein, B-vitamins
useless products: methane, CO2
harmful products: ammonia, nitrate


absorption of VFA from reticulo-rumen

1. membrane on lumen side is permeable to free and anion forms of VFA
2. membrane on blood side is permeable to free acid form only
3. carbonic acid formed from CO2 and water acts as a H donor for VFA transport
4. bicarb is produced and released into the rumen


roughage diets high in cellulose and low in starch produce what?

active bacteria: cellulolytic and saccharolytic

products: acetate


starch diets high in starch and low in cellulose produce what products and have what active bacteria?

active bacteria: amylolytic
products: propionate


what does proprionate form via the normal microbial process

proprionate --> lactate --lactate fermentation req'd--> pyruvate --> quick changes to high concentrates --> lactic acidosis


what is the effect of high quality forage and 20-50% concentrate on rumen content?

rumen content: pH 6-7; VFA = 60-70; acetate > proprionate > butyrate

effect on health: normal, healthy


what is the effect of excessive forage of low quality and little concentrate

pH 6.5 - 7, low VFA and low microbial activity

effect on health: poor production and growth, rumen impaction, protein energy, mineral and vitamin deficiency


what is the effect of 60% concentrate and low forage or fiber length

pH = 5 -6.5, high VFA and high microbial activity

health effects: high production, rapid growth, chron. rumen acidosis, laminitis, ketosis and rumen parakeratosis


what is the effect of sudden exposure to extremely high level of concentrate

pH = 4 -5.5 high VFA and lactate

health effects: acute rumen acidosis


what is the effect of normal level of forage, high protein/NPN concentrate

pH 6.5-7.5 low VFA and high ammonia

health effects: rumen alkalosis, urea toxicity


what are the VFA ratios of acetate: propionate:butyrate on a roughage diet

acetate 65: propionate 25: butyrate 10


what are the VFA ratio of acetate: propionate:butyrate on a concentrate diet

acetate 50: propionate 40: butyrate 10


effects of rumen pH

effiency of microbial growth varies with changing rumen pH

rumen pH from 5 - 7.2 - lower pH values associated with concentrate feeding

cellulolytic bacteria - methanogenic bacteria and protozoa are severely affected once hte rumen pH falls below 6


changes in diet

most important factor influencing microbial numbers and proportions

changing the diet invokes a period of transition in the microbial population wtih changing of numbers and proportions of species

this adaptation period may take several days or weeks

most dramatic changes in microbial population due to diet are associated with changes form a forage-based diet to one with highly fermentable carbohydrates (high concentrate diets)

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