Term
| What does to ruminate mean? |
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Definition
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Term
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Definition
| stomach consisting of a nonsecretory forestomach and a secretory stomach compartment - the abomasums |
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Term
| How many compartments do true ruminants have? |
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Definition
| 4 - rumen, reticulum, omasum, abomasum |
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Term
| What is the name of the secretory stomach compartment? |
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Definition
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Term
| Which compartments comprise the forestomach? |
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Definition
| microbial reticulum, rumen, omasum |
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Term
| What is the distinguishing functional feature of the forestomach? |
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Definition
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Term
| What is the principal digestive role of the forestomach? |
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Definition
| microbial fermentation to produce end products such a volatile fatty acids that the ruminant can absorb and use as energy |
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Term
| Microbial fermentation of the ingesta mainly occurs by |
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Definition
| hydrolsis and anaerobic oxidation by means of the microbes generating ATP for their own use |
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Term
| How is the surface area of the lining membrane increased in the stomach compartments? |
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Definition
| all compartments are increased by characteristic folding of luminal surfaces |
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Term
| The abomasum has ______ folds and the omasum has ________ _________. |
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Definition
| spiral; papillated lamellae |
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Term
| What structural feature gives the reticulum its name? |
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Definition
| luminal surface is a honeycomb network of low hexagonal ridges; papillated in in sheep and smooth in cattle |
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Term
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Definition
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Term
| Motor nerve fibers to the forestomach are principally ______ ______ fibers originating in the right and left _______ centers within the dorsal vagal nuclei of the medulla oblongata in the hindbrain. |
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Definition
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Term
| Nervous discharges in the vagal motor nerves are essential for the |
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Definition
| major contraction cycles of the forestomach (primary and secondary cycles) |
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Term
| Splanchnic motor nerve fibers supply |
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Definition
| all regions of the ruminant stomach |
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Term
| When stimulated, splanchnic nervers |
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Definition
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Term
| Tension receptors in all stomach compartments are slowing adapting _____________ located in the muscle layer with the contractile elements (smooth muscle cells). |
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Definition
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Term
| Tension receptors are excited by _________ _________ of the viscus and especially by active contraction of the _________ _________. |
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Definition
| passive distension; smooth muscle |
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Term
| What type of fibers innervate tension receptors? |
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Definition
| finely myelinated B fibers |
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Term
| Epithelial cells of the forestomach lie close to the |
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Definition
| basement membrane of the luminal epithelium |
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Term
| Epithelial receptors of the forestomach behave as both |
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Definition
| mechanoreceptors and chemoreceptors |
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Term
| Epithelial recptors surmount the _________ _________ of the reticulum in sheep and between the club-shaped papillae of the cranial _______ ______. |
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Definition
| hexagonal ridges; ruminal sac |
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Term
| Greatest excitation of epithelial receptors of the forestomach is produced by |
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Definition
| repetitice - lightly moving tactile stimuli and range of chemicals - acids, alkali, hypotonic/hypertonic solutions |
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Term
| Mucosal receptors of the abomasums are most concentrated in the _____ and _____ regions. |
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Definition
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Term
| Epithelial/mucosal recptors are innervated by |
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Definition
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Term
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Definition
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Term
| Describe the pseudoruminant anatomy |
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Definition
| forestomach has two interconnecting compartments corresponging to a reticulum and a rumen but lacks an omasum |
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Term
| Do pseudoruminants chew cud? |
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Definition
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Term
| Dentition in pseudoruminants is |
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Definition
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Term
| The ruminants pregastric fermentation vat - forestomach allows it to |
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Definition
| consume diets that may be too fibrous for nonruminant animals |
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Term
| Ruminants have the ability to break down _____ and related compounds allowing it to become the major nutrient |
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Definition
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Term
| Ruminant digestion allow the synthesis of high biological value microbial protein from |
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Definition
| low biological value plant proteins |
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Term
| Ruminants can "recycle" metabolic end products such as |
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Definition
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Term
| Name 4 disadvantages to ruminant digestion. |
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Definition
| adequate food must be supplied at regular intervals, complicated mechanisms are required to keep the fermentative vat functional - large amounts of alkaline saliva, powerful mixing movements, elimination of gases for regurgitation of cud; must receive end products from microbial digestion VFA's |
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Term
| In roughage, the main nutrients are _________ carbohydrates and __________ as opposed to concentrates where most of the carbohydrate is ___________ and ___________ |
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Definition
| structural and extracellular; nonstructural and intracellular |
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Term
| What is the special dietary importance of legumes in their seed and leaf form? |
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Definition
| high protein content due to their ability to fix atmospheric nitrogen |
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Term
| What are the optimal fermentative conditions? (7) |
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Definition
| regular addition of chewed food, presence of suitable number of microbs, steady removal of end products of fermentation, mixing devices, onward propulsion of unfermented material to abomasums and intestines, anaerobic conditions, temp pressure pH etc, |
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Term
| What are the main types of ruminal microbes? |
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Definition
| mixed interdependent population of bacteria but also yeast like fungi and protozoa |
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Term
| What is accomplished by chewing cud and plant material? |
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Definition
| the waxy covering on most plant surfaces must be removed in order for microbes to ferment, this is removed via mastication |
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Term
| How many stages are in the fermmentative process? |
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Definition
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Term
| Stage 1 of fermentative process |
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Definition
| hydrolysis of polysaccharides to fructose |
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Term
| Stage 2 of fermentative process |
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Definition
| anaerobic oxidation by Embden-Meyerhof pathway to pyruvate |
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Term
| Stage 3 of fermentative process |
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Definition
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Term
| Stage 4 of fermentative process |
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Definition
| synthesis of new bacterial product - protein, and hydrogen is used in formation of methane and other compounds |
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Term
| Under anaerobic conditions in the forestomach, how are reduced coenzymes reoxidized? |
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Definition
| anaerobic oxidation reactions allow the microbes to generate ATP for their own energy such as maintenance and growth - so ruminal environment has large need for variety of hydrogen accepting reactions |
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Term
| Primary bacteria are those that |
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Definition
| degrade actual constituents of the diet |
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Term
| Primary bacteria are also called |
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Definition
| cellulolytic or amlolytic |
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Term
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Definition
| end products of primary bacteria |
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Term
| Secondary bacteria produce |
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Definition
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Term
| Protozoa are ________ to ruminal flora and are very _________ to abnormal intraruminal conditions |
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Definition
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Term
| Protozoan presence in a rumen sample is |
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Definition
| good indicator of normality |
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Term
| Most protozoa are located in the |
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Definition
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Term
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Definition
| over proliferation of bacteria in times of starch loading by engulfing starch particles |
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Term
| When passed out of the forestomach into the lower gastrointestinal tract protozoa provide the ruminant with |
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Definition
| higher biological value microbial protein than bacteria and small amounts of unfermented starch |
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Term
| Why is it desirable for a ruminant's diet to be changed slowly? |
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Definition
| flora of roughage diets are different from concentrate diets and it take about 2 weeks for a new population balance of microbial spp and #s to be est. |
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Term
| What is stratification of ruminoreticular contents? |
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Definition
| digesta is not a homogenous mass - there is a mat of fibrous material on top with underlying soupy fluid made of fine particles and above the mat is mostly methane gas and CO2 |
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Term
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Definition
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Term
| Methane formation is carried out by |
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Definition
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Term
| Fermentation of cellulose is slow because |
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Definition
| cellulolytic bacteria have a low metabolic rate, therefore population rates are slow to change as well |
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Term
| Degradation of starches is performed by |
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Definition
| several spp of primary amyloytic bacteria, not capable of methane formation |
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Term
| Unlike cellulolytic bacteria the amyloytic bacteria have |
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Definition
| faster fermentation rates, shorter doubling times, and matches lower ruminal pH |
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Term
| High concentration (starch rich) diets have a _______ ruminal pH compared to cellulose diets due to higher VFA concentrations. |
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Definition
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Term
| What are the consequences of sudden changes from roughage to concentrate feeds? |
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Definition
| amylolytic bacteria spike in numbers causing rapid accumulation of VFAs and lactic acid driving a decrease in pH which makes conditions to acidic for both kinds of bacteria to survive |
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Term
| What are the origins of nitrogenous compounds in the rumen? |
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Definition
| plant amides, nitrites, nitrates, and endogenous urea |
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Term
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Definition
| nonprotein nitrogen compounds |
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Term
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Definition
| diffuse across the rumen wall into ruminal fluid and enter with saliva |
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Term
| Urea is rapidly broken down into |
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Definition
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Term
| Ruminant diets generally do not contain more than _____% dry matter as _____. |
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Definition
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Term
| What VFAs are produced by fermentation? |
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Definition
| acetic, propionic (esp when starch fed), valeric,isobutyric, isovaleric, and butyric acids |
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Term
| Carbonic anhydrase promotes the formation of _________ _______ in the ruminant. |
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Definition
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Term
| Carbonic acid dissociates into |
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Definition
| bicarbonate ion and hydrogen ions |
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Term
| Granulosum cells of the forestomach epithelium contain |
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Definition
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Term
| Hydrogen ions associate with VFA anions to form undissociated VFAs that can |
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Definition
| diffuse more easily across the epithelium to leave bicarbonate ions in the ruminal fluid |
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Term
| The other half of VFAs are neautralized by |
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Definition
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Term
| What causes lactic acid to accumulate when there is an abrupt switch to starch-rich diets? |
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Definition
| propionate bacteria are inactivated so lactic acid in both D and L isomeric forms accumulates |
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Term
| What are the consequences of lactic acid accumulation? |
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Definition
| unmetabolized acid will cause a metabolic acidosis |
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Term
| What is the rate of gas production in cattle following a meal? |
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Definition
| peak of 40 L/hr in cattle 2-4 hrs after meal |
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Term
| What is the origin of CO2? |
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Definition
| arises form decarboxylation reactions of fermentation and neutralization of H+ BY HCO3 |
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Term
| What is the origin and fate of CH4? |
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Definition
| arises from reduction of CO2 and form by methogenic bacteria, end up in dorsa area of rumen and released into environment before regurgitation of cud |
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Term
| What is the origin of H2S |
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Definition
| arises from the reduction of sulfates and from sulfur-containing aa's (toxic gas) |
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Term
| What is the origin of H2? |
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Definition
| normally present in trace amounts |
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Term
| What is the origin of O2? |
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Definition
| trapped by ingested food and water or enters by diffusion from blood |
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Term
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Definition
| quickly used by facultative anaerobic bacteria, naturally low O2 environment is essential for majority of rumenal microbes |
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Term
| What is the orgin of ammonia in rumen? |
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Definition
| arises from the deamination of dietary proteins, from NPN and urea in saliva, and diffusion across the forestomach wall and from blood |
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Term
| What is the fate of ammonia? |
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Definition
| can be incorporated into microbial protein - suitable if VFAs present and ample suply of readily fermentable CHO's if not absorbed at NH4+ which is removed from portal blood and converted to urea or ammonia toxicity will occur |
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Term
| What is the ultimate fate of microbial protein? Why is it beneficial? |
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Definition
| used by other microbes and not immediately available, must be digested in the abomasum by a lysosyme and the microbes then yield a higher biological value protein - between 27-45% of total DM |
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Term
| During mastication a mixture of shearing and grinding actions occur which make sure surfaces of teeth remain |
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Definition
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Term
| Chewing of _____ is easily recognized by fast irregular chews, whereas chewing of _____ is much more slowly and evenly. |
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Definition
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Term
| Movements of teeth excite the sensory buccal mechanoreceptors around teeth sockets which in turn provide potent excitatory inputs to both |
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Definition
| salivary and gastric centers |
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Term
| The different sequences of swallowing and reguritating are coordinated in what area of the brain? |
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Definition
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Term
| The major salivary glands in ruminants that produce half of the total daily salivary output are the |
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Definition
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Term
| The salivary pH is highly |
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Definition
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Term
| _______ is an important mechanism/substance for the neutralization of about half of the VFAs produced in the forestomach. |
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Definition
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Term
| Increases in salivation are due to the excitation of secretory (acinar) cells by _____________ liberated by ____________ nerve endings and can be blocked by _________. |
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Definition
| ACh; parasympathetic; atropine |
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Term
| Parotid and other major glands also ________ their secretory rates in response to distention of the esophagus,reticulum, reticulo-omasal orifice, and ruminoreticular fold as a result of exciting tension receptors located in these sites. |
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Definition
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Term
| Concurrent stresses and excitement may ______ increases in salivation |
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Definition
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Term
| The fibrous mat in the rumen appears to have a direct physical role in facilitating the release of _____ from the underlying foam. |
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Definition
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Term
| Gas is forced upward through the fibrous mat in the rumen by |
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Definition
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Term
| Gases are eliminated every 1-2 minutes by |
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Definition
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Term
| When eructation is performed, the ruminal contents are held back by the _____________ ______ in sheep and the ________ _________ _________ in cattle. |
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Definition
| reuminoreticular fold; cranial ruminal pillar |
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Term
| The gas that is not expelled out of the mouth can be absorbed into the _______ and cand produce undesirable milk taints. |
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Definition
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Term
| Mechanism by which gas accumulating and distending the dorsal ruminal sac triggers a refflex sequence of event which leads to its expulsion. |
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Definition
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Term
| Rumination has a ________ rhythm. |
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Definition
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Term
| Highest incidences of rumination occur during |
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Definition
| afternoon, middle of the night, and while being milked |
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Term
| Reguritation begins with an |
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Definition
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Term
| Rumination may be abolished by introduction of |
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Definition
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Term
| Pseudorumination occurs when |
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Definition
| regurgitation takes place, liquid is swallowed and no solid material remains to be chewed in the mouth |
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Term
| Chewing cud leads to a three fold to five fold increase in |
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Definition
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Term
| Feeding roughage promotes |
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Definition
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Term
| Rumination occupies about ______ _______ of a ruminant's lifetime. |
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Definition
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Term
| Omasum is ________ in pseudoruminants. |
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Definition
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Term
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Definition
| true grazing ruminants such as cattle |
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Term
| Unlike the reticulum, omasal contractions are |
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Definition
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Term
| Due to the large surface area presented by the omasal leaves, this becomes an important site for |
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Definition
| absorption of VFAs, electrolytes, and water |
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Term
| The omasum is a _____ site of fermentation, ______ site of absorption, and helps regulate onward propulsion of ______. |
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Definition
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Term
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Definition
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Term
| The abomasum in homologous to what structure in the nonruminant? |
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Definition
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Term
| The abomasum receives a _________ flow of fluid from the forestomach |
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Definition
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Term
| Abomasal dysfunction is _______ in many gastrointestinal disorders |
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Definition
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