Anatomy and physiology- digestion Flashcards
what is the overall goal of nutrition
-to deliver a diet that meets nutrient requirements for a specific stage of production in a cost effective way
what is digestion
the process by which large complex molecules are broken down into simpler molecules
what are the three major complex molecules
proteins
fats
carbohydrates
what are the functions of the digestive food tract
-prehension
-mastication
-digestion/fermentation and absorption of feed
-elimination of solid waste
what organs are included in the digestion tract
-mouth
-pharynx
-esophagus
-stomach (1,3,4)
-small intestine
-large intestine
-rectum
-accessory glands (salivary glands, liver, gallbladder, pancreas)
what does the length and complexity of the digestive tract depend on
it varies species to species
carnivores have a shorter one
herbivores have a longer one
what is prehension
-the manner in which animals harvest and convey feed to their mouth
-they use their lips, teeth, and tongue
what is the diet like of concentrate selectors
-low fibre
what is the diet like of intermediate types
mix of low fibre and high
what is the diet like of grass/roughage eaters
high fibre
how does the mouth help with digestion
-teeth/lips grasp and chew the feed
-mix it with saliva before swallowing (lubrication)
-some digestion of carbohydrates due to salivary amylase
what is the purpose of mastication of food
-mechanical reduction of the particle size
-increased SA for microbial digestion
-mixes feed and saliva (swallowing)
how do ruminants and chickens masticate their food
-ruminants eat quickly then re-masticate at a later time (chewing cud)
-chickens rely on grit in their gizzard to mechanically grind their feed
what are some general traits of monogastric digestion
-single stomach
-limited gut capacity
-digestion principally by enzymes
-limited microbial activity(present in large intestine)
-limited ability to digest fiber
what happens once food has traveled down the esophogus and into the stomach in monogastrics
stomach serves as a resivoir for short term storage and digestion
enzymes start to break down feed
what enzymes and hormones are found in the stomach of monogastrics
-low pH breaks down some feed particles
-HCl
-activation of proteolytic enzymes (pepsinogen to pepsin)
-denaturation of proteins
-hormone secreating area (ghrelin-hunger hormone)
what enzymes are present in the small intestine in monogastrics
-presence of bile from gall bladder
-digestive enzymes secreted largely from the pancreas (some from intestinal mucosa)
what are the parts if the small intestine in a monogastric
-duodenum
primarily digestive
-jejunum
longest
digestion + absorption
-ileum
primarily absorptive
what makes up the large intestine of a monogastric
-cecum
-large area where small and large intestine meet
-hind gut microbial digestion (horses)
-colon (water reabsorption)
-rectum (excretion of waste)
-microbial fermentation occurs in large intestine
what are the functions of saliva in ruminants
-lubrication (mastication and bolus swallowing)
-enzymatic activity
-source of nutrients for ruminal microorganisms
-influences nutrient removal rate from rumem
-buffering capacity
-antifoaming agent
-source of antibodies
what four stomaches make up the ruminant
-rumen
-reticulum
-omasum
-abomasum
what is cud chewing
-when animal is resting
-regurgitate ingesta from reticulum
-re-mastication and re-swallowing
what is eructation
gases generated by fermentation
what are some characteristic features of a ruminent
-the rumen is the largest stomach compartment
-largest number of papillae
what is fermentation vat and what does the rumen do
-microbes digest or ferment feeds to make short chain fatty acids (the animals energy supply)
-the rumen absorbs SCFA
-blood supply to rumen walls absorbs SCFA
why is it beneficial that the rumen is so big for the animal
-allows large meals followed by regurgitation and rumination
-this make it so that the pray animals dont always have to be exposed they can eat lots of food quickly
how do the microorganisms in the rumen work
-they facilitate digestion under anaerobic fermentation
-contains billions of microorganisms (bacteria, protozoa, fungi, archea)
-they have the ability to digest fiber (hemicellulose and cellulose)
-type of microorganisms change with the type of feed consumed (grain vs forage)
how much energy do microbes produce for ruminants
they digest fibre to produce 75% of the energy which is absorbed through the rumen wall
what are the short chain fatty acids that microbes produce
acetate, propionate, butyrate
what causes acidosis
to much acid production (low pH)
what is the main source of protein for ruminants
bacteria are comprised mainly of protein and digested as the primary source of protein
what vitamins do microbes make
k and b
under most conditions cattle with healthy rumens dont need added k/b vitiman
what kind of nitrogen do microbes provide to ruminants
non protein nitrogen sources (urea, ammonia)
what gasses make up the anaerobic environment in the rumen
65 CO2
27 CH4
7 N2
.6 O2
.2 H2
what is the temperature and pH of the rumen
38-41C
extreme pH: 4.5 to 7.2
normal range pH: 6-6.9
what things do cattle supply to the microbes to make it a symbiotic relationship
-creat anaerobic condition
-cattle break down the food for the microbes
what is the reticulum
-pouch like structure in forward area of body
-connected to rumen by tissue fold
-honey comb structure
-simular function to rumen
what is the esophageal groove
allows milk to go straight from reticulum to abomasum
what does the omasum play a role in
-squeezing and absorbing some of the excess fluids from digesta
-site for SCFA, water, electrolyte absorption
what are the physical characteristics of the omasum
-compartmentalized via laminae
-globe shaped
what is the abomasum
-the forth compartment
-true stomach of a cow where acid and some enzymatic digestion occurs
-simular to monogastrics
what is the only stomach compartment in ruminates that have glands
the abomasum
what is the fibre mat in ruminants
it sits on top of the liquid portion of the stomach
where are the bacteria found in the rumen
on the fiber mat and the liquid portion
enzymes vs bacteria in rumen vs monogastrics
-monog digestion occurs principally by enzyme action plus hind gut fermentation
-ruminant digestion occurs principally by bacterial action. foregut fermentation-bacterial enzymes with further digestion with enzymes post rumen
what is the crop in avians
feed storage and moistening
what is the proventriculus in avians
contains HCl and enzymes place of chemical digestion
what is the gizzard in chickens
muscular stomach- mechanically breaks down food
what is the cloaca in avians
common chamber for GI and urinary tract
what is the vent in avians
common exit for GI and urinary tract
