Voluntary feed intake Flashcards
DistensionorFillFeedback
Mightadapttotheloading
Poorqualityforage
Unlikelytobetheonlyfactor or wouldeatas+whentherumenempties,however,theydotendtoeatinmeals/phases
chemostatic feedback
effect of volatile fatty acids (VFA)
Acetate - depression of feed intake
Propionate - same as acetate but less powerful
Butyrate - more effectiveincausingruminal stasis, Problemwithpoorly fermentedfeeds.
factors which decr voluntary food intake (VFI)
Bodyfat
Pregnancy
Inertfill
DietNDF
water with/in food - effect of VFI
Waterdrunkwithdryfoodhaslittleeffect
waterintheplantmaterialcanhaveasignificanteffect in decr VFI
non starch polysaccharides(NSP)
water holding ability
slowdownthepassage offeedthroughtheintestine.
Theoppositeeffectbychoppingoffeed
inert fill
Intakedecr +flowrateincr - notenoughtocompensateforlowerintake.
similartoeffectofgrowingfoetus(sheepinlatepregnancy)
Incr flowrate-feedisnot fermentedtosamedegree
moredigestiblefeedshouldbeused
Rumenoutflowrate
mainfactorisparticlesizereachingtheOmasum
dependsontheeaseoffeedbreakdownbychewing andfermentation.
Pressureintherumenhaseffectinpushingfeedsthrough
Ruminal Acidosisdisturbstheoutflow
glucostatic theory
short term control
“glucoreceptors”inCNSaresensitivetotherateatwhichtheyareutilizingglucose
lowglucoseutilizationratesexciteneuralactivity-hungersensationsandfood
High utilizationratesproducetheoppositeeffect,andperipheralarterio‐venousglucosedifferences serveasanindexofutilizationratesbythe glucoreceptors intheCNS
HepaticOxidationTheory(HOT)
ATPlevelsinliverdeterminethevagal stimulation -lowlevelsrelatetoastimulatedhungercentre
SourcesforATPintheliverare –VFA, BHBA, NEFA
negativefeedbackoftheseinVFI
thermostatic theory
Animalseattomaintainbodytemperature.
ruminantsnotagoodestimationastherumenisexothermic.
mostanimalsthetheoryisbetterstatedthattheyeattoavoidhypothermia.
poultry - relationshipbetweenintakeandmaintenanceofbodytemperatureisgood
Lipostatic theory
hypothalamicfeedbackloop - whichbodyfatreservesmodulatefoodintakeandenergyexpenditure.
Thegreaterthefatstorethelowertheappetite
leptin
produced by fat tissue
more fat = more leptin in circulation
-ve effect on feed intakes
DMI of a dairy cow
2.5%ofBodyweight(kg)+10%ofmilkyield(kg)
NeutralDetergentFiber (NDF)
in cell walls
measureofplantfiberthatismostusefulinbalancingrumen
‐ healthyrationsandinpredictinghowmuchforage a cow can eat
NDFisthebestsinglemeasureofForageQuality
acid detergent fiber (ADF)
determinestheamountofresidueremainingafter boilingafeedsampleinanaciddetergentsolution.
predicttheenergycontentofforagesasitisinverselyrelatedtodigestibility
anti nutritional factors
littleeffectastheyaredestroyedintherumen.
tannins ifeateninlargequantity- precipitatingenzymessecretedbymicrobialbacteria+reducefermentationintherumenthusgreatlyreducingDMI.
Tanninscanbeveryunpalatablesothatalonemayreduceintake.
protease inhibitors
inhibittrypsin,chemotropismandotherproteases
foundinlegumes-beansandpeas,butalsoincereals,potatoes,andotherproducts
impairedgrowthandpoorfoodutilization, longertransittimesandlowerintake
lectins
glycoproteinsmainlyfoundin legumes:beans,peas,lentils. Theirpresenceresultsinpoorfoodutilizationandimpairedgrowth.
glucosinolates
cabbageandrelatedspeciesesp oilseedrape
Effectsthyroidfunction
pica
eating disorder - eating non-food substances
persistentlicking,chewingoreating ofwood, soil etc
can occur in all cattle - mainly outdoor problem
pica - sporadic cases
primaryorsecondarybraindisorder
toxicity
metabolicdisease
pica - herd outbreaks
problemsofparasitism,obesity,
mineraldeficiency(Pmostcommon,Na,Cu,Co)
undernutrition(protein-energydeficit)andwithlow roughagefeedssuchaslushgrass.
Slurry/urinedrinking
herdproblemincalvedcowswinteredindoors
orinyards
moreaestheticthaneconomic,asgeneralherdhealthand productivityisusuallynormal
infectious urine can spread disease
