水产动物营养与饲料学-双语教学课件chapter4-DigestibilityandAbsorption.ppt
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水产动物营养与饲料学-双语教学课件chapter4-DigestibilityandAbsorption.ppt
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Chapter4DigestibilityandAbsorption,General1.Methodsofdigestibilitydetermination*2.Factorsaffectingdigestibility3.Nutrientdigestibility,GeneralThenutritionalvalueofafeedstuff(营养价值)?
(1)itschemicalcomposition(它的化学组成)
(2)itsbioavailability-theamountofthenutrientsorenergytheanimalscanabsorbanduse.(对养分或能量的吸收利用率),Definitionofthebioavailability
(1)intermofdigestibility(消化率)
(2)inthecaseofenergy,metabolizability(可代谢性),Digestibility(消化率)Thefraction(propotion)ofthenutrientorenergyintheingestedfeedstuffthatisnotexcretedinthefeces(饲料中的养分或能量减去粪中排出养分或能量),Metabolizability(可代谢性)Thefractionofthedigestedenergythatisnotexcretedintheurineandthroughthegills.(消化能减去尿能及鳃能),Digestibleenergy(DE)消化能,Metabolizableenergy(ME)代谢能,1.Methodsofdigestibilitydetermination(消化率的测定方法)1.1IndirectMethod(间接法)1.2Directmethod(直接法)1.3Assaydiets(测定饲料),1.1IndirectMethodDeterminationprinciplenondigestiblemarker(不可消化的标记物)chromicoxide(Cr2O3)(三氧化二铬)0.5to1.0percentinthedietY2O3(钇)100ppm,*Digestibilitycoefficientofnutrient=100100percentmarkerinfeedpercentnutrientinfecespercentmarkerinfecespercentnutrientinfeed营养素的消化率100100(饲料中指标物的含量/粪便中指标物的含量粪便中营养素的含量/饲料中营养素的含量)Digestioncoefficientsforenergy,crudeprotein,carbohydrates,lipids,anddrymatter.,Theadvantagesofindirectmethod(间接法的优点)
(1)Iteliminatestheneedtoquantitativelycollectalloftheexcreta(不需要收集全部的粪样),
(2)andthetestfishcaneatvoluntarily(而且试验鱼还能够自由采食).,Fecescollection(收粪)Properfecalcollectiontopreventlossofsolublenutrientsintothewateriscriticalindigestiontrials.(正确的收粪方法可以防止可溶性养分在水中的损失,这在消化试验中十分关键)Thecalculationofdigestibilitywhenasignificantamountofsolublenutrientshaveleachedfromthefecesgivesdigestioncoefficientsthatareerroneouslyhigh.(如果有显著量的可溶性氮已从粪中渗出,就会使消化率错误地偏高),Someinvestigationstocollectthefeces
(1)Directlyfromtherectumusinganalaspiration(肛门吸出法直接从直肠收集),
(2)Surgicalexcision(外科切除法),(3)Strippingtominimizetheproblemofnutrientleaching(或剥离法直接从直肠收集粪样,降低养分渗出),(4)Siphonedoutoftank.,罗非鱼的生长性能及饲料利用,1.2DirectMethod(直接法)Determinationprincipleallthefeedconsumedbythefish,(需要测定鱼摄食的全部饲料量)andalloftheresultingexcreta.(和全部的排粪量),Thedisadvantagesofdirectmethod(直接法的缺点)fishareimmobilized(鱼的活动受限),force-fed(要进行强饲),andsostressedthattheutilizationofthefeedmaybecompromised(应激条件下会影响饲料的利用).,Materialsofendogenousormetabolicoriginintheexcreta(粪中含有内源性或代谢性物质)apparentdigestibilitytruedigestibilityDistinction(?
)betweenapparentdigestibilityandtruedigestibilitydigestiveenzymesepithelium,rainbowtrout3.1%ofthefecalnitrogencamefromendogenoussources,(内源性氮大约占粪氮的3.1)WTEndogenousproteincontent73.1%198.4%,1.3AssayDiets(饲料测试)DietdigestibilityIngredientdigestibilityincombinationwithotheringredientsintheassaydiet.(被测原料和其他原料配合成测试饲料来评定消化率),Stepsofdeterminationofingredientdigestibility
(1)todeterminetheDCofthereferencedietandassaydiettheindirectmethod
(2)tocalculatethedigestibilityofthetestingredientaccordingtothefollowingexpression.(利用公式计算被测原料的消化率),Drymatterdigestibilityoftestingredient=Digestioncoefficientoftestdiet70%digestioncoefficientofreferencediet被测饲料原料的干物质消化率被测饲料的消化率70参考饲料的消化率EX1EX2,2.FactorsAffectingDigestibility(影响消化率的因素)
(1)Watertemperature
(2)MealsizeFeedingfrequencyFishsizeInteractionamongnutrientsFeedprocessing,
(1)Watertemperaturelittleaffected,rainbowtrout7to18nodifferenceswerefoundinADCpandADCeADC:
apparentdigestibilitycoefficientscommoncarpThesame,
(1)Watertemperature,channelcatfishTherateofmovementofingestathroughthedigestivetractofwasfoundtoincreaseattemperatureabove26,butnoincreaseindigestibilitycoefficientswasnoted.(但消化率没有增加)asmallincreaseincrudefatsdigestibilityat18versus9whenhighlysaturatedanimalfatswerefed(ChoandKaushik,1990).,
(2)Mealsize(摄食量),mealsizedigestiveandabsorptiveefficiencies(摄食量增大时,消化和吸收率下降),(3)Fishsize?
Rainbowtrout6g,lowADC10g,ADC,(4)FeedingfrequencyFeedinggrequencyADC?
(5)InteractionamongnutrientsStarchandproteinCelluloseandothernutrientsOxideoilandprotein,(6)Feedprocessingingredientparticlesize,Rainbowtrout(whitefishmeal)Chineseshrimp(peanutmeal),ADCofPeanutmealinChineseshrimp,(6)FeedprocessingingredientprocessingEXSoybeanPressureproductSolventextractionproductEXFishmealOverheating,(6)FeedprocessingExtrusionprocessingstarch?
protein?
3.NutrientDigestibility(营养成分的消化率)ADCofdrymatter,continued,3.1DigestibilityofProtein(蛋白质消化率)Proteininmostfeedstuffsthathavebeenproperlyprocessedarehighlydigestibletofish.Thedigestioncoefficientsforproteininprotein-richfeedstuffsareusuallyintherangeof75to95%.Proteindigestibilitytendstobedepressedastheconcentrationofdietarycarbohydrateincreases.Salinitydoesnothaveanimpactonproteindigestibility.Itwasfoundthatnodiffer
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