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Precision Feeding of Dairy Cows: Maximizing Metabolizable Protein and Reducing Feed CostsStephen M. Emanuele, Ph.D. PAS - QLF Dairy Business Development Manager

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Precision feeding of dairy cows requires two steps. First, you must provide the proper mix of sugars, starches, fermentablefiber,NPNandaminoacidstotherumenbacteriatomaximizemicrobialproteinproduction.Second,youmustprovidethepropermixofaminoacidsintherumenundegradableproteinsuppliedbythediet.Metabolizableproteincomesfrommicrobialproteinandrumenundegradableprotein.Microbialproteinishighqualitymetabolizableproteinandprovidesthecorrectmixofaminoacidstooptimizemilkcomponentproduction.Thequalityofthemetabolizableproteinfromthedietwillbevariableanddependentonthequalityandsourcesofrumenundegradableproteininthediet.Thebenefitofmaximizingmetabolizableproteinproductionisbeingabletofeedlowercrudeproteindietswithoutdecreasingmilkormilkcomponentyield.

Manydairyproducerswouldliketoincreasemilkandprotein.Milkyieldandmilkproteinyieldareincreasedbyformulatingdairydietstosupplyoptimalamountsoflysineandmethionineaspartofthemetabolizableprotein(NRC2001).Thereisacommonmisconceptionamongnutritioniststhatwecannoteffectivelyformulatedairycattledietstosupplylysineandmethioninebecausewecannotconfidentlypredictthesupplyofaminoacidsinthemetabolizableproteinreachingtheduodenum.UseofdairyformulationsoftwaresuchasCNCPS,CPM,DalexandNRCmakesitpossibletopredictthesupplyoflysineandmethionineinthemetabolizableproteinreachingtheduodenum for absorption.

What can be achieved by maximizing metabolizable protein and balancing lysine and methionine in the diet at appropriate levels?

A more precise feeding program Effi ciency through increased performance and/or lowering feed cost

Guidelines to maximize metabolizable protein production

1. Sugarcontentofthedietshouldbebetween5-7%ofdietdrymatterandshouldsupply0.75-1.2lbsupplementalsugarfromamolasses-basedliquidsupplement.

2. Sugarplusstarchcontentofthedietshouldnotexceed31%ofdietdrymatter.Forexampleifthedietcontains6%sugar,themaximumstarchcontentshouldbe25%.

3. ForageNDFasapercentoftotalNDFinthedietshouldbebetween70%and80%4. Ifyoufeedadietcontaininglessthan23%starchmakesurethatyouhaveplentyoffermentablefiberinthe

diet.Highqualityalfalfahayisanexcellentsourceofsolubleandinsolublefermentablefiber.5. TotalNFCinthedietshouldfallbetween38–42%ofdietdrymatter.6. Estimatedmicrobialproteinproductionfromtherumenshouldbe1400–1600gramsperdayandmicrobial

proteinshouldsupply50–60%ofthemetabolizableproteininthediet.

7. RDPasapercentofdietDMshouldbebetween10.5%and11.5%.TheamountofRDPrequiredinthediet will be a function of the amount of rumen fermentable carbohydrate in the diet.

8. Peptidebalanceshouldbebetween100–110%9. Setthelysinecontentofthediettoaminimumof6.8%ofthemetabolizableprotein.Thiswillprovide

aminimumof180–190gramsofmetabolizablelysineinthediet.10.Setthemethioninecontentofthediettoaminimumof2.3%ofthemetabolizableprotein.Thiswill

provideaminimumof60–65gramsofmetabolizablemethionine.

Guidelines for Lowering Feed Costs without a Loss in Milk or Milk Components

1. Whensoybeanmealpriceexceeds$300perton,thecostperpoundofproteinwillexceed$0.3125perpound.Replacesomeofthesoybeanmealinthedietwithproteinfromforage,QLFliquidsupplementanddistiller’s grains.

2. Userumenprotectedaminoacidstosupplypartofthelysineandmethionineneededinthediet.Useofrumenprotectedaminoacidsmakesitpossibletooptimizemilkproteinproductionwithouthavingtofeedhigh protein diets.

3. Donotoverfeedprotein.Whenformulatingdietstooptimizemetabolizableproteinproduction,youcanformulatedietsat16.5%crudeprotein.

4. Useproductswhichhavebeenshowntostimulatedrymatterintakeduringthetransitionperiod.Whencowshavehigherdrymatterintakepre-calving,theyhavehigherdrymatterintakepost-calvingandthiswillleadtoasmoothertransitionandgreatermilkyieldinthefirst50DIM.Highermilkyieldduringthefirst50DIMwillleadtohighermilkyieldduringtheentirelactationwhenpersistencyoflactationisnormal.UseofQLFliquidsupplementduringthetransitionperiodwillboostdrymatterintake.

5. UseQLFliquidsupplementtoprovideuniformdeliveryofionophorestotheTMRwhichwillincreasefeedefficiency.

6. Monitormilkproductionefficiencyfortheherd.Yourgoalshouldbegreaterthan1.6.Ifaherdisproducing80poundsof3.5%fat-corrected-milkandtheaveragedrymatterintakefortheherdis52pounds,thenmilkproductionefficiencyis1.54.Efficiencyvalueslessthan1.6mayindicatethatfermentationintherumenisnotoptimized.

Use of QLF TMR 40 to Lower Feed Costs

1.2 pounds of QLF TMR 40 can replace 1 pound of soybean meal

SoybeanMeal(48%CP)

$/Ton

CostperPound

$

Costfor1.2poundsofTMR40

$

Savingsfromreplacing2poundsofsoybeanmealwithTMR40

$330 0.165 0.168 0350 0.175 0.168 0.014400 0.200 0.168 0.064450 0.225 0.168 0.114475 0.237 0.168 0.138

Table 1. Cost Comparison of Soybean meal and QLF TMR 40

ExampleintabledoesnotincludetheeffectofsugarfromTMR40onrumenfermentationorforagedigestion.

Step 2 of Precision Feeding is to make sure the diet supplies enough lysine and methionine to optimize the yield of milk components

We can use animal performance in dose response trials to estimate the lysine and methionine requirement. The valueslistedintable2representtheamountofabsorbablelysinerequiredtomaximizemilkproteinyieldasreportedinthecitedtrials.Highproducingcows(>75lbs/day)appeartorequirebetween185and221gramsofabsorbablelysinetooptimizemilkproteinyield.Tosupplygreaterthan185gramsofmetabolizablelysine,thedietshouldcontain6.8%-7.2%lysineasapercentofthemetabolizableprotein.Forexample,ifadietsupplies2800gramsofmetabolizableproteinwithalysinecontentof6.8%,thenthedietwouldsupply190gramsofmetabolizablelysine.Thevalueslistedintable3representtheamountofabsorbablemethioninetooptimizemilkproteinyieldasreportedinthecitedtrials.Tomaximizemilkproteinyield,itappearstorequireamini-mumof2.4%methionineasapercentoftheMP.Itappearsthatcowsproducinggreaterthan75lbofmilkwillrequire58-65gramsofmetabolizablemethioninetooptimizetheyieldofmilkprotein.

MilkYieldlb/d

MilkProteinContent,%

Lysinesuppliedasa%oftotalessentialaminoacids(%EAA)

AbsorbableLysineSuppliedg/d Reference

77 3.20 14.8 221 Rulquinetal.199077 3.05 15.2 204 Schwab200673 2.99 13.9 197 Schwab200668 3.16 14.5 195 Schwab200681 2.97 14.5 242 Pisulewskietal.1996101 2.94 NR1 1852 Sochaetal.2005

Table 2. Lysine required for maximum yield of milk protein based on milk yield and composition.

1NotReported2Asreportedinthecitedreference

Table 3. Methionine required for maximum yield of milk protein based on milk yield and composition.

MilkYieldlb/d

MilkProteinContent,%

Methionine supplied as a%oftotal(EAA)or(TAA)or(MP).

AbsorbableMethionine Suppliedg/d

Reference

77 3.02 5.1 (%EAA) 52 Rulquinetal.199377 3.0 5.0(%EAA)(2.4%MP) 58 NRC200177 3.26 2.2(%TAA) 74 Sochaetal.200881 2.94 >5.0(%EAA) 77 Pisulewskietal.199684 3.15 2.4(%TAA) 77 Sochaetal.200890 3.02 2.7(%TAA) 62 Sochaetal.2008

The most efficient way to supply lysine and methionine to the cow is to maximize microbial protein production in the rumen and you can accomplish this by feeding supplemental sugar in the diet from QLF liquid feed. As stated previously diets should contain 5 – 7% sugar and this usually requires the feeding of 0.75 to 1.2 pounds of supplemental sugar in the diet.

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Conclusion:Precisionfeedingofdairycowsmakesitpossibletooptimizetheproductionofmetabolizableproteinfromthediet.Thebenefitsofoptimizingtheproductionofmetabolizableproteinaremoreefficientmilkproductionwhichwillleadtolowerfeedcosts.Youwillalsobeabletooptimizetheproductionofmilkcomponentswhichwilladdvaluetomilkinthosemarketsthatpayproducersformilkproteinandmilkfat.Maximizingtheyieldofmetabolizableproteinfromthedietrequirestheproperbalanceofsugars,starchesandfermentablefiberinthediettodrivemicrobialproteinproductionintherumen.ThesecondstepinmaximizingmetabolizableproteinproductionistoprovidetheproperbalanceofaminoacidsinthedietaryRUP.Evaluationofdoseresponsetrialswithdairycows,wouldsuggestthattooptimizemilkproteinyieldincowsproducinggreaterthan75poundsofmilkwillrequiregreaterthan185gramsofmetabolizablelysineandgreaterthan58gramsofmetabolizablemethionine.

References:

Gruinard,J.andH.Rulquin.1994.Effectsofgradedamountsofduodenalinfusionsoflysineonthemammaryuptakeofmajormilkprecursorsindairycows.J.DairySci.77:3565-3576

NRC.2001.NutrientRequirementsofDairyCattle7threv.ed.NationalAcademyofScience,WashingtonDC.Pisulewski,P.M.,H.Rulquin,J.L.PeyraudandR.Verite.1996.Lactationalandsystemicresponsesofdairy

cowstopostruminalinfusionsofincreasingamountsofmethionine.J.DairySci.79:1781-1791Rulquin,H.,L.LeHenaffandR.Vertie.1990.Effectsonmilkproteinyieldofgradedlevelsoflysineinfused

intotheduodenumofdairycowsfeddietswithtwolevelsofprotein.Reprod.Nutr.Dev.(Suppl2):238SRulquin,H.,P.M.Pisulewski,R.VerteandJ.Guinard.1993.Milkproductionandcompositionasafunction

ofpostruminallysineandmethioninesupply:anutrient-responseapproach.LivestockProductionScience37:69-90

Schwab,C.1996.Rumen-protectedaminoacidsfordairycattle:Progresstowardsdetermininglysineandmethioninerequirements.AnimalFeedScienceandTechnology59:87-101

Schwab,C.G.,C.K.Boaz,N.L.WhitehouseandM.M.A.Messiah.1992a.Aminoacidlimitationandflowtotheduodenumatfourstagesoflactation.1.Sequenceoflysineandmethioninelimitation.J.DairySci.75:3486

Schwab,C.G.,C.K.Bozak,N.L.WhitehouseandV.M.Olson.1992b.Aminoacidlimitationandflowtotheduodenumatfourstagesoflactation.2.Extentoflysinelimitation.J.DairySci.75:3503-3503

Socha,M.T.,D.E.Putnam,B.D.Garthwaite,N.L.Whitehouse,N.A.Kierstead,C.G.Schwab,G.A.DucharmeandJ.C.Robert.2005.Improvingintestinalaminoacidsupplyofpre-andpostpartumdairycowswithrumen–protectedmethionineandlysine.J.DairySci.88:1113-1126

Socha,M.T.,C.G.Schwab,D.E.Putnam,N.L.Whitehouse,B.D.GarthwaiteandG.A.Ducharme.2008.Extentofmethioninelimitationinpeak-,early-,andmid-lactationdairycows.J.DairySci.91:1996-2010