Enhancing the fatty acid profile of milk through forage ... the fatty acid profile of milk through forage-based ... dairy farming, dairy fatty acids, grass milk, GrassmilkTM ... led
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Enhancing the fatty acid profile of milk through forage- based rations, with nutrition modeling of diet outcomes
Charles M. Benbrook1,2 | Donald R. Davis3* | Bradley J. Heins4 | Maged A. Latif5 | Carlo Leifert6 | Logan Peterman5 | Gillian Butler7 | Ole Faergeman8 | Silvia Abel-Caines5 | Marcin Baranski6
AbstractConsumerdemandformilkandmeatfromgrass-fedcattleisgrowing,drivenmostlybyperceivedhealthbenefitsandconcernsaboutanimalwelfare.InaU.S.-widestudyof1,163milksamplescollectedover3years,wequantifiedthefattyacidprofileinmilkfromcowsfedanearly100%forage-baseddiet(grassmilk)andcomparedittoprofilesfromasimilarnationwidestudyofmilkfromcowsunderconventionalandorganicmanagement.WealsoexploredhowmuchtheobserveddifferencesmighthelpreversethelargechangesinfattyacidintakesthathaveoccurredintheUnitedStatesoverthelastcentury.Keyfeaturesofthefattyacidprofileofmilkfatincludeitsomega-6/omega-3ratio(lowerisdesirable),andamountsoftotalomega-3,conju-gatedlinoleicacid,andlong-chainomega-3polyunsaturatedfattyacids.Foreach,wefindthatgrassmilkismarkedlydifferentthanbothorganicandconventionalmilk.Theomega-6/omega-3 ratioswere, respectively, 0.95, 2.28, and 5.77 in grassmilk, or-ganic, and conventional milk; total omega-3 levels were 0.049, 0.032, and0.020g/100g milk; total conjugated linoleic acid levels were 0.043, 0.023, and0.019g/100g milk; and eicosapentaenoic acid levels were 0.0036, 0.0033, and0.0025g/100gmilk.Becauseofoftenhighper-capitadairyconsumptionrelativetomostothersourcesofomega-3fattyacidsandconjugatedlinoleicacid,thesediffer-encesingrassmilkcanhelprestoreahistoricalbalanceoffattyacidsandpotentiallyreduce the riskof cardiovascular andothermetabolicdiseases.Althoughoily fishhavesuperiorconcentrationsoflong-chainomega-3fattyacids,mostfishhavelowlevelsofα-linolenicacid(themajoromega-3),andanomega-6/omega-3rationear7.Moreover,fishisnotconsumedregularly,oratall,by~70%oftheU.S.population.
NearlyhalfofAmericanssufferfromoneormorediet-drivenchronicconditions includingcardiovasculardisease (CVD),overweightandobesity, and diabetes (DHHS, 2015; Massiera etal., 2010; FDA,2015;ARS,2010).Sevenof the10 leadingcausesofdeath in theUnitedStateswerediet-relatedin2013(IHME,2016a),andnonearecurableviamedicalinterventionalone,despitehealthcarespendingintheUnitedStatesthatisthehighestpercapitaintheworld(IHME,2016b).Thesesoberfactsareamongthereasonswhythereisgrow-inginterestintheUnitedStatesamongscientistsandconsumersinalteringdietstopreventorslowtheprogressionofmetabolic,car-diovascular,andotherchronicdiseases.
Potentialdietalterationsincludereducingintakesofomega-6(ω- 6)fattyacids(FAs)andincreasingintakesofomega-3(ω-3)FAs,thusdecreasingdietaryω- 6/ω-3ratios.Theseratioshavebecomehistori-callyhighinWesterndietsduringthelastcentury,reachingabout15,comparedtoestimatedevolutionaryratiosnear1(Hibbeln,Nieminen,Blasbalg, Riggs, & Lands, 2006; Simopoulos, 2006). These largechangesareduetobothincreasedintakesofω-6FAsanddecreasedintakesofω-3FAs.Moderngrainfeedingoffarmanimalshascontrib-uted to these ω-6increasesandω-3decreasesinWesterndiets.
ThemorenaturalFAprofileoforganicandgrass-fedmeatandmilkhas receivedmuchattention in recentyears (Średnicka-Toberetal.,2016a,b).TheFAprofileinmodernmeatandmilkcanbesub-stantially changed by shifting animals from grain- or concentrate-rich rations to diets largely based on grass and legume forages(Butleretal.,2011;Daley,Abbott,Doyle,Nader,&Larson,2010;O’Callaghanetal.,2016;Schwendeletal.,2015;Stergiadisetal.,2012).Thisshiftincreasesω-3FAsandconjugatedlinoleicacid(CLA)anddecreasesω-6FAsinmeatandmilk,changesthatmayhelppreventCVD and other chronic conditions (Leikin-Frenkel, 2016; Hibbelnetal.,2006;Simopoulos,2006).Themagnitudeofthesechangesismarkedlygreaterthanmostofthenutritionaldifferencesbetweenorganicallyandconventionallygrownplant-basedfoods(Benbrook,Butler,Latif,Leifert,&Davis,2013;Baranskietal.,2014;Średnicka-Toberetal.,2016a,b).
Thereisrisingdemandforbeefanddairyproductsfromgrass-fedcattle.In2016,natural-foodretailleaderWholeFoodsMarketiden-tifiedgrass-fedmeatanddairyasa top trend,basedonconsumerinterestandrapidsalesgrowth(PRNewswire,2016;WholeFoodsMarket Blog, 2015). Three-quarters of self-identified natural-foodandorganicconsumerspurchasegrass-fedbeefanddairy (MarketLohas,2016).Similar interests inhumanhealthandanimalwelfareled in 2015 to themarketing in Italy, and laterMexico, of “LatteNobile”(NobleMilk),producedbycowsfedprimarilygrassandhay(Rennaetal.,2015;Lombardietal.,2014;AssociazioneLatteNobileItaliano(http://www.lattenobile.it/).
Besidesprohibitinggrain incowrations,CROPPsetsgrassmilkstandardsforpastureaccess,supplemental feeds,andanimalcare(see Appendix for details). Farmers in the grassmilk program re-ceiveapricepremiumof~15%comparedtotheorganicmilkprice.CROPPcloselymonitorstheFAcontentofrawgrassmilk,toassurecompliancewithitsminimumrequirementsof(1)39to41mgtotalω-3FA/100gofmilk,dependingongeographicalregion,(2)26.6to32.8mgtotalCLA/100gofmilk,and(3)anω- 6/ω-3ratio≤1.2.
The number of farms shipping grassmilk to CROPP proces-sors has grown from five California producers in 2011 to 140farmsthroughouttheUnitedStatesattheendof2016.These140farms represented about 9% of CROPP’s 1,618 dairy-farm mem-bers(CROPP,2016).Milk,yogurt,andcheesemadefromgrassmilkaremarketedunderCROPP’sOrganicValleybrand. In addition tomeetingUSDA’sorganicgrazingstandard(Rinehart&Baier,2011),CROPP’sgrassmilksuppliersmaynotfeedgrainorsilagefromgraincropsharvestedfromfields thathavereachedthe“boot”stageofdevelopment(whenseedheadsformandstarttofillout).Nongrainsupplementsincludingmolasses,alfalfapellets,sugarbeets(chippedorwhole),mineral supplements, andkelpareallowed tomeet theenergyneedsoflactatingcowsandsupportanimalhealth.
Somesupplementalfeedisoftenneededtosustaincowhealthduring months of peak production, or when high-quality, foragefeeds are not available in sufficient quantity. Despite reliance onsomesupplementalfeeds,forage-basedfeedsmakeupthevastma-jorityofannualDryMatterIntake(DMI)ongrassmilkfarms.
Farmersinthegrassmilkprogramarealsorequiredtodocumentthatlactatingcowsconsumeover60%ofDMIfrompastureduringthe grazing season (compared to 30% under the USDA organicstandard),withagrazingseasonofat least150days(comparedto120daysunderfederalorganicrules).Thelengthofthegrazingsea-soncanbereduced incasesofextremedroughtorotherweatherevents or natural disasters, or by the tolerance of soils to animaltraffic.
Thenongrazingportionofrationsongrassmilkfarmsmustcomefrom conserved, organic, forage-based feeds, including dried orfermentedforages(alfalfa,clover,grasshay,etc.).Cerealcropshar-vestedpriortotheirbootstage,suchasbarley,oats,andBMRcorn(“brown mid-rib” phenotypes developed for early silage harvest),canalsobe fed, as theFAprofileof such immaturegrain crops issimilartowidelygrowngrassspeciesincowpastures(see“ResultsandDiscussion”formoredetail).Harvestedfeedstuffsaretypicallypreservedbyfermentationon-farmtoproducebaleageorsilage,orstoredasdryhay.
Themilkfatmustcontainat least0.25%oftotalCLAand0.5%oftotalω-3FAs,andtheLA/ALAratiomustbelowerthan4yearround(Renna etal., 2015). Pastures must be diverse, with at least fourmajorplantspecies,andthequalityofhayismonitoredwithasen-soryanalysis(Rubino,2014).
As estimated below, most organic milk analyzed in Benbrooketal. (2013) came from cows receiving ~20% of their yearlyDMIfromgrain-basedfeeds.Onanannualbasis,theUSDAorganicstan-dard technically allows up to ~90%DMI from sources other thangrazing(asonly30%ofDMImustcomefromgrazingduringamini-mumof120daysperyear),althoughonmostorganicdairiesintheUnitedStates,forage-basedfeedsplayamuchgreaterrolethanisminimallyrequired(CROPP,2016;Rinehart&Baier,2011).
Here,wereporttheaddedimpactsonnutritionallyimportantFAlevelswhenlactatingcowsarefedanearly100%forage-baseddietyear round,andwemodel the impactof thesechangeson typicalU.S.diets.WealsocomparetheimpactsofgrassmilkdairyproductsandfishonFAintakes.
2 | METHODS
MilkFAanalysesreportedinthisstudycomefromCROPP’squality-controltestingofitsgrassmilk.Bulk-tank,rawmilksamplesfromeachparticipatingfarm(140in2016)werecollectedatleastbimonthlyinsterileplasticbottles,packedwithice-packs,andshippedovernightto Silliker, Inc., an ISO/IEC 17025 accredited laboratory in Crete,Illinois. It used AOACmethod 996.06, as revised in 2001 (AOACInternational, 2012), with modified internal standard (C13:0) andtemperatureprogram[initialT=100°(nohold),ramp2°/minto214°(hold 10min), ramp 3°/min to 240° (hold 16min)]. The laboratoryused capillary columnSupelcoSP-2560,100m×0.25mm,0.2μm film.Inunitsofg/100gofmilk,thelaboratorydidnotquantifyindi-vidualFAamounts<0.001,butitdidquantifythosesmallamounts(ifdetected) inunitsof%of totalFA, togivethebestmeasureoftotalFA.This laboratoryanditsmethodsandreportsareidenticaltothoseusedinBenbrooketal.(2013).However,inthispaper,wereportamountsofadditional,minorFAthatwerenotreportedinthe2013paper,duetotherelativelysmallnumberofsamplesin2013.
ThedetectedandsummedisomersofreportedtotalCLAincludecis-9, trans-11 (commonly 75–90% of the total); trans-9, trans- 11; cis-9,cis- 11; trans-10,cis-12;andcis-11,trans-1318:2.Thereportedtrans-18:1includesmainlytrans-1118:1,vaccenicacid.
comeprimarily fromthree regionsof theUnitedStates—Midwest,Northeast,andCalifornia.AsmallgroupofsamplescamefromtheMiddle-EasternUnitedStatesbeginninginJune2016.Forcompari-sonwithrawgrassmilk,wealsoreportFAresultsfrom69samplesofprocessed,wholegrassmilk,takenfrompasteurized,retailcontain-ers (not homogenized). These sampleswere taken in a systematicmanner similar in locationand season to the rawmilk samples. In2014, therewere 22 samples—12 from theMidwest and 10 fromCalifornia;in2015,therewere23samples—fivefromtheMidwest,sixfromCalifornia,and12fromtheNortheast;andin2016,therewere24samples—sixfromtheMidwest,sixfromCalifornia,and12fromtheNortheast.
Asinthe2013study(Benbrooketal.,2013),wereportaveragesof three ω- 6/ω-3ratios:LA/ALA,ω- 6/ω-3,andω- 3/ω-6,whereω- 6 includessevenFAs(18:2LA+18:3γ-linolenic(GLA)+20:2eicosa-dienoic+20:38,11,14-eicosatrienoic+20:4arachidonic(AA)+22:2docosadienoic+22:4docosatetraenoic),andω-3includes7FAs(18:3ALA + 18:4 stearidonic/moroctic + 20:3 11,14,17-eicosatrienoic +20:5EPA+22:3docosatrienoic+22:5DPA+22:6DHA).Weincludetheaverage ratio,ω- 3/ω-6, for comparisonwithotherpapers thatreportthisinvertedratio.
2.1 | Statistical analysis
DigitallaboratoryresultsweretransferredtoanExcelspreadsheetandspot-verifiedagainstprintedlaboratoryreports.(Therawdataare available fromMALorDRD.) The reportedFA concentrations(g/100gofmilk)in1,163rawmilksampleswereinspectedforoutli-ersbynormalprobabilityandboxplots,andfivesevere,highoutlierswereexcluded,mostlybyconsensusamongDRD,MB,BH,andCMB(18:3γ-linolenic=0.028,trans-18:3=0.075,20:1=0.070,11,14,17–20:3=0.040,and22:6DHA=0.025,alling/100gofmilk).WealsoremovedthecorrespondingvaluesexpressedasapercentoftotalFAs.Anadditionalfouroutlierswerefoundandremovedonlyinthevalues expressed as a percent of total FA: sumof FA=102.998%(high), sum of saturated FA=87.690% (high), 18:1=0.330% (low),andsumofcis-monounsaturated=4.89%(low).Theremovedvaluesrepresentineachcaseonly1in1,163samples(<0.1%).Nooutlierswerefoundinthe69samplesofretailgrassmilk.
Means, counts, standard deviations (SDs), coefficients of vari-ation (CVs),andstandarderrors (SEs)werecalculated inMicrosoftExcel.We reportSDs, CVs, andSEswith 1 or 2 significant digits.BecausethestatisticaluncertaintyofameanismeasuredbyitsSE,wereportmeanstothesamenumberofdecimalplacesastheSEs. Withsamplecountsashighas1,163,SEsandthestatisticaluncer-taintyofmeanscanbemuchsmallerthanthelaboratoryprecisionforindividualmeasurements.
Akaike informationcriterion for repeatedmeasures (Littell,Henry,&Ammerman,1998).WereliedontheSatterthwaitecorrectiontoadjustthedegreesoffreedomforunequalvariances.AlltreatmentresultsarereportedasleastsquaresmeansseparatedbytheTukeyprocedurewithsignificancedeclaredatp < .05.
2.2 | Diet scenarios and LA/ALA ratios
WemodeledhypotheticaldietscenariosbasedonthoseinBenbrooketal.(2013)totestthepotentialeffectsofswitchingwhole-fatdairyproductsmadefromconventionalmilk,toorganicmilk,and,finallyinthisstudy,tograssmilk.Forthesediets,wecalculatedoveralldietaryintakesofLAandALA, and theLA/ALA ratio, themajordetermi-nantoftheω- 6/ω-3ratio.Wecouldnotcalculatetheω- 6/ω-3ratioitself, because there is insufficient data on totalω-6 andω-3 FAsinmostof the foods inour scenarios.However, theω- 6/ω-3 ratiocloselytrackstheLA/ALAratio,andbothratiosarehistoricallyhighinmostWesterndiets,duetoincreasedω-6intakesanddecreasedω-3intakes(Hibbelnetal.,2006;Simopoulos,2006).
Here,weuse the samemodeldietsandassumptionsas in thepreviousreport(Table1inBenbrooketal.,2013),andaddnewdietscenariosusingdairyproductswiththeFAprofileofgrassmilk.AsinBenbrooketal.(2013),weusefull-fatdairyproducts(exceptforyogurt),toquantifythemaximum,realisticallyattainableshiftinFAintakes from a switch to grass-milk-based dairy products. For yo-gurt,weusethehighest-fatformgenerallyconsumedintheUnitedStates,sweetened“low-fat”yogurtwithfruit,containing1.41gfatper100g.Sweetenedwhole-fatyogurtisnotusuallyavailable.
Wemodeleddiets foramoderatelyactivewoman,age19–30,consuming 2,100kcal/day. In threemain scenarios, 20%, 33%, or45%ofthatenergycamefromfat.Withinthosescenarios,wecon-structeddietsthatcontaineithermoderateamountsofdairyprod-ucts(threedailyservings,asrecommendedintheDietary Guidelines for Americans(DHHS,2015),or50%higheramounts(4.5servings/day).Whole milk, Cheddar cheese, low-fat yogurt, and ice creamas a “dairy dessert” were the dairy products included (Table 1 inBenbrooketal.,2013).
For the LA andALA contents of dairy fat, the previous studyuseditsmeasured12-monthaverageconcentrationsinconventionaland organicmilks (Benbrook etal., 2013). For the LA andALA innondairy foods, theauthorsusedUSDA’s standard referencedatafor 8 common foods to represent “typical-LA nondairy sources”(USDA,2015).Thosefoodsaveraged23.23gLAand1.841gALAper 100kcal of fat, for an LA/ALA ratio of 12.6. To illustrate theeffects of reducing LA intake, they substituted three of the eightfoodswithsimilar,low-LAfoodsandingredients(e.g.,canolaoilin-steadof soyoil, themajor oil used inmany foods). These revisedeight “low-LAnondairy sources”averaged13.84gLAand2.731gALAper100kcaloffat,withanLA/ALAratioof5.07.
With these assumptions, the2013 authors calculated the LA/ALAratiosfor12dietswithtypical-LAnondairysources(3fatlevels×2 levelsofdairyconsumption×2 typesofdairy fat) and foranadditional12dietswithlow-LAnondairysources.Here,weaddto
Wesetouttoanswertwokeyquestions.First,towhatextentdoesshifting lactating dairy cattle to nearly 100% forage-based feedsalter the FA profile of their milk compared to currently availableconventionalandorganicmilksintheUnitedStates?Thefollowingsubsectionpresentsresultsfrom3yearsofnationwidesampling,in-cludingseasonalandregionalvariations.
Table1showsconcentrationsof37mainFAs (quantifiedamounts>0.001g/100gmilk)inraw,wholegrassmilk,averagedover3years(2014–2016), reported as g/100g ofmilk and as a percentage oftotalFAs.ForeachFA,thereare1,163values, lessthenonquanti-fied samples and any outliers removed (as explained inMethods).SeeTable1footnotesaandbfordetails.Thecoefficientsofvariation(CV=SD/mean)areameasureofvariabilityamongsamples.
TableS1showsthesameinformationfor14minorFAsingrass-milk. Table2 shows the same information as Table1 for 69 retailsamples of grassmilk taken during 2014–2016. The FA profiles ofthese samples of processed, whole-fat grassmilk were measuredto determine whether there were any significant changes in theFAprofileofgrassmilkasaresultofprocessingandpasteurization.ForFAconcentrationsexpressedasapercentageoftotalFAs,theamountsinTables1and2areverysimilar,asexpected:ThemeansinTable2average101±SD5%ofthemeansinTable1(for33FAswith n>50%oftheanalyzedsamples).However,forFAconcentra-tionsexpresseding/100gmilk,themeansinTable2averageonly75±SD4%ofthemeansinTable1(for38FAswithn>50%oftheanalyzedsamples).Thesevaluesare<100%,mainlybecause fat isremovedfromrawmilktoproduceretailwholemilkwithastandard-ized3.25%fatcontent.
Table3comparesselectedFAlevelsandratiosinorganicgrass-milk to those in retail conventional milk and organic milk fromBenbrooketal.,2013.WeincorporatedinTable3resultsfromthe1,163samplesofrawgrassmilk(Table1)ratherthantheresultsfrom69samplesofprocessedgrassmilk(Table2).Wedidsobecausethe1,163samplesofgrassmilkprovideamoreaccurate,year-roundFAprofile of grassmilk than the69 retail samples. The retail conven-tionalandorganicmilk samplesaverage~3.1%totalFAs,whereastheraw,grassmilksamplesaverage~3.6%FAs.Duringtheprocess-ingofrawgrassmilk,~0.5%offatisremovedtomeetthestandardofidentityforfatinwholemilk.Accordingly,inTable3,weadjustedtherawgrassmilkFAamountstoequaltheaveragetotalFAcontent
in the retail conventional andorganicmilks. The last twopairs ofcolumnsshowtheoften-largepercentagedifferencesbetweencon-ventionalandadjustedgrassmilk,andbetweenorganicandadjustedgrassmilk.
The p-valuesinTable3arefromtwo-tailedttests.Theseareac-curate for individualpairwisecomparisonswithineachof the twopairs of columns considered alone, but they somewhat overstatethestatisticalsignificanceofdifferencesbetweenpairsofcolumns,andtheydonotaccountformultiplecomparisonswithincolumns.However,thesecaveatsareminorinviewoftheusuallyextremelysmallp-valuesbyttest.anovamethodsarequestionableduetotheunbalanced data and several years betweenmeasurements. TotalsaturatedandmonounsaturatedFAlevelsintheadjustedgrassmilkshowonlysmallpercentagedifferenceswith those in theconven-tionalandorganicmilks.But largepercentagedifferencesoccur in
theamountsoftotalω-3andω-6FAs,andtotalCLA.Themeanlevelof totalω-3 in the adjusted grassmilk samples ismore than twicethatintheconventionalsamples(up147%).Theshiftfromorganicmanagementtonearly100%forage-baseddietsongrassmilkfarmsincreasestheleveloftotalω-3FAsby52%.Inthecaseoftotalω- 6 FAs, the level drops52% in adjustedgrassmilk samples comparedto conventional samples and drops 36% from organic to adjustedgrassmilk.
adjusted grassmilk averages43%more20:5EPA and27%more22:5DPA, twoof threecritical long-chainω-3FAs.Thepercentincrease in 22:6 DHA cannot be calculated, because there wastoo little found in the conventional and organic samples testedin 2011–2012. We estimate that the absolute average increaseinDHAisabout0.0006g/100gofmilk (Table3footnote f). It iswidelyagreedthattypicalWesterndietsprovideinsufficientsup-pliesoflong-chainω-3FAs, leadingtheEuropeanFoodStandardAgencytorecommendatleastadoublingofaveragedailyintakesof long-chain ω-3 FAs (EPA, DPA, and DHA), especially duringpregnancy(EFSA,2010).
LimiteddatafromfoursmallfarmsforNobleMilkinItalyshowshifts in FA profile qualitatively similar to those in grassmilk, butsmaller,asexpectedgiventheupto30%grainandconcentratesal-lowedincowrations(Lombardietal.,2014).InNobleMilk,theratios
Total transFAconcentrations (excludingCLA)wereone-thirdhigherin grassmilk compared to the similar levels in the organic and con-ventionalmilksshowninTable3.Otherstudieshavealsofoundthatpastureandforage-basedfeedsincreasethelevelsoftransFAinmilk,mainly trans-18:1, simultaneouslywith increases inCLA, a groupof
aForFAsreportedinunitsofg/100gmilk,meansandtheotherstatisticsarebasedonquantifiedamounts≥0.001g/100g(samples<0.001g/100gnot included). Hence, forminor FAswith n substantially <69,means are elevated, and other statistics are based on the distribution of samples≥0.001g/100gmilk.bForunitsof%oftotalFAs,meansandotherstatisticshavethesamepropertiesasnotedaboveforunitsofg/100gmilk.ForafewminorFAs,thelaboratoryquantifiedupto5moresamplesinunitsof%oftotalFAsthanitdidinunitsofg/100gmilk,increasingthen-valuesshownhere.Inrarecases,then-valuesdifferalsoby±1duetodifferencesinthenumberofoutliersremoved.cAnaverageofsumsreportedbythelaboratoryforeachsample.ThelaboratorysumsincludeminorFAsreportedinTableS1butnottabulatedhere,sotheyusuallyslightlyexceedthesumofmeansfortheindividualFAslistedhere.dAnaverageofsumsofall7FAsforeachsample.ThisaverageisslightlysmallerthanthesumofmeansshownforeachFA,becausesomeofthelattermeansaresubstantiallyelevatedbyexclusionofvalues<0.001mg/100gmilk(footnotea).
e Notreportedbecausequantifiableamounts≥0.001g/100gmilkwerefoundinonly2of160conventionaland4of218organicsamples.
f Meanof249samples(21%of1162)withquantifiedamounts≥0.001g/100gmilk.WeestimatetheaverageDHAcontentofall1162samplesisabout0.0006g/100gmilk,roughlyhalftheunadjusted
TransFAhasabad reputationbecauseofevidence that sourcesfrom partially hydrogenated vegetable oils strongly increase LDLcholesterol,decreaseHDLcholesterol,andhavemultipleothermet-aboliceffectsassociatedwithCVD.Theseadversefindingsareoftenassumed toapplyequally tonatural sourcesof trans FAs.However,such assumptions are unwarranted, because there are large differ-ences between the two sources of transFAs.First,industrialsourcescontainupto60%transFAs,comparedtoamaximumof5to8%ofFAs inmilk (5.4%and6.0% inTables1and2) (Stender&Dyerberg,2003).Second,thedistributionofisomersdiffersgreatlyinthemaintransFAinmilk,trans-18:1(about72%and75%oftotaltransFAsinTables1and2).Inindustrialsources,thepositionofthetransbondhasabroad,near-Gaussiandistributionfromthe6thtothe16thcarbonatom,whereasmilkandotherruminantsourcespeakstronglyatthe11thcarbonatom,withonlysmallamountsatotherpositions(Stender&Dyerberg,2003).
Trans- 18:1 with the transbondatthe11thcarbonatomisvacce-nicacid(VA),themajorprecursortoCLA(rumenicacid)inmilk.Atthehighrangeofhumanintakes,VAhaslittleornoadverseeffectonriskfactorsforCVD(Lacroixetal.,2011).VAinthecow’sudderispartiallyconvertedtorumenicacid,themajorCLAinmilk(75%to90%)(Lock&Bauman,2004;Tyburczyetal.,2008).HumansarealsoabletoconvertsomeVAinmilktothisformofCLA(Lock&Bauman,2004;Turpeinenetal.,2002;Tyburczyetal.,2008).Despitehavingatransdoublebond,rumenicacidhasprovenbenefitsinanimals,es-peciallyanticarcinogenicactivityagainstdiversecancertypes(Lock&Bauman,2004).Inhumans,thereissuggestivesupportforactivityagainstcoloncancerfromalarge,epidemiologicalstudyinSweden(Larsson etal., 2005) and possibly against breast cancer (Dilzer&Park,2012).
Motard-Bélanger etal. (2008) conducted a double-blind, ran-domizedcrossoverstudyof“high”and“moderate”dietary intakesof trans FAs from specially produced milk. They concluded thathigh intakes of these trans FAs “may adversely affect cholesterolhomeostasis,”but thatmoderate intakes “that arewell above theupperlimitofcurrenthumanconsumptionhaveneutraleffectsonplasmalipidsandothercardiovascularriskfactors.”Their“moder-ate”intakewas4.2g/2,500kcal,where4.2gistheamountoftotaltrans FAs in2.64kgof retail grassmilk (Table2), or10.8 servingsofonecup(244g).The“high”amountwas10.2g/2,500kcal,2.43timeshigherthanthe“moderate”amountandfarbeyondevenex-ceptionallyhighlevelsofdairyproductconsumptionintheUnitedStates.
Moreover,thereissomeevidenceofbenefitsfromVAassociatedwith its conversion toCLA (Kuhnt,Degen,& Jahreis, 2016).A re-centmeta-analysisincluded13randomized,controlledinterventiontrials that used dairy products as the primary source of trans FA,inamountsashighas4.2%ofenergy (10.9g trans FA/2,500kcal)(Gayet-Boyer,Tenenhaus-Aziza,Prunet,&Chardigny,2014).Theau-thorsfoundthattheselevelsoftransFAhavenoharmfuleffectsonHDLcholesterol,LDLcholesterol,ortheirratio.
Our large, nationwide, 3-year dataset allows assessment of theregional and seasonal consistency in the impact of nearly 100%forage-based feedon theFAprofileof grassmilk.Table4 showsmodest, but sometimes statistically significant, regional differ-encesingrassmilkcompositionfortotalω-6andω-3FA.Thehigh-estaveragelevelsofω-3FAsingrassmilkcamefromtheMidwestand Northeast (1.60% and 1.58% of total FA), while Californiahad the lowest (1.40%), about a 14% difference. Likewise, theMidwestandNortheasthadthetwohighestaverageconcentra-tions of total ω-6 FAs. For total CLA, there are no statisticallysignificantregionaldifferences.AverageratiosofLA/ALAandω- 6/ω-3 varied by 7% across the 4 regions, but these differences
California Mideast Midwest Northeast SEM p- value
Observations 85 54 582 442
Totalω- 3 1.40c 1.434bc 1.601a 1.575ab 0.04 .002
Totalω- 6 1.364ab 1.309b 1.477a 1.495a 0.04 .002
TotalCLA 1.282 1.165 1.300 1.379 0.07 .09
LA/ALA 1.091 1.022 1.035 1.047 0.03 .62
ω- 6/ω- 3 1.189 1.232 1.206 1.151 0.07 .75
*Least squaremeans.Meanswithin a rowwithout common superscripts aredifferent atp < .05. MeanswereevaluatedusingTukey’smultiplecomparisonstest.
are not statistically significant (p > .05). There were no regionaldifferencesforthemajorFAsinmilk—totalsaturatedandtotalcis-monounsaturatedFAs(notshown).
SomeregionalandseasonalvariationintheFAprofileofgrass-milkisexpected,drivenbydifferencesinthequalityandinbotanicalcompositionof freshandstored forage (RavettoEnrietal.,2017).Suchvariationsareoften triggeredby climatic conditions that aremost extreme during extended drought or heavy rains leading towater-logged soils or flooding. The length of the outdoor grazingperiodalso impacts foragequality, asdoesmanagementattentiontosustainingapropermixofgrassandlegumespeciesinpastures(sothathigh-quality,immatureforagesarepresentinpasturesfromspring through the fall). The timing of forage harvests and how,and howwell, forage-based feeds are conserved also impact for-age composition. Despite all these factors, our results show thatCROPPfarmersswitchingtograssmilkstandardshaveconsistently
SeasonalhighsandlowsingrassmilkFAsareshowninTable6,averaged over all 1,163 samples (2014–2016). The ω- 6/ω-3 ratiopeakedinJulyandbottomedinDecember,withavariationof30%fromlowtohigh.Forω-6andω-3levels,themaximumvariationwassomewhatless,21%to22%.ThelargestseasonalvariationoccurredintotalCLAconcentration,whichmorethandoubledinSeptembercomparedtoApril.SaturatedandmonounsaturatedFAlevelsdidnotvarysignificantlybymonth(notshown).
Figure1 shows themonthly variation in averageω- 6/ω-3 ratioinallgeographicalregionsduring2014–2016.FigureS1showssim-ilarplotsforthethreeseparategeographicalregionswiththemostsamples (sample numbers are 85 for California, 582 forMidwest,and442 forNortheast).TheCalifornia regionshowsnotably littlemonthlyvariationinω- 6/ω- 3.
For Noble Milk, reported seasonal variations from four smallfarmsinItalyareconsiderablylargerthaningrassmilkfortotalω- 3 FAs(twofoldlarger)andtotalCLA(nearlythreefoldlarger).However,seasonal variations in LA/ALA andω- 6/ω-3 aremodest (Lombardietal.,2014).
AccordingtoCROPPrecords,cowsunderOrganicmanagementon its farms receive about 56%of dailyDMI frompasture duringan average 183-day season and hence about 28%of their annualDMI fromgrazing.OnCROPPfarmsproducingGrassmilk,pastureaccountsforanaverage80%ofDMIovera190-daygrazingseason,or42%ofannualDMI.Stored,forage-basedfeedsaddnearly52%ofdailyDMIonOrganicfarms,and58%onGrassmilkfarms,bringingtheirtotalsfromforage-basedfeedsto,respectively,about80%andnearly100%ofDMI.
In the milk from these four management systems, the ratiosof ω- 6/ω-3decline fromanestimated8withMinimumForages tomeasured values of 5.8 inConventionalmilk, 2.3 inOrganicmilk,and0.95inGrassmilk(Table7).Simultaneously,theannualaverage
amounts of total CLA in conventional to retail grassmilk increaseabout fourfold from about 0.010 to 0.043g/100gmilk. For totalCLA,theimpactofpastureandforagefeedingappearstoincreaseastheirproportionofannualDMIincreasesbeyond80%,anobser-vationthatdeservesfurtherexploration.
Ingraincrops, stageofgrowth impacts theFAcompositionoffeedstuffs in cow rations, aswell as theFAprofileofmilk (Darbyetal.,2012;Darbyetal.,2013;Duvicketal.,2006).SupplementalTextS1andTableS2comparetheFAsincommonforagegrassandlegumecropswiththoseofseveralcerealcropsatvariousstagesofmaturity.
3.5 | Nutrition modeling of grass milk effects on dietary LA/ALA ratios
Tables1–3 show that increasing forage-based feeds in rations forlactatingcowscansignificantlyaltertheFAprofileofmilk;however,a key question remains.Will consumption of dairy products fromcowsfedall,ormostly,forage-basedfeedshaveameaningfulimpactonhumanintakesofFAs,andpotentiallyonpublichealth?
The18scenariosineachofthesetwocases(high-andlow-LAintakes)entailed three levelsof fat intake (20%,33%,and45%oftotal energy), two levels of dairy product consumption (3 and4.5servings/day),andthreevariationsofdairyfat(fromcowsmanagedunder the conventional, organic, and grassmilk systems discussedhere,withtheirvaryingrelianceongrazingandforagerationsshowninTable7).
Ourmodeling focuseson total intakesofLAandALAand theLA/ALAratio(ratherthanω-6,ω-3,andω- 6/ω-3),becausetheUSDAdoesnotpublishsufficientandreliabledataonthetotalω-6andω- 3 contentsofmanycommonfoods.Butformanyfoods,itdoesreport
Weassessthedegreetowhicheachofthe36dietaryscenariosreducestheLA/ALAfromthebaselinelevelof11.3for3servings/day of conventional milk, typical-LA sources of nondairy fat, and33%ofenergyfromfat.Thelowertheratio,thegreaterthebody’sabilitytoconvertdietaryALAtotheessential,longer-chainω-3FAs.Thisconversionismostimportantforpregnantandlactatingwomenand for those who consume little or no oily fish (Brenna, 2002;Burdge&Calder,2005).Oilyfishare,perserving,superiorsourcesfor EPA andDHA, but even oily fish do not contain enoughALAtosignificantlyalterdietaryratiosofLA/ALAorω- 6/ω-3(Benbrooketal.,2013;USDA,2015).
Table8givessample results fromournutritionmodelingcal-culationsforfourdietswithtypicalintakesoftotalfat(33%ofen-ergy)anddairyfatwiththeFAprofileofadjustedgrassmilk.Thesefour diets include those with moderate (recommended) (DHHS,2015)dairyintake(3servings/day)andhighdairyintake(4.5serv-ings/day), with either typical-LA or low-LA sources of nondairyfat.Forthesefourdiets,thetableshowsthedairyandnondairycontributionstodietaryintakesofLAandALA,theLA/ALAratioandchangesinthisratiorelativetothebaselineratioof11.33forrecommended intakesofconventionaldairyproducts (Benbrooketal.,2013).Thus,itshowstheimpactondietaryLA/ALAratiosofswitchingfromconventionaltograssmilkdairyproductsforthesefour diets.We performed similar calculations for correspondingdietswithlowandhighamountsoftotaldietaryfat(20%and45%ofenergy).
Aswediscussbelow,reductionsindietaryLA/ALAratiosofthismagnitudeseemofpotentialpublichealthsignificance.Muchofthereductions can be achieved with grassmilk dairy products alone,withoutreducingintakesofnondairyLA.TheopportunitytoreducetotaldietaryLA/ALAratiosfrom11.33toaslowas3.14,andwithoutmajorchangesindietarypatterns,seemsnotabletous.Inourmodeldiets, there are no changes inmost foods, including French fries,chocolatechipcookies,chicken,pork,andbeef.ThemodeledfoodchoicesrepresentanattainableoptiontoimproveFAintakesinwaysthatwilllikelyreducetheriskforcardiovascularandothermetabolicdisorders,atleastforsomeindividuals.Manyotherfactors—genet-ics, age, health status, and environmental exposures—will interactindeterminingthemagnitudeofsuchimpacts(Simopoulos,2006).
Figure2showsthefullresultsofournutritionmodeling,includ-ingdietswithlowandhighintakesoftotaldietaryfat(20%and45%ofenergy).Fordietswithtypical-LAnondairyfatsources(leftsideofFigure2),thedecreasesindietaryLA/ALAratiosareenhancedinthedietswithonly20%ofenergyfromfatandattenuatedinhigh-fatdiets.Fordietswith low-LAnondairy fatsources (rightsideofFigure2), there is littledependenceon theoverall levelofdietaryfat, but the reductions in dietary LA/ALA ratio are much larger,including evenwith conventional dairy fat.Organic and grassmilkdairyfathavethemostimpactondietswithtypical-LAnondairyfat,comparedtodietswithlow-LAnondairyfat.
ALA from other fat (g)c Total LA (g) Total ALA (g)
Total LA/Total ALA ratio
Typical-LAnondairyfatsources
Moderatedairyintake
0.41 0.41 9.91 0.79 10.32 1.19 8.64
Highdairyintake
0.62 0.62 5.77 0.46 6.39 1.07 5.95
Low-LAnondairyfatsources
Moderatedairyintake
0.41 0.41 5.90 1.17 6.32 1.57 4.01
Highdairyintake
0.62 0.62 3.44 0.68 4.06 1.29 3.14
aThistableextendsTable3inBenbrooketal.,2013toincludegrassmilk.ThemodeleddairyservingsareinTable1ofthatpaper.Init,thebaselineLA/ALAratiois11.33,formoderateconsumptionofconventionaldairyfat.bBasedonLA,ALA,andtotalFAfromTable1,8.79kcal/gdairyfat,and0.933gmilkFA/gdairyfat.Forexample,LA0.41=313kcal(2013Table1)/8.79×0.0447/3.585×0.933.cBased on 23.23g LA and 1.841g ALA per 100kcal nondairy fat and 8.90kcal/g nondairy fat For example, LA 9.91=380kcal (2013Table1)/8.90×23.23/100.Correspondingcalculationsforlow-LAnondairyfatuse13.84gLAand2.731gALAper100kcalnondairyfat.
14 | BENBROOK Et al.
Fortypicaldietswith33%ofenergyfromfatandtypical-LAnon-dairyfat(leftsideofFigure2),switchingfrommoderateamountsofconventional tohighamountsofgrassmilkdairyproducts reducestheLA/ALA ratio from11.33 to5.95, a47% reduction.The sameswitch for diets with low-LA nondairy fat decreases the LA/ALAratiofrom5.11to3.14.
LAandALAareessentialhumannutrients,buttheybothcomple-mentandcompetewitheachother,andtheirdietaryratiomatters.Theyareelongatedbyparallelandcompetingpathwaysto,respec-tively,AA(fromLA)andEPA(fromALA),whichinturnareconvertedinto eicosanoids that regulate many body functions. EicosanoidsderivedfromAAareproinflammatoryandthrombogenic,andsev-eralhavebeenlinkedtocarcinogenesis,whereasthosederivedfromALAtendtosuppressinflammation,thrombosis,andcarcinogenesis,especiallywhen theω- 6/ω-3 ratio approaches 1 (Larsson,Kumlin,Ingelman-Sundberg,&Wolk,2004).
DHAisindependentlyimportant,becauseitisrequiredinthede-velopmentoftheinfantbrainandocularsystem(Ailhaud,Massiera,Alessandri, & Guesnet, 2007; Donahue etal., 2011), as discussedfurtherbelow.
ImpairedconversionofALAtoEPAandDHAisofconsiderableconcernintheUnitedStates,becausemostAmericansdonotcon-sume adequate fish tomeet the recommended average intake of250mg/dayofEPA+DHA(DHHS,2015;EPA,2002).Hence,theymustpartlyrelyondietaryintakeofEPAandDHAfrommeatanddairyproductsorsupplements.Indeed,inthelate1990s,over70%ofAmericansage18orolderconsumednofishandshellfish(EPA,2002).
3.6 | Contribution of grass milk dairy products and fish to fatty acid intakes
Oilyfisharetheultimate,directsourceofthelong-chainω-3PUFAs,EPA,DPA,andDHA.DHAispresentatverylowconcentrationsinotherfoods,includinggrassmilk,butitplaysavitalroleinthede-velopment of an infant’s and child’s brain, eyes, and nervous sys-tem(Bondietal.,2013;Moonetal.,2013;Ryanetal.,2010).Forthe70%ofAmericanswhoconsumeessentiallynofish,theefficiencyofconversionofALAto long-chainω-3FAs iscritically important,especially for thosewith elevated need, such as growing childrenandwomenwhoarepregnantorbreastfeeding.Forthisconversion,ALAfromdairyproductsandotherfoodsplaysdualroles.FirstasaprecursortoEPA,DPA,andDHA,andsecondbydecreasingtheLA/ALAratio,andhencethetendencyofLAtocaptureandutilizetheenzymesneededtoconvertALAtolong-chainω-3FAs.
Although high in long-chain ω-3 FAs, oily fish do not containsignificant amounts of either LAorALA, and for this reason, fish
F IGURE 2 DecreasesindietaryLA/ALAratiosforanadultwomanconsumingtwolevelsofconventional,organic,andgrassmilkdairyproductsandtwotypesofnondairyfat.Thedietscontainmoderate“Mod.”(3servings/day)or“High”(4.5servings/day)amountsofdairyproductsmadefromconventional(“Conv.”),“Organic,”or“Grassmilk,”inthecontextsoftotalfatcontributing20%,33%,or45%ofenergy,andnondairyfatcontainingtypicalamountsofLA(leftside)orlowamountsofLA(rightside)
a Samefoodsandportionsasinthemodeleddietsin(Benbrooketal.,2013;Table1)andTable8.Calculationsusedailyservingweight,Table1amountsper100g,0.933gFApergdairyfat,andthefollow
b UsinganestimatedaverageDHAcontentof0.0006g/100gmilk,roughlyhalfofthe0.00106inTable1forthe249highestsamples.Forthisestimate,weassumedthatthe913unquantifiedsamples
d Table4in(Benbrooketal.,2013)(averageofcannedtuna,tilapia,halibut,sockeyesalmon,catfish,trout,&Atlanticsalmon).
e Table1in(EPA,2002).
16 | BENBROOK Et al.
consumptiondoesnotsignificantly impactoveralldietaryratiosofLA/ALAorω- 6/ω-3.Benbrooketal.(2013)usedUSDAdataontheFAcontentsofsevencommonlyconsumedfishspecies(cannedtuna,tilapia,halibut,sockeyesalmon,catfish,trout,andAtlanticsalmon)tocalculate theamountsofLA,ALA,EPA,DPA,andDHAfrom8ouncesof fishperweek, theamount recommended in theDietary Guidelines for Americans (DHHS,2015).Thisweeklyamountofthe7fishspeciessuppliesbetween1(cannedlighttuna)to58mg/day(Atlanticsalmon)ofALA,withanaverageof20mg/day(Table4inBenbrooketal.,2013).ThisdailyamountofALAissmallcomparedtothe137mgin1.5cupsofgrassmilk,orthe162mgina1.5-ounceservingofcheddarcheesemadefromgrassmilk(seebelow).
Table9showstheamountsofkeyFAfromgrassmilkdairyprod-uctsinourdietarymodeling.Theseamountscomplementthedatapre-sentedinTable3ofBenbrooketal.(2013)forconventionalandorganicdairyproducts.Table9alsoshowstheFAcontentofthe7commonlyconsumedfishmentionedabove.Inadditiontotheserecommendedamountsofdairyand fish (DHHS,2015),Table9alsoshowstheFAcontentof the lower, actual per-capita consumptionsofdairyprod-ucts(270g/day)andfish(9.1g/day).Actual,averageper-capitaintakesare28%ofrecommendedforfishand42%ofrecommendedfordairyproducts(Lin,Variyam,Allshouse,&Cromartie,2003).
Wefindthatnearly100%grass-andlegume-basedfeedingoflac-tatingdairycowstypicallyyieldsmilkfatwithratiosofLA/ALAandω- 6/ω-3closeto1,comparedto5.8formilkfromcowsonconven-tionallymanaged farms, and 2.3 for typical (but not nearly 100%grass-fed)organicdairyfarms.Ourdietarymodelingscenariosshowthat replacing recommended daily servings of conventional dairyproductswithgrassmilkproductsandavoidingsomefoodshighinLA could substantially decrease historically high dietary ratios ofLA/ALA(andthusω- 6/ω-3ratios)fromcurrentvaluesof>10toaslowas3.1. Suchdecreaseshave several potential healthbenefits,including an enhanced ability to convert dietaryALA to the long-chainω-3FAsEPA,DPA,andDHA.Thesenutrientsaretypicallynotconsumedatrecommendedlevels(DHHS,2015),andareespeciallyneededduringpregnancyandlactation,bychildren,andbythema-jorityofAmericanswhoeatlittleornofish.
BecauseofthewidelyvaryingFAprofileofdairyproductsde-pending on production systems, coupled with large variations intheir fatcontent (whole, reducedfat,andfat free), thewidelydis-seminatedpromotionalclaim“milkismilk”(DairyReporter,2003)ishardtosquarewiththenatureofdairyproductscurrentlysoldandconsumedintheUnitedStatesandelsewhere.
Shifting lactating dairy cows to rations containing substantialportionsofforage-basedfeedsandlessgraindramaticallydecreasestheamountsofLAinmilk,whilealsoelevatinglevelsofALA,long-chainω-3FAs,andtotalCLA.TheseattainableshiftsintheFApro-fileofmilkanddairyproductsareoneofseveralpracticalwaystopotentiallyimprovethequalityofAmericandiets.Theshiftscanbeaccomplishedwith existing dairy industry infrastructure andwithlikelymodestimpactonfoodexpendituresafteratransitionperiod.
Furtherresearchisneededtodeterminerealisticallyattainableshifts inFA consumption in thewidediversityof diets across theU.S.populationandtoassessthecostofalternativepathstowardhealthierfatintakes.Likewise,furtherresearchisneededtoidentifyprofitable and scalable changes in livestock feed rationsand foodmanufacturingthatwilllowerdietaryω- 6/ω-3ratiosandincreasein-takesoflong-chainω-3FAsandCLA.Improvedunderstandingoftherelationshipbetweenfatqualityandhealthoutcomeswillhelpguidelivestockanddairyfarmers,thefoodindustry,governmentagencies,scientists,andphysicianssearchingforpromisingwaystopromotepublichealth.
ACKNOWLEDG EMENTS
We appreciate the “jobwell done” by the CROPPCooperative re-gionalpoolstaffincollectingthebulk-tanksamplesandgettingthemtothelaboratory.WethankthetechnicalstaffatSilliker,Inc.,fortheirattentiontodetailandhelpworkingthroughtechnicaldetails.Wealsoacknowledge andhonor the commitment and skill of the grassmilkfarmersinCROPP,allofwhomfacedaraftofchallengesinconvertingtheiroperationstonearly100%forage-basedfeed.Theauthorsaregrateful for funding fromCROPPCooperative, Lafarge,Wisconsin;LowInputBreeds, Sixth Framework Programme for Research,TechnologicalDevelopmentandDemonstrationActivities,EuropeanCommunity(grantno.222623);andtheSheepdroveTrust,UK.
E THIC AL S TATEMENTS
Thisstudydoesnot involveanyhumanoranimal testing.Regardingconflicts of interest, CROPP Cooperative sells grassmilk via itsOrganicValley brand.MAL is the ExecutiveDirector of Research&Development and Quality Assurance at CROPP Cooperative. LPandSA-CareontheresearchandtechnicalservicesstaffofCROPPCooperative.BJHisfacultysupervisoroftheUniversityofMinnesotaWest Central Research andOutreach Center’s organic dairy,whichmarkets its milk through CROPP Cooperative and Organic Valley.CMBwasChiefScientistofTheOrganicCenter,2005–2012,fundedinpartbyCROPPCooperative;DRDwasaconsultanttosamecenter,2011–2012. CMBwas program leader for theMeasure toManage
| 17BENBROOK Et al.
programatCenterforSustainingAgricultureandNaturalResources,Washington State University, 2012–2015, forwhich CROPPwas afunder;DRDwasaconsultanttothesameprogram,2012–2015.
ORCID
Donald R. Davis http://orcid.org/0000-0001-8343-1268
R E FE R E N C E S
AGA.(2016).GrassfedDairyStandards.AmericanGrassfedAssociation(AGA). Retrieved from http://www.americangrassfed.org/wp-con-tent/uploads/2016/12/AGA-Grassfed-Dairy-Standards-V7.1-Web.pdf
Ailhaud, G., Massiera, F., Alessandri, J.-M., & Guesnet, P. (2007).Fatty acid composition as an early determinant of child-hood obesity. Genes and Nutrition, 2, 39–40. https://doi.org/10.1111/j.1467-789X.2004.00121.x
AOAC International. (2012). Official methods of analysis of AOACInternational, 19th ed. Retrieved from http://www.aoac.org/aoac_prod_imis/AOAC/Publications/Official_Methods_of_Analysis/AOAC_Member/Pubs/OMA/AOAC_Official_Methods_of_Analysis.aspx
APHIS. (2014).Dairy2014:DairyCattleManagementPractices in theUnited States, 2014.NAHMS #692.0216. USDA-Animal and PlantHealth InspectionService (APHIS)-VeterinaryServices (VS)-Centerfor Epidemiology and Health (CEAH), Fort Collins, CO. Retrievedfrom https://www.aphis.usda.gov/animal_health/nahms/dairy/downloads/dairy14/Dairy14_dr_PartI.pdf
ARS. (2010).ReportoftheDietaryGuidelinesAdvisoryCommitteeontheDietaryGuidelines forAmericans,2010.AgriculturalResearchService (ARS), U.S. Department of Agriculture. Retrieved fromhttps://www.cnpp.usda.gov/sites/default/files/dietary_guidelines_for_americans/2010DGACReport-camera-ready-Jan11-11.pdf
Barański,M.,Średnicka-Tober,D.,Volakakis,N.,Seal,C.,Sanderson,R.,Stewart, G. B., … Leifert, C. (2014). Higher antioxidant and lowercadmium concentrations and lower incidence of pesticide resi-duesinorganicallygrowncrops:Asystematicliteraturereviewandmeta-analyses.British Journal of Nutrition,112,794–811.https://doi.org/10.1017/s0007114514001366
Benbrook,C.M.,Butler,G.,Latif,M.A.,Leifert,C.,&Davis,D.R.(2013).Organic production enhances milk nutritional quality by shiftingfatty acid composition: A United States–Wide, 18-month study.PLoS ONE, 8(12), e82429. https://doi.org/10.1371/journal.pone. 0082429
Bondi,C.O.,Taha,A.Y.,Tock,J.L.,Totah,N.K.,Cheon,Y.,Torres,G.E., … Moghaddam, B. (2013). Adolescent behavior and dopamineavailabilityareuniquelysensitivetodietaryomega-3fattyacidde-ficiency.Biological Psychiatry,75, 38–46. https://doi.org/10.1016/j.biopsych.2013.06.007
Brenna, J. T. (2002). Efficiency of conversion of alpha-linolenicacid to long-chain n-3 fatty acids in man. Current Opinion in Clinical Nutrition and Metabolism Care, 5, 127–132. https://doi.org/10.1097/00075197-200203000-00002
Burdge, G. C., & Calder, P. C. (2005). Conversion of alpha-linolenicacid to longer-chain polyunsaturated fatty acids in human adults.Reproductive Nutrition and Development, 45, 581–597. https://doi.org/10.1051/rnd:2005047
Butler, G., Nielsen, J. H., Larsen, M. L., Rehberger, B., Stergiadis, S.,Canever, A., & Leifert, C. (2011). The effect of dairymanagementandprocessingonqualitycharacteristicsofmilkanddairyproducts.NJAS – Wageningen Journal of Life Sciences,58,97–102.https://doi.org/10.1016/j.njas.2011.04.002
CROPP. (2016). Organic Valley/CROPP Cooperative AnnualReport. Retrieved from https://issuu.com/organicvalley/docs/ov_annualreport_2017_web_version
DairyReporter.(2003).‘Milkismilk’campaignreachesthousands.Dairy Reporter. Retrieved from http://www.dairyreporter.com/Markets/Milk-is-milk-campaign-reaches-thousands
Daley,C.A.,Abbott,A.,Doyle,P.S.,Nader,G.A.,&Larson,S. (2010).A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutrition Journal, 9, 10. https://doi.org/10.1186/1475-2891-9-10
Darby, H., Monahan, S., Cummings, E., Harwood, H., & Madden, R.(2013). 2012 Small Grain Forage Trial. Univ Vermont Extension.Retrieved from http://www.uvm.edu/extension/cropsoil/wp-con-tent/uploads/2012-Small-Grain-Forage-Report-with-FA1.pdf
Darby, H., Monahan, S., Cummings, E., Madden, R., Gervais, A., &Harwood, H. (2012). 2011 small grain forage trial. Univ VermontExtension.Retrievedfromhttp://www.uvm.edu/extension/cropsoil/wp-content/uploads/2011_Spring_Grains_Forage.pdf
DHHS. (2015). Dietary Guidelines for Americans, 2015-2020, 8thedn. U.S. Department of Health and Human Services and U.S.Department of Agriculture. Retrieved from https://health.gov/dietaryguidelines/2015/guidelines/
Dilzer,A.,&Park,Y.(2012).Implicationofconjugatedlinoleicacid(CLA)in human health.Critical Reviews in Food Science and Nutrition,52,488–513.https://doi.org/10.1080/10408398.2010.501409
Donahue,S.M.A.,Rifas-Shiman,S.L.,Gold,D.R.,Jouni,Z.E.,Gillman,M.W., &Oken, E. (2011). Prenatal fatty acid status and child ad-iposity at age 3 y: Results from aUS pregnancy cohort.American Journal of Clinical Nutrition, 93, 780–788. https://doi.org/10.3945/ajcn.110.005801
FDA. (2015). Scientific Report of the Dietary Guidelines AdvisoryCommittee, Part D. Chapter 1: Food and Nutrient Intakes, andHealth: Current Status and Trends – Continued. Food and DrugAdministration (FDA). Retrieved fromhttps://health.gov/di-etaryguidelines/2015-scientific-report/06-chapter-1/d1-2.asp
Gayet-Boyer, C., Tenenhaus-Aziza, F., Prunet, C., & Chardigny, J. M.(2014). Istherea linearrelationshipbetweenthedoseofruminanttrans-fattyacidsandcardiovascularriskmarkersinhealthysubjects:Resultsfromasystematicreviewandmeta-regressionofrandomisedclinicaltrials.British Journal of Nutrition,114,1914–1922.https://doi.org/10.1017/S0007114514002578
Hibbeln,J.R.,Nieminen,L.R.G.,Blasbalg,T.L.,Riggs,J.A.,&Lands,W.E.M.(2006).Healthyintakesofω-3andω-6fattyacids:Estimationsconsideringworldwidediversity.American Journal of Clinical Nutrition,83,1483S–1493S.
IHME. (2016a).Avoidable risk factors takean increasing tollonhealthworldwide. Institute for Health Metrics and Evaluation (IHME).
Retrieved from http://www.healthdata.org/news-release/avoidable-risk-factors-take-increasing-toll-health-worldwide
IHME. (2016b). Financing Global Health 2016: DevelopmentAssistance, Public and Private Health Spending for the Pursuitof Universal Health Coverage. Institute for Health Metrics andEvaluation (IHME). Retrieved from http://www.healthdata.org/policy-report/financing-global-health-2016-development-assis-tance-public-and-private-health-spending
Kuhnt,K.,Degen,C.,&Jahreis,G.(2016).Evaluationoftheimpactofru-minanttransfattyacidsonhumanhealth:Importantaspectstocon-sider. Critical Reviews of Food Science and Nutrition,56,1964–1980.https://doi.org/10.1080/10408398.2013.808605
Lacroix, E., Charest, A., Cyr,A., Baril-Gravel, L., Lebeuf, Y., Paquin, P.,Chouinard, P. Y., Couture, P., & Lamarche, B. (2011). Randomizedcontrolledstudyoftheeffectofabutternaturallyenrichedintransfatty acids on blood lipids in healthy women.American Journal of Clinical Nutrition,95,318–325.
Larsson,S.C.,Bergkvist,L.,&Wolk,A.(2005).High-fatdairyfoodandconjugated linoleic acid intakes in relation to colorectal cancer in-cidence intheSwedishMammographyCohort.American Journal of Clinical Nutrition,82,894–900.
Larsson, S.C.,Kumlin,M., Ingelman-Sundberg,M.,&Wolk,A. (2004).Dietary long-chain n-3 fatty acids for the prevention of cancer:Areviewofpotentialmechanisms.American Journal of Clinical Nutrition,79,935–945.
Leikin-Frenkel, A. I. (2016). Is there a role for alpha-linolenic acid inthefetalprogrammingofhealth?Journal of Clinical Medicine,5,40.https://doi.org/10.3390/jcm5040040
Lin,B.-H.,Variyam,J.,Allshouse,J.E.,&Cromartie,J.(2003).Foodandagricultural commodityconsumption in theUnitedStates: Lookingahead to 2020. USDA Economic Research Service. Ag Econ RepAER-820.Retrievedfromhttps://www.ers.usda.gov/webdocs/publi-cations/41525/30932_aer820_002.pdf?v=41254
Littell,R.C.,Henry,P.R.,&Ammerman,C.B.(1998).StatisticalanalysisofrepeatedmeasuresdatausingSASprocedures.Journal of Animal Science,76,1216–1231.https://doi.org/10.2527/1998.7641216x
Lombardi,G.,Probo,M.,Renna,M.,Astegiano,S.,Bellio,A.,RavettoEnri,S.,Lussiana,C.,Cornale,P.,Malfatto,V.,Mimosi,A.,Gariano,G.R.,Gramaglia,M.,Decastelli,L.,&Battaglini,L.M.(2014).ThePiedmontNobleMilk as a tool to improve the competitiveness ofmountainfarms.Journal of Nutritional Ecology and Food Research,2,233–236.https://doi.org/10.1166/jnef.2014.1081
Mansson, H. L. (2008). Fatty acids in bovine milk. Food and Nutrition Research,52,1821.https://doi.org/10.3402/fnr.v52i0.1821
MarketLohas.(2016).BeyondtheNaturalLabel:2016HealthyLOHASShopper Survey Reveals What’s Next #NaturalProducts Trendsfor @NatProdExpo. Retrieved from http://www.marketlohas.com/uploads/7/2/5/4/7254872/2016_market_lohas_mambotrack_health___natural_consumer_study_press_release_web_final_.pdf
Massiera,F.,Barbry,P.,Guesnet,P.,Joly,A.,Luquet,S.,Moreilhon-Brest,C.,…Ailhaud,G.(2010).AWestern-likefatdietissufficienttoinduceagradualenhancementinfatmassovergenerations.Journal of Lipid Research,51,2352–2361.https://doi.org/10.1194/jlr.M006866
McDonald, P., Edwards, R. A., Greenhalgh, J. F. D., & Morgan, C. A.(2006).Animal nutrition,6thedn.UpperSaddle,NJ:PrenticeHall.
Molkentin,J.(2009).Authenticationoforganicmilkusingδ13Candtheα-linolenicacidcontentofmilk fat.Journal of Agricultural and Food Chemistry, 57, 785–790. https://pubs.acs.org/doi/abs/10.1021/jf8022029
Moon,R.J.,Harvey,N.C.,Robinson,S.M.,Ntani,G.,Davies,J.H.,Inskip,H.M., … SWS Study Group. (2013).Maternal plasma polyunsatu-ratedfattyacidstatusinlatepregnancyisassociatedwithoffspring
bodycompositioninchildhood.Journal of Clinical Endocrinology and Metabolism,98,299–307.https://doi.org/10.1210/jc.2012-2482
Motard-Bélanger,A.,Charest,A.,Grenier,G.,Paquin,P.,Chouinard,Y.,Lemieux,S.,…Lamarche,B.(2008).Studyoftheeffectoftransfattyacidsfromruminantsonbloodlipidsandotherriskfactorsforcardio-vasculardisease.American Journal of Clinical Nutrition,87,593–599.
Nissen, S. E. (2016). U.S. Dietary guidelines: An evidence-free zone.Annals of Internal Medicine,164, 558–559.https://doi.org/10.7326/m16-0035
NOFA-NY. (2016). 100% Grass Fed Program Certification Manual.NortheastOrganicFarmingAssociationofNewYork.Retrievedfromhttps://www.nofany.org/files/NOFA-NY_Grass_Fed_Certification_Manual.v2.pdf
O’Callaghan,T.F.,Hennessy,D.,McAuliffe,S.,Kilcawley,K.N.,Dillon,P.,O’Donovan,M.,&Ross,R.P.(2016).Effectofpastureversusin-doorfeedingsystemsonrawmilkcompositionandqualityoveranentirelactation.Journal of Dairy Science,99,9425–9440.https://doi.org/10.3168/jds.2016-10985
Ramsden,C.E.,Hibbeln,J.R.,Majchrzak,S.F.,&Davis,J.M.(2010).n-6fattyacid-specificandmixedpolyunsaturateddietaryinterventionshavedifferenteffectsonCHDrisk:Ameta-analysisofrandomisedcontrolledtrials.British Journal of Nutrition,104,1586–1600.https://doi.org/10.1017/s0007114510004010
Ravetto Enri, S., Renna,M., Probo,M., Lussiana, C., Battaglini, L.M.,Lonati, M., & Lombardi, G. (2017). Relationships between botan-ical and chemical composition of forages:Amultivariate approachto grasslands in the Western Italian Alps. Journal of the Science of Food and Agriculture, 97, 1252–1259. https://doi.org/10.1002/ jsfa.7858
Renna,M.,RavettoEnri,S.,Probo,M.,Lussiana,C.,Cornale,P.,Bellio,A.,…Lombardi,G.(2015).ProductionregulationsandcharacteristicsofcowPiedmonteseNobleMilk [abstract]. Italian Journal of Animal Science,14,33.
Rinehart,L.,&Baier,A. (2011).Pasturefororganicruminant livestock:understanding and implementing the national organic program(NOP)pasturerule.AgriculturalMarketingService,U.S.Departmentof Agriculture. Retrieved fromhttp://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRDC5091036
Rubino,R.(2014).AspecialsectiononlatteNobile:Anevolvingmodel.Journal of Nutritional Ecology and Food Research,2,214–222.https://doi.org/10.1166/jnef.2014.1077
Ryan,A.S.,Astwood,J.D.,Gautier,S.,Kuratko,C.N.,Nelson,E.B.,&Salem,N.Jr(2010).Effectsoflong-chainpolyunsaturatedfattyacidsupplementation on neurodevelopment in childhood: A review ofhumanstudies.Prostaglandins, Leukotrienes and Essential Fatty Acids,82,305–314.https://doi.org/10.1016/j.plefa.2010.02.007
SAS Institute. (2014). SAS/STAT Software, Release 9.4. SAS Inst. Inc.,Cary,NC.
Schwendel,B.H.,Wester,T.J.,Morel,P.C.,Tavendale,M.H.,Deadman,C.,Shadbolt,N.M.,&Otter,D.E.(2015).Invitedreview:Organicandconventionally produced milk-an evaluation of factors influencingmilkcomposition.Journal of Dairy Science,98,721–746.https://doi.org/10.3168/jds.2014-8389
Simopoulos, A. P. (2006). Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: Nutritional implications forchronic diseases. Biomedicine and Pharmacotherapy, 60, 502–507.https://doi.org/10.1016/j.biopha.2006.07.080
Siri-Tarino,P.W.,Chiu,S.,Bergeron,N.,&Krauss,R.M.(2015).Saturatedfatsversuspolyunsaturatedfatsversuscarbohydratesforcardiovas-culardiseasepreventionandtreatment.Annual Review of Nutrition,35,517–543.https://doi.org/10.1146/annurev-nutr-071714-034449
APPENDIX Grass milk standards and oversightIn2016,acoalitionofdairy industryandcertificationorganiza-
tionsdefinedabroadnationalstandardfor“100%Grass-feddairy”(AGA, 2016). These organizations included Pennsylvania CertifiedOrganic, American Grassfed Association, Northeast OrganicFarmingAssociation[NewYork(NOFA-NY,2016)&Vermontchap-ters],MapleHillCreamery,andCROPPCooperative.Thatcoalitionadopted CROPP’s Grassmilk standards as part of its consensusstandard.CROPP’sinternalstandardscurrentlycomplywiththena-tional consensus, and the cooperative continues to takeanactiveroleinsolidifyingthelanguageandcertificationrequirementsasso-ciatedwithnearly100%grass-feddairyclaims.
Feeding requirementsInaddition to thedryhayand fermentedhay feeds thatareal-
animalwelfare.Avarietyof indicatorsassociatedwithanimalwel-fareandherdhealtharefindingtheirwayintocertificationrequire-ments.Thesemetricsincludethebodyconditionoflactatingcows,outdoor access, use of antibiotics and hormones, physical altera-tions,lameness,livingconditions,andsourcesofanimalstress.CROPPgrassmilkfarmersaresubjecttothesameanimal-carere-
portingandherd-healthverificationsthatareusedthroughoutthecooperative. These include the National Milk Farmers AssuringResponsibleManagement(FARM)requirementsforbodycondition,lameness,access tooutdoorsandwater,ventilation,andhandling.Some CROPP animal-welfare requirements go beyond those im-posedbyFARM,suchasprohibitionofoxytocin,adrugusedtoas-sistincalving.On-siteauditsareperformedbystaffanimal-carespecialistsand
qualifiedfieldstaffatleasteverythirdyearthroughoutafarm’stran-sitionandparticipation in theprogram.Audit follow-upaddressesanyconcernsandsetsforthrequiredimprovements.Routinevisits
Slots,T.,Butler,G.,Leifert,C.,Kristensen,T.,Skibsted,L.H.,&Nielsen,J.H.(2009).Potentialstodifferentiatemilkcompositionbydifferentfeedingstrategies.Journal of Dairy Science,92,2057–2066.https://doi.org/10.3168/jds.2008-1392
Smit, L. A., Baylin, A., & Campos, H. (2010). Conjugated linoleic acidin adipose tissue and risk of myocardial infarction. American Journal of Clinical Nutrition, 92, 34–40. https://doi.org/10.3945/ajcn.2010.29524
Średnicka-Tober,D.,Barański,M.,Seal,C.J.,Sanderson,R.,Benbrook,C.,Steinshamn,H.,…Leifert,C.(2016a).HigherPUFAandn-3PUFA,conjugatedlinoleicacid,α-tocopherolandiron,butloweriodineandseleniumconcentrationsinorganicmilk:Asystematicliteraturere-viewandmeta-andredundancyanalyses.British Journal of Nutrition,115,1043–1060.https://doi.org/10.1017/s0007114516000349
Średnicka-Tober,D.,Barański,M.,Seal,C.J.,Sanderson,R.,Benbrook,C.,Steinshamn,H.,…Leifert,C. (2016b).Compositiondifferencesbe-tweenorganicandconventionalmeat;asystematicliteraturereviewandmeta-analysis.British Journal of Nutrition,115,994–1011.https://doi.org/10.1017/S0007114515005073
Stergiadis,S.,Leifert,C.,Seal,C.J.,Eyre,M.D.,Nielsen,J.H.,Larsen,M.K.,…Butler,B.(2012).EffectoffeedingintensityandmilkingsystemonnutritionallyrelevantmilkcomponentsindairyfarmingsystemsinNorthEastofEngland.Journal of Agricultural and Food Chemistry,60,7270–7281.https://doi.org/10.1021/jf301053b
Turpeinen,A.M.,Mutanen,M.,Aro,A.,Salminen,I.,Basu,S.,Palmquist,D. L., & Griinari, J. M. (2002). Bioconversion of vaccenic acid to
conjugated linoleic acid in humans. American Journal of Clinical Nutrition,76,504–510.https://doi.org/10.1093/ajcn/76.3.504
USDA. (2015). National nutrient database for standard reference, re-lease 28. U.S. Department of Agriculture (USDA). Retrieved fromhttp://ndb.nal.usda.gov
Vargas-Bello-Pérezz, E.,&Garnsworthy,P.C. (2013).Trans fatty acidsand their role inmilkofdairy cows.Ciencia e Investigación Agraria,40,449–473.https://doi.org/10.4067/S0718-16202013000300001
Whole Foods Market Blog. (2015). Whole Foods Market expertsforecast top 10 food trends for 2016. Whole Foods Market.Retrieved from http://media.wholefoodsmarket.com/news/whole-foods-market-experts-forecast-top-10-food-trends-for-2016.
How to cite this article:BenbrookCM,DavisDR,HeinsBJ,etal.Enhancingthefattyacidprofileofmilkthroughforage-basedrations,withnutritionmodelingofdietoutcomes. Food Sci Nutr. 2018;00:1–20. https://doi.org/10.1002/fsn3.610
by CROPP staff also help track and troubleshoot any problemsuniquetoagivenfarmorregion.Expertadvice isavailabletograssmilkfarmerstohelpthemim-
prove their forage quality and production levels, cow health, andprofitability. Regular testing of bulk-tankmilk FA levels is used tomonitor compliance with the nearly 100% forage-based feedrequirement.
Challenges and benefits of increasing reliance on forage-based feedsIncreasing forage-based feeds usually reducesmilk production.
have RHAs in the range 14,000 to 18,000lb/cow, while mostgrassmilkoperationsachieveRHAsintherange6,000to16,000lb/cow.During the spring and early summer, cows in early lactationtendtoproducemoremilk,makingitdifficulttomeetenergyneeds,especiallywithoutasupplementalenergysource(e.g.,molasses).Increased reliance on grazing and forage-based diets requires
careful management of soil fertility, pasture composition, forageproduction, and animal health (especially locomotion).Annual and
perennialforagecropsaremanagedcollectivelythroughouttheyeartoprovideforbothgrazingandconservedwinterfeed.Theextremerelianceonpastureandconserved foragesmaymake these farmslessresilientinthefaceofprolongeddroughtconditions.Itremainsto be seen whether availability and cost of high-quality, off-farmconservedforageputthesefarmsatincreasedriskduringperiodsofprolonged drought, leading to near-complete forage crop/pasturelosses.In addition to challenges, grass milk farmers receive benefits.
Theseincludeapricepremium(about15%onCROPPfarms),gen-erally reducedfeedcosts,andprotectionfrompricespikes inor-ganic grains and grain-based supplements. Agronomically, thesefarms generally havemore tolerance for wet springs, which candelayrow-cropfarmingpracticesandincreaseweedmanagementchallenges.Environmentalbenefitsalsoaccompanytheshifttogreaterreli-
anceonforage-basedfeedsandtheincreasedacreageinperennialgrasscommunities.Soilhealthtendstoimprove,becauseofreducedtillage and year-round perennial grass cover. This improvement insoilhealthgenerallyresultsinreducedsoilerosionandlesssedimentandnutrientrun-offintolocalwatershedscomparedtoconventionaltillage,orconservationtillage-basedcroprotations.