HAY DRYING, PRESERVATIVES, CONDITIONING, ASH CONTENT

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1 HAY DRYING, PRESERVATIVES, CONDITIONING, ASH CONTENT Dr. Dan Undrsandr Univrsity of Wisconsin Drying forag for hay has always bn a challng. Whil w cannot control th wathr w can manag cut forag to maximiz drying. Th purpos of this papr is to giv a fw principls of hay and silag making and discuss machinry availabl rlativ to ths principls. Thn w will also talk about minimizing ash in hay to optimiz th total digstibl nutrints of th forag. Undrstanding Forag Drying Our undrstanding of conditioning and th nd for conditioning has changd as w hav rvisitd th factors affcting forag drying. In drying hay w nd to maximiz us of sunlight to nhanc drying to minimiz ful us and cost of drying. Rmmbr that, if w cut a 2 t/a dry mattr yild, w must vaporat about 5.7 tons of watr pr acr from th crop bfor it can b bald or 3 t/a of watr pr acr bfor it can b choppd for silag. If w undrstand and us th biology and physics of forag drying proprly, not only dos th hay dry fastr and hav lss chanc of bing raind on, but th total digstibl nutrints (TDN) of th harvstd forag may b highr. Th gnral pattrn of drying forags is shown in th figur blow. Whn forag is cut, it has 75 to 80% watr and must b drid down to 60 to 65% moistur contnt for haylag and down to 12 to 16% moistur contnt for hay (lowr figurs for largr Squnc of Drying Forags bals). Th first phas of drying is moistur Phas I loss from th lavs through th stomats. (Approximatly 60% of plant watr is in th lavs.) Stomats ar th opnings in th laf surfac that allow moistur loss to th air to cool th plant and carbon dioxid uptak from th air as th plant is growing. Stomats opn in daylight 70% 20% Conditioning Phas II Wathr rgulatd Phas III Tim and clos whn in dark and whn moistur strss is svr. Cut forag laid in a wid swath maximizs th amount of forag xposd to sunlight. This kps th stomats opn and ncourags rapid drying, which is crucial at this stag bcaus plant Moistur 14 80% Stomatal opning Osmotic & Cll forcs

2 rspiration continus aftr th plant is cut. Rspiration rat is highst at cutting and gradually dclins until plant moistur contnt has falln blow 60%. Thrfor, rapid initial drying to los th first 15 to 20% of moistur will rduc loss of starchs and sugars and prsrv mor total digstibl nutrints in th harvstd forag. This initial moistur loss is not affctd by conditioning. Th scond phas of drying (II) is moistur loss from both th laf surfac (stomats hav closd) and from th stm. At this stag conditioning can hlp incras drying rat, spcially on th lowr nd. Th final phas of drying (III) is th loss of mor tightly hld watr, particularly from th stms. Conditioning is critical to nhanc drying during this phas. Conditioning to brak stms vry two inchs allows mor opportunitis for watr loss sinc littl watr loss will occur through th waxy cuticl of th stm. Undrstanding ths principls will allow us to dvlop managmnt practics in th fild that maximiz drying rat and TDN of th harvstd forag. Th first concpt is that a wid swath immdiatly aftr cutting is th singl most important factor maximizing initial drying rat and prsrving of starchs and sugars. In trials at th UW Arlington Rsarch Station (Figur 2a & 2b), whr alfalfa was put into a wid swath, it rachd 65% moistur in 10 hours or lss and could b harvstd for haylag th sam day as cutting. Th sam forag from th sam filds put into a narrow windrow was not rady to b harvstd until 1 or 2 days latr! Figur 2a. May 29, 30, 31, 2007 wid swath vs narrow swath drying rat Figur 2b July 30, 31, Aug wid swath vs n arrow swath drying rat u r t s60 i o m t n50 r c p 40 wid sw ath narrow swath r tu is 60 o m t50 n rc p40 wid swath narrow swath am Day 1 2pm Day 1 5pm Day 1 9am Day 2 2pm Day 2 5pm Day 2 9am Day 3 2pm Day 3 tim 9am Day 2pm Day 5pm Day 9am Day pm Day tim 2 5pm Day 2 9am Day 3 2pm Day 5pm Day 3 3 In fact, a wid swath may b mor important than conditioning for haylag. Th importanc of a wid swath is supportd from drying masurmnts takn at th Wisconsin Farm Tchnology Days in 2002 (Figur 3), whr diffrnt mowrconditionrs mowd and conditiond strips of alfalfa and put th cut forag in windrow widths of th oprators choic. Moistur contnt of th alfalfa was masurd 5.5 hours aftr mowing. Each point is a diffrnt machin that includd sickl bar and disc mowrs and conditionrs with, stl, rubbr or combination rollrs. Across all mowr typs and dsigns, th most significant factor in drying rat was th width of th 15

3 Moistur contnt (%) Figur 3. Moistur contnt of alfalfa 5.5 hours aftr cutting with various windrow width to cut width ratios, WI Farm Tchnology Days, y = Ln(x) R 2 = Windrow width/cut width windrow. Th machinry industry is rapidly rsponding to produc quipmnt that can mak wid swaths. In Figur 3, not th on outlying point at 70% moistur contnt and a windrowwidth/cut-width ratio of This shows how much drying can b slowd by impropr adjustmnt of th conditionr. W usd to mak wid swaths in th past, but hav gradually gon to making windrows that ar smallr and smallr prcntags of th cut ara as mowrs hav incrasd in siz. Gnrally, as mowrs hav gottn biggr, th conditionr has stayd th sam siz, rsulting in narrowr windrows. Thr is som variation among maks and modls and growrs should look for thos machins that mak th widst swath. Putting alfalfa into wid swaths (72% of cut width) immdiatly aftr cutting rsults in improvd quality of alfalfa haylag compard to narrow windrows (25% of cut width) in a study at UW Arlington Rsarch Station in 2005 (Tabl 1). Alfalfa was mowd with a discbin, conditiond, and forag was sampld two months aftr nsiling in tubs. Th alfalfa from th wid swaths had 2.3% lss NDF, and 1.8% mor NFC. Th NFC diffrnc is both a quality and yild diffrnc as th 1.8% loss in narrow windrows was to rspiration whr starch is changd to carbon dioxid and lost to th air. Th haylag from th wid swath had almost 1% mor TDN and mor lactic and actic acid. Th highr acid contnt would indicat lss rapid spoilag on fdout and th ovrall improvd forag quality would b xpctd to rsult in 300 lbs mor milk pr acr. Tabl 1 Diffrnc in composition of alfalfa haylag mad from narrow and wid swaths, UW Arlington, 2005 Factor Wid Narro w Diffrn c NDF, % NFC, % Ash, % TDN, 1X Lactic acid, % Actic Acid, % Rlativ Forag Quality Som ar concrnd that driving ovr a swath will incras soil (ash) contnt in th forag. In Tabl 1, th ash contnt of haylag from wid-swath alfalfa was actually lss than from narrow windrows. Whil narrow windrows ar not usually drivn ovr, thy tnd to sag to th ground, causing soil to b includd with th windrow whn it is pickd up. Wid swaths tnd to lay on top of th cut stubbl and stay off th ground. Furthr driving on th swath can b minimizd by driving on whl on th ara btwn swaths and on nar th middl of th swath whr cut forag is thinnr. 16

4 Grasss, spcially if no stms ar prsnt, must b into a wid swath whn cut. Whn put into a windrow at cutting, th forag will sttl togthr, dry vry slowly and b difficult to loosn up to incras drying rat. In summary, an xtnsiv sris of studis Rotz and Chn collctd 5,000 data points on conditiond alfalfa from 1977 to 1984 in East Lansing, MI. Thy rcordd wathr data including tmpratur, rlativ humidity, solar insolation and wind vlocity, and crop-rlatd data such as maturity, cutting, soil moistur contnt, swath dnsity (width and yild) and swath surfac tmpratur. Whn finishd, Rotz and Chn had an quation that dscribd 75% of th variability associatd with hay drying. Thir rsults stat that hay drying is improvd with incrasd plant surfac ara xposd to th sun, gratr solar radiation, highr tmpratur and lowr swath dnsity. Thir quation also stats that drying is dcrasd with highr soil moistur. Th factors not includd in th modl (.g., wind spd and rlativ humidity) may also play a rol in hay drying by ithr influncing othr factors in th quation or making up th 25% of th varianc not dscribd by th quation. Prsrvativs/Dssicants. First, it is important to rcogniz that two totally diffrnt typs of products with diffrnt mods of action ar sold: on is a dsiccant which is a compound applid to th hay at cutting to incras drying rat and th othr is a prsrvativ which is applid to hay as it is bald to allow baling of wttr than normal hay without spoilag during storag. Both products ar usually applid through a spray systm, which costs $600 to $1000, ithr on th mowr (for dssicants) or on th harvsting quipmnt (for prsrvativs). Th dsiccants that ar ffctiv contain potassium or sodium carbonat. This compound disturbs th waxy cuticl of th alfalfa stm to allow it to dry fastr. Dsiccants work only on lgums such as alfalfa, trfoil, and clovrs. Effctivnss varis with climatic conditions. Dsiccants rduc drying tim most whn drying conditions ar good. Thus, thy tnd to work bttr on scond and third cuttings in Wisconsin. Thy ar rcommndd for hay making and ar of lss usfulnss whn forag is harvstd as haylag. Prsrvativs ar applid to th hay as it is harvstd and prvnt hating and spoilag of hay bald at high moistur contnts. Prsrvativs ar cost ffctiv if usd only whn ndd to prvnt rain damag to hay and if applid uniformly to windrow as it is ntring th balr. Th most ffctiv prsrvativs for alfalfa ar organic acids, (primarily propionat and actat) and thir drivativs such as sodium diactat. Propionat (propionic acid) has bn most commonly usd and any product containing a high prcntag of this compound will b ffctiv. Us of ammonium propionat (also calld buffrd propionic acid) rathr than propionic acid is rcommndd bcaus th product is lss caustic - thrfor safr to handl and lss corrosiv to machinry. Whn purchasing prsrvativs, compar cost on a pr pound of propionic acid basis. Othr additivs do littl if anything to prsrv hay. Som hay prsrvativ products dilut th propionic acid and rquir gratr product us rats. 17

5 Rats of propionic acid rquird to prsrv hay vary with th moistur contnt of th hay. As indicatd in th chart abov, th amount of propionic acid rquird varis from 10 lb/ton for hay at % moistur, 20 lb/ton for % moistur and 30 lb/ton for % moistur. Not that rats ar for pounds of propionat not product. Thrfor a product with 50% propionat would nds to b applid at twic th abov rats. Us of prsrvativs for hay abov 35% moistur is not rcommndd. Anhydrous ammonia is an ffctiv prsrvativ for grasss. Anhydrous ammonia should not b usd on alfalfa du to th potntial for formation of toxic compounds. Anhydrous ammonia can b injctd into bals or rlasd into a stack of bals covrd and tightly sald with plastic. Ammonia should b applid at th rat of lbs/ton with highr rats usd for hay nar 35% moistur and lowr rats usd whn moistur is nar 20%. Currntly, vidnc is not sufficint to indicat that any microbial hay prsrvativs ar ffctiv in prsrving hay. Raking. Raking should occur whn hay is abov 40% moistur to rduc laf loss. Tdding and raking/mrging can also nhanc drying by fluffing up th windrow to xpos diffrnt portions of th hay to sunlight and to allow air movmnt through th windrow. Each can caus laf loss in alfalfa (incrasingly with gratr drynss of th forag). Tdding is sldom ncssary for alfalfa if on startd with a wid swath but is usful for grasss. Grassy hay oftn nds to b rakd twic (or tddd and thn rakd into a windrow) sinc grass lavs sttl togthr mor than alfalfa hay. Summary of hay drying rcommndations Mowing and conditioning to maximiz hay drying rat should: Bgin with a wid swath (gratr than 70% of cut ara) to maximiz laf drying and stop rspiration. Kp th swath off th ground to nhanc drying and rduc soil contamination. 18

6 Ash in forag W havn t paid much attntion to ash until rcntly whn w hav bgun using th summativ quation to stimat nrgy of forag. Now instad of stimating nrgy from acid dtrgnt fibr most stimat nrgy from th following summativ quation: Total digstibl nutrints (TDN) = NFC*.98 + CP*.93 + FA*.97* NDF * NDFD/100 7 NFC = non-fibr carbohydrats = DM - Ash - CP - EE - NDF, % of DM CP = crud protin, % of DM FA = fatty acids = EE - 1, % of DM EE = thr xtract, % of DM NDF = nutral dtrgnt fibr, % of DM NDFD = (48 hr in vitro NDF digstion), % of NDF Whn stimating nrgy from ADF, th ash contnt is unsn. Now that ash contnt is usd to calculat th non-fibr carbohydrats (NFC), it is obvious that ach 1% ash is 0.98% lss NFC (and thrfor TDN). Whil som minrals ar ncssary for th forag growth and may b bnficial to animals ating th forag, w want to kp th ash contnt to th minimum bcaus ash provids no caloris and, in fact, ash rplacs nutrints. Ash in forag coms from two sourcs: intrnal,.g. minrals lik calcium, magnsium, potassium and phosphorus, and xtrnal,.g. dirt, bdding, sand, tc. Th avrag intrnal ash contnt of alfalfa is about 8% and of grasss is about 6%. Additional ash in a hay or silag sampl is contamination with dirt, sand, tc. As shown in tabl 2, a summary of ash contnt of forag sampls submittd to th Univrsity of Wisconsin Soil and Forag Analysis Laboratory, th avrag ash contnt of haylag is 12.3% and of hay is 10.3%. Assuming th silag is mainly alfalfa and th hay has a highr prcntag of grass, forag sampls ar avraging about 4% ash contamination from xtrnal sourcs. Not that som sampls hav bn as high as 18%. This mans som farmrs hav fd almost 1 pound of dirt for ach 5 pounds of hay or silag! Tabl 2. Ash Contnt of Forag Sampls, UW Marshfild Soil and Forag Tsting Laboratory Typ Statistic % Ash Haylag Avrag 12.3 Maximum 18.0 Minimum 5.7 Hay Avrag 10.3 Maximum 17.6 Minimum 8.8 Growrs can do svral things along ach stp of harvsting, storag and fdout to minimiz ash. Avoid harvsting lodgd forag -as dirt oftn sticks to th downd forag whn th soil is wt. This can t always b avoidd but can b rducd by 19

7 planting varitis that stand bttr and by harvsting arly in th spring to rduc th potntial for a wind storm knocking th alfalfa/grass down. Rais th cuttr bar of a disc mowr - to lowr ash and rais forag quality. Rsarch suggsts that alfalfa can b cut as short as 1.5 inchs for maximum yild. Each inch abov this hight will rsult in 0.5 t/a lss yild for th yar. (Though, if th mixtur includs smooth bromgrass, orchardgrass, or timothy, cutting hight should b 3 to 4 inchs to avoid shortnd stand lif of th grass). Howvr, lowr cut forag with a disc mowr will hav highr ash contnt whn th soil surfac is dry. Thus, raising th cuttr bar lowrs ash and raiss forag quality whil lowring th cuttr bar rsults in gratr yild. Each individual must dcid on th tradoffs thy want to tak but gnrally a cutting hight of 2.5 to 3 inchs sms bst in most cass. Us flat knivs on th disc movr to pick up th last ash whn mowing. Svral disk knif typs ar availabl as shown in th pictur. Th flat knif at th lft will pick up th last ash whil th middl knif, at a 14 dgr angl, will crat som suction to pick up mor downd hay and ash (whn soil is dry). Gnrally, thos sttings that pick up downd hay bst also rsult in th most ash contnt whn th soil is dry so on nds to dcid which is most important. Kp windrow off th ground by starting with a wid swath and placing th cut forag onto dns stubbl will liminat harvsting a layr of soil on th bottom of windrows. Putting hay into a wid swath also incrass drying rat. Th windrow should b high nough so that it can b rakd or mrgd without th rak touching th ground. Kp rak tins from touching th ground this can b don if th forag is on top of stubbl and th ground is lvl. Whl raks tnd to incorporat mor ash bcaus thy ar ground drivn. W should visualiz that, whn w ar raking and raising a cloud of dust, w ar adding 1 to 2 prcnt ash to th hay. Minimiz moving hay horizontally to rduc stons and othr ash. It is bttr to mov two swaths on top of a third in th middl rathr than to rak all to on sid. 20

8 Using a windrow mrgr rathr than raking will rsult in hay or silag with lss ash contnt sinc th windrow is pickd up and movd horizontally by a convyr rathr than bing rolld across th ground. Mrging can rsult in 1 to 2% lss ash in th hay or silag. Mrgrs may not b conomical for small oprations but Custom harvstrs may b an option to considr if mrgd hay with lowr ash contnt is dsird. Stor hay bals off th ground sinc bals that st on th ground pick up watr from th soil and mold. This molding procss causs loss of TDN and incrass th ash concntration. Mor important, th wt hay will pick up a layr of ash on th bottom if bals ar sitting on th ground. Stor silag pils/tubs on concrt or asphalt to minimiz ash contamination. Silag can b rmovd with minimal dirt contamination whn conditions ar dry but dirt may b pickd up with th silag whn conditions ar wt and it is muddy around th silag pil or tub. Thr will always b som soil contamination of grass and lgum hay or silag. Howvr appropriat harvsting and storag managmnt can rduc th ash contnt of th hay or silag. W should all try to b 1 or 2 % blow th avrags in tabl on. Anyon with 10% or lss ash has don a good job of minimizing ash contnt of hay or silag. Rfrncs: Charmly,-E; Savoi,-P; McRa,-KB; Lu,-X Effct of macration at mowing on silag consrvation, voluntary intak, digstibility and growth rat of strs fd prcision-choppd or round bal silags. Canadian-journal-of-animal-scinc. 79(2): Rotz, C.A. and Y. Chn, Alfalfa Drying Modl for th Fild Environmnt. Transactions of th ASAE, (5): p Savoi, P., Bint, M., Choinièr, G., Trmblay, D., Amyot, A. and Thériault R Dvlopmnt and valuation of a larg-scal forag mat makr. Trans. Am. Soc. Agric. Eng. 36: