Minimizing Losses in Hay Storage and Feeding - MSUcares

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Table 2. Losses of forage quality during storage of round-baledgrass and grass-legume hay.*___________________________________________________________________________in vitro Relative $ valueCrude digestible feedHay type Fraction protein dry matter value loss___________________________________________________________________________- - - % of dry wt. - - - index $/TGrass unweathered 13.5 58.8 72 —weathered 16.4 42.5 75 9.72Alfalfa unweathered 14.2 56.5 86 —weathered 16.9 34.2 79 22.68____________________________________________________________________________*SOURCE: Lechtenberg, V.L., K.S. Hendrix, D.C. Petritz, and S.D. Parsons. 1979. Compositional changes and lossesin large hay bales during outside storage. pp. 11-14 In Proc. Purdue Cow-Calf Res. Day. West Lafayette, IN, 5Apr. 1979. Purdue Univ. Agric. Exp. Stn. West Lafayette, IN.1 Hay value determined: Y = (0.81 x RFV index) - 14.8 where Y = $/ton of hay. Minnesota Quality-TestedHay Auction Data. SOURCE: Martin, N.R., & Duane Schriever. 1996. Minnesota forage update Vol. XXI, No. 2, p. 5.usually greater for legumes than forgrasses (Table 2).Some heating of hay is normal, butextreme heating (above 120 o F) lowersforage quality along with dry matter.Microbial activity associated withheating uses soluble carbohydrates,which reduces digestibility andincreases fiber levels. A reduction involuntary intake accompanies excessiveincreases in NDF.In addition to causing huge dry matter losses,weathering lowers forage quality, reduces palatabilityand intake, and increases feeding losses due toanimal refusal. Cattle ate only the center portion ofthis highly weathered bale.UNDERSTANDING THEWEATHERING PROCESSFrom the preceding discussion, itshould be obvious that most of the haystorage losses which occur are associatedwith hay being stored outside in asituation in which it is exposed to theelements, resulting in weathering. Thelonger hay is exposed to unfavorableweather conditions, the greater losseswill be.How Weathering OccursBales stored outside on the groundwithout covers increase sharply inmoisture content during storage. Thisis especially true for the outer 2 to 3inches of the bale in which moisturemay increase by as much as 120%.Weathering begins slowly, but thenaccelerates because weathered hay ismore easily penetrated by rain, anddoesn’t dry as rapidly thereafter.In areas of high and/or frequentrainfall, or with hay which does notshed water readily, the method ofstorage can make the differencebetween less than 5%, or more than50%, dry matter loss from weathering!Furthermore, losses of more than 14%of the total crude protein and morethan 25% of the total digestiblenutrients can occur in the most highlyweathered portions of a bale. Animportant associated factor is that thepalatability of weathered portions ofbales is decreased, which lowers intakeand increases refusal.Thatch FormationIn theory, a round bale should form athatch that will, at least initially, shedalmost all of the rain which falls on thetop of the bale, but any of severalfactors may prevent this from occurring.Examples of forage crops whichhave the potential to thatch well whenpackaged in a uniform, dense bale arefine-stemmed, leafy, weed-freebermudagrass or tall fescue.Hay made from coarse-stemmedforage crops will not thatch well. Thisis due to large stems, hollow stems, orother physical factors which do notallow thatch formation. For example,water can easily penetrate the tops ofbales of many summer annual grasses,thus quickly beginning the weatheringprocess. Coarse-stemmed weeds withinhay can also provide an avenue forwater to penetrate bales.Once a wet layer forms, a bale doesnot shed water well and moisture levelsinside the bale are likely to continue toincrease during the storage period. Asthe wet, moldy area on the top of thebale deepens, less and less dryingoccurs between rains. Hence, onceweathering gets underway, it usuallyproceeds much faster than with newlybaled hay.Understanding the importance ofthatch formation is made easier byconsidering the amount of water whichmust be shed during storage. A 6 footlong by 6 foot diameter bale willreceive about 22 gallons of water foreach inch of rain. Therefore, if there4
In the eastern United States, storing bales outsideunprotected for several months will typically resultin at least 5 or 6 inches of hay around the topand sides which has essentially no feeding value.Losses on the bottoms of bales are usually evengreater due to contact with wet soil.are 30 inches of rainfall during thestorage period, a bale will receive 660gallons of water.Location Of WeatheringFor hay harvested at a low moisturelevel, weathering usually occurs inthree layers. The outside is typicallywet, dark, and rotten and has nofeeding value. Underneath is a thinnerlayer of moist and heavily molded haywhich is of relatively low quality. Athird transition layer, which mayexhibit light mold and have a highermoisture content than the outer surfacelayers, usually surrounds the unweatheredinterior.The sides of round bales shed waterbetter than the tops because less surfaceis directly exposed to rain. Therefore,an isolated uncovered bale should haveless weathering on the sides than onthe top. However, moisture can betrapped where bales touch on therounded sides, and this trappedmoisture delays drying and thus resultsin greater weathering during storage.Data suggest that often 50% ormore of the storage losses associatedwith outside storage occur in thevicinity of the bale/soil interface (thatis, at the bottom of the bale). Dry haytouching damp soil draws moistureinto the bale. Hence, if hay and soil arein contact, large weathering lossesoccur on the bottoms of bales evenwhen they are stored on a well-drainedsite. As a bale begins to weather on thebottom, it will flatten and allow evenmore hay/soil contact, and more toparea will be horizontally exposed torainfall, each of which increases theamount and rate of weathering.FACTORS AFFECTING OUTSIDESTORAGE LOSSESIn research trials in the eastern UnitedStates in which large round bales havebeen stored outside without protectionfor six months or more, dry matterlosses of 30% or greater have beencommon. Some of the most importantfactors relating to the extent and dollarvalue of outside storage losses areas follows:Bale DensityIn general, the denser or more tightlyhay is baled, the lower the amount ofspoilage that will occur, assuming haymoisture at baling is 18 to 20% orlower. Bale density is affected greatly bythe type of baler being used, with somelarge round balers providing a densityup to twice as great as other balers. Theaverage density of a bale is less criticalthan the density on the outer surface.Other factors may also affect baledensity. By making proper baleradjustments and taking time to do agood job, an experienced baler operatorcan often produce bales which aremuch tighter than those someone elsemight produce using the same equipment.Some fine-stemmed hays such asbermudagrass naturally tend to producea tight bale which sheds watermuch better than coarse-stemmed hayssuch as johnsongrass, pearl millet, orsorghum-sudangrass.Having well-formed, tight bales isan important factor in reducing storagelosses. Most haying equipment companiescan provide information thatdiscusses the steps (or tricks) required toproduce dense, uniform bales whenusing their products. The density ofround bales (at least in the outer fewinches) should be a minimum of 10pounds of hay/cubic foot.While increased bale densityreduces spoilage by reducing moisturepenetration, it also reduces the rate atwhich moisture and heat can escapefrom a bale.Thus, as density increases, it becomesincreasingly important to make certainthat hay is in a safe moisture range forbaling. Unfortunately, leaf shatter fromlegume hays also increases with decreasinghay moisture levels.A low moisture content, use of a forage crop withstems fine enough to form a thatch, and a baledensity of at least 10 pounds/cubic foot in theouter portions of bales are important factorsaffecting resistance to weathering during outsidestorage.Other Field OperationsOr TechniquesReduction of storage losses can beginwith the formation of the hay swathprior to baling. A uniform swath ofproper size for the baler being used willhelp to produce a dense, uniform bale.Other things being equal, smallerwindrows facilitate dense bales becausethey result in more layers per roll;however, leaf shatter of legumes, as wellas baling time, may be increased.Operating rakes, tedders, and balers inthe same direction as hay was cut mayalso help make a tighter bale.5
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Minimizing Losses in Hay Storage and Feeding - MSUcares

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