winter grazing in a grass-fed system: effect of stocking...

Research ArticleWinter Grazing in a Grass-Fed System Effect of StockingDensity and Sequential Use of Autumn-Stockpiled Grasslandon Performance of Yearling Steers

Domingo J Mata-Padrino E E D Felton W B Bryan and D P Belesky

West Virginia University Morgantown WV 26506 USA

Correspondence should be addressed to Domingo J Mata-Padrino djmatapadrinomailwvuedu

Received 27 September 2016 Revised 15 December 2016 Accepted 22 January 2017 Published 19 February 2017

Academic Editor David Clay

Copyright copy 2017 Domingo J Mata-Padrino et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Winter grazing can help reduce the need for purchased feeds in livestock production systems when finishing cattle on pasture Ourobjective was to evaluate the influence of stocking density and grazing stockpiled forage on performance of yearling steers duringwinter Three grasslands were winter grazed for two years I naturalized pastureland and II and III sown and managed for hayproduction during the growing season but grazed in winter Two stocking densities were used low 741 and high 1235 steers haminus1Herbagemass was estimated before and after each grazing event and disappearance (consumption weathering and trampling) wasthe difference between both Forage mass and residual differed by stocking density (SD) year (YR) and grazing interval (GI) anddisappearance differed by YR and GI Grass and dead constituents of botanical composition differed by YR and GI No differenceswere found for legumes and forbs CP differed by YR and GI and NDF and ADF differed only by YR Steer average daily gain was015 kg dminus1 in 2011 and 068 kg dminus1 in 2012 and varied by YR and GI Acceptable gains in 2012 may be a product of environmentalconditions that influenced herbage mass and nutritive value during stockpile and animal behavior during winter

1 Introduction

Sustaining livestock on pasture throughout the year in tem-perate regions is dictated by weather conditions within andamong years Herbage production during the growing seasonoften is restricted by precipitation deficits even when daylength and temperatures are favorable [1] In autumn andwinter decreasing temperatures and photoperiods contributeto forage plant dormancy and eventually the cessation ofactive growth In some instances forage plants adapted towater deficit and high temperatures and forage capable ofsustaining some growth at lower temperatures can be usedto stabilize variation in herbage production Since pasturesthroughout the Appalachian region comprise many differentspecies of grasses legumes and forbs some level of sustainedproductivity would be more likely when temperature andprecipitation trends vary with climate variability [2] In cool-temperate regions this might mean that plants adapted towarm-season growing conditions would persist and extend

the interval of active herbage production and thus grazingtime in late autumn and winter However when pasturegrowth is less than that required to meet grazing animalneeds stored or purchased feeds must be provided [3] Incool-temperate regions winter typically is the time whenstored feeds are used to sustain grazing livestock performanceon pasture Winter grazing may contribute to profitability offorage-based production systems by reducing the need forpurchased or stored feeds

Volesky et al [4] noted that stockpiled forage should begrazed during late autumn and early winter (November andDecember) in the central US to take advantage of herbagequantity and nutritive value Delaying herbage use beyondlate autumn is likely to result in mass and nutritive valuelosses [5 6] This occurs because of tissue damage caused byexposure to weather [7 8] Susceptibility to weather-relateddamage may be a function of the species stockpiled [9]

Animal performance is influenced by interactions occur-ring among herbage mass nutritive value weather and

HindawiInternational Journal of AgronomyVolume 2017 Article ID 2375954 9 pageshttpsdoiorg10115520172375954

2 International Journal of Agronomy

grazing behavior such as selectivity among sward compo-nents grazing time and location and previous experience[1 10] Recommendations for winter grazing often are basedupon general knowledge about forage growth developedduring the growing season for a given location However thisapproach may neglect changes in grazing animal behavioras herbage growth ceases with less favorable weather-relatedgrowing conditions During winter livestock may spendless time foraging over a large area and more time on arelatively smaller area of pasture [11] This typically contrastswith longer periods of foraging that occur during milderweather conditions Patton et al [1] noted that grazinginfluenced the amount of herbage produced and that modestgrazing intensity improved production over nongrazed areasWade and Carvalho [12] stated that at an empirical levelanimal responses to stocking methods and stocking densityare now well known However livestock response to theinteractions of weather herbage mass nutritive value andgrazing behavior is complex and not well understood

Livestock production systems that include winter grazingas a component of pasture management must take intoaccount season-long influences and interactions of live-stock grazing activities with the forage resources availableConsiderations include weather location of winter feedingsites on the pasture edaphic features and pasture botani-cal composition during the stockpiling period Short-termvariations in production and chemical composition couldbe related to management and weather during the growingseason [13] whereas long-term changes could be a product ofmanagement and environment interacting with time [1]

Mata-Padrino et al [14] noted that when grasslandscomprising different locally adapted forage species weregrazed simultaneously herbage quality declinedmore quicklyon naturalized permanent grassland while tall fescue dom-inant swards maintained herbage quality the longest andorchardgrass dominant swardswere intermediate To validatethis observation we grazed the grasslands in a sequencerelated to tolerance to late-season weather conditions forthis experiment Our objective was to determine whetheraverage daily gain of steers and total gain per hectare wereinfluenced by stocking densitywhenusing stockpiled herbagesequentially

2 Materials and Methods

21 Site Conditions The experiment was conducted at theWest Virginia University Reedsville Experiment Farmlocated in Preston County WV (39∘301015840N 79∘471015840W 537melevation) on the Appalachian High Plateau of the easternUSThree grasslands grazed during winter from 2004 to 2009were divided into 24 paddocks of 0405 ha The paddockswere grazed by 24 Bos taurus steers divided into two groupsto create low 741 and high 1235 steers haminus1 stocking densities(SD) each replicated three times We created a sequentialgrazing scheme based on previously observed resilience ofthe grassland communities to winter conditions [14] Eachgrassland represented one of three grazing intervals (GI)coincident with pasture type (Table 1) In order to maintain

Table 1 Sequence and schedule for winter grazing

Year Grazing intervalIdagger II III

2011 In Nov 2 Nov 22 Dec 16Out Nov 22 Dec 16 Jan 4


daggerI naturalized permanent grazingland II orchardgrass cultivated pasture-land III tall fescue cultivated pastureland

the sequence based on grassland endurance to late autumn-winter conditions the second grazing interval comprisedtwice the number of paddocks as the initial and final grazinginterval

The experiment on winter grazing of autumn-stockpiledherbage was conducted from August 2011 to January 2013with herbage stockpiling beginning in August of each yearand later grazed from early November until early JanuaryGrasslands were defined as follows and will henceforth bereferred to as I naturalized permanent grazingland and IIand III sown and managed primarily to hay productionduring the growing season but grazed during winter Thesequence beganwith grassland I which consisted of amixtureof orchardgrass (Dactylis glomerata L) velvet grass (Holcuslanatus L) timothy (Phleum pratense L) other grasses oflesser quality and presence in the sward white clover (Tri-folium repens L) red clover (T pratense L) and forbs Forbsincluded ground ivy (Glechoma hederacea L) dandelion(Taraxacum officinale Weber ex F H Wigg) dock (Rumexspp L) plantain (Plantago spp) and horsenettle (Solanumcarolinense L) followed by grassland II that consisted mainlyof orchardgrass timothy alfalfa (Medicago sativa L) whiteand red clover and forbs including Canada thistle (Cirsiumarvense (L) Scop) bedstraw (Galium aparine L) groundivy and dock and grassland III that consisted mainly oftall fescue (Schedonorus arundinaceus (Schreb) Dumort)orchardgrass and white and red clover along with the forbsbedstraw plantain ragweed (Ambrosia artemisiifolia L) andsmartweed (Polygonum pensylvanicum L)

Soil was sampled annually (0 to 5 cm depth) at 20 to 25locations along a predetermined transect in each grasslandfor estimates of soil nutrient status Lime (dolomitic) wasapplied to maintain pH above 58 and triple superphos-phate and potassium chloride were applied to maintainsoil available P and K above 65 kg haminus1 and 195 kg haminus1respectively Daily maximum and minimum temperaturesand precipitation were recorded at the experiment site

22 Plant Measurements

221 Forage Mass Herbage mass was determined using theplate meter technique described by E B Rayburn and SB Rayburn [15] in each paddock within each grasslandSeventy-five sward height measurements were made in eachpaddock before and after grazing Sampling sites were locatedby global satellite positioning at fixed intervals on four tran-sects within each paddock Means of all sampling sites within

International Journal of Agronomy 3

a given paddock provided an estimate of the sward heightfor each The difference between forage mass determinedbefore grazing and residual herbage mass after each grazingevent was assumed to represent herbage disappearanceDisappearance comprises the herbage consumed by grazinganimals as well as senesced damaged and detached leaves

Sward height was converted to herbage mass using thefollowing equation

Forage mass (kg haminus1)

= 26615 ∙ sward height (cm) + 265(1)

This equation was derived from data collected from eachof the paddocks in each grassland unit from 2004 through2009 [14]

222 Botanical Composition and Nutritive Value Prior tograzing each paddock 6 forage samples were collected forbotanical composition and nutritive value analyses along thesame transects used to estimate herbage mass Samples wereclipped to the soil surface within a 007m2 quadrat Samplescollected were placed in paper bags and stored at 0∘C untilprocessed Herbage samples were hand-sorted into grasseslegumes forbs and dead material Grasses and forbs wereseparated further by species Grasses included orchardgrasstall fescue timothy velvet grass and other grasses whichrepresented infrequently occurring sward components Forbsincluded bedstraw Canada thistle ground ivy dandeliondock horsenettle smartweed ragweed plantain and otherephemeral and infrequently occurring forbs Individualspecies and total sampled area weights were determinedand the percentage of each component of the sward wascomputed Individual sward components were placed inpaper bags and air-dried at 60∘C in a forced-draft oven for48 h Dry samples were weighed and then recombined bygrassland Two subsamples collected from each grasslandwere ground using a stainless steelWileymill (Model 4 A HThomas Philadelphia PA) equippedwith a 1mmparticle sizescreen All nutritive analyses were performed in duplicateDry matter (105∘C) ash and crude protein (CP) (Kjeldahl Ntimes 625) were determined according toAOAC [16] proceduresNeutral detergent fiber (NDF) acid detergent fiber (ADF)and lignin were determined sequentially according to VanSoest et al [17] usingmodifications outlined in theANKOMcopy

fiber analysis procedure (ANKOM Technology MacedonNY)

23 Animal Measurements Steers used during 2011-2012were born and raised in Virginia whereas those used in2012-2013 were born and raised at the Reedsville farm wherethe experiment was conducted Steers were assigned eachyear randomly among paddocks by weight and frame sizeat the start of the winter grazing Animals were treated forinternal and external parasites at the beginning of the wintergrazingThree grazing intervals were coincident with grazinggrasslands I II and III in sequence Animals were weighedat the start of each grazing interval until the conclusionof the experiment providing a total of four live weight

measurements per animal for each year A uniform methodfor weighing livestock is critical when comparing livestockresponses to treatment or conditions in both commercial andresearch settings [18] We removed grazers from paddocksat 0700 h and then weighed the animals between 1000 and1100 h for each weighing date Animals were returned topaddocks at 1200 h on the same day All animals were handledin the same manner at each weighing event to help minimizedifferences attributable to grazing behavior Productivity perhectare was calculated each year for treatment and for thecomplete grazing interval

24 Statistical Analysis Paddock was the experimental unitfor grassland and animal measurements All forage data wereanalyzed as a completely random design replicated threetimes using the PROC-MIXED procedure of SAS [19] Forgrazing management and botanical composition data themodel included year stocking density grazing interval andtheir interactions Analysis of nutritive value included yeargrasslands and their interaction in the model In both analy-ses a repeated measurement statement and the denominatordegrees of freedom using the Kenward-Roger option wereincluded Average daily gain was calculated for each grazinginterval and reported as season-long total gain The modelused to analyze ADG included year stocking density grazinginterval and their interactions and a repeated measurementstatement and the denominator degrees of freedom usingthe Kenward-Roger option were computed Treatment leastsquares means were calculated and means compared usingLSR when the F test for means was significant (119875 lt 005)Initial weight each year was compared between stockingdensities with one-way ANOVA using the PROC-MIXEDprocedure of SAS

3 Results and Discussion

31 Weather Conditions Precipitation and air temperaturevaried by month and year during the stockpile and wintergrazing interval of the experiment years and when com-pared to location 30-year mean (Figures 1 and 2) Variableweather conditions would contribute to variations observedin herbage accumulation in late summerearly fall and inanimal performance during the grazing period Total pre-cipitation was above normal throughout the duration of theexperiment (2011-2012) however it was less than the 30-year mean in August andNovember 2012 Temperatures weresimilar to the 30-yearmean and less than the long-termmeanonly in November 2012

During stockpile precipitation and air temperature havea significant influence on forage production and quality andcould be more important determinants of sward composi-tion herbage mass and nutritive value than managementimposed during late summer and autumn [1 6]

Winter grazing in grass-fed systems is highly dependenton weather [14] Also during winter grazing temperaturesand snow cover can affect grazing behavior and animalperformance [20ndash22] Duringwinter-stocking period of 2011-12 snow covered the grasslands for a few days Nevertheless


0

50

100

150

200

250

Aug Sep Oct Nov Dec Jan

Mon

thly

pre

cipi

tatio

n (m

m)

2011-122012-13

30 years

Figure 1 Monthly precipitation and 30-year mean values atReedsville WV

minus5

0

5

10

15

20

25


Mon

thly

mea

n ai

r tem

pera

ture

(∘C)

2011-122012-13

30 years

Figure 2 Monthly mean air temperature and 30-year mean valuesat Reedsville WV

inDecember 2012 and January 2013 snow covered the pasturefor a longer period which restricted grazer access to herbage

32 Grassland Characterization Riesterer et al [23] pro-posed a schedule to use stockpiled grasslands in Wisconsindepending on species endurance Similarly our previouslyreported observations [14] suggested a sequence of use basedon resistance toweathering A thorough understanding of thepregraze pastures was needed to help explain any differencewhich may occur as a result of stocking density on averagedaily gain of yearling steers during winter

321 Forage Mass Stockpiled forage mass determined priorto each winter grazing interval averaged 2948 kg haminus1 forthe two-year experiment (Table 2) Stockpiled forage massmeasure at the two stocking densities showed differences(119875 = 00155) attributable to weather and soil moisturevariability during the stockpile Year and grazing intervalwere also different (both 119875 lt 00001) with the difference

Table 2 Forage mass residual forage mass and forage disappear-ance of each grassland for two years

Year Grazing intervaldagger Forage mass Residual Disappearancekg haminus1

2011I 3900a 1701b 2199a

II 3164b 1517c 1647b

III 3257b 1480c 1777b

2012I 2562c 1848a 714d

II 2141d 1419d 722d

III 2664c 1592b 1072c

Means in the same column followed by a different lowercase letter aredifferent at the 005 probability leveldaggerI naturalized permanent grazingland II orchardgrass cultivated pasture-land III tall fescue cultivated pastureland

probably attributable to precipitation during stockpile andweathering during the winter grazing intervals (Table 4)Interactions were significant for YR lowast GI (119875 lt 00001) andSD lowast YR (119875 = 00022) An explanation for these inter-actions may be the different way cold weather influencedthe grasslands during each year and differences associatedwith pregraze herbage mass and stocking densities Herbageproduction was lower for the same grasslands during winterof 2005ndash2009 when using strip-grazing management [14]The increase in production obtained in this experiment maybe explained by the use of a grazing sequence based ongrassland that helped avoid the deterioration of herbagemassand quality resulting from late autumn and winter weatherconditions Prigge et al [24] and Baker et al [25] foundsimilar forage production for orchardgrass during autumnat the WVU Reedsville Experiment Farm Tall fescue massdetermined in our experiment was less than that reported inNorth Carolina [26] but similar to the amounts obtained atMorgantown West Virginia [6 7] Wooster Ohio [27] andColumbia Missouri [28]

Volesky et al [4] observed that orchardgrass was moresusceptible than tall fescue to effects of snow compressionand as a result would present relatively less herbage availablefor grazing Collins and Balasko [6] found that herbagemass of stockpiled tall fescue declined from 2500 kg haminus1in December to 2250 kg haminus1 by February demonstratingpossible loss attributable to leaf senescence or weatheringDisappearance averaged 2794 kg dminus1 for the low stockingdensity and 2954 kg dminus1 for the higher performance showedthat despite trampling and differences in pregrazing andresidual foragemass the steers could remove similar amountsof forage in both stocking densities (Table 3)

Residual forage mass differed between treatments (119875 lt00312) however it is the resultant effect of using the residualherbage on pastures with greater stocking rate as a deter-minant to move animals to the next grassland In additiongrazing interval (119875 lt 00001) showed the effect of weatheringas the season advances Residual herbage was influenced byYRtimesGI (119875 = 00011) andYRtimes SD (119875 = 00008) interactionsHerbage disappearance differed by year and interacted withstocking density (both 119875 lt 00001) Grazing interval


Table 3 Forage mass residual forage mass and forage disappear-ance by stocking density for two years

Year Stocking densitydagger Forage mass Residual Disappearancekg haminus1

2011 Low SD 3234a 1661a 1737a

High SD 3509b 1447b 1847a

2012 Low SD 2355c 1565c 781b

High SD 2399c 1574c 834b

Means in the same column followed by a different lowercase letter aredifferent at the 005 probability leveldaggerSD stocking density Low SD = 741 steers haminus1 and high SD = 1235 steershaminus1

Table 4 Analysis of variance of forage mass residual herbageforage disappearance and forage use as a function of stockingdensity grazing interval year and their interactions

Source of variation Forage mass Residual DisappearanceP value

Stocking density (SD) 00155 00312 NSYear (YR) lt00001 00623 lt00001Grazing interval (GI) lt00001 lt00001 00009SD lowast YR 00022 00008 lt00001YR lowast GI lt00001 00011 NSSD lowast GI NS NS NSSD lowast YR lowast GI 00010 00175 00427daggerSD stocking density Low SD = 741 steers haminus1 and high SD = 1235 steershaminus1

showed differences for herbage disappearance but did notdiffer between stocking densities (Table 4) Forage mass inthis experiment was determined by canopy height thosemeasurements would be influenced by snow compressionand trampling Furthermore the effects of weathering andanimal impact would depend on stocking densities andsward components Despite the influence of limiting factorsanalyzing forage mass in winter grazing situations may helpexplain the balance between herbage consumption swarddecomposition and subsequently animal performance

322 Botanical Composition Grass and forbs were influ-enced by year and grazing interval regardless of stockingdensity All principal botanical components were influencedby year interactingwith grazing interval (Table 5)Differencesin endurance of grass species in each grazing interval and pre-cipitation and temperature patterns during the two years thatthe experiment lasted may have contributed to this responseeven with the different pattern of snow precipitation andtime that snow was covering grassland both years In 2011grazing intervals II and III had much more dead materialthan grazing interval I and more than any interval in 2012(Figure 3) Grass was the predominant component in 2011in grazing interval I a relatively wet and warmer year andprimarily was represented by ldquoother grassesrdquo Converselyduring 2012 cultivated cool-season grasses represented agreater proportion in the grass component (Figure 4) butagain the botanical composition of naturalized grasslands

Table 5 Analysis of variance for main components of grasslandbotanical composition as a function of stocking density grazinginterval year and their interactions

Source of variation Grass Legume Forb Dead119875 value

Stocking density (SD) NS NS NS NSYear (YR) 00124 NS NS lt00001Grazing interval (GI) 00425 NS NS lt00001SD lowast YR NS NS NS NSYR lowast GI lt00001 00348 00089 lt00001SD lowast GI NS NS NS NSSD lowast YR lowast GI NS NS NS NS

grazed in interval I performed differently with a decreasinggrass proportion Tall fescue was the most reduced cultivatedcool-season grass during 2011 Proportion of other grassesand forbs along with higher air temperatures during stockpileand lower air temperatures in December 2011 may explainthat reduction in tall fescue proportion and the patterns ofsenesced herbage observed during winter grazing in 2011-2012 Legume did not have a considerable contribution to theforage available for winter grazing Legume level increased in2012 compared with 2011 grazing interval II with the greatestamount of legume Conversely the legume proportion ingrazing interval III corresponding with tall fescue pasturewas less in 2012 compared with 2011 The interaction YR lowastGI for legume component could be explained by changesin the legume component Hitz et al (2000) reported alsoa reduction in legume proportion when associated withfescue in winter grazing The greatest percentages of forbsoccurred duringDecember 2011 during grazing interval II anorchardgrass dominant pasture with bedstraw the dominantforb (Figure 5) Hobbs et al [29] found that orchardgrasspastures had an encroachment of weeds estimated in therange of 12ndash20 that was similar to forb proportion inorchardgrass dominant pasture In both years tall fescuedominant pastures compared to other pastures had fewerforbs which is consistent with published results for tall fescuepastures [29 30] Bedstrawwas themost prevalent forb notedduring winter grazing in grazing intervals II and III andthrived during dry and relatively cooler conditions occurringduring the stockpiling interval of late summer and autumnGround ivy was dominant in grazing interval I but was alsomore abundant in all pastures when warmer temperaturesoccurred during stockpiling in 2011-2012 Dandelion seemedto be present in greater amounts during the relatively colderstockpiling interval of the 2012-2013 season (Figure 5)regardless of grazing interval

323 Chemical Composition Crude protein (CP) concen-tration differed during the two years of the experiment(119875 = 00003) and also differed by grazing interval (Tables6 and 7) In 2011 CP concentration differed little betweengrazing intervals but in 2012 the CP during grazing intervalI was less than the CP of subsequent intervals Variations


Table 6 Crude protein (CP) neutral detergent fiber (NDF) acid detergent fiber (ADF) and lignin of forage collected from each grasslandduring a period of two years

Year Grazing interval associated with grasslanddagger CP NDF ADF Ligningsdotkgminus1

2011I 138c 572b 300a 47II 146c 545b c 255b 45III 145b c 619c d 281c 62

2012I 138c 575b 296a 46II 190a 510d 243c 58III 152a 613d 284c 64

Means in the same column followed by a different lowercase letter are different at 119875 lt 005daggerI naturalized permanent grazingland II orchardgrass cultivated pastureland III tall fescue cultivated pastureland

020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead

Figure 3 Botanical composition of grasslands used for winter graz-ing in three consecutive grazing intervals (I II and III) at ReedsvilleWV Grazing Interval I = naturalized permanent grazingland II =orchardgrass cultivated pastureland and III = tall fescue cultivatedpastureland

05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)

OrchardgrassFescueTimothy

Velvet grassOther grasses

Figure 4 Proportion of dominant species in the grass componentof grasslands used for winter grazing in three consecutive grazingintervals (I II and III) at Reedsville WV Grazing Interval I =naturalized permanent grazingland II = orchardgrass cultivatedpastureland and III = tall fescue cultivated pastureland

in weather N fertilization and botanical composition con-tributed to these differences Naturalized grassland had thelowest concentration of CP and the greatest proportion ofother grasses Concentrations of CP were the greatest in thecultivated grasslands being greater in orchardgrass than intall fescue dominant grasslands This is consistent with other

02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs

Figure 5 Proportion of dominant species in the forb componentof grasslands used for winter grazing in three consecutive grazingintervals (I II and III) at Reedsville WV Grazing interval I =naturalized permanent grazingland II = orchardgrass cultivatedpastureland and III = tall fescue cultivated pastureland

published work from the region [14 25 31] Declining CPthrough fall and winter has been reported in some studieswith fescue orchardgrass and other cool-season grassesbut fescue was consistently reported to be more resistantto the effects of winter weather conditions [4 9 14 3233] Collins and Balasko [6 7] reported that between mid-December and February in vitro dry matter digestibility oftall fescue decreased significantly Forage CP concentrationin this experiment was greater than previously publisheddata from this location [14 25 32] Results suggest thatsequential grazing of forage from most to least susceptible todeterioration related to winter weather conditions may havecontributed to sustained herbage nutritive value Time ofsampling may also be a factor that contributes to differencesin CP concentration between grazing intervals Perez-Prietoet al [34] found that ryegrass grasslands performed similarlyinwinter and they related this to leafy conditions of the swardHerbage ADF and NDF concentrations differed with year(Table 7) being higher in 2011 Grazing interval I maintainedsimilar values both years but higher concentrations of deadmaterial in the cultivated grasslands could be associated withhigher proportions of dead material in 2011 [35] They also


Table 7 Analysis of variance for crude protein (CP) neutraldetergent fiber (NDF) acid detergent fiber (ADF) and lignin as afunction of grazing interval and year and their interaction

Source of variation CP NDF ADF LigninP value

Grazing interval (GI) 00010 NS NS NSYear (YR) 00003 lt00001 00004 NSYR lowast GI 00007 NS NS NS

Table 8 Average daily gain by grazing interval and treatment overtwo years

Year Grazingintervaldagger

ADG(kg dminus1) SEMŁ Stocking

densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085

Low SD 021 0065II 044III minus026 High SD 009 0056

Total 015 0043

2012

I 2000085


Total 068 0043daggerI naturalized permanent grazingland II orchardgrass cultivated pasture-land III tall fescue cultivated pasturelandDaggerSD stocking density Low SD = 741 steers haminus1 and high SD = 1235 steershaminus1ŁSEM standard error

found that orchardgrass fiber concentrationwas less than thatof tall fescue Volesky et al [4] reported for orchardgrassNDFconcentrations between 562 and 629 g kgminus1 from Decemberthrough January with slightly greater NDF for tall fescueduring the same period Meyer et al [28] reported NDF andADF concentrations similar to those presented here Culti-vated grasslands during the winter of 2012-2013 had chemicalcomposition that was comparable to high quality forage inspring (eg high CP and low fiber) Lignin concentrationwassimilar across all grasslands

33 Animal Performance Initial body weight of steers wasnot different between stocking densities and averaged 249 kgfor both years 241 kg dminus1 in 2011 and 256 kg dminus1 in 2012Steer performance differed with year (119875 lt 00001) andtended to differ with stocking density (119875 = 00662) Thegroup managed at 741 steers haminus1 (low density) consistentlygainedmore steers on the higher density (741 steers haminus1) andthere was no stocking density by year interaction (Tables 8and 9) Paddocks stocked at the lower density for the samelength of time led consistently to greater residual herbagemass however no differences for forage use were observedbetween the two stocking densities (119875 = 06048) Differencesattributable to year may arise from the influence of weatheron animal behavior and forage botanical and chemical com-positionWinter 2011-2012 was slightly warmer with minimalsnow cover of short duration (one day in December 2011

Table 9 Analysis of variance for average daily gain by stockingdensity grazing interval year and their interactions

Source of variation P valueStocking density (SD) 00662Year (YR) lt00001Grazing interval (GI) lt00001SD lowast YR NSYR lowast GI lt00001SD lowast GI NSSD lowast YR lowast GI NS

and two days in January 2012) during grazing interval IIIwhile tall fescue was grazed Snow covered grasslands forshort intervals duringDecember 2012 during grazing intervalII Pasture was virtually continuously snow-covered duringgrazing interval III in late December and early January of2013 Dunn et al [21] suggested that grazing experienceduring winter influences foraging behaviorWe observed thatsteers tended to grazemore intensively in a limited area whentemperatures were low or snow cover occurred which wasalso observed by Krysl and Hess [22] Wade and Carvalho[12] concluded that an inverse relationship between herbageintake and animal performance is a function of stocking den-sity where higher densities contribute to decreased availableherbage per animal In winter that relationship may havea stronger impact as the animal grazing behavior changesBotanical composition of pastures to be winter-grazed isusually determined at the end of the stockpile howeverchanges in the short term may influence herbage qualityand animal winter grazing behavior could affect overallperformance [20 21]

Animal productivity (kg haminus1) was much higher for win-ter grazing in 2012-2013 than in 2011-2012 (Figure 6) Inaddition the lower stocking rate led to more gain per hectarein 2011-2012 however in 2012-2013 it was the higher stockingrate that produced the most animal gain per hectare Thisresponse might be explained by the influence of weather onforage quality and on animal behavior In 2011-2012 foragemass disappearance and forage usewere higher than in 2012-2013 However forage quality was compromised in 2011-2012by greater amounts of deadmaterial especially for grasslandsused during grazing intervals II and III

The results for productivity show that the effect ofstocking density was the opposite in 2011-2012 of what it wasin 2012-2013 In spite of lower forage mass and utilizationsteers foraged more effectively in 2012-2013 under drier andcooler conditions with more snow cover

4 Conclusions

Our results support the conclusion that performance targetsfor ADGduring winter grazingmust consider environmentalconditions during the grazing periods and the influence ofweather during the late summer-autumn stockpile interval onforage quantity and quality available for winter grazing How-ever it would be required to consider as well the influence of


0

100

200

300

400

500

2011 2012

Low stocking densityHigh stocking density

(kg h

aminus1)

Figure 6 Productivity (kg haminus1) by stocking density during wintergrazing over two years

SD on steer ADG Our outcomes revealed a favorable trendby decreasing SD during winter grazing The proportion ofsenesced herbage as a fraction of sward botanical composi-tion during winter is related to weather conditions duringthe stockpile intervalWeather also influenced animal grazingbehavior during winter grazing and subsequently influencedanimal performance and appeared to supersede aspects ofmanagement such as grassland composition and stockingrate Grassland responses were not influenced by stockingdensities which implies that productivity per unit of land areaduring winter depended upon forage quality and the sourceof grazing animals

Competing Interests

The authors declare that they have no competing interests

Acknowledgments

The authors thank Rodney Kiser and the WVU Reedsvillefarm personnel for their help with sitemanagement livestockhandling and field data collection and Eric Nestor andKaraHaught for conducting herbage nutritive value chemicalanalyses Funding for this research was provided by the ldquoEco-nomic Pasture-Based Beef Systems for Appalachiardquo USDA-ARS (1932-21630-002-00D) Beaver WV specific cooperativeagreement partnership with West Virginia University Vir-ginia Tech and Clemson University

References

[1] B D Patton X Dong P E Nyren and A Nyren ldquoEffectsof grazing intensity precipitation and temperature on forageproductionrdquo Rangeland Ecology amp Management vol 60 no 6pp 656ndash665 2007

[2] D P Belesky and D P Malinowski ldquoGrassland communities inthe USA and expected trends associated with climate changerdquoActa Agrobotanica vol 69 no 2 article 1673 2016

[3] J P Flores and B Tracy ldquoImpacts of winter hay feeding on pas-ture soils and plantsrdquo Agriculture Ecosystems and Environmentvol 149 pp 30ndash36 2012

[4] J D Volesky B E Anderson and M C Stockton ldquoSpecies andstockpile initiation date effects on yield and nutritive value of

irrigated cool-season grassesrdquo Agronomy Journal vol 100 no4 pp 931ndash937 2008

[5] E B Rayburn R E Blaser and D D Wolf ldquoWinter tall fescueyield and quality with different accumulation periods and nratesrdquo Agronomy Journal vol 71 no 6 pp 959ndash963 1979

[6] M Collins and J A Balasko ldquoEffects of N fertilization andcutting schedules on stockpiled tall fescue I Forage yieldrdquoAgronomy Journal vol 73 no 5 pp 803ndash807 1981

[7] M Collins and J A Balasko ldquoEffects of N fertilization andcutting schedules on stockpiled tall fescue II Forage qualityrdquoAgronomy Journal vol 73 no 5 pp 821ndash826 1981

[8] J C Burns and D S Chamblee ldquoSummer accumulation of tallfescue at low elevations in the humid Piedmont II Fall andwinter changes in nutritive valuerdquo Agronomy Journal vol 92no 2 pp 217ndash224 2000

[9] V S Baron A C DickM Bjorge andG Lastiwka ldquoStockpilingpotential of perennial forage species adapted to the Canadianwestern Prairie Parklandrdquo Agronomy Journal vol 96 no 6 pp1545ndash1552 2004

[10] J Hodgson J M Rodriguez Capriles and J S Fenlon ldquoTheinfluence of sward characteristics on the herbage intake ofgrazing calvesrdquo The Journal of Agricultural Science vol 89 no3 pp 743ndash750 1977

[11] J C Malechek and B M Smith ldquoBehavior of range cows inresponse to winter weatherrdquo Journal of Range Management vol29 no 1 pp 9ndash12 1976

[12] M H Wade and P C F Carvalho ldquoDefoliation patternsand herbage intake on pasturesrdquo in Grassland Ecophysiologyand Grazing Ecology G Lemaire J Hodgson A MoraesC Nabinger and P C F Carvalho Eds pp 233ndash248 CABInternational New York NY USA 2000

[13] MH Poore andM EDrewnoski ldquoReview utilization of stock-piled tall fescue in winter grazing systems for beef cattlerdquoProfessional Animal Scientist vol 26 no 2 pp 142ndash149 2010

[14] D Mata-Padrino E Felton and W B Bryan ldquoWinter manage-ment of yearling steers in a grass-fed beef production systemrdquoAgronomy Journal vol 107 no 3 pp 1048ndash1054 2015

[15] E B Rayburn and S B Rayburn ldquoA standardized platemeter forestimating pasture mass in on-farm research trialsrdquo AgronomyJournal vol 90 no 2 pp 238ndash241 1998

[16] Association of Official Analytical Chemists Official Methods ofAnalysis Association ofOfficialAnalytical Chemists ArlingtonVa USA 17th edition 2002

[17] P J Van Soest J B Robertson and B A Lewis ldquoMethods fordietary fiber neutral detergent fiber and nonstarch polysaccha-rides in relation to animal nutritionrdquo Journal of Dairy Sciencevol 74 no 10 pp 3583ndash3597 1991

[18] A K Watson B L Nuttelman T J Klopfenstein L W Lomasand G E Erickson ldquoImpacts of a limit-feeding procedure onvariation and accuracy of cattle weightsrdquo Journal of AnimalScience vol 91 no 11 pp 5507ndash5517 2013

[19] R C Littell G A Milliken W W Stroup and R D WolfingerSAS Systems for Mixed Models SAS Institute Inc Cary NCUSA 1996

[20] S K Beverlin K M Havstad E L Ayers and M K PetersenldquoForage intake responses to winter cold exposure of free-ranging beef cowsrdquo Applied Animal Behaviour Science vol 23no 1-2 pp 75ndash85 1989

[21] R W Dunn K M Havstad and E L Ayers ldquoGrazing behaviorresponses of rangeland beef cows to winter ambient tempera-tures and agerdquo Applied Animal Behaviour Science vol 21 no 3pp 201ndash207 1988


[22] L J Krysl and B W Hess ldquoInfluence of supplementation onbehavior of grazing cattlerdquo Journal of Animal Science vol 71no 9 pp 2546ndash2555 1993

[23] J L Riesterer D J Undersander M D Casler and D KCombs ldquoForage yield of stockpiled perennial grasses in theupper midwest USArdquoAgronomy Journal vol 92 no 4 pp 740ndash747 2000

[24] E C Prigge W B Bryan and E S Goldman-Innis ldquoEarly-and late-season grazing of orchardgrass and fescue hayfieldsoverseeded with red cloverrdquo Agronomy Journal vol 91 no 4pp 690ndash696 1999

[25] M J Baker E C Prigge andW B Bryan ldquoHerbage productionfrom hay fields grazed by cattle in fall and springrdquo Journal ofProduction Agriculture vol 1 no 3 pp 275ndash279 1988

[26] M H Poore M E Scott and J T Green Jr ldquoPerformanceof beef heifers grazing stockpiled fescue as influenced bysupplemental whole cottonseedrdquo Journal of Animal Science vol84 no 6 pp 1613ndash1625 2006

[27] J P Schoonmaker S C Loerch J E Rossi and M L BorgerldquoStockpiled forage or limit-fed corn as alternatives to hay forgestating and lactating beef cowsrdquo Journal of Animal Sciencevol 81 no 5 pp 1099ndash1105 2003

[28] A M Meyer M S Kerley R L Kallenbach and T L PerkinsldquoComparison of grazing stockpiled tall fescue versus feedinghay with or without supplementation for gestating and lactatingbeef cows during winterrdquo Professional Animal Scientist vol 25no 4 pp 449ndash458 2009

[29] C S Hobbs T W Jr High and I Jr Dyer ldquoOrchardgrassand fescue pastures for producing yearling slaughter steersrdquo inUniversity of Tennessee Agricultural Experiment Station BulletinUniversity of Tennessee Agricultural Experiment Station OakRidge Tenn USA 1965

[30] K Saikkonen K Ruokolainen O Huitu et al ldquoFungal endo-phytes help prevent weed invasionsrdquo Agriculture Ecosystemsand Environment vol 165 pp 1ndash5 2013

[31] K A Archer and A M Decker ldquoAutumn-accumulated tall fes-cue and orchardgrass I growth and quality as influenced bynitrogen and soil temperaturerdquo Agronomy Journal vol 69 no4 pp 601ndash605 1977

[32] J A Balasko ldquoEffects of N P and K fertilization on yield andquality of tall fescue forage in winterrdquo Agronomy Journal vol69 no 3 pp 425ndash428 1977

[33] W R Ocumpaugh and A G Matches ldquoAutumn-winter yieldand quality of tall fescuerdquo Agronomy Journal vol 69 no 4 pp639ndash643 1977

[34] L A Perez-Prieto J L Peyraud and R Delagarde ldquoPastureintake milk production and grazing behaviour of dairy cowsgrazing low-mass pastures at three daily allowances in winterrdquoLivestock Science vol 137 no 1-3 pp 151ndash160 2011

[35] K A Archer and A M Decker ldquoAutumn-accumulated tall fes-cue and orchardgrass ii effects of leaf death on fiber compo-nents and quality parametersrdquo Agronomy Journal vol 69 no 4pp 605ndash609 1977

Submit your manuscripts athttpswwwhindawicom

Nutrition and Metabolism

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Food ScienceInternational Journal of

Agronomy


International Journal of



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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Applied ampEnvironmentalSoil Science

Volume 2014

AgricultureAdvances in


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BiodiversityInternational Journal of


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GenomicsInternational Journal of


Plant GenomicsInternational Journal of


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EcologyInternational Journal of


Veterinary Medicine International


Cell BiologyInternational Journal of


Evolutionary BiologyInternational Journal of



grazing behavior such as selectivity among sward compo-nents grazing time and location and previous experience[1 10] Recommendations for winter grazing often are basedupon general knowledge about forage growth developedduring the growing season for a given location However thisapproach may neglect changes in grazing animal behavioras herbage growth ceases with less favorable weather-relatedgrowing conditions During winter livestock may spendless time foraging over a large area and more time on arelatively smaller area of pasture [11] This typically contrastswith longer periods of foraging that occur during milderweather conditions Patton et al [1] noted that grazinginfluenced the amount of herbage produced and that modestgrazing intensity improved production over nongrazed areasWade and Carvalho [12] stated that at an empirical levelanimal responses to stocking methods and stocking densityare now well known However livestock response to theinteractions of weather herbage mass nutritive value andgrazing behavior is complex and not well understood

Livestock production systems that include winter grazingas a component of pasture management must take intoaccount season-long influences and interactions of live-stock grazing activities with the forage resources availableConsiderations include weather location of winter feedingsites on the pasture edaphic features and pasture botani-cal composition during the stockpiling period Short-termvariations in production and chemical composition couldbe related to management and weather during the growingseason [13] whereas long-term changes could be a product ofmanagement and environment interacting with time [1]

Mata-Padrino et al [14] noted that when grasslandscomprising different locally adapted forage species weregrazed simultaneously herbage quality declinedmore quicklyon naturalized permanent grassland while tall fescue dom-inant swards maintained herbage quality the longest andorchardgrass dominant swardswere intermediate To validatethis observation we grazed the grasslands in a sequencerelated to tolerance to late-season weather conditions forthis experiment Our objective was to determine whetheraverage daily gain of steers and total gain per hectare wereinfluenced by stocking densitywhenusing stockpiled herbagesequentially

2 Materials and Methods

21 Site Conditions The experiment was conducted at theWest Virginia University Reedsville Experiment Farmlocated in Preston County WV (39∘301015840N 79∘471015840W 537melevation) on the Appalachian High Plateau of the easternUSThree grasslands grazed during winter from 2004 to 2009were divided into 24 paddocks of 0405 ha The paddockswere grazed by 24 Bos taurus steers divided into two groupsto create low 741 and high 1235 steers haminus1 stocking densities(SD) each replicated three times We created a sequentialgrazing scheme based on previously observed resilience ofthe grassland communities to winter conditions [14] Eachgrassland represented one of three grazing intervals (GI)coincident with pasture type (Table 1) In order to maintain

Table 1 Sequence and schedule for winter grazing

Year Grazing intervalIdagger II III



daggerI naturalized permanent grazingland II orchardgrass cultivated pasture-land III tall fescue cultivated pastureland

the sequence based on grassland endurance to late autumn-winter conditions the second grazing interval comprisedtwice the number of paddocks as the initial and final grazinginterval

The experiment on winter grazing of autumn-stockpiledherbage was conducted from August 2011 to January 2013with herbage stockpiling beginning in August of each yearand later grazed from early November until early JanuaryGrasslands were defined as follows and will henceforth bereferred to as I naturalized permanent grazingland and IIand III sown and managed primarily to hay productionduring the growing season but grazed during winter Thesequence beganwith grassland I which consisted of amixtureof orchardgrass (Dactylis glomerata L) velvet grass (Holcuslanatus L) timothy (Phleum pratense L) other grasses oflesser quality and presence in the sward white clover (Tri-folium repens L) red clover (T pratense L) and forbs Forbsincluded ground ivy (Glechoma hederacea L) dandelion(Taraxacum officinale Weber ex F H Wigg) dock (Rumexspp L) plantain (Plantago spp) and horsenettle (Solanumcarolinense L) followed by grassland II that consisted mainlyof orchardgrass timothy alfalfa (Medicago sativa L) whiteand red clover and forbs including Canada thistle (Cirsiumarvense (L) Scop) bedstraw (Galium aparine L) groundivy and dock and grassland III that consisted mainly oftall fescue (Schedonorus arundinaceus (Schreb) Dumort)orchardgrass and white and red clover along with the forbsbedstraw plantain ragweed (Ambrosia artemisiifolia L) andsmartweed (Polygonum pensylvanicum L)

Soil was sampled annually (0 to 5 cm depth) at 20 to 25locations along a predetermined transect in each grasslandfor estimates of soil nutrient status Lime (dolomitic) wasapplied to maintain pH above 58 and triple superphos-phate and potassium chloride were applied to maintainsoil available P and K above 65 kg haminus1 and 195 kg haminus1respectively Daily maximum and minimum temperaturesand precipitation were recorded at the experiment site

22 Plant Measurements

221 Forage Mass Herbage mass was determined using theplate meter technique described by E B Rayburn and SB Rayburn [15] in each paddock within each grasslandSeventy-five sward height measurements were made in eachpaddock before and after grazing Sampling sites were locatedby global satellite positioning at fixed intervals on four tran-sects within each paddock Means of all sampling sites within





= 26615 ∙ sward height (cm) + 265(1)












0

50

100

150

200

250


Mon

thly

pre

cipi

tatio

n (m

m)

2011-122012-13

30 years


minus5

0

5

10

15

20

25


Mon

thly

mea

n ai

r tem

pera

ture

(∘C)

2011-122012-13

30 years







2011I 3900a 1701b 2199a

II 3164b 1517c 1647b

III 3257b 1480c 1777b

2012I 2562c 1848a 714d

II 2141d 1419d 722d

III 2664c 1592b 1072c








2011 Low SD 3234a 1661a 1737a

High SD 3509b 1447b 1847a

2012 Low SD 2355c 1565c 781b

High SD 2399c 1574c 834b


















020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead


05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)





02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs










densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014




























= 26615 ∙ sward height (cm) + 265(1)












0

50

100

150

200

250


Mon

thly

pre

cipi

tatio

n (m

m)

2011-122012-13

30 years


minus5

0

5

10

15

20

25


Mon

thly

mea

n ai

r tem

pera

ture

(∘C)

2011-122012-13

30 years







2011I 3900a 1701b 2199a

II 3164b 1517c 1647b

III 3257b 1480c 1777b

2012I 2562c 1848a 714d

II 2141d 1419d 722d

III 2664c 1592b 1072c








2011 Low SD 3234a 1661a 1737a

High SD 3509b 1447b 1847a

2012 Low SD 2355c 1565c 781b

High SD 2399c 1574c 834b


















020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead


05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)





02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs










densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014

























0

50

100

150

200

250


Mon

thly

pre

cipi

tatio

n (m

m)

2011-122012-13

30 years


minus5

0

5

10

15

20

25


Mon

thly

mea

n ai

r tem

pera

ture

(∘C)

2011-122012-13

30 years







2011I 3900a 1701b 2199a

II 3164b 1517c 1647b

III 3257b 1480c 1777b

2012I 2562c 1848a 714d

II 2141d 1419d 722d

III 2664c 1592b 1072c








2011 Low SD 3234a 1661a 1737a

High SD 3509b 1447b 1847a

2012 Low SD 2355c 1565c 781b

High SD 2399c 1574c 834b


















020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead


05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)





02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs










densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014



























2011 Low SD 3234a 1661a 1737a

High SD 3509b 1447b 1847a

2012 Low SD 2355c 1565c 781b

High SD 2399c 1574c 834b


















020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead


05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)





02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs










densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014






























020406080

100120

I II2011

III I II2012

III

Perc

enta

ge (

)

GrassLegume

ForbsDead


05

1015202530354045

I II2011

III I II2012

III

Perc

enta

ge (

)





02468

101214

I II2011

III I II2012

III

Perc

enta

ge (

)

Dandelion

Ground ivy

Horsenettle

BedstrawPlantain

Broadleaf plantain

Smartweed

Other forbs










densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014































densityDaggerADG

(kg dminus1) SEMŁ

2011

I 0280085


Total 015 0043

2012

I 2000085










4 Conclusions



0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014

























0

100

200

300

400

500

2011 2012


(kg h

aminus1)



Competing Interests


Acknowledgments


References








































Journal of




Agronomy





Microbiology




Volume 2014









































Journal of




Agronomy





Microbiology




Volume 2014
























winter grazing in a grass-fed system: effect of stocking...

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