Mob Grazing Research - University of Nebraska-Lincoln. Jerry Volesky, Walt Schacht, Miles Redden, Jordan Johnson, and Ben Beckman

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1 Mo Grzing Reserch - University of Nersk-Lincoln Jerry Volesky, Wlt Schcht, Miles Redden, Jordn Johnson, nd Ben Beckmn An ongoing reserch project ws initited in 2010 to evlute vrious plnt, soil, nd niml responses to different grzing methods on Sndhills suirrigted medow. Ultr-high stocking density grzing, or mo grzing, ws one of the methods; it involves concentrting grzing livestock into smll pddocks to chieve stocking densities of 200,000 l/cre or greter. Mintining nimls t these densities usully requires moving nimls through multiple pddocks per dy. In mo grzing system, ech pddock is typiclly grzed only once per growing seson. Prctitioners report wide vriety of enefits including incresed forge production, incresed plnt diversity, improved distriution of livestock grzing, improved soil function, nd rpid rte of soil development (Gompert 2010; Peterson 2010). The high stocking densities used in mo grzing systems reportedly result in even distriution of grzing pressure, hoof ction, nd excret cross psture (Peterson 2014; Peterson nd Gerrish 1995). The ojectives of our reserch re to quntify the effects of mo grzing on vegettion productivity, species diversity, forge utiliztion, nd hrvest efficiency s well s niml performnce nd forge qulity when compred to more trditionl grzing nd hrvest methods. Additionlly, soil chrcteristics including structure, microil popultions, orgnic mtter, cron, nd nutrient composition s well s plnt root growth, litter decomposition rtes, nd dung eetles re eing investigted in this reserch. Reserch Methods The project is eing conducted t the University of Nersk-Lincoln Brt Brothers Rnch locted pproximtely six miles northwest of Rose in Rock nd Brown counties. Vegettion of the medow study is productive mixture of introduced cool-seson grsses nd fors with ntive wrm-seson grsses, sedges, nd rushes. Annul plnt production is out 4000 to 5000 l/cre. In ddition to the mo grzing tretment, this ongoing reserch project includes 4- psture rottion with single grzing period (4-PR-1), 4-psture rottion with two grzing periods (4-PR-2), mid-july hying, nd control (no hrvest of live stnding vegettion during the growing seson) (Tle 1). In 2011, continuous grzing tretment t stocking rte equl to the other tretments ws dded to the study. Becuse this tretment ws not prt of the originl experiment, ll vegettion dt from these pstures re excluded from the nlysis. They were used only for nlysis of niml ctivity. There re two replictions of the tretments with ech comprised of the prescried numer of pstures. Grzing tretments were grzed y yerling steers with n verge weight etween 700 nd 780 l.

2 Tle 1. Stocking rte, stocking density, nd grzing dys per seson in n individul psture or pddock. Tretments Stocking rte Stocking density Grzing dys (AUM/cre) (l/cre) per pddock or psture Mo grzing (120 pddocks) , psture rottion once-over (4-PR-1) 3.0 6, psture rottion twice-over (4-PR-2) 3.0 4, Continuous 3.0 1, Hying Control (non-grzed) The tretments hve een pplied nnully since Prior to initition of the study, the medow ws hyed nnully. The mo nd 4-PR-1 tretments egin grzing in erly to mid- June nd continue for 60 dys. The 4-PR-2 tretment egins in lte My nd continues for 80 dys. The 4-PR-2 ws selected s conventionl method of grzing medows with My strt dte to tke dvntge of cool-seson vegettion growth nd second grzing period to tke dvntge of new vegettion growth following the first grzing period. The mo grzing period ws designed to strt lter in the growing seson in order to chieve optimum conditions for trmpling 60% of the stnding herge, which ws the trget for uilding soils. The 4-PR-1 hd the sme strting dte nd grzing seson length s the MOB so tht their effects could e compred directly. Over the first four yers of the study, grzing strt dtes vried slightly to ccommodte drought or excessively wet conditions. In 2010, 2011, nd 2012, cttle in the mo tretment were moved twice dily into new pddock (0.14 cre) t out 7:00 AM nd 2:00 PM. Stocking rtes were reduced 25% in 2013 in ll tretments due to poor vegettion growth, nd pddock size ws reduced in the mo nd numer of moves ech dy incresed to three to mintin stocking density similr to previous yers. Vegettion smpling included estimtion of production y clipping qudrts in rndomly locted grzing exclosures plced in ech psture. Trmpling, hrvest efficiency (niml consumption), nd utiliztion (trmpling + hrvest efficiency) were lso mesured 3 times in the mo tretment during the grzing period nd ech time 4-psture tretments moved to new psture. Vegettion ws sorted into live, stnding ded, trmpled herge, nd litter (ded plnt mteril on the ground surfce) ctegories. Bsl cover nd species composition were estimted using the modified step-point method in lte June of ech yer. Qulity nlysis of ville vegettion (pre-grzing) ws conducted on clipped smples collected during the grzing period in ll tretments. Anlyses included crude protein (CP) nd neutrl detergent fier (NDF). Animl response mesurements included performnce (dily gin) nd niml ctivity (steps/dy). Animl ctivity ws mesured y rndomly selecting two steers from ech tretment group nd fitting them with dt-recording pedometers.

3 Results nd Discussion Growing seson precipittion nd tempertures vried widely over the first four yers of the study. Well-ove verge precipittion occurred in 2010 nd 2011, drought occurred in 2012, nd ner verge precipittion in Spring nd erly summer temperture were elow verge in 2011 nd 2013, well-ove verge in 2012, nd ner verge in Vegettion Production Annul vegettion production did not differ etween ny of the grzed tretments or control. Overll, production during the first two yers of the study (2010 nd 2011) verged 4580 l/cre compred to 3710 l/cre during 2012 nd Drought conditions nd recovery were likely the fctors in the lower production during the lst two yers. There ws no difference etween grzed tretments in the mount of litter (Fig. 1). However, litter iomss in the non-grzed control ws out 400% greter thn the grzed tretments. The ccumultion of litter in the control would e expected ecuse of the lck of vegettion removl or niml impct. Similrly, the mount of stnding ded vegettion ws greter in the control compred to grzed tretments. Litter in grzed tretments nd control, B e Litter (l/cre) d A A A c c Mo 4-PR-1 4-PR-2 Control Figure 1. Litter iomss in grzed tretments nd control. cde Within tretments, yer rs with like lowercse letters do not differ (P > 0.05). AB Within tretments, rs with like uppercse letters do not differ (P > 0.05). Utiliztion, Trmpling, nd Hrvest Efficiency Utiliztion is the comined mount of trmpling nd hrvest efficiency (consumption). Utiliztion under mo grzing verged 88% nd ws greter thn the 4-PR-2 tretment ech yer nd greter thn in 4-PR-1 during 2010, ut not in 2011 nd 2013 (Tle 2). In ll tretments, differences in utiliztion etween yers my e ffected y production s well s strting dte where it ws oserved tht erly in the seson when vegettion ws shorter nd vegettive, the mount trmpled ws less.

4 Tle 2. Utiliztion of stnding live herge (%) in the 4-PR-1, 4-PR-2, nd mo grzing tretments in 2010, 2011, nd Tretment (%) PR-1 65 A 85 A 85 A 4-PR-2 49 B 71 B 60 Bc MOB 88 C 89 A 86 A ABC Different uppercse letters within columns differ (P < 0.05) c Different lowercse letters within rows differ (P < 0.05) The verge mount of live vegettion trmpled under mo grzing ws 60%. This ws t our plnned level for mo grzing nd out 58% to 125% greter thn in the 4-PR-1 nd 4- PR-2, respectively (Figure 2). The increse in trmpling in the mo tretment is likely result of stocking density, the ssocited high grzing pressure, nd incresed niml ctivity. Field oservtions found tht trmpling in the 4-PR tretments ws ptchy nd uneven. Overll, there ws difference in percent trmpled etween yers, with 2011 hving the highest. This could e result of the high production nd extended period of wet condition tht yer. % of ville vegettion Trmpled * * 4-PR-1 4-PR-2 MOB Tretment Figure 2. Percent trmpled vegettion in 4-PR-1, 4-PR-2, nd mo grzed psture during 2010, 2011, nd Tretments with like lowercse letters do not differ (P > 0.05). Disppernce (hrvest efficiency) of vegettion under mo grzing verged 28%. This ws similr to the 4-PR-2 tretment, ut significntly less thn the 4-PR-1 tretment (Figure 3). Overll, disppernce did not differ etween yers. High hrvest efficiencies re regulrly reported y mo grzing prctitioners, ut dt from this study re contrdictory.

5 % of ville vegettion Disppered 4-PR-1 4-PR-2 MOB Figure 3. Disppernce (hrvest efficiency) in 4-PR-1, 4-PR-2, nd mo grzed pstures in 2010, 2011, nd Tretments with like letters do not differ (P > 0.05). Botnicl Composition There were no grzing tretment effects on otnicl composition of vegettion. However, differences etween yers were oserved (Tle 2). Wrm-seson grsses were more undnt in 2012 compred to the previous two yers, ut were slightly less in 2013, nd similr to their undnce in 2010 nd Cool-seson grsses declined cross ll tretments from 2010 to Annul climtic vrition my hve een the primry driving fctor in the decrese in cool-seson grsses in ll grzing tretments nd control plots. Extreme rinfll events resulted in inundted conditions over lrge portion of the tretment re during the grzing seson of Most cool-seson grsses cnnot tolerte sturted or inundted soil conditions for extended periods of time nd mny my hve drown during this period. Drought in 2012 lso likely hd detrimentl effect on cool-seson grsses. Sedges incresed in reltive composition cross ll tretments from 2010 to 2013 (Tle 3). It is expected tht sedges would e plnt group to increse with the high rinfll in 2010 nd 2011, ut surprisingly, their composition incresed in the 2012 drought. The composition of fors ws t its highest level in 2013 (Tle 3). Prticulrly in ll grzed tretments, field oservtions suggest tht increses in red nd white clover were primrily responsile for the overll increse in fors. Tle 3. Reltive composition (%) of plnt functionl groups of wrm-seson grsses, coolseson grsses, sedges, rushes, nd fors for Plnt group (%) Wrm-seson grsses Cool-seson grsses c 35 d Sedges c 34 c Rushes Fors Within plnt group (rows), percentges with like letters do not differ (P > 0.05).

6 For ground cover in ll grzed tretments nd the control, the percent litter hs incresed from 93% to 98% from 2010 to Correspondingly, the percentge of re soil hd declined from 4.9% in 2010 to 1.9% in These chnges would e expected ecuse prior to 2010, this medow site hd een nnully hyed. Qulity of Aville Vegettion In 2010, crude protein content (6.7%) of ville vegettion ws similr etween mo nd 4-PR-1 during July nd August smpling dtes. However, crude protein of vegettion during the second cycle (lte July nd August) of the 4-PR-2 (8.7%) ws higher thn the other two tretments. It is likely tht the increse in CP content during the second cycle of the 4-PR-2 is result of new vegettive growth following the first cycle. Crude protein content verged 7.4% in 2011 nd 2013 with no differences etween tretments or dtes. Neutrl detergent fier (NDF) verged 67% nd ws similr etween tretment with the exception of 2011, where NDF in the 4-PR-2 (63%) ws lower thn tht mesured in 2010 or Animl Performnce Averge dily gins (ADG) in 2011, 2012 nd 2013, in the 4-PR-2 tretment differed mong yers, ut were greter thn the 4-PR-1 nd mo tretments in ll yers (Fig. 4). The 4- PR-1 tretment hd greter ADG thn the mo tretment in 2011 nd 2012 ut ws not different from the mo in In 2013, ADG in the mo ws significntly greter thn in Lower ADG in 2012 compred to 2013 in the 4-PR-2 pstures is likely relted to the drought nd less herge production. The greter ADG of the 4-PR-2 steers is likely the result of steers estlishing grzing lwns in their first occuption of psture, nd then concentrting grzing on highly nutritious regrowth on these lwns during the second occuption. Visul ssessment of the 4-PR-2 tretments indicted tht these grzing lwns hd tendency to estlish on pproximtely the sme re ech grzing seson. Low gins under mo grzing re likely result of high grzing pressure nd limited forge intke due to the high levels of trmpling. Averge dily gin of grzed tretments, Dily gin (l/dy) PR-1 4-PR-2 Mo c c c Within yers, rs with like letter do not differ (P > 0.05) Figure 4. Yerling steer verge dily gin, during

7 Animl Activity Except for the lte June period, steers under mo grzing took more steps ech dy thn steers in the 4-PR-1 or continuous grzing (Fig. 6). The increse in niml ctivity in the mo pstures is likely result of the multiple dily moves nd psture shpe. In 2013, steers were moved three times dily through pstures mesuring only 13 ft. wide nd 312 ft. long. While ech move my contriute to high ctivity levels, oservtions indicted thn this long rectngulr psture shpe fvored incresed niml ctivity. As steers entered psture, the first steers to enter egin grzing lmost immeditely forcing the reminder of the steers to trvel round them to otin new forge. This perpetuted lepfrog effect, in which n individul my hve hd to trvel the length of the psture to circumvent the rest of the herd nd find fresh forge. Dily Animl Activity Steps steer -1 dy Continuous 4-PR-1 Mo c L. June E. July M. July L. July E. Aug Figure 5. Animl ctivity (steps/steer/dy) t different periods of the grzing seson, Within dy, peks in niml ctivity in mo grzing corresponded to the times when nimls were moved to new pddock (Fig. 6). Steers in 4-PR-1 nd continuous lso hd three outs of higher ctivity within dy. Figure 6. Averge dily ctivity (steps/steer/hour) in continuous, 4-PR-1, nd mo grzing tretments, 2013.

8 Conclusions Ultr-high stocking density of mo grzing ws n effective method of incresing vegettion trmpling compred to trditionl four-psture rottion. Trmpling in the mo tretment of this study verged 60% which ws the trget level of trmpling. Mo grzing prctitioners hve indicted this level of trmpling s the optimum level for incresing soil function. In the fourth yer of this study, the incresed trmpling hs not resulted in ny significnt chnges in vegettion production or species composition compred to trditionl fourpsture rottions. Hrvest efficiency under mo grzing ws less thn we hd expected. This ws likely result of the high rte of trmpling which limited forge ville for consumption. Mo grzing does not seem relistic from livestock production perspective if 60% trmpling is desired. At 60% trmpling, hrvest efficiency is limited requiring moderte stocking rtes or reduced niml intke which limits niml production. This low niml performnce mkes MOB grzing very difficult to justify from n niml production perspective. Significnt increses in vegettion production would e required to offset the effects of mo grzing on niml performnce s well s the dditionl infrstructure nd lor required in high mngement intensive grzing system like mo grzing. References Gompert, T The power of stock density. In: Proc.: Nersk Grzing Conference. Kerney, NE Peterson D Soil Helth nd Production Benefits of Mo Grzing. Retrieved from: Peterson D How mo grzing impcts your soils. Retrieved from: Peterson, P. R., nd Gerrish, J. R Grzing mngement ffects mnure distriution y eef cttle. Proc. Am. Forge Grsslnd Council, Lexington, p