Corn silage is a very versatile and palatable feed that fits well into many cattle feeding programs. Insufficient rainfall in several areas of the country in recent years has resulted in many additional acres of corn being ensiled due to the low potential grain yield. Harvesting drought-stricken corn silage results in at least partial salvage of the crop. However, many farmers have expressed concern about the feeding value of drought-damaged corn silage and how it can be best incorporated into feedlot rations for optimal performance and maximal economic return

Carlson, C.

Embry, I.

Kuhl, G.

Shubeck, F.

English

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Cattle Feeders Field Day Proceedingsand Research Reports, 1979 Animal Science Reports1979Utilization of Drought-Stricken Corn Silage byYearling SteersG. KuhlSouth Dakota State UniversityC. CarlsonI. EmbryF. ShubeckFollow this and additional works at: http://openprairie.sdstate.edu/sd_cattlefeed_1979This Report is brought to you for free and open access by the Animal Science Reports at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in South Dakota Cattle Feeders Field Day Proceedings and Research Reports,1979 by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For moreinformation, please contact michael.biondo@sdstate.edu.Recommended CitationKuhl, G.; Carlson, C.; Embry, I.; and Shubeck, F., "Utilization of Drought-Stricken Corn Silage by Yearling Steers" (1979). SouthDakota Cattle Feeders Field Day Proceedings and Research Reports, 1979. Paper 11.http://openprairie.sdstate.edu/sd_cattlefeed_1979/11CATTLE FEEDERS DAY UTIL IZATION O F  DROUG H T-ST R I C K EN CORN SI LAG E BY YEA R L ING ST E E RS G. K u h l ,  C .  Carl son,  I .  E m b ry ,  and F. S h u be c k  Department of A n i mal  Science Ag Experi ment Stat i o n  S o u t h  Dakota State U n i vers ity A.S.  79-6 Corn si lage is a very versatile and palatable feed that fits well into many cat tle feeding programs . Insuffi cient rainfall in s everal areas of the country in recent years has res ulted in many addi tional acres of corn being ens iled due to th e low potential grain yi eld . Harves ting drough t-s tri cken corn a s  s ilage results  in at leas t partial salvage of  the crop . However,  many farmers h ave exp ress ed concern about the feeding value o f  drought- damaged corn si lage and how it can b e  bes t incorporated into fee dlo t rations for op timal performance and maximal economic return . Corn s ilage typi cally contains a cons iderable amount of  grain . However,  th e amount of grain in s i lage may vary from es s entially none from a s eve rely drough t-s tri cken crop to as much as 50% of th e s i lage dry mat ter from a hi gh-y ie lding corn crop . In view of the large di ff erence in energy values of corn fo dder and co rn grain , th e energy values of si lage-bas ed rations would be expected to be influenced to  a consi derab le degree by the proportion of  grain in the corn si lage . However, when th e corn plant fails to produce ears , or when grain yi eld is markedly reduced,  there is s ome concentration of avai lab le nutri ents in the s t alk and leaves . Even though much research has b een conducted wi th corn silage fed to  growing and finishing cattle ,  ques tions s till remain as to  the mos t  appropriate amount o f  addi tional corn grain to feed with si lage ,  espe cially wh en the s ilage contains minimal amounts of  grain . The obj ective of this s tudy was to examine the feedlot performance of  cattle fed whole-plant drought-st ricken corn si lag e wi th varying levels of added corn grain . Procedures Sixty- four y earling Herefor d-Angus s teers averaging about 550 lb . were purchas ed at a local sale barn for the exp eriment ini tiated on February 1 7 ,  1 9 7 7  at the S outh eas t Experiment Farm near B eresford.  The cat t le were allotted into 8 p ens o f  8 h ead each on the basis o f  shrunk weight obt ained after an 1 8-hour s tand without feed and wat er . Four treatments representing di f ferent l evels o f  added cracked corn were s tudied,  wi th 2 pens ass igned to each treatment . Th e 4 experi­mental rations were as follows : 5 6  - 2 -DEY Mat ter Bas is As Fed Basis Treatment Corn Silage Corn Grain Corn Silage Corn Grain # 1  1 00% 1 00 %  # 2  75% 25% 88% 1 2 %  # 3  50% 50% 72% 28% #4  25% 75% 46% 54% The corn silage was from drought-stri cken corn with an estimat ed grain yi eld of 4-5 bush els / acre and a silage yi eld of  3-3 . 5  tons /acr e .  Average dry mat ter content of the silage was about 34% with an average p rotein content of  10 . 9 % ,  dry basis . Th e corn grain was purchas ed locally as needed and averaged 1 3% moisture . A cus tom mixed 32% crude p rotein supp lement was fed at the rat e o f  2 lb . p e r  head dai ly throughout the trial . Th e composition of  th e s upplement was 18% ground corn, 6 8% s oybean meal (44% prot ein) , 7% di calcium phospha t e ,  2% limes tone , 5% tra ce mineral salt and a vitami n A ( 1 0 , 000 IU/ lb . s upp l . ) and Rumensin premix . The leve l o f  Rumens in in the supplement was adj us ted periodi cally in order to maintain the equivalent of about 30 g .  of Rumensin p er ton of air-dry feed in all rati ons . The cattle were vac cina ted for b lackleg , malignant edema and red nos e ( IBR) and imp lanted wi th Synovex-S at the b eginning of  the experi­ment . The cattle on the 100% corn s i lage ration were full-fed si lag e from the beginning of  the experiment , whereas the s t eers on the other treat­ments were gradually brought up ·to a full feed of grain and corn si lage . The increas e t o  full feed on the high-grain ( 75% cracked corn , dry basi s )  rati on was accomp lished over a 10-day p eri o d .  The cat t le were f ed in open,  s loped concrete lots wi thout access to sh elter . The cat tle were w eighed at monthly intervals throughout the tria l ,  with dai ly f eed records kep t on each p en .  The experiment was terminat ed for each treatment group wh en their average full body weights approached 1 1 50 lb . The cat t le were marketed on a grade and yield basis s o  that detailed carcass meas urements were ob taine d .  Results The res ults of the trial are pres ented in Tab le 1 .  Average final shrunk body weights were 1082 , 1 1 1 3 ,  1 1 40 and 1 106 lb . for the cattle fed 100 , 75,  50 and 25% , respectively , of  their r�tion dry mat t er as drought-stri cken corn silage . P ercent shrink r es ulting from an 1 8-hour stand without feed and water tended to be greater on th e high-s ilage rations . As expected, catt le on th e all-s ilage ration required the longest time on f eed ( 2 86 days ) ,  whi le the high-grain fed steers t ook th e leas t time ( 2 08 days ) . The overall dai ly gains (based on sh runk initial and final body weigh ts )  of  the 4 experimental treatments were 1 . 9 4 ,  2 . 24 ,  5 7  - 3 -2 . 5 7 ,  and 2 . 76 lb . for the 100 , 7 5 ,  50 and 25%  corn silage rations , respec tively . Th e daily gains a chieved by the high-si lage f ed s teers tended to fall o f f  more sharp ly than that o f  thei r high-grain fed count erparts as the cat t le approached finished weights .  This ob serv­ation appeared to be related in part to the errati c late fall climatic condit ions to whi ch only the high-silage fed s teers were expos ed . Th e cattle were somewhat overfinished at s laughter,  as can b e  obs erved from the tabulated carcas s data . Th e nutritional impact of carrying cat tle too long is a s ub s t antially increas ed maintenanc e energy require­ment along wi th exces sive fat deposit ion ,  thereby res ulting in depressed terminal performance .  For examp le , th e average dai ly gains (bas ed on fi lled feedlot wei ghts ) achi eve d on the exp erimental rati ons up to mean body weights of 1025-1050 lb . were 2 . 30 ,  2 . 46 ,  2 . 7 8  and 2 . 9 9  lb . for the 100 ,  7 5 ,  50 and 25% corn silage rati ons , respectively . The average daily feed cons umption results are also shown in Tab le 1 .  Based on thes e data , the average dry mat t er intakes of  th e 4 sets of s t eers were 1 9 . 5 4 ,  20 . 9 6 ,  2 2 . 1 2 and 20 . 9 3  lb . for the 100% through 25% corn si lag e rations , respect ively . The amount of  feed required per 100 lb . gain is als o pres ented in the tab le .  Using data of this typ e ,  one can calculate th e feed c os ts per 100 lb . gain b as ed on any given s et of feed pri ces . For examp l e ,  if we value drought-s tri cken corn si lage at $ 1 5 / ton ,  #2 corn at $ 2 . 00/b ushel and the 32% prot ein supp le­ment at $ 1 50/ ton, including handling and process ing , then the feed cos ts per 100 lb . gain of these cattle would have b een $ 2 8 . 5 1 ,  $ 30 . 0 3 ,  $ 3 1 . 2 1 and $ 30 . 6 2 for the 100 ,  75 , 50 and 25% corn si lag e rations , respectively . Th e carcass results are shown at the bottom of the tab le .  Dress ing percent (warm carcass weight / final filled wei ght x 100)  de creas ed with in creasing levels of corn s i lage in th e ration a res ult primarily at trib utable to the greater gut fi ll as sociated with inc reasing amounts of  roughage in the ration . Level of  corn si lage feeding app eared to have little influence on c arcas s fat thi cknes s ,  rib- eye area , quality or yield grade independent of  carcas s wei ght differences . The cattle on all rations gra ded an average of low choi ce or hi gher . Carcass maturi ty , fi rmnes s ,  rib -eye co lo r ,  % ki dney fat and the incidence o f  liver abs ces s es were not si gni ficantly related to the level of  corn si lage feeding . 5 8  - 4 -Tab le 1 .  Utilization of  Drought-S tricken Corn as Silage Percent Corn S ilag e in th e Rati on 100% 75% 50% No . Animals 16  16  16  Days on Feed 2 86 260 238 Ini tial Shrunk wt . ,  lb . 5 2 7  529 529  Final Shrunk wt . ,  lb . 1082 1 1 1 3  1 1 40 Avg . Dai ly Gain , lb . 1 . 9 4  2 . 2 4  2 . 5 7  Avg . Daily Ra ti on ,  lb . Corn Silage 5 3 . 7 42 . 7  30 . 4  Corn Grain 5 . 8  1 1 . 8 Supp lement 2 . 0  2 . 0  2 . 0  Feed/ 1 00 lb . Gain , lb . :  Corn Silage 2 7 7 1  1 900 1 1 86 C orn Grain 2 5 7  46 1 Supplement 1 0 3  88 7 8  Carcass Wt . , lb . 6 4 5  6 8 9  7 1 8  Dres sing P ercent b 5 8 . 1 59 . 7 6 1 . 6  Fat Thicknes s ,  in . 0 . 6 7  o .  82 0 . 82 Rib Eye Area , sq . in . 1 1 . 20 1 1 . 35 1 1 . 88 Yield Grade 3 . 6 3  4 . 2 1 4 . 1 8 Quality Grade c 1 9 . 2  20 . 2  2 0 . 8  Dry Mat ter a 25% 16  208 5 30 1 1 06 2 .  76 1 4 . 4  16 . 5  2 . 0 524  596 72 7 19 6 3 . 0  0 . 85 12 . 2 5 4 . 1 2 1 9 . 7 aBalance o f  rat ion composed o f  cracked corn ,  p lus 2 lb /head/day of  s upplement . bMeas ured over rib eye between 1 2  and 1 3th rib . c 1 9=Low Choi c e ;  20=Avg . Choi ce . 5 9  - 5 -Summary and Conclusions S ixty-four y earling bla ck-baldy s t eers ( 1 6 per trea tment ) were fed four rati ons cons is ting of 100 , 7 5 , 50 and 25% corn silage ( dry matt er basis ) with the b alance of  th e ration b eing made up of  cracked corn , in order to examine the feedlot performance o f  cattle fed drought­damaged corn si lage supplemented with vari ous levels of adde d grain . All cat t le re ceived 2 lb . o f  a 32% p rotein meal p er h ead daily in order to p rovide supplemental p rotein, minerals , vitamin A and Rumens in . Res ults of this experiment illus trate that good p erformance can be ob tained by f eeding drought-s t res s ed corn si lage to growing and finishing cat tle . Average daily gain rang ed from 1 . 94 lb . on the all corn s i lage ration t o  2 . 76 lb . on the hi ghest grain ration . B ased upon this experi­ment and other s tudi es conducted at this station and elsewh ere,  the f eeding value of  drought-s tricken corn si lage will usually b e  within 7 5-95% of normal corn si lage , depending upon the length , timing and s everity of  drought damage .  This indi cat es that while drought-stress ed corn silage is low iµ grain content,  a higher than normal amount of avai lable energy must be present in the s t alks and leaves in order to support the level of  performance ob s erved . Thus , the major impact of drought condi tions on the ensiled corn crop is that of  reduced tonnage p er a cre and increas ed harves ting cos ts p er t on rather than on a mark­edly decreas ed feeding value . Carcass measurements revealed li ttle influence o f  level o f  added grain in th e rati on on carcas s characteris ti cs when di f ferences in car­cas s weight were taken into account . This experiment indicat es that drought- damaged corn si lage will likely b e  higher in crude pro tein than norma l . The crude protein con­tent o f  the corn s i lage averaged 1 0 . 9 %  ( dry b asis ) in this trial,  as comp ared with 8 . 0- 8 . 5% connnonly found in normal corn s ilage . B ecaus e of  this , farmers are advi s ed t o  have their corn silage analyz ed for protein so that rations can be properly formulated with only the minimum protein supplementation necess ary . This study demons trates that drought-s tricken corn silage can b e  effe ctively utilized in f eedlot rations a s  a means of  salvaging a p oor corn grain crop while at the same time p ermit ting more comp lete uti lization of  the forage and grain from an acre of  corn . 60  

Utilization of Drought-Stricken Corn Silage by Yearling Steers

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Utilization of Drought-Stricken Corn Silage by Yearling Steers

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