Three experiments were conducted to determine if measurable urea-nitrate interrelationships exist in sheep under feedlot conditions, and the extent of nitrogen utilization from urea and nitrate by sheep fed rations containing suboptimum quantities of protein. Dietary conditions imposed provided for the simultaneous adaptation of lambs to urea and sodium nitrate (experiment 1); an exposure to sodium nitrate without prior adaptation after lambs has been brought to a full feed on a ration containing urea (experiment 2); and the use of soybean meal, urea and sodium nitrate independently as protein supplements to rations providing suboptimum levels of crude protein (experiment 3)

Embry, L. B.

Emerick, R. J.

Hoar, D. W.

King, H. R.

English

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Sheep Field Day Research Reports,1970 Animal Science Reports1970Urea-Nitrate Interrelations in Sheep Under FeedlotConditionsD. W. HoarSouth Dakota State UniversityL. B. EmbryH. R. KingR. J. EmerickFollow this and additional works at: http://openprairie.sdstate.edu/sd_sheepday_1970This 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 Sheep Field Day Research Reports, 1970 by an authorizedadministrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, pleasecontact michael.biondo@sdstate.edu.Recommended CitationHoar, D. W.; Embry, L. B.; King, H. R.; and Emerick, R. J., "Urea-Nitrate Interrelations in Sheep Under Feedlot Conditions" (1970).South Dakota Sheep Field Day Research Reports, 1970. Paper 7.http://openprairie.sdstate.edu/sd_sheepday_1970/7• • South Dako ta S tate Unive rs i ty Brookings , South Dako ta Depar tment o f  Animal S cience Agr i cul tural Experimen t S ts tion Urea-Ni tra te In terrela tions In Sheep Unde r Feedlot Condi tions 1 A . S .  Series 69- 5 2  D .  W .  Hoar , L .  B .  Emb ry , H .  ·R .  King and R .  J .  Emerick S uble thal leve l s  of ni trate in ruminan t rations have been shown to have the p o tential for reducing we igh t  gains . Several sources of nonpro tein n i t ro gen , including urea and n i t ra te , are known to be u t i l i zed by rumen mic rob es for p ro tein syn thesis a f ter convers ion to a common in te rmedia te , ammonia . Th is has led to the speculat ion tha t the p resence o f  urea may res ul t  in a dec rease in the utiliza tion o f  n i trate o r  i ts reduc tion produc ts , thereby increas ing the apparen t toxic i ty o f  n i t ra te . Whe ther the toxici ty o f  n i t ra te for ruminan ts may be inc reased by feeding rations con taining urea has no t been shown p revious ly . Three experiments were conduc ted to de te rmine i f  meas urab l e  u re a ­n i t ra te in terre la tionships exi s t  in sheep unde r feedlot condi tions , and the ex ten t o f  ni trogen util i zation from urea and ni tra te by sheep fed rat ions containing s ubo p t imurn quan ti ties of p ro tein . Die tary condi tions imposed p rovided for the s imul tane ous adap tation o f  lamb s  to urea and sodium ni trate ( experimen t 1 ) ; an · expos ure to s odium ni trate w�tho ut prior adap tation a f te r  l amb s  had been b ro ugh t  to a ful l  feed o n  a ration containing urea (expe rimen t2 ) ; and the use o f  soyb ean meal , ure a and s odium n i trate independen tly as p ro tein s upplemen ts to rat ions providing s ubop timum levels of c rude p ro tein (expe rimen t 3 ) . Procedures Exper imen t 1 E i gh ty ewe and we ther lamb s , p revious ly drenched with th iabend a zo le and vaccinated for con trol of en te ro toxemia , we re allo t ted on basis of s ex ,  we igh t  and s or ted in to 8 pens of 10 lamb s  each (4 ewe s and 6 wea thers ) for four rep l i cated treatmen ts . Al l lamb s were ful l- fed ra t ions cons is tin g  of 3 parts corn s i lage ( 6 7 . 7% moi s ture ) to 1 part concentra tes ( ro l led shel led corn and s upp lemen t s ) . Trea tmen ts cons is ting o f  addit ions to the con cen t rate por tion o f  the ra tion were a s  fol lows : ( 1 ) ure a , ( 2 )  ure a p l us sodium n i t rate , ( 3) s oybean meal and ( 4) s oyb ean meal p lus s odium n i t ra te . The addi tion o f  2% urea ( 4 2% n i trogen) to the concent ra te mix tures res ulted in about 1% urea in the to tal air- dry ( 1 2% moi s t ure ) ration . Soyb ean meal ( 7% o f  air-dry r a t ion) was us ed a t  the expense o f  corn to furnish an equiv­alen t amoun t  of p ro tein in the rations not con t aining urea . Before � 1Taken large ly from paper pub li shed in the Journal of Al;timal S cience , Vo l .  2 7  ( 2 ) : 5 5 7 .  1 9 6 8 . - 4 7  -- 2 -the addi tion o f  ni tra te , all rations had a crude pro tein con ten t o f  1 0 . 8% .  S odium ni trate , when us ed , was ad ded at a leve l  o f  5% i n  the concent rate por tion res ul t ing in 2 . 5% in the to tal air-dry rat ion . Sodium ch loride was us ed in non-n i trate rations to p rovide sodium in an amount equivalen t to that in the s odium n i t ra te rations . Trace mine ral s a l t  and dicalcium phosphate were als o  p rovided free ac ces s . The l amb s were s tarted on feed a t  the rate o f  2 . 0  lb . per h ead daily . Feed was increased g radual ly to a ful l  feed ove r  a period o f  2 weeks while main taining the 3 : 1 ratio o f  corn s il age t o  concen tra te s . The lamb s we re implanted wi th 3 mg . die thyls ti lbes tro l  at the b eg inning of the experimen t .  All the concen trat� mixes con tained 20 mg . o f  chlorte tracycl ine and 2 , 000 I � U �  o f  vi tamin A . per pound . Blood s amples were ob tained on days 2 1  and 8 1 o f  the 82-day experimen tal period and analy zed for to tal hemo glob in and me themo glob in . Some dea th losses occurre d from causes unrela ted to the experimental trea �men ts and wei gh t  gain da ta we re cal culated only for l ambs com­ple ting the trial . Feed consump tion data· were adj us ted by ·s ub trac t ing an average value for each lamb los t o r  removed . Experimen t 2 E i gh ty-eigh t  ewe lamb s , p revious ly drenched wi th thiab endazole and vaccinated fo r preven tion of en tero toxemia , were �!lot ted on b as i s  o f  wei gh t  in to a· pens o f  1 1  lamb s e ach . Four repl i c_ated t reatments we re used as in experimen t  1 . However ,  sodium nit rate was no t added to the ra tions un t i l  afte r  a 2-week p re trea tment period during whi ch the l amb s  we re fed the experimental rations with sodium ni trate ommi t te d . Sodium ni tra te was then added to the app ropr!ate rations , and fee d  in­take at thi s  time was about 2 .  2 lb • . ( ai r-.dry) per l amb daily . O ther p ro ce dures were followed as in expe r iment 1 with few excep­tions . The l amb s did no t re ceive diethls t i lbes trol . The urea sour�e con tained . 45% ni tro gen ins tead of 4 2% , b ut i t  was added a t  a level o f  1 . 86% o f  the concen trat� mixture res ul ting in the s ame amoun t o f  non­pro tein n i t rogen from urea as in the previous experiment .  Be fore the addi t i on of sodium ni t ra te , the ration� had a · c rude pro tein con ten t of 10 . 6% .  Me themo glob in and to tal hemo glob in were de te rmined periodical ly during the experiment .  Expe riment 3 Nine ty-six ewe lamb s  were vac cina ted for p reven tion o f  en tero­toxemia and were b rough t  to a full feed during a 2-week preliminary perio d on a ration cons i s ting o� 3 pa�ts corn s i l age ( 65 . 4% mo is ture ) to 1 part ground corn grain . The lamb s  were all o t ted on basis o f  weigh t  into 8 pens o f  1 2  l amb s  each fo r four replicated treatmen t s . A con tro l  group con tinued to receive the p re treatmen t  rat ion whi ch c on tained 8 . 04 %  crude pro tein ( 1 2% mois ture b as i s )  by analys is . O ther tre a tmen ts cons is ted of the add i tion o f  2 . 90% s odium n i trate , 1 . 0 6% urea (45% ni t rogen) or 6 . 86% s oyb ean meal to the concen trate por tion - 48 -• ·' • • • . _ • • - 3 -o f  the respe c tive rations resul ting in 1 . 45% sodium ni trate , 0 . 5 3% urea or 3 . 4 3% soyb ean meal in the to tal air-dry rations . Each o f  these s upplemen ts p rovi ded addi tional n i t rogen equivalen t to 1 . 5% c rude pro te in in the to tal air-dry ration . All concen trate mix tures contained 2 mg . die thyls tilbes trol and 2 , 00 0  I . U .  of vi tamin A per pound • Sodium sulfate was added to the con trol , nit ra te and urea rations to furnish the cal cula ted amo un t  of s ul fur in the soyb ean meal ration . Sodium chloride was added to the con trol , soybean meal and urea rations in amoun ts equivalen t to the sodium contrib uted by sodi um  n i t rate in the n i trate ra tion . Trace mineral salt and d i calcium phosphate were availab le free access . Me thods for b lood analys is and the calcula tion o f  feed intake when los ses o ccurred were as des cr ibed for experimen t  1 .  Res ul ts Expe riment 1 Lamb s fed rations o f  corn and co rn silage wi th 1% urea ( air-dry b as i s )  gained 19 . 5  ( urea-con t rol) and 16 . 5% ( urea-n i t rate) less than lambs fed corresponding rations wi th the s ame level o f  c rude p ro tein but s upplemen ted ·with S'P)'bean meal ( tab le 1 ) . Thi s  level o f  ure a  als o  appeared to r educe feed in take and to increase feed requireme�ts per uni t  of gain • When s odium ni trate ( 2 . 5% o f  air-dry ra tion) was included in the ra tion , rate o f  gain was decreased for lambs fed s oybean meal but was essentia l ly unchange d  fo r those fed urea . Rat ions con taining sodium ni trate were cons umed in s l i gh tly larger amoun ts than those wi thout nitra te , and the accompanying lower weigh t gains resul ted in higher feed requirement s  per uni t  o f  gain . Howeve r ,  me themoglob in val ues ob tained at 2 1  and 8 1  days were low and we re about the s ame for sheep fed rations wi th and w i thout ni trate . The re were no vis ib le s i gns o f  nitrate tox ic i ty during the expe riment .  Experiment 2 In the ab sence o f  nit rate , l ambs fed urea gaine d 16 . 9% less daily than those fed the corresponding s oybean me al ration . Gains were 1 5 . 5% lowe r when sodium n i t ra te was fed in conj unc tion wi th soyb e an meal , but sodium n i trate had almo s t  no e f fec t  when fed w i th urea . Carcass characteri s tics showed only minor variations b e tween ration t re atmen ts . Res ul ts o f  experiment 2 di ffer from expe riment 1 p rimari ly in the greater reduc tion o f  weigh t  gain a t t ributed to n i trate when fed in the soyb ean meal ration . This di f fe rence be tween experimen ts is acco un te d  f o r  mainly o n  the b as is o f  results ob tained during the f i rs t  2 weeks of the experimen ts . In experiment 1 ,  the lamb s we�e b rough t  to a full feed during the firs t 2 weeks on the experimental rations . Dtrting . �his t ime , lamb s ( experiment 1 )  receiving the n i trate ration�- made gains that exceeded thos e  of lamb s  re ceiving the corresponding control rations . In experiment 2 ,  n itrate was no t added until the lambs bad6 be�1k. brough t  t o  a full feed o n  the contro l  rations . Under these condi tions whi ch allowed - 49 -- 4 -no gradual adaptation to · ni trate , average daily gains for · lamb s  fed· · the s�:Yr <>m·• ,ne-,.., 1. i 1 i t: r�:» t-c . i.� tJ on was only 0 . 0 3  lb . dai�y during the · firs t  2-week ped od while lamb s fed s oybe�n meal wi thout ni tra te gained 0 . 20 lb . dai ly .  Ni trate added to the urea ration resul ted in no reduc tion in average daily gains during this period . These data indi cate that the prior adap tation to urea in the s econd experiment was probably an important fac tor in the greater ini tial tolerance of  urea-fed lambs to the ni tra te . The me themoglobin data ( table 2)  tend to support this conclus ion . Howeve r ,  there were no vis ib le s igns or deaths at trib­utable to nitrate toxici ty . Experimen t 3 Data ob tained wi th lamb s  fed the low-pro tein ration s upplemen ted wi th . s oybean meal , urea or sodium nitrate to ob tain equal levels o f  crude pro tein are presented in tab le 3 .  The crude pro tein con tent (9 . 54% , air-dry b asls ) o f.rations ob tained from s upp l emen ta tion of the control rat'ion (" 8 .  04% ·pro t�in ·, air-dry bas is)  :fs· below req ui rements commonly reconwiende<I fo r fat teni fig lambs . Howeve r ,  i t  was cons ide red that  rations borderline or mildly de.fi ci e n t  fn pro tein conten t would p rovide a more cri tical comparlson be tween the sources of supp lemen tal  ni tro gen . Lamb s  fed the low-p ro tein control ra tion gained 0 . 2 75 lb . daily . The addition o f  soybean neal , urea or so�ium ni t rate to increase the to tal c rude p ro tein conten t by 1 . 5 percen tage uni ts improved weight  gains by 21  - 24% wi th only s l i gh t  di fference s being observed between the pro te in sources . Feed consump tion was highes t · for groups o f . lambs re ceiving the supplemen tal sources o f  pro tein . There was also · an improvement in feed efficiency in compars ion to · the control group wi th lamb s fed urea or sodium nit rate having feed requiremen ts s lightly less than for soybean Dleal . Me themoglobin values were low fo r all groups · of  lambs at 2 and � 2 1  days . on treatmen t . -·earcass da ta were simi1ar for : the various groups at termination o f . the_ experimen t .  The s imilari ty in the utili zation o f  s oybean meal ,  urea and sodium nitrate as sources o f  crude pro tein in the third experiment di f fers from the trend es tab lished in the firs t two experiments . The experimeu ts di ffer in that rations used in experiment 3 had lower l evels of urea (0 . 5 3% vs . 0 . 9 3% )  and sodium nitrate ( 1 . 45% vs . 2 . 5% )  and sulfur was added to the urea and sodium nitrate rations . The resul ts o f  the experiment support the conclusion that  nitrate below a toxi c level may serve as a · ·source of  crude ·pro tein comparable to an equivalen t amourit of nit rogen f rom s oybean mea l  and urea in fi ni sh i ng rations for r umi n an ts . 5 0  � . . · . .  • .� • • • · .  • • - 5 -Summary In two experiments , sodium ni trate ( 2 . 5% o f  ration , air-dry basis) tended to reduce weight gains when fed in rations wi th soybean meal ( 7% ,  air-dry basis)  but it had only a s light  e ffect  in rations wi th an equivalen t amoun t of crude p ro tein from urea ( 1% ,  air-dry basis ) where gains were al ready below those o f  lambs fed soybean meal . In thes e  ins tances , lambs fed urea gained 1 6 . 5  t o  19 . 5% less than lambs fed soybean meal . No evidence was ob tained to suppo rt a ni trate-urea interrelationship . In a third experiment , the crude pro tein c on ten t o f  an 8 . 04% po rtein ration was increased to 9 . 54% us ing s oybean meal , urea o r  sodium nitrate to furnish equivalen t amoun ts o f  ni trogen . Under these condi tions , the three ni trogen s ources were utilized equally as well as sources of crude pro tein . Table 1 .  E f fects o f  Urea and Ni trate on Lamb Performance (Experiment 1 - 82 days ) . _ _ _ _ _ _ _ _ - ·-- - -- - · - - _ _ _ _ _ _  _ Number o f  lambs  Ini t .  wt . , lb . Av . daily gain , lb . Av . daily feed , lb . a Feed/lb . gain , lb . a Av . hemoglob in , gm . / 100 ml . 2 1  days 81 days Av . me themoglob in , gm . / 100 ml . 2 1  days 8 1  days al 2% mois ture bas is Soybean Meal Control Sodium �i ti;at� . 19 18 75 . 9  74 . 4  0 . 32 8  0 . 306 2 . 9 3 3 . 10 8 . 96 10 . 09 14 . 12 1 3 . 54 1 3 . 3 3  1 3 . 9 3 0 . 1 1 0 . 16 0 . 50 0 . 40 - 5 1 -Urea - -- -Control Sodium Nitr_a�e-20 19 75 . 0  76 . 6  0 . 264 0 . 255  2 . 7 3 2 . 84 10 . 3 1  1 1 . 20 1 3 . 99 1 3 . 66 1 3 . 56 1 3 . 85 0 . 15 0 . 2 1  0 . 4 3  0 . 48  - 6 -Table 2 .  E f fects o f  Urea and Ni trate on Lamb Per formance ( Experiment 2 - 109 days) . No . of  lanibs !ni t . wt . , lb . Av . daily gain , lb . Av . daily feed , lb . a Feed/lb .bgain , lb . a Marbling Carcass grade c _ Dressing pe�cent Av. hemoglobin , gm . / 100 ml . 1 day 2 days 3 days 4 days 7 days 2 3  days 53 · days · · Av . methemoglob in , gm . / 100 ml .  1 day 2 days 3 days 4 days 7 days 23 dayg 53 days . a12% mois ture bas is Soybean Meal Control Sodium Nitrate 20 66 . 0  0 . 326 3 . 06 9 . 42  5 . 4 1 1 . ·1 . 50 ." 7  1 1 . 4  1 1 . 0  1 2 . 1  1 3 . 5 0 . 02 0 . 10 0 . 15 0 . 10 2 1  6 2 . 9  0 . 2 75 2 . 7 3 9 . 9 1  5 . 2 1 1 . 4  50 . 5  1 1 . 6  1 1 . 2  1 1 .  3 1 1 .  3 1 1 . 1 1 3 . 1 1 3 . 6 0 . 25 3 . 0 3 0 . 52  0 . 34 0 . 2 7 0 . 34 0 . 50 bMarbling scqre : small , 5 ;  moderate , 6 .  CGrade score : good , 8 ;  choice , 1 1 ;  p rime , 14 . Urea Con trol Sodium Ni trate 2 1  · 65  . 1  : . 0 . 2 7 1  2 .  7 7  10 . 2 7 5 . 3  1 1 . 6  50 . 3  1 1 .  7 1 1 . 1 1 2 . 0  1 3 . 6  0 . 16 0 . 1 2 0 . 0 7  0 . 1 2 2 1  6 5 . 1  0 . 264 2 .  7 7  10 . 56 5 . 1 10 . 9  48 . 9  10 . 5  10 . 5  10 . 1  10 . 0 . 10 . 4  1 2 . 3  1 3 . 1 0 . 50 1 . 3 3 0 . 7 3 0 . 2 1 0 . 15 0 . 35 0 . 38 Table 3 .  E f fects o f  Equal  Ni tro gen Levels from Ure a ,  Soybean Meal and Sodium Ni trate on Lamb Performance (Experiment 3 - 90 days ) . Con trol Urea Soybean Sodium No . lambs Ini t .  w t .  , lb . Av . daily gain , lb . Av. daily feed , lb . a a Feed /lb . b gain , lb . Marb ling Carcass grade c Dress ing percent Av. hemo glob in ,  gm . / 100 ml . 2 days 2 1  days Av . me themoglob in , gm . / 100 ml . 24 7 2 . 4  0 . 2 75 2 . 55 9 . 34 5 . 1 l L O  49 . 0  1 1 . 99 1 2 . 79 2 days 0 . 06 ��-2_l�d_ay_s����������__,0 . 12 a 12% mois ture bas is 2 0  7 2 . 6  0 . 3 34 2 . 73 8 . 20 5 . 2  10 . 8  46 . 8  1 2 . 84 1 3 . 1 3  0 . 06 . _ Q _._{)_]  bMarbling s core : smal l ,  5 ;  moderate , 6 .  cGrade score : good , 8 ;  choice , 1 1 ;  prime , 14 . - 5 2 -Meal Nitrate 2 2  2 4  7 2 . 6  72 . 8  0 . 34 1  0 . 334 2 . 86 2 . 64 a . 42 1 . 9 2 5 . 4  5 . 0  1 1 . l  10 . 7  4 8 . 2  48 . 4  1 1 . 49 12 . 99 1 2 . 4 3 1 2 . 79 0 . 04 0 . 0 7 • 0-6. ___ o .  o_ • • • 

Urea-Nitrate Interrelations in Sheep Under Feedlot Conditions

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Urea-Nitrate Interrelations in Sheep Under Feedlot Conditions

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