TIIE EFFECT OF THE ESSENTIAL TO NONESSENTIAL AMINO ACID RATIO ON TURKEY PERFORMANCE AND CARCASS COMPOSITION

Transcription

1 TE EFFECT OF THE ESSENTL TO NONESSENTL MNO CD RTO ON TURKEY PERFORMNCE ND CRCSS COMPOSTON M. R. BEDFORD nd J. D. SUMMERS Dteprtment of niml nd Pouhry Science, University of Guelph, Guelph, Ontrio, Cnd NiG 2Wl. Received 28 Oct. 1987, ccepted 6 My Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. Bsopono, M. R. ND Sulruens, J. D The effect of the essentil to nonessentil mino cid rtio on turkey performnce nd crcss composition. Cn. J. nim. Sci. 68: The effect of ltering the proportion of dietry protein supplied s essentil mino cids (li) on the performnce nd crcss chrcteristics of young turkeys (to 3 wk of jge) ws investigted t three dietry protein levels (, nd 3O%) using semipurified diets. Four rtios of E to nonessentil mino cids (NE) were employed (i/0:, 60:40, 50:50 nd 40:60) t ech dietry protein level. Mxim in weight gin, percent nd totl crcss protein nd feed intke were observed when E supplied 60% of totl protein (i.e., the 60:40 rtio) t ech protein level. The differences in $'eight gin nd totl crcss protein were lrgely ttributed to differences in feed intke, since feed conversion efficiency ws reltively unffected by ltering the E: NTE rtio. More specificlly, weight gin ws shown to be limited by totl protein irrtke. Since weight gin ws mximized t the 60:40 rtio diets (in which ll E re supplied t 128% of requirement) t lest one of the E requirement vlues is incorrect. Key words: Turkeys, essentil mino cids, protein requirement [Effets sur le rendement et l composition de l crcsse des dindons du rpport des cides min6s essentiels sur les cides min6s non essentiels.] T'itre br6g6: cides min6s dns les rtions pour dindons. rlous vons 6tudi6 les effets d'une modifiction de l proportion des prot6ines limentires fournies sous forme d'cides min6s essentiels (E) sur le rendement et les crct6ristiques de l crcsse de jeunes dindons (usqu'd l'dge de trois semines) recevnt trois niveux de prot6ines limentires (, et%) dns des rtions semi-purifi6es. (lutre rpports des E sur les cides min6s non essentiels (NE) ont 6t6 utilisds ('/0:, 60:40, 50:50 et 40:60) pour chque niveu de prot6ines limentires. rs vleurs mximles du gin de poids, du pourcentge et de l teneur totle en prot6ines de crcsse et de l consommtion d'liments ont 6t6 observ6es lorsque les E repr6- sentient 60% de 'pport totl en prot6ines des rtions (rpport 60:40) pour chcun des niveux de prot6ines. Les diff6rences observ6es dns le gin de poids et l teneur totle en prot6ines de l crcsse dtient lrgement ttribubles ux diff6rences de cons,ommtion, puisque les modifictions du rpport E:NE influient reltivement peu sur 'indice de consommtion. Plus pr6cis6ment, le gin de poids s'est v6r6 limit6 pr l'pport totl en prot6ines. Puisque le rpport 60:40 (rtions dns lesquelles tous les E dtient fournis dns une proportion 6gle i l28vo des besoins des sujets) donn6 un gin de poids mximl, nous concluons qu'u moins une des vleurs des besoins en E est incorrecte. Mots c16s: Dindons. cides min6s essentiels. besoins en prot6ines Cn. J..nim. Sci. 68: (Sept. 1988) 899

2 900 CNDN JOURNL OF NML SCENCE Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. Much work hs been devoted to determining the energy nd mino cid requirements of young turkeys (Wrnick nd nderson 1973; Owen et l. 1981; Sts nd Potter 1982; Hurwitz et l. 1983; Jckson et l. 1983). With respect to mino cid requirements, results hve been vrible. Wrnick nd nderson (1973) determined wht they considered to be minimum essentil mino cid (E) requirements. However, these uthors demonstrted tht providing ll E t 15% bove the determined vlues resulted in improved gin nd feed efficiency. Sts nd Potter (1982) concluded tht the poor performnce of turkey poults fed % compred with 3O% crude protein diet my hve been due more to dehciency of nitrogen per se rther thn to ny one mino cid being limiting. However, lter work by Jckson et l. (1983) contrsted with these results nd suggested tht the poor performnce of birds fed lower protein diet ws due to sulphur mino cid defrciency. There is obviously need to reconcile these inconsistencies in order to determine the E nd totl nitrogen requirements of the young growing turkey. Recent work (Bedford nd Summers 1985) indicted tht in order to obtin mximum gin nd crcss protein, the broiler chick diet must supply E t prticulr proportion of dietry protein. This reltionship my lso pply to the growing turkey, nd if so, my shed some light on the reson(s) for the inconsistencies in reported mino cid requirement vlues. MTERLS ND METHODS Twelve diets were formulted to orovide 12.54MJ kg-l ME.. or % ciude protein nd E:NE rtios of 40:60. 50:50. 6O:40 or 70: in 3 x 4 fctoril experiment. Dy-old mle turkeys were housed in electriclly-heted Petersime cges nd were offered wter nd cofilmercil strter diet d libitum until 6 d of ge, t which time eight birds were group weighed nd rndomly ssigned to one of four replicte cges for ech tretment. t d ofge, group weights nd feed intkes were recorded. Two birds per replicte were rndomly selected nd used for whole crcss nlysis. These birds were killed by cervicl disloction nd subsequently stored t -20"C until nlyzed. The whole, fethered crcsses were cut into strips nd ground nd reground in Hobrt met grinder. Subsmples were then freeze dried nd stored t -2O'C until used for nlysis of totl protein nd ft by the mcro-kjeldhl nd petroleum ether extrction procedures, respectively (ssocition of Offrcil nlyticl Chemists 1970). l1 diets contined corn nd soyben mel in the sme rtio (1.13:1). The D isomer of DLmethionine ws considered to hve 100% potency nd ws therefore clssed s essentil nitrogen. ll synthetic mino cids were of 98.5% gurnteed purity (United Sttes Biochemicls, Clevelnd, Ohio). Diets were formulted to supply ech E t 85, 106, 128 of 149% of its requirement level (Summers nd Leeson 1976, requirement defined s g E kg-l crude protein) which resulted in the sum ofll E supplying 40, 50, 60, orto% of the crude protein frction of the diet (Tbles, 2 nd 3). This ws chieved by restricting the corn/soy frction of the diet such tht ll E were supplied below the multiple of requirement level tht ws desired. Synthetic mino cids were then dded to bring ll E up to the multiple of requirement level desired (Tbles 1, 2 nd 3). Therefore, in ech diet, ll E were supplied in the sme proportion to one nother s found t requirement levels (Tble 3) s reported by Summers nd Leeson (1976). Synthetic mino cids were first premixed with the crbohydrte frction of the diet. The mino cid mixtures were ssumed to hve metbolizble energy vlues similr to tht of the crbohydrte frction (30 kcl kg ') nd were substituted ccordingly. Glycine ws incorported into the diet s both n E nd NE source (Tble 1). The tbles ofingredient composition provided by Summers nd Leeson (1976) were used to clculte diet composition. The experiment ws set up s completely rndomized design nd orthogonl contrsts were pplied to determine the significnce of liner, qudrtic or cubic response models with respect to the effect of the E:NE rtio on ech prmeter over the verge of ll protein levels, ccording to the generl liner models procedure (Goodnight et l. 1982). n some cses (i.e., totl crcss protein nd weight gin), significnt interctions between dietry protein level nd the E:NE rtio were detected. The dt for these prmeters were therefore renlyzed t ech protein level to determine the effect of the E:NE. Feed intke nd initil weight were included s covrite in the model when the dt for weight gin, feed conversion efficiency nd totl crcss ft nd protein were nlyzed.

3 BEDFORD ND SUMMERS MNO CDS N TURKEY RTONS Tble 1. Composition of synthetic mino cid mixtures (%) Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. E:NE rtio mino cid 70: 60:40 50:50 40:60 DL-Methionine L-Lysine HC Glycine L-rginine HC L-Vline L-Histidin.e L-Leucine, L-soleucine L-Threonine L-Tryptoprhn L-Phenyl.lnine Nonessenl.il nitrogen source L-Glutmte Glycine '7.82 t'7.41 o.j t O < < t lo ll mino cids were of t iest 98.5% pvity (United Sttes Biochemicls, Clevelnd, Ohio) Diet CPil Er\ff ll ]Cl 1Cl 6Cl 6Cl 6Cl 5Cl 5Cl 5Cl 4Cl 4Cl 4Cl Corn s t r ' Corn SBM+ strch Tble 2. Diet composition (%)f < lngredient Cellulose r.z) t.' lo Ft Clcium /V$ phosphte Limestone mixll 2.N 2.W 3. 2.O0 2.N 2.lo ^1 L.t t r Z.JL r ' ' JJ tll diets contined 2.5 g kg iodized slt (0.015% K), 5 g kg vitmin mix nd 2.5 g kg-' minerl mix (see below). \'itmin mix dded (per kilogrm of diet) 8000 U vitmin, 1600 CU vitmin D3, 11.0 mg vitmin E,9.0 mg riboflvin, 13.0 mcg vitmin B12,.0 mg nicrn,900 mg choline chloride, 1.5 mg vitmin K, 1.5 mg folic cid, 0.2 mg biotin nd 125 mg ethoxyquin. Minerl mix dded (per kilogrm of diet) 55.0 mg mngnese, 0.1 mg selenium, 50 mg zinc, 5 mg copper nd mg iron. ll ingredients were ssumed to hve nutrient composition s reported by Summers nd Leeson (1976). +SBM : soyben mel (48%). $/V : niml nd vegetble ft blend. tl mix : mino cid mix (see Tble 1). //CP : dietry crude protein (%). fte == percent of crude protein supplied s essentil mino cids. RESULTS The E:NE rtio hd significnt qudrtic effbct on feed intke (Tble 4), percent crcss protein nd totl crcss ft when verged over ll protein levels (Tble 5). For these prmeters. the response mximum

4 902 CNDN JOURNL OF NML SCENCE Tble 3. Clculted mino cid content of exoerimentl diets Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. Dietry crude proteln (%) Requirementt{ Requirement Requirement Me + % E Cys Lys Glv rg ' l r '7 o.92 L61.t] 1.07 r ' t 1.06 r ' t J JJ 1.33 r ^ Vl mino cid His r.n r O Leu le Thr t t t t t.4' r.0'/ r t2 r.23 1.t4 Trp Phe + Tyr o.23 t r t.' r s frequirement vlues re presented s percent of dietry crude protein. lthe 40% E diets supplied ll E t 85% of requirement; the 50% E diets supplied ll E t lo6% of requirement; the 6O% E diets supplied ll E t 128Vo of requirement; the 7O% E diets supplied ll E t 149% of requirement. Tble 4. Effect of mnipultion of the E:NE_rtio t_vrious dietry protein levels on the performnce of turkev Doultst E:NE rtio Dietry protein (%) 40:60 50:50 60:40 70: Contrst lo l) '. +f ',78 + t l Feed conversion fficiency tlteight gin (g) Feed intke (g) E intke (g) to t J.) x +.s n+ None$ None None None 755 +t s fvlues re the men t the stndrd error of the men. Eight birds per pen, four pens per diet. fq : qudrtic contrst significnt. $None : liner, qudrtic nd cubic contrsts not signihcnt (P>0.05). vlue ws chieved t the 60:40 E:NE rtio (70: in the cse of totl ft). There ws no response in feed conversion effrciency (FCE) with respect to the E:NE rtio

5 BEDFORD ND SUMMERS - MNO CDS N TURKEY RTONS 903 Tble5. EffectofmnipultionoftheE:NErtiotvriousdietryproteinlevelsonthecrcsscomposition of turkev ooults E:NE rtio Dietry protein (%) 50:50 70: Contrst Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only Totl crcss protein (g) ' ' ', ', Percent crcss protein (dry mtter bsis) 6',7.4 + O ' ' ' Totl crcss ft (g) tj.t r t ' Percent crcss ft (dry mtter bsis) O ! r ll fvlues re the men + the stndrd error of the men. Two birds per pen, four pens per diet. +Q : qudrtic contrst significnt. $None : liner, qudrtic nd cubic contrsts not significnt (P>0.05). None None$ + None None None for ll levels of protein (Tble 4). Percent crcss ft ws lso unffected by the E:NE rtio (Tble 5). The remining prmeters exhibited protein x E:NE interction nd were therefore \lyzed t ech protein level for the type of response. Totl crcss protein ws unffected by the E:NE rtio except tthe3o% dietry protein level (Tble 5). The weight gin dt showed qudrtic response to the E:NE t the nd % crude protein levels but no significnt response tthe% crude protein level (Tble 4). The use of feed intke s covrite resulted in no significnt effect of the E:NE rtio on weight gin of birds fed the % protein diet nd totl crcss protein of birds fed the nd % protein diets. The primry interest of this study ws not to exmine the effect of dietry protein on turkey poult performnce but rther tht of vrying the proportion of dietry protein supplied s E. Nevertheless, performnce nd crcss composition responded to dietry protein in fshion which ws in generl greement with previous work with turkeys nd broilers (Jckson et L 1982; Bedford nd Summers 1985). DSCUSSON The fct tht inclusion of the covrite feed intke removed the E:NE rtio effect on weight gin (t % protein) nd totl crcss protein (t nd% protein) suggests tht the E:NE rtio is influencing these prmeters through its influence on feed intke. Feed intke ws mximized over ll protein levels t the 60:40 E:NE rtio.suggesting tht the turkey responds to specific proportion of dietry crude protein being supplied s E. However, the turkey does not seem to djust to reduced dietry E density by incresing feed consumption since feed intke ws depressed t the lower E:NE rtios. t the 70: rtio, feed intke ws lso depressed which suggests tht the turkey does hve mechnism to limit excessive E intke. E intke did not seem to be the only fctor governing weight gin. The dt suggested tht weight gins

6 904 CNDN JOURNL OF NML SCENCE Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. hl E H T N tr 400 tr n tr - reched mximum t 140 g E intke, beyond which there ws no further response (Fig. l). However. the response to protein intke reched predicted mximum t 310 g intke, which is well beyond the rnge encountered, (Fig. 2) suggesting tht the turkey is cpble ofresponding to dditionl intke of nitrogen even when E requirements hve been met. f 1 g of E intke is pproximted to 1 g of protein intke, then for bird eting 800 g, 310 g of this should be protein of which 140 g should be E, which pproximtes 38% protein diet nd 45:55 E:NE rtio. Perhps the reson why the optimum occurred t the 60:40 rtio in this study ws result of birds only E NTKE/G Fig. 1. The reltionship between body weight gin g-r nd essentil mino cid intke g-r (ED. E:NE rtio 40:60 50:50 60:40 70: Legend: tr E e c c e_ E E o e c c Model fittedl weight gin g : R : ntercept : M M2 : -0.0 Crude protein level of diet (%) intercept + M(E) + M2(E2) P : , stndrd error : 56.8 P : , stndrd error : 1.27 P : stndrd error :

7 BEDFORD ND SUMMERS MNO CDS N TURKEY RTONS Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. being ble to meet their E requirements t these rtios without being ble to consume sufficient nitrogen to relize their full potentil. Feed conversion efficiency ws reltively unffected by the E:NE rtio t ech protein level, there being only slight reductions noticeble in efficiency s the rtio Fig. 2. The reltionship between body E:NE rtio 40:60 50:50 60:40 70: Legend: decresed from 60:40 to 40:60 E:NE t nd % crude protein. Weight gin, therefore, ws dictted more by differences in feed intke thn by differences in the efficiency of conversion between diets. Birds consuming similr mounts of E, e.g.,% crude protein, 60:40 diet nd the % crude protein, 70: diet (Tble 4) did weight gin g-r nd dietry protein intke g-r (DP). Crude protein level of diet (%) Model fitted; weight gin : intercept -F M(DP) + M2(DP2) R : ntercept : P : , stndrd error : M 4.3 P : ,'stndrd error : 1.13 M2 : P : stndrd error : tr F o e c o

8 906 CNDN JOURNL OF NML SCENCE Cn. J. nim. Sci. Downloded from by on 11/23/17 For personl use only. not perform similrly. The percent crcss ft, totl crcss ft nd totl crcss protein dt suggest tht prt of the reson for this difference could be due to birds fed the 60:40, % protein diet hving more energy vilble for synthetic ctivities compred with those fed the 70:, 3O% diet.n consuming similr mounts of E, those birds fed the higher E:NE diets did not hve to consume s much feed nd hence energy s those fed the lower E:NE protein diets. This did not lter the percent crcss crude protein nd ft. but did result in those birds fed the% 60:40 diets producing greter yield of protein nd ft (Tble 5). s lredy mentioned, the percent crcss ft dt show no significnt response to the E:NE rtio t ll protein levels (Tble 5). Percent.crcss ft nd protein dt re guge of the prtitioning of productive energy, wheres totl crcss ft nd protein re guges of the prtitioning of productive energy nd totl feed intke. The dt suggest tht the E:NE rtio exerts its influence on gin more by influencing feed intke rther thn directing productive energy to protein synthesis t the expense offt. This observtion is in contrst to the recent findings of Bedford nd Summers (1985) in similr experiment using broiler chicks. t ws shown tht for the broiler chick, the E:NE rtio ffected feed intke nd prtitioning of productive energy eqully. This highlights differences between species nd suggests tht the broiler chick should not be used s model for determining the mino cid requirements for the turkey. Most prmeters of economic vlue reched their optimum t the 60:40 rtio. Since ll E were supplied r 128% of requirement t this rtio, this further suggests tht the mino cid requirement vlues my not reflect the true requirements of the turkey. n conclusion, both the E nd totl protein requirements my well be underestimtes of the true requirements of the turkey poult. This my explin why beneficil effects hve been observed when either E (Wrnick nd nderson l9l2) or dietry protein concentrtions (Sts nd Potter 1982) were incresed. ssocition of Olhcil nlyticl Chemists Officil methods of nlysis. llth ed. OC, Wshington, D.C. Bedford, M. R. nd Summers, J. D nfluence of the rtio of essentil to non essentil mino cids on performnce nd crcse composition of the broiler chick. Br. Poult. Sci. : t. Goodnight, J. H., Sll, J. P. nd Serle, W. S SS user's Guide; Sttistics Edition. Sttisticl nlysis System nstitute nc., Cry, N.C. Hurwitz, S., Ben-Gl,., Brtov,. nd Tlpz, H. f983. The response of growing turkeys to dietry nutrient density. Poult. Sci. 62: Jckson, S., Sts, R. J. nd Potter, L. M Reltive deficiencies of mino cids nd nitrogen per se in low protein diets for young turkeys. Poult. Sci. 62: Ntionl Reserch Council Nutrient requirements of Poultry. 8th. Rev. ed. NS-NRC, Wshington, D.C. Owen, J.., Wldroup, P, W., Mbry, C. J. nd Slgter, P, J Response of growing turkeys to dietry energy levels. Poult. Sci. 60: Sts, R. J. nd Potter, L. M Deficient mino cids in % protein corn-soyben mel diet for young turkeys. Poult. Sci. 61: Summers, J. D. nd Leeson, S Poultry nutrition hndbook. Ontrio Ministry of griculture nd Food. Toronto. Ont. Wrnick, R. E. nd nderson, J. O Essentil mino cid levels for strting turkey poults. Poult. Sci. 52: