Interntionl Journl of Poultry Science (): 8-, 00 Asin Network for Scientific Informtion 00 Digestible Sulfur Amino Acid Requirement of Mle Turkeys During the to 8 Week Period D. T. Moore, K. Bker, K. Thompson, E. Blir nd J. D. Firmn University of Missouri-Columbi, 6 Animl Sciences Deprtment, Columbi, MO 6, USA Emil: FirmnJ@missouri.edu Abstrct: Two floor pen trils were conducted to determine the digestible sulfur mino cid (SAA) requirement of mle turkeys for the periods of 8 to 9 dys nd 06 to 6 dys. The experiments were designed using 8 pens llowing eight tretments of six replicte pens using rndomized block design. For the 8 to 9 dy period, 9 toms were sorted by weight nd ssigned tretment. Digestible SAA levels rnged from. to.9 g/kg of diet. For the 06 to 6 dy period, toms were sorted by weight nd ssigned tretment. Digestible SAA levels rnged from.0 to.0 g/kg of diet. These levels were obtined by titrting synthetic methionine into low protein diet. The other synthetic mino cids were dded bck to the low protein diet t levels sufficient to provide growth similr to positive control diet. The positive controls for the periods were stndrd corn, soyben mel, nd met mel diets bsed on NRC (99) recommendtions. Performnce prmeters mesured for the tril were body weight gin nd feed conversion. Prts yield of birds on the second tril were lso tken with no significnt differences between SAA levels found. The dt were nlyzed by nlysis of vrince followed by splined regression nlysis. The digestible SAA requirements for body weight gin nd feed conversion of mle turkeys re.9 nd.0 g/kg for the 8 to 9 dy period nd.7 nd. g/kg for the 06 to 6 dy period, respectively. Key words: Turkey; mino cid; methionine; cysteine Introduction Over $ billion yer is spent on turkey feed in the United Sttes (Firmn, 997). One of the most expensive components of turkey diets is protein or more specificlly mino cids. In corn nd soyben mel bsed diets methionine is the most limiting mino cid, t lest during the strter period (Wrnick nd Anderson, 968). The importnce of methionine is indicted by its three mjor functions in poultry: s methyl donor, in protein synthesis, nd s precursor to cysteine (Grber nd Bker, 97). The totl sulfur mino cid (SAA) requirement for the strting turkey hs been tested previously (Boling nd Firmn, 997; Almquist, 9; D Mello, 976; Kummero et l., 97; Murillo nd Jensen, 976; Potter nd Shelton, 979; Wrnick nd Anderson 97; Hurwitz et l., 98). Behrends nd Wibel (980) found the requirement of SAA for turkeys 8 to weeks of ge to be 0.7% nd for turkeys 6 to 0 weeks of ge to be 0.8%. The totl SAA requirements for turkeys 8 to nd to 6 weeks of ge were found to be 0.9 nd 0.7%, respectively (Potter nd Shelton, 980). Hurwitz et l. (98) found the requirement to be 0.8 nd 0.8% for the 6 to 0 nd 0 to week periods respectively. The NRC (99) suggested requirement during the 8 to 9 dy period is Mterils nd Methods 0.% SAA nd during the 06 to 6 dy period is For the 8 to 9 dy nd the 06 to 6 dy experiments, 0.%. These dt re somewht out of dte given the bsl diets contining 89. nd 80 g/kg intct crude chnges in genetic potentil of modern turkeys nd were protein were formulted using corn, soyben mel, nd determined using totl rther thn digestible mino cid met product mel (Tbles nd ). Crystlline mino levels. cids were dded bck to the diet (with the exception of 8 An idel mino cid rtio for the turkey hs recently been developed (Firmn nd Boling, 998). An idel protein is one tht contins the exct mounts of mino cids needed for the niml without deficiencies or excesses (Bker et l., 99). In order to determine n idel mino cid rtio it is necessry to know the digestible mino cid requirement of ech essentil mino cid for the turkey. Utiliztion of n idel mino cid rtio for turkeys my reduce feed costs. It hs been shown tht diets formulted on digestible bsis were superior to diets formulted on totl mino cid bsis (Fernndez et l., 99). Previous reserch in our lb found the digestible SAA of strting hen poults to be 0.76% (Boling nd Firmn, 997). The digestible SAA requirement's found in this series of experiments for gin for 7 to 6, to, 7 to 6, nd 67 to 78 dys re 0.8, 0.78, 0.6, nd 0.%, respectively nd feed: gin for these periods re 0.8, 0.77, 0.66, 0.7, nd 0.0% respectively. No reserch hs been done on the digestible SAA requirement of the turkey beyond weeks. Therefore, the objective of these experiments ws to determine the digestible SAA requirement for mle turkeys beyond weeks of ge.
Moore et l.: Sulfur Amino Acid Requirements in Turkeys methionine) to meet essentil mino cid levels. Methionine ws titrted to the bsl diet for the desired totl sulfur mino cid levels for ech tretment. All other essentil mino cids were dded bck t levels estimted to be the digestible requirement (shown in Tbles nd ) for turkeys from to nd to 8 weeks of ge bsed on previous work in our lb (Firmn nd Boling, 998). Glutmic cid ws dded to ll experimentl diets to obtin level of nitrogen equivlent to 0 g/kg crude protein for the first period nd 0 g/kg crude protein for the second period for ll experimentl diets. All experimentl diets were formulted on digestible bsis using lest-cost diet formultion softwre. The digestibilities of the feedstuffs were determined by nlyzing the corn, soyben mel, nd met mel product for protein nd AA content t the Experiment Sttion Chemicl Lbortory (University of Missouri, Columbi, MO) using the AOAC method :98.0 (990). A Beckmn 600 nlyzer equipped with high performnce ction exchnge resin column performed the seprtion of the AA. Norleucine ws used s the internl stndrd nd the mino cid detection ws ccomplished with postcolumn ninhydrin derivitiztion. Cecectomized turkeys were then utilized to determine the digestible mino cid content of the feedstuffs using procedures previously published (Firmn nd Remus, 99). This informtion ws then used to formulte the bsl diets using lest-cost formultion softwre. Bsl rtions were mixed nd ech dietry tretment ws cquired by the titrtion of DL-methionine nd glutmic cid into the bsl diet. The positive control diet ws n industry stndrd corn, soyben mel, nd met mel diet tht contined 6 g/kg crude protein in the first experiment nd 0 g/kg crude protein in the second experiment. (Tbles nd ). In the 8 to 9 dy experiment, the bsl diet contined. g/kg digestible SAA of which 9% ws from methionine. For the second experiment, the bsl diet contined.0 g/kg digestible SAA of which 7% ws methionine. DL-methionine ws then titrted to the bsl diets to obtin experimentl diets contining digestible SAA on either side of the estimted requirement of.7 g/kg of the diet for the first experiment nd.0 g/kg of the diet for the second experiment bsed on previous work (Boling nd Firmn, 997). Methionine dditions for the first experiment resulted in diets contining.,.8,.,.,.9,.,., nd.9 g/kg digestible SAA, respectively. For the second experiment, methionine dditions resulted in diets contining.0,.,.6,.9,.,.,.7, nd.0 g/kg digestible SAA, respectively. Glutmic cid ws dded reciproclly into ll of the experimentl diets to mintin similr nitrogen content. Mle British United Turkeys of Americ (BUTA) poults were obtined from commercil htchery t dy of ge. The poults were fed corn, soyben mel, nd met mel diet bsed on NRC (99) requirements until the strt of the trils. At the strt of both trils, birds were pulled from pool of 000 birds. In the first experiment, 9 birds were plced in 8 floor pens with floor re of.9 squre meters. For the second experiment, birds were used. The birds were weighed, bnded nd weight sorted by computer to provide both similr totl pen weight nd distribution of birds within pens. Lighting ws mintined t hours per dy throughout the tril period. Feed nd wter were provided d libitum. The trils were designed s rndomized blocks contining six replictes for ech tretment. Ech tretment ws rndomly llocted to six blocks of eight pens such tht ech titrtion level ws llotted to ech block one time except for the tretment with the highest level of methionine nd the positive control. This tretment nd the positive control ech hd three replictes per tretment due to the number of pens vilble. All tretments were rndomized within ech block. The experiments were conducted in commercil type, curtin sided, 8 pen floor tril fcility with litter floors. For the first nd second experiments, the birds were plced on tril t 8 nd 06 dys of ge nd were tken off tril t 9 nd 6 dys of ge, respectively. At the conclusion of the tril, feed ws removed from the birds hours prior to weighing. Birds were individully weighed nd the feed of ech pen ws weighed to monitor feed disppernce. One bird per pen ws processed for crcss yield dt. The dt were nlyzed by nlysis of vrince using windows bsed sttisticl nlysis softwre (JMP ; SAS Institute, 990). Block effects were not significnt nd this error term ws eliminted from the nlysis. The growth nd feed conversion requirements for digestible SAA were estimted using splined-regression nlysis on replictes (Robbins, 986) with SAS (SAS Institute, 990) softwre. This procedure estimtes the requirement bsed on the intersection of lines defining the sloped, liner portion of the growth curve nd line fitting the plteu (point t which incresing SAA content does not result in improved performnce) portion of the dt. While this method of nlysis hs been criticized (Fisher et l., 97), more recent work bsed on computer modeled dt hs shown tht the splined or segmented regression hs much higher probbility of correctly estimting the requirement thn do estimtes bsed on qudrtic response criteri t either 90 or 9% of the symptote (Lmberson nd Firmn, 00). Level of significnce ws set t p < 0.0. Results nd Discussion Results from the first tril re shown in Tble. Weight gin rnged from 6 g gined per bird to 8 g. Gin ppered to plteu bove the. g/kg SAA level lthough some vrition existed bove this level. Feed intke in the plteu region roughly followed body weight gin 9
Moore et l.: Sulfur Amino Acid Requirements in Turkeys Tble : Composition (g/kg) of bsl nd NRC-bsed Tble : Composition (g/kg) of bsl nd NRC-bsed positive positive control diet for the 8 to 9 dy period control diet for the 06 to 6 dy period. Ingredients Bsl diet NRC diet Ingredients Bsl diet NRC diet g/kg g/kg g/kg g/kg Corn 70. 667. Corn 6.6 706. Soyben mel 6.9 7. Soyben mel 69 80. Pork mel 0 0 Pork mel 0 Sucrose 7. Sucrose 7.7 Lrd 78 Lrd 67.8 9 Diclcium Phosphte.6 7. Diclcium Phosphte. 9.7 N Bicrbonte N Bicrbonte DL-Methionine 0.08 Limestone 7.7 Limestone 8.06. Slt.8. Slt 0. Choline chloride.6 0. Choline chloride. 0. Avtek 0. 0. Avtek 0. Bciferm 0. 0. Bciferm 0. Trce-minerl mix Trce-minerl mix.0.0 Vitmin premix 0.7 0.7 Vitmin premix 0.7 0.7 Selenium premix 0. 0. Selenium premix 0. 0. CuSO 0. 0. Clculted Anlysis Crude Protein (g/kg) 89. 6 ME (MJ/kg) 6.8 6.8 Clcium (g/kg) 7. 60 Phosphorus (g/kg).. Methionine (g/kg).7.7 Cystine (g/kg).8.8 Lysine (g/kg).7 9. Threonine (g/kg). 6. Vline (g/kg).8 8.8 Arginine (g/kg).. Histidine (g/kg)..8 Isoleucine (g/kg). 7. Leucine (g/kg) 9..7 Phenyllnine + Tyrosine (g/kg) 7.. Tryptophn (g/kg) 0.9. Synthetic mino cids were dded so the bsl diet would contin the totl digestible mount of the following essentil mino cids: lysine, 0.76%; threonine, 0.8%; vline, 0.70%; rginine, 0.79%; histidine, 0.%; isoleucine, 0.%; leucine, 0.9%; phenyllnine + tyrosine, 0.79%; tryptophn, 0.8%. The mino cids in the bsl diet re on digestible bsis while mino cids in the NRC diet re on totl bsis. Protein is on totl bsis in both diets. Synthetic mino cids nd glutmic cid were dded bck t the expense of sucrose to obtin % protein equivlent. The minerl premixes provided the following mounts per kilogrm of diet: mngnese, 0 mg; zinc, 0 mg; iron, 60 mg; iodine, mg; mgnesium, 7 mg; selenium, 0.8 mg. The vitmin premix provided the following mounts per kilogrm of diet: vitmin A,,00 mg; vitmin D,,77 mg; vitmin E, mg; nicin, 8. mg; d-pntothenic cid, mg; riboflvin, 0 mg; vitmin B 6,. mg; mendione,. mg; folic cid,. mg; thimin,.7 mg; biotin, 0. mg; vitmin B, 0.0 mg. Avtec (lslocid) is provided to prevent coccidiosis; Bciferm (bcitrcin methylenedislicylte) is provided for incresed feed efficiency. CuSO 0. 0. Clculted Anlysis Crude Protein % 80 0 ME (MJ/kg).06.06 Clcium (g/kg) 7.. Phosphorus (g/kg)..8 Methionine (g/kg)..8 Cystine (g/kg).6.7 Lysine (g/kg). 7.6 Threonine (g/kg).. Vline (g/kg). 7.6 Arginine (g/kg).9 9. Histidine (g/kg).. Isoleucine (g/kg).8 6. Leucine (g/kg) 7.8 Phenyllnine + Tyrosine (g/kg) 6.. Tryptophn (g/kg) 0.8.8 Synthetic mino cids were dded so the bsl diet would contin the totl digestible mount of the following essentil mino cids: lysine, 0.76%; threonine, 0.8%; vline, 0.70%; rginine, 0.79%; histidine, 0.%; isoleucine, 0.%; leucine, 0.9%; phenyllnine + tyrosine, 0.79%; tryptophn, 0.8%. The mino cids in the bsl diet re on digestible bsis while mino cids in the NRC diet re on totl bsis. Protein is on totl bsis in both diets. Synthetic mino cids nd glutmic cid were dded bck t the expense of sucrose to obtin % protein equivlent. The minerl premixes provided the following mounts per kilogrm of diet: mngnese, 0 mg; zinc, 0 mg; iron, 60 mg;iodine, mg; mgnesium, 7 mg; selenium, 0.8 mg. The vitmin premix provided the following mounts per kilogrm of diet: vitmin A,,00 mg; vitmin D,,77 mg; vitmin E, mg; nicin, 8. mg; d-pntothenic cid, mg; riboflvin, 0 mg; vitmin B 6,. mg; mendione,. mg;folic cid,. mg; thimin,.7 mg; biotin, 0. mg; vitmin B, 0.0 mg. Avtec (lslocid) is provided to prevent coccidiosis; Bciferm (bcitrcin methylenedislicylte) is provided for incresed feed efficiency. 0
Moore et l.: Sulfur Amino Acid Requirements in Turkeys Fig. : Fig. : Fig. : Gin of tom turkeys fed grded levels of digestible SAA to weeks of ge. with 9% confidence intervls ws found to be.9 g/kg +/- 0. mg/kg. Gin of tom turkeys fed grded levels of digestible SAA 06 to 6 dys of ge. with 9% confidence intervls ws found to be.7 g/kg +/- 0.6 mg/kg. Feed: gin of tom turkeys fed grded levels of digestible SAA 8 to 9 dys of ge. with 9% confidence intervls ws found to be.0 g/kg +/- 0. mg/kg. Fig. : Feed:gin of tom turkeys fed grded levels of digestible SAA from 06 to 6 dys of ge. with 9% confidence intervls ws found to be.0 g/kg +/- 0. mg/kg. Tble : Growth performnce of tom turkeys fed titrted levels of digestible sulphur mino cids (SAA) from 8 to 9 dys of ge Digestible Weight Adjusted SAA (g/kg) Gin (g) Feed:Gin. 6 c.7.8 b 9 b.. cd.. bc 07..9 ef 8.08. 7.7. c 0..9 f 8 *.8* PC** ef *.0* Pooled SEM 66 0. Pooled SEM* 9 0.9 SEM* hs only three replictes, but SEM hs six replictes.**nrc bsed positive control diet. Tble : Growth performnce of tom turkeys fed titrted levels of digestible SAA from 06 to 6 dys of ge Digestible Weight Adjusted SAA (g/kg) Gin (g) Feed:Gin.0 77 b 6.0. b 9..6 bcd 6.89.9.7. 89.7. de.69.7 bc 097.00.0 97 *.88* PC** de 6 *.9* Pooled SEM 7 0.6 Pooled SEM* 79 0.9 SEM* hs only three replictes, but SEM hs six replictes.**nrc bsed positive control diet.
Moore et l.: Sulfur Amino Acid Requirements in Turkeys Tble : Crcss dt for tom turkeys fed titrted levels of SAA from 06 to 6 dys of ge Digestible Dressing Ft Pd Pectorlis Pectorlis Leg Thigh Wing SAA (%) % % Mjor % Minor % % % % 0. 7. 9.6.7..9. 0. 7.. 0.7.9.6..7 0.6 7.6.6 9.8....8 0.9 7.6. 0..... 0. 7.9.6 0..8..9.9 0. 7. 9.9.6.6..6 0.7 7.9 0..6...9 0. 7.8*.7* 8.7* *.9*.6*.0* PC** 7.*.*.*.9*.7*.9*.8* Pooled SEM 0.7 0.8 0. 0.9 0.9 0.7 0. Pooled SEM*.0 0.9 0.77 0.7 0. 0. 0.7 SEM* hs only three replictes, but SEM hs six replictes. No significnt differences were noted in ny prmeter. **NRC bsed positive control diet. yielding similr feed efficiency vlues in this portion of the curve. Anlysis of vrince ws used to determine the level of significnce between tretments nd the positive control diet, nd through the use of splined regression nlysis the digestible SAA requirement for the 8 to 9 dy tom turkey ws determined to be.9 nd.0 g/kg for gin nd feed conversion, respectively (Fig. nd ). The NRC (99) corn nd soyben mel-bsed diet hs n pproximte SAA digestibility of 8% (Firmn, 99; Firmn nd Remus, 99). Using this number, the estimted SAA requirement of the NRC diet would be pproximtely.7 g/kg expressed on digestible bsis. The requirement determined in this experiment ws somewht lower thn this level. The difference in requirement my men n overfeeding of SAA to mle turkeys during this period. The percent of the totl methionine SAA in the sufficient diet ws % methionine nd 6% cystine, respectively. This is below the mximum level of cystine s percent of totl SAA found by Behrends nd Wibel (980) to be cceptble. Conversion of methionine to cysteine is not 00% bsed on differing moleculr weights. However, if 0:0 reltionship is considered idel, then the potentil difference in the determined requirement of the totl SAA in this study would be less thn %. Results from the second tril re shown in Tble. Weight gin rnged from 77 g gined per bird to g. The plteu in gin ppered to be bove the.6 g/kg SAA level lthough vrition occurred bove this level. Feed intke in the plteu region gin roughly followed body weight gin yielding similr feed efficiency vlues in this portion of the curve. Anlysis of vrince ws used to determine the level of significnce between tretments nd the positive control diet, nd through the use of splined regression nlysis, the digestible SAA requirement for the 06 to 6 dy mle turkey ws determined to be.7 nd. g/kg for gin nd feed conversion, respectively (Fig. nd ). Using 8% digestibility, the estimted digestible SAA requirement of the NRC diet is.8 g/kg. This number is very similr to the findings of this experiment. The percent of the SAA in the sufficient diet ws 7% methionine nd % cystine, respectively. Agin, if 0:0 reltionship is considered idel, then the potentil difference in the determined requirement of the totl SAA in this study would be pproximtely.6%. It should be noted however, tht most prcticl diets include the ddition of methionine source which would then be included in the clcultions for totl SAA. While the rtios of methionine:cysteine re constntly chnging in the experimentl diets, the level of methionine tht would hve been dded to diet t the determined requirement is only slightly bove those levels seen in prcticl formultion. Prt of the importnce of determining digestible mino cid requirements is to develop n idel mino cid rtio for turkeys. This would llow diets to be formulted on digestible bsis using vrious feedstuffs under vrible conditions. Idel proteins express ech essentil mino cid bsed on percent reltive to lysine, due to the ese of determining the lysine content in feedstuffs nd its overll importnce in poultry nutrition. Using previous lysine dt (Bker et l., unpublished), the percent digestible SAA to lysine ws determined to be 9% in the first tril nd 68% in the second tril period. In the field of turkey nutrition n idel rtio hs been estimted (Firmn nd Boling, 998) with the SAA:lysine rtio t 9% during the strter period. Work done by Chung nd Bker (99) indicted tht the percent digestible SAA to lysine ws 60% for swine. The SAA to lysine rtio ws found to be 7% for the broiler chicken by Bker nd Hn (99), lthough this is difficult to compre due to differing growth periods. The incresed reltive requirement of the SAA is probbly due to the incresed mintennce costs ssocited with the older bird. The bility of the industry to feed lower protein diets is lso indicted by this study when synthetic mino cids re dded bck to the diet in the proper mount. For exmple, the test diet in the second experiment contined 80 g/kg intct crude protein nd the synthetic methionine t the digestible requirement level performed s well s the control diet bsed on the NRC (99) requirements contining 0 g/kg crude protein (Tble ). This result is similr to other reserch tht hs indicted turkeys cn exhibit stisfctory growth with low protein diet by
References Almquist, H. S., 9. Amino cid requirement of chickens nd turkeys- review. Poult. Sci., : 966-98. AOAC., 990. Officil methods of nlysis. th ed. Assocition of Anlyticl Chemists, Arlington, VA. Bker, D. H. nd Y. Hn, 99. Idel mino cid profile for chicks during the first three weeks posthtching. Poult. Sci., 7: -7. Bker, D. H., C. M. Prsons, S. Aoygi nd Y. Hn, 99. Digestible mino cid requirements of broiler chickens bsed upon idel protein considertions. Proceedings of the Arknss Nutrition Conference, pp: -. Bldini, J. T., H. R. Rosenberg nd J. Wddell, 9. The protein requirement of the turkey poult. Poult. Sci., : 9-. Behrends, B. R. nd P. E. Wibel, 980. Methionine nd cystine requirements of growing turkeys. Poult. Sci., 9: 89-89. Boling, S. D. nd J. D. Firmn, 997. Digestible sulfur mino cid requirement of strting turkeys. Poult. Sci., 76: 87-877. Chung, T. K. nd D. H. Bker, 99. Idel mino cid pttern for 0-kilogrm pigs. J. Anim. Sci., 70: 0-. D mello, J. P. F., 976. Requirements of the young turkey for sulphur mino cids nd threonine: Comprison with other species. Br. Poult. Sci., 7: 7-6. Fernndez, S. R., S. Aoygi, Y. Hn, C. M. Prsons nd D. H. Bker, 99. Limiting order of mino cids in corn nd soyben mel for growth of the chick. Poult. Sci., 7: 887-896. Firmn, J. D., 997. Erly stge turkey nutrition nd idel protein: Implictions for ll spects of poultry th production. Proceedings of Alltech s Annul Symposium, pp: 7-78. Firmn, J. D., 99. Utiliztion of low protein diets for turkeys. BioKyow Technicl Review-7. Firmn, J. D., 99. Amino cid digestibility of soyben mel nd met mel in mle nd femle turkeys of different ges. J. Appl. Poult. Res., : 0-. Moore et l.: Sulfur Amino Acid Requirements in Turkeys dding bck the essentil mino cids (Bldini et l., Firmn, J. D. nd S. D. Boling, 998. Idel protein in 9; Firmn, 99; Sell et l., 99; Wibel et l., turkeys. Poult. Sci., 77: 0-0. 99). Firmn, J. D. nd J. C. Remus, 99. Amino cid The crcss dt of the finl experiment showed no digestibility of feedstuffs in femle turkeys. J. Appl. significnt differences between birds fed the required Poult. Res., : 7-7. levels of digestible SAA nd birds fed the industry Fisher, C., T. R. Morris nd R. C. Jennings, 97. A stndrd positive control diet (Tble ). Further work in model for the description nd prediction of the the re needs to be performed s these birds were on n response of lying hens to mino cid intke. Br. industry stndrd diet until 06 dys so chnges in prts Poult. Sci., : 69-8. yield hd little time to mnifest themselves. Grber, G. nd D. H. Bker, 97. Sulfur mino cid nutrition of the growing chick: Quntittive spects Acknowledgements concerning the efficcy of dietry methionine, This work ws supported by the Missouri Soyben cysteine nd cystine. J. Anim. Sci., : 00-0. Merchndising Council nd the Missouri Agriculturl Hurwitz, S., Y. Frish, A. Br, U. Eisner, I. Bengl nd Experiment Sttion. M. Pines, 98. The mino cid requirements of growing turkeys.. Model construction nd prmeter estimtion. Poult. Sci., 6: 08-7. Kummero, V. E., J. E. Jones nd C. B. Lodholt, 97. Lysine nd totl sulfur mino cid requirements of turkey poults, one dy to three weeks. Poult. Sci., 0: 7-78. Lmberson, W. R. nd J. D. Firmn, 00. A comprison of qudrtic versus segmented regression procedures for estimting nutrient requirements. Poult. Sci., 8: 8-8. Murillo, M. G. nd L. S. Jensen, 976 Methionine requirement of developing turkeys from 8- weeks of ge. Poult. Sci., : -8. Ntionl Reserch Council, 99. Nutrient Requirements th of Poultry. 9 Revised edition. Ntionl Amy Press, Wshington, D.C. Potter, L. M. nd J. R. Shelton, 979. Methionine nd protein requirements of young turkeys. Poult. Sci., 8: 609-6. Potter, L. M. nd J. R. Shelton, 980. Methionine nd protein requirements of turkeys 8 to 6 weeks of ge. Poult. Sci., 9: 68-7. Robbins, K. R., 986. A method, SAS progrm, nd exmple for fitting the broken-line to growth dt. The University of Tennessee Agriculture Experiment Sttion. Reserch Report, 86-09. SAS Institute, 990. SAS User s Guide, Sttistics, version edition. SAS Institute Incorported, Cry, NC. Sell, J. L., M. J. Jeffrey nd B. J. Kerr, 99. Influence of mino cid supplementtion of low-protein diets nd metbolizble energy feeding sequence on performnce nd crcss composition of toms. Poult. Sci., 7: 867-880. Wibel, P. E., C. W. Crlson, J. K. Liu, J. A. Brnnon, nd S. L. Noll, 99. Replcing protein in cornsoyben turkey diets with methionine nd lysine. Poult. Sci., 7: -8. Wrnick, R. E. nd J. O. Anderson, 97. Essentil mino cid levels for strting turkey poults. Poult. Sci., : -. Wrnick, R. E. nd J. O. Anderson, 968. Limiting essentil mino cids in soyben mel for growing chickens nd the effect of het upon vilbility of the essentil mino cids. Poult. Sci., 7: 8-87.