TAP CHI KHOA HOC SO 16 118 www.hm.edu.vn
MOI QUAN HE GIU'A NANG LlTgfNG TRAO DOI, PROTEIN THO VA CAC AXIT AMIN DOI VCtt GA THJT
V6 Van Hung Trudng Bgi Hpc Hd TTnh Email: kung.vovan@}im.edu.vn Ngdy nhdn bdi (received): 15/3/2019
Ngdy nhdn bdn sica (revised): 2/4/2019 Ngdy nhdn ddng (accepted): 15/4/2019
Tdm tit
Tir nhieu ket qua nghien cuu, khuyen ngbi, bdi vi6t nay cbi ra rang: Nang lugng ttao ddi (ME), protein tbd (CP) va cac axit amin (aa) cd mdi quan hi mat thiet vdi nhau trong thdc an chan nudi ga thit. ME/CP (kcal/CP%) phdi nam trong khoang nhat dinh (nhin chung thdp nhdt Id khodng 121 & giai dogn kh&i dpng, cao nhdt Id khodng 178 & giai dogn kit thuc). Trong khi do, chat lugng CP phu thudc vao cac aa thiet yiu, nhat la lysine, methionine + cystine, threonine. Vi the, mgt sd tac gid chi de cap den ty le aa thiet yeu/ME trong khau phan. Mdt sd aa lai cd sy tucmg tac vdi nhau nbu methionine va cystein, phenylalanine va tyrosine. Cdc gidng ga, giai doan, dieu kien nudi khac nhau thi cd muc ME, CP va aa thiit yiu khac nhau.
Tir khda: Nang lugng trao ddi, protein thd, axit amin.
The relationship between metabolism energy and crude protein and amino acids for broiler
Abstract
According to many research results and recommendations, this paper shows that Energy metabolism (ME), crude protein (CP) and amino acids (aa) are closely related in broiler feeds. ME / CP (kcal / CP%) must be within a certain range (generally the lowest is about 121 at the inception phase, the highest is around 178 at the end).
Meanwhile, CP quality depends on the essential ingredients, especially lysine, methionine + cystine, threonine. Therefore, some authors only mention the percentage of essential / ME in the diet. Some have interactions such as methionine and cysteine, phenylalanine and tyrosine. Bifferent breeds of chickens, stages and conditions have different levels of ME, CP and aa.
Keywords: Energy metabolism, crude protein, amino acids.
ISSN 0856-7594.2019 Journal of Science, Voi. XVI All ngfrts reserved.
1. Dat van de
Miic nang luong Irao d6i (kcal ME) va protem tho trong thiic an (% CP) co m6i quan h? chat che vdi nhau nen khi xay dung khiu phin cho gia cim nguoi ta luon hit siic chii trgng. Tuy nhien, chat luong protem tho phu thupc vao s6 luijng va ty le cac axit amin trong do, dac biet so lupng va ty le cac axit amin thiSt yhi. Do do, lam ro cac m6i quan he nay de phuc vu nghien ciiu, hpc tap va van dimg kiSn thiic vao thuc tiln chan nuoi la hit sue quan trpng.
2. N$i dung
2.1. Mdi quan he giOa ning luong trao tSi va protein thd iii varigi thit Nang lupng va protein co m6i tuong quan nhit dinh. BM thiSu nang lupng trao d6i, CO the se phan giai protein de cung cap nang lupng, do do, he s6 chuy&i hoa thiic an cho don vi san pham (FCR) tang len. Khi thira nang lupng trao doi, ca the se tang cuong tich luy mo (Tir Quang Hidn, Phan Dinh ThSm, 2002). Gia cim nuoi thit chi co thS tang khdi lupng 6 muc cao khi ty le giira nang lupng trao doi (ME) va protein tho (CP) nim trong kha nang tu dilu chinh ciia chiing. Vi vay, ty le ME/CP (kcal/CP%) trong thiic an qua cao hoac qua thap deu ^inh hucmg lon den tang khoi lupng, sii dung cac chat dinh du&ng ciia thiic an va chat lupng san pham (Jackson va cs., 1982 - din tir Tir Quang Hiln va cs., 2013).
Khi miic nang lupng an vao cao, khoang 85% nang lupng tich liiy trong md va 15%
nang lupng du trir trong protein. Khi miic nang lupng an vao thap, mpt lupng mo co the dupc huy ddng, trong khi protein dupc tich liiy (Boekholt va cs., 1994 - dan tir Nguyen Diic Hung, 2006). Ga sinh trudng tdt vdi miic nang lupng 2.800 kcal/kg thiic an (TA) va muc protein 23%, 22%, 18% iing vdi giai doan khdi dpng, smh trudng va ket Ihiic. Khi tang nang lupng trong khiu phin se lam tang iupng md. Khi tang protein khau phan se lam tang ty le nudc va protein trong thit nhung lam giam lupng md va nang lupng trong tint (Baghel, Pradhan, 1989).
Ty le ME/CP tang din theo giai doan phat trien cua ga. Ci giai doan diu, ty le nay thudng thip vi mat dp ME thip va % CP lai cao so vdi giai doan sau; ngupc lai, giai doan sau mat dp ME tang len nhung % CP lai giam trong khiu phan so vdi giai doan truac. Nhin chung, yen ciu mat dp dinh duong cho ga thit d giai doan trudc vin cao hon giai doan sau trong khiu phin. Kamran va cs. (2008) khing dinh rang, nuoi ga thit khiu phin cd CP thip vdi ty le ME/CP khdng ddi da anh hudng xiu din su sinh trudng. Tir Quang Hiln va cdng su (2013) cho biit, cac nudc thudng quy dinh ty le ME/CP (kcal/CP%) vao khoang 130 - 150 cho ga thit giai doan diu va 160 - 170 vao giai doan sau (nuoi theo 2 giai doan). Con NRC, 1994 (Hpi dong Nghien ciiu Qudc gia Hoa Ky) thi khuyin cao, ty le ME/CP (kcal/CP%) trong thiic an cila ga thit dl tang khdi lupng trung binh giai doan khdi dpng la: 139 (ME: 3.200 kcal/kg TA; CP: 23%); giai
ISSN 0866-7594.2019 Journal of Sdenre, Vol XVI. AH nghts reserved.
TAP CHI KHOA HOC SO 16 120 www.hm.edu.vn
doan sinh trudng la: 160 (ME; 3.200 kcal/kg TA; CP: 20%); giai doan kSt thuc la: 178 (ME: 3.200 kcal/kg TA; CP: 18%). Hang Ross broiler, 2009 (dan tu Tu Quang Hiln va cs., 2013) khuyin cao ty le ME/CP (kcal/CP%) ttrong thuc an cua ga thjt dk tang khoi luong cao giai doan khdi dpng la: 138 - 121 (ME: 3.025 kcal/kg TA; CP: 22 - 25%);
giai doan sinh trudng la: 149 - 136 (ME: 3.125 kcal/kg TA; CP: 21 - 23%); giai doan ket thuc la: 168 - 152 (ME: 3.200 kcal/kg TA; CP: 19 - 21%).
Thdi giMi gan day, nhieu tac gia ciing da nghien cuu vk ME va CP cho cac ddi ttrong ga khac nhau: Mbajiorgu va cs. (2011) da nghien cuu tren ga Venda ban dia va thdy ring, ty le ME/CP 62 MJ ME/kg protein (ttrong duong 148 kcal ME/1% CP) la tdi uu cho luong an vao va sinh trudng; ME/CP 63 MJ ME/kg protein (tuong duong 150 kcal ME/1%
CP) la tdi uu cho FCR giai doan 1 - 42 ngay tudi; ME/CP 60 MJ ME/kg protein (tuong duong 143,6 kcal ME/1% CP) la toi uu cho sinh trudng va FCR cua ga trong giai doan 43 - 91 ngay ttx6i; ttxy nhien, ME/CP: 62 MJ ME/kg CP (ttrong duong 148 kcal ME/1% CP) la tdi uu cho lugng an vao ciia ga trdng giai doan 43 - 91 ngay tudi. Ket qua khang djnh^
ME/CP: 62 MJ ME/kg CP (ttrong ducmg 148 kcal ME/1% CP) la t6i uu cho lugng an vao ma khong phan biet Ida tudi va tinh biet ciia ga. Moosavi va cs. (2012) da nghien cuu tren ga Ross 308 va ket luan nuoi ga thit ME thap va CP thap da giam sir tang trudng, nhung chi tieu thit khong bi anh hudng. Haunshi va cong su (2012) da nghien cuu de danh gia anh hudng nang lugng trao ddi va ham lugng protein thd khac nhau tren ga Aseel giai doan 1 - 56 ngay tuoi. Ngjiien cuu ket luan rang, viec cung c3.p ME 2.600 kcal/kg va 16% CP se la ly tudng cho su phat triSn t6i uu ciia ga trong giai doan nay. Tuy nhien, de co dugc FCR tot hon, chS dg Hinh dudng khSu phin ME 2.800 kcal/kg va 16% CP se la ly tudng. Lqbal Z.
va cs. (2014) da nghien cuu va ket luan rang, tieu thu thiic an cua ga broiler giam, trong khi dd FCR dugc cai thien khi mat do dinh duong khau phan tang len. CP va ME co the giam tuong ung tdi 19,3% va 2771 kcal/kg thuc an, ma khong lam giam kha nang san xuat cua ga thit (tang khoi lugng, chat lugng thit).
2.2. Mdi quan hf giira ndng lugng trao doi vd axit amin ddi v&igd thit Da so cac nha khoa hoc cho rang, viec nghien cuu ty le giira nang lugng trao doi vdi cac axit amin trong khiu phin se cho kit qua chinh xac hon so vdi ty le giua nang lugng vdi % protein thd. Tuy nhien, viec nghien cuu nay doi hoi rat cdng phu va ton kem nen rat khd thyc hien (Nguyen Duy Hoan, 2010).
Giua nhu ciu tung loai axit amin va ham lugng protein tho tong sd trong khau phan cd quan he qua lai. Niu ty le cac axit amin trong protein can doi vdi nhu cau vat nudi thi protein bi oxy hoa di thanh nang lugng se thip. Niu ham lugng protein tho cao nhung khong can d6i cac axit amin, dac biet la axit amin thiit yeu thi nhu ciu ttmg loai axit amin cung se thay ddi. Do do, nhu ciu axit amin dugc biiu thi theo nang lugng (vi du: g axit amin/MJ
ISSN 0866-7594.2019 Journal of Saence, Vol. XVI, All ngtits resenred.
ME). Lysine la axit amin dupc su dung dl xac dinh nhu ciu cho cac axit amin thiit yiu cdn lai dua vao ty le cua chiing trong protein ly hrdng (Le Diic Ngoan, Du Thanh HSng, 2014).
Neu axit amin thiet yen trong khiu phin thip, ga se giam tdc dp sinh trudng va hieu qua chuyen ddi thiic an thap. Vdi cac khau phan cimg lupng axit amin thiit yiu, ga se cd cimg lupng axit amin an vao ma khdng phai cimg lupng nang lupng (Skiimer va cdng su, 1991 - din tir Nguyin E)iic Hung, 2006).
Heunichs, 2009 (din tir Nguyin Duy Hoan, 2010) da dl xuit ty le ME/lysme cua ga 1 - 21 ngay tali la 2728, ga 22 - 42 ngay tudi la 2900, 43 - 56 ngay tudi la 3494. Cdn Leeson, Summers (2008) khuyen cao mirc lysine (g)/nang lupng trao ddi (Meal) ddi vdi ga broiler gidng Hubbard la 2,47 g/Mcal; ddi vdi ga broiler gidng Cobb la 2,68 g/Mcal; ddi vdi ga broiler gidng Ross la 2,80 g/Mcal.
2.3. Mdi quan hegiifa cdc axit amin vdi nhau vd cdc axit amin vdi protein Giua eac axit amin cd su tuong tac vdi nhau. Q ga, nhu ciu lysine tang khi khiu phSn thSp methionine, arginine va vitamin nhdm B. Su tuong tac gay ra do su chuyin ddi mpt axit amin nay thanh mot axit amin khac. Neu khau phan thieu cystine hoac dang cystein trao ddi ciia no thi cystine se dupc tdng hpp tir methionine. Do do, nhu can methionine phuc thudc vao ham lupng cysteine hoac cystine trong Ichiu phin va hai axit amin nay ludn ludn di chung vdi nhau. Vi vay, thuat ngir: "Nhu cau methionine cdng cystine" dupc su dung. Tuy nhien, methionine lai khdng dupc tdng hpp tir cystine, vi vay methionine phai ludn ludn cd mat mdt phin de dap ung nhu cau cua con vat. Phenylalanine va tyrosine cd quan he tuang tu. 6 ga, glycine va serine cd the chuyen ddi cho nhau. Neu protein duac su dung cho san sinh nang luong thi nhu cau axit amin ciing se thay ddi. Axit amin dupc su dung nhilu nhit trong thiit lap niiu cau dinh duang la lysine. Trong thuc te, cac axit amin trong khiu phin ludn vupt ra ngoai ty le mong mudn, vi vay sil dvmg bi thieu hut so vdi nhu ciu. Axit amin bj thiiu hut dd gpi la axit amin gidi han. Lysme va methionine la hai axit amin gidi han diu tien trong hau het cac loai thurc an cho vat nudi Viet Nam (Le Diic Ngoan, 2002).
Do cysteine cd thi dupc tong hpp tir methionine nen cysteine (hoac cystine) cd the dap ling dupc 50% nhu ciu tdng lupng axit amin chita luu huynh (methionine + cysteme).
Bing each nay, cysteine cd thi lam giam nhu cau ddi vdi methionine. Tuong tu nhu ddi vdi nhdm axit amin chiia luu huynh, phenylalanine cd the dap nhu can cua tdng lupng phenylalanine va tyrosine (axit amin cd nhan thom) vi su chuyin hda phenylalanine cd the tao thanh tyrosine. Tyrosme cd thi dap iing tdi thiiu 50% tdng nhu ciu ciia hai loai axit amin nay nhung nd khdng phai la ngudn duy nhit va khdng the thay thi cho phenylalanine vi nd khdng thi chuyin dupc thanh phenylalanine (Hd Trung Thdng va cdng su, 2006).
M6i quan he giua axit amin va protein thi hien chat lupng protem. Theo Le Diic
ISSN 0866-7594.2019 journal of Saence, Vol XVI. All nghts reserved.
TAP CHI KHOA HOC SO 16 122 www.hm.edu.vn
Ngoan, Du Thanh Hiing (2014) thi protein ly tudng la loai protein can ddi axit amin thiit yeu va khong thiet yeu, do do nd cung cip dly dii va dung ty le cac axit amin thiet yen ma vat nudi yen cau.
Khi su dung protein ly tudng cho ga thit, se cd 3 lgi ich, do la: Tang tdc do tang trudng va giam FCR; giam protein tdng sd cua khau phan; giam nito thai tiet, han che 6 nhilm moi trudng.
Ga thit an khau phan cd ty le protein tho thSp (18% CP giai doan khdi dgng va 16%
gjai doan ket thiic) cd bo sung axit amin tot hon so vdi ga an khau phan cd ty le protein tho 20% d giai dogn khdi dong va 18% d giai doan kit thiic nhung khong dugc bd sung axit amin (Querubin va cgng su, 1989).
Kamran va cs. (2011) da tien hanh thi nghiem de nghien cuu tac ddng cua viec giam protein thd (CP) trong khau phSn tren ga thit Hubbard tu 1 - 35 ngay tuoi. Bon khau phan an da dugc xay dung. Khiu phin A (ddi chung) vdi 23, 22 va 20% CP iing vdi giai doan khdi dgng, sinh trudng va ket thiic. Khiu phan B, C va D muc CP da giam xudng cdn 22, 21 va 20% trong giai doan khdi dgng; 21, 20 va 19% trong giai doan sinh trudng va 19, 18 va 17% trong giai doan ket thuc. Tat ca cac khau phan su dung 2.925, 3.075 va 3.125 kcal/kg ME. Lysine ti6u hda dugc duy tri d miic 1,10, 1,02 va 0,90%
cho giai doan khdi dgng, giai doan sinh trudng, giai doan ket thiic va axit amin gidi han ciing dugc su dung theo khuyen cao. Ket qua thay rang: Muc tang khdi lugng, lugng thiic an an vao, FCR, tdng ME an vao va hieu qua su dung ME tuong tu nhau giua cac Id thi nghiem. Tuy vay, tong lugng protein an vao giam va hieu qua sir dung protem tang vdi khau phan co miic CP thap trong toan bd giai doan sinh trudng. Dac diem chat lugng thit gifla cac Id thi nghiem giong nhau. Cac tac gia ket luan, miic CP cd the giam ma khong anh hudng xau den kha nang san xuat (tang khoi lugng, chat lugng thit, FCR) ciia ga khi dugc bd sung cac axit amin gidi han.
Muc lysine trong khau phin van ludn ludn dugc cac nha khoa hgc chii trpng.
Christian Wecke va cs. (2016) da tien hanh nghien cuu theo phuong phap can bang nito (N) de danh gia lai yeu cau lysine cua mgt dong ga trong thit hien dai (Ross 308), sir dung tam khiu phin co 6% - 34% CP. D6i vdi giai doan khdi diu (10 - 20 ngay tu6i), liic khdi lugng ga 600 g, yeu ciu lysine ttr 741 mg din 823 mg moi ngay, tuong iing ty le ttong thiic an la 1,06% den 1,18%. Giai doan sinh trudng (25 - 35 ngay tudi), khdi lugng ga bmh quan 1800 g, yeu ciu tu 1272 mg din 1473 mg lysine mdi ngay, tuong iing ty le lysine ti-ong khiu ph§n la 0,85% din 0,94%.
Ji-Hyuk Kim (2014) da nghien cuu di kiem tra cac gia dinh rang, mit can bing hon hgp axit amin din din tang san xuit nhiSt (HP). Thi nghiem dugc dua tt-en khiu phin vdi cac muc protein tho (CP) khac nhau nhimg muc lysine cd dinh (axit amin gidi han diu
ISSN 0366-7594.2019 Journal of Science, Vol XVI. All rigWs reserved.
tien). Ga trdng thit 21 ngay tudi (n = 50) dupe chia lam 5 nhdm, 5 lin lap lai, 2 con/Id. Nam khiu phin vdi miic CP lin lupt la 18, 21, 24, 27, 30% vdi mdt mirc lysme khdng ddi (1,1%). Cac miic CP khdng cd tac ddng ddi vdi lupng an vao. Tuy nhien, mat dp CP da ed inh hudng dang kl din luong nudc udng (P <0,01). Vdi lysme khdng doi va CP khac nhau, da tang 75% lupng N an vao khi mat dp CP tang. Dilu nay din din tang 150% lupng N bai tiet, khdng cd thay ddi san xuat nhiet. Gia sir san xuit nhiet diing vdi kit qua xac dinh thuc nghiem, khau phan CP cd xu hudng tang khdng tuong quan vdi lupng an vao axit amin gidi han diu tien.
Ng'ambi va cdng su (2009) da tiln hanh thi nghiem dl xac dinh ty le lysine/CP din kha nang san xuat cua ga trdng broiler Ross 308. Trong mdi Id thi nghiem khiu phan gidng nhau vl nang lupng va nito nhung khac nhau vl ty le lysine/CP. Chia thanh giai doan la khdi ddng (1 - 21 ngay) va giai doan sinh trudng (22 - 42 ngay). Ty le lysine/CP tdi uu cho tang trudng va FCR lin lupt la 0,066 va 0,077, trong giai doan khdi dpng. Lysine/CP tdi tru cho tdc do sinh trudng, FCR, thit nguc va ham luang nito lin lupt la 0,073, 0,073, 0,069 va 0,079, trong giai doan smh trudng. Lysine/CP khdng anh hudng lupng an vao va kha nang tieu hda. Ket qua chi ra rang, tai mdi giai doan, che dp lysine/CP dupc tdi uu hda cho ca tdc dp tang trudng va FCR. Tuy nhien, ty le nay tdi uu cho thit nguc thap ban so vdi tdc dp tang trudng va FCR. Nhung phat hien nay cd y nghia ve xay dung khau phan an cho ga thit.
Usama Aflab va cpng su (2007) da tien hanh nghien ciiu miic lysine chan nudi ga Hubbard trong dilu kien miia He d Pakistan, dinh dudng thap. Ket qua nghien ciiu chi ra rang: Giai doan 4 - 2 1 ngay tudi, nhiet dp trung binh dao ddng tir 28 - 40 "C, vdi miic ME 2.700 kcal/kg, protem thd 18,6%, thi miic lysme tdng sd thich hpp la 0,97 - 0,98%; giai doan 21 - 40 ngay tudi, nhiet dp trung binh tit 23 - 26 °C, vdi miic ME 2.750 kcal/kg, protein 17,1% thi mirc lysine tdng sd thich hpp la 0,87%. iTdc tinh lysine tieu hda thich hijp giai doan 4 - 2 1 ngay tudi la 0,84 - 0,85%; giai doan 21-40 ngay tudi la 0,75%.
3. Kit lu|n
Mdi quan he giiia ME, CP va aa ddi vdi ga thit dupc thi Men cu the d ty le ME/CP, su cd mat ciia aa thiit yiu trong CP, aa/ME, su tucmg tac giua cac aa vdi nhau, miic cac aa thich hpp cho ga thit trong khiu phin, ma chii yiu dua vao cac ty le lysine, methionine + cystine, threonine va ty le giiia chiing. Lysine cdn dupc quan tam nghien ciiu trong mdi quan he vdi protein thd, nhu mdt vai trd trpng tam de can ddi cac axit amin.
Cac mdi quan he tren thay ddi khac nhau trong dieu kien chan nudi khac nhau, gidng ga khac nhau, giai doan nudi khac nhau. Nhin chung, ME/CP (kcal/%) thap nhit la khoang 121 d giai doan khdi ddng, cao nhit la khoang 178 d giai doan ket thiic. Miic lysme (g)/MB (Meal) ddi vdi ga broiler gidng Hubbard, Cobb va Ross lan lupt dupc khuyin cao
ISSN 0866-7594.2t}19JoumalofSaen(£.Vol.XV1.Allrrghtsiesened.
TAP c m KHOA HOC SO 16 124 www.hm.edu.vn
la 2,47, 2,68 va 2,80. De giam CP tu 23, 22, 20% xuong cdn 20, 19 va 17% d giai doan khdi ddng, smh trudng va kit thiic thi yeu ciu ty 1$ lysine tieu hda trong khiu phin la 1,10, 1,02 va 0,90% (ddi vdi ga thit Hubbard). Chan nuoi tt-ong diiu kien nhiet do cao, lysine trong khau phan phai cao hon so vdi nhiet do thich hgp.
Neu chiing ta van dung t6t cac kit qua n ^ e n cuu, khuyin cao tien, se gdp phan nang cao hieu qua ttong chan nuoi ga thit.
TAI LIfU THAM KHAO
/. Tdi lieu Tieng Vift
Hd Trung Thdng, Le Van An, Nguyen Thi Lgc, D6 Quy Hai, Cao Dang Nguyen (2006), Gido trinh Hda Sinh dpng vat, Nxb. Ndng Nghiep.
Le E)uc Ngoan (2002), Gido tiinh dinh duang ^a sue, Nxb. Ndng nghiep. Ha Npi.
Le E)uc Ngoan, Du Thanh HJng (2014), Gido trinh dinh duong vdt nudi, Nxb. Dai hgc Hue.
Nguyen Duy Hoan (2010), Binh duang protein gia cdm. Nxb. Dai hgc Thai Nguyen.
Nguyen Bdc Hung (2006), Gido trinh Chdn nudi gia cdm, Nxb. Ndng n ^ e p . Ha Npi.
Tu Quang Hien, Tr§n Van Phimg, Phan Dinh Tham, Tran Thanh Van, Tir Trung KiSn (2013), Dinh duang vd thicc dn chdn nudi - Tdi lieu ditng cho ddo tgo Tien sT, Nxb.
Ndng nghiep. Ha Npi.
Tir Quang Hien, Phan Dinh Tham (2002), Gido trinh thuc dn vd dinh duang dpng vdt - hi cao hpc, Nxb. Ndng nghiep. Ha Ngi.
IL Tdilifu Hing Anh
Ba^el R. D., Bradhan K. S. (1989), "Influence of energy, proteine and limiting amino acid levels on live weight, meats yield and processing losses in broiler during cold season", Indian J.
Nub-., VoL 6, No. 3, pp. 255 - 258.
Christian Wecke, Anja Pastor, Frank Liebert (2016), "Vedidation of Ihe lysine requirement as reference amino add for ideal in-feed amino acid ratios in modem &st growing meat - type chickens", Open Jourrml of Animal Sciences,"Wol. 6, pp.185-194.
Haunshi S., Panda A. K.,Rajkumar U.,Padhi M. K.,Niranjan M., Chatterjee R. N., (2012),
"Effect of feeding different levels of energy and protein on performance of Aseel breed of chicken during juvenile phase", US National Library of Medicine National Instimtes of Health. Trop. Anim. Health Prod., Vol. 44, pp. 1653 -1658.
Ji Hyuk Kim (2014), "Effect of protein: Lj^ine ratio on energy and nittogen metabolism in broiler chickens", IntemationalJoumal ofPoultiy Science, Vol. 13, No. 7, pp. 421- 428.
Kamian Z., Sarwar M., Nisa M., Nadeem M. A., Mahmood S., Babar M. E., Ahmed S. (2008),
"Effect of low-protein diets having constant energy-to-protein ratio on performance and
ISSN 0866-7594,2019 Journal of Science, Vol. XVI. WI nghts reserved.
caicass characteristics of broiler chickens from one to thirty-five days of age", US National Library of Medicine National Institutes of Health, Poult. Sci., 2008 Mar, pp. 468 -474.
Kamran Z., Nisa M. U., Nadeem M. A., Sarwar M., Amjid S. S., Pasha R. H. and Nazu S.
(2011), "Effect of low cmde protein diets with constant metabolizable energy on performance of broiler chickens irom one to thirty-five days of age", Indian Journal of Animal Sciences, Vol. 81, No. 11, pp. 1165 -1172
Leeson S., Summers J. D. (2008), "Feeding programs for broiler breeders", Cotnmercial Poultry Nutrition, Nottingham, England 2008, pp. 302.
Lqbal Z., Mughal A., Kamran Z., Ali A., Ahsan U. (2014), "Effect of constant ME: CP at different levels of CP and ME on growth performance and meat characteristics of broilers from 1-28 days", Archiva Zootechnica, Vol. 17, No. 2, pp. 43 - 53.
Mbajiorgu C. A., Ng'ambi J. W., Norris D. (2011), "Effect of varying dietary energy to protein ration level on growth and productivity of indigenous Venda chickens", Asian Journal of Animal and Veterinary Advances, VoL 6, No. 4, pp. 344 - 352.
Moosavi M., Chaji boujarpour M., Rahimnahal S., Kazemi A. R. (2012), "Effect of different levels of energy and protein with constant ratio on performance and carcass characteristics in broiler chickens", Intemational Research Journal of Applied and Basic Sciences. Vol. 3, No. 12, pp. 2485 - 2488.
Ng'ambi J. W., Maoba S. M., Norris D., Malatje M. S., Mbajiorgu C. A. (2009), "Effect of dietary lysine to crude protein ratio on performance of male Ross 308 broiler chickens", Tropical Animal Health and Production, Vol. 41, pp. 11 - 16 NRC - National Reseach Council (1994), Nutrition requerements of poultry, 9" revised
adition. National Academy press, Washington D.C.
Querubin L. J., Alcantara P. F., Pagaspas V. O., AreUano L. Z. (1989), "Amino acid supplementation of low protein and high copra meal diets of starter and finisher broiler dief, Amimal Husbrandy and Agricultural journal (Philippines). Vol. 22, No. 11, pp. 28-44.
Usama Aftab, Muhammad Ashraf, Abdul Samad Mumtaz and ZMrong Jiang (2007),
"Lysine requirement of broiler chickens fed low -density diets under tropical conditions". Association of Production Societies, The Asian - Australasian, Asian- Aust. J. Anim. Sci., Vol. 20, No. 6, pp. 939 - 943.
ISSN 0866-7594.2019JoumalofSdent«, Vol XVI All righls reserved.
