Ảnh Hưởng Của Các Mức Năng Lượng Trao Đổi Và Một Số Acid Amin Thiết Yếu Lên Sinh Trưởng Và Chất Lượng Thân Thịt Của Gà H’Mông

1

Chng 1: M U

1.1 Tnh cp thit ca lun n

G l i tng khng th tch ri ngnh chn nui ti Vit Nam, trong

g nui th vn lun gi v tr quan trng trong pht trin kinh t ca h ngho

(ng Th Hnh, 1999) [65] v chi ph u t cho h thng chn nui ny tng

i thp (Okitoi et al., 2007) [173]. Trong cc ging g nui th vn ca Vit

Nam, g Hmng thuc nhm g c da, tht v xng en (V Quang Ninh, 2001

[233]; o L Hng, 2001 [64]; Ng Kim Cc v ctv., 2002 [157]; Dng Th

Anh o v ctv., 2011 [64]) v tht g c gi tr dinh dng cao v ngt nh hm

lng axit amin cao (Lng Th Hng v ctv., 2007 [129]). G Hmng c

nui BSCL t nm 2007 trn 6.000 con ti tnh Tin Giang v Vnh Long (H

Lm, 2011) [90], ch yu bng phng thc chn th hoc bn chn th. Hn na

tht g Hmng c nh gi l ngon v ngt (Trn Trng Trung, 2011 [226];

H Lm, 2011 [90]).

Nng lng trao i v axit amin trong khu phn nh hng chnh n sinh

trng v pht trin ca g. ng thi vic b sung protein vo khu phn mang

hiu qu l nh s cn i cc axit amin. C th ch tng hp protein t mu axit

amin cn i, b sung axit amin gii hn to s cn i (L c Ngoan v ctv,

2004) [119]. Trong khi, axit amin l n v nh nht tng hp nn protein (Fuller,

2004) [75], nn n l thnh phn nh hng n sinh trng ca g. Ngy nay,

bng axit amin l tng theo lysine c s dng rng ri trong cng thc khu

phn ca g (Baker, 1997 [16]; Mack et al., 1999 [131]; Baker et al., 2002 [18]).

Khi gim protein th v b sung axit amin vo khu phn h tr tt cho tiu

th thc n v tng trng ca g tht (Yamazaki et al., 1998 [244]; Aletor et al.,

2000 [7]). Hn na, nng lng trao i v axit amin khc nhau nh hng

n sinh trng v cht lng tht (Arajo et al., 2005 [11]; Corzo et al., 2005

[42]). Do nng lng trao i v axit amin lin quan khng ch n tng giai

on pht trin v sn xut ca g m cn nh hng n cht lng tht.

Chi ph thc n nui g chim 60 - 90 % tng chi ph sn xut (Gunaratne et

al., 1992) [78], nn li nhun thu c ph thuc ln vo chi ph thc n. Hn

na, cc nh my ch bin thc n chn nui nhp khu trn 3,7 triu tn

nguyn liu/nm (Mai Hng, 2013) [133]. Do tng li nhun cho ngi

nui th nn tn dng thc n c sn ca a phng v kt hp vi chn th.

2

Ngoi ra, nghin cu nh gi nh hng ca nng lng trao i v axit

amin trong khu phn ln sc sn xut v cht lng tht g Hmng cha c.

Hn na, kt qu thc hin ti ny s to thm nhng la chn mi v ging

v phng thc nui g th vn ti BSCL.

1.2 Mc tiu ca lun n

Xy dng khu phn n thch hp da trn nhu cu nng lng trao i v

lysine v xc nh phng thc nui thch hp trong tng ma cho g Hmng

nui BSCL.

Mc tiu c th:

Xc nh nh hng ca cc mc nng lng trao i v lysine ln sc sn

xut tht ca g Hmng qua tng giai on sinh trng.

Xc nh nh hng ca cc khu phn ln sc sn xut v cht lng tht

g Hmng.

Xc nh nh hng ca phng thc v ma v nui ln sc sn xut v

cht lng tht g Hmng.

1.3 i tng v phm vi nghin cu

Nghin cu g Hmng c nui tht ti tnh Tr Vinh vi phm vi gm:

- Nghin cu nh hng ca nng lng trao i v lysine ln sc sn xut

ca g Hmng nui tht t 0 n 14 tun tui;

- Nghin cu nh hng ca khu phn khc nhau ln sc sn xut v cht

lng thn tht ca g Hmng t 0 n 14 tun tui;

- Nghin cu nh hng ca phng thc nui v ma v ln sc sn xut v

cht lng thn tht ca g Hmng t 5 n 9 tun tui.

1.4 Nhng ng gp mi ca lun n

1. Mc nng lng trao i v lysine tt nht trong khu phn nui g

Hmng tht giai on 0-4; 5-9; 10-14 ln lt l 3.000 v 1,1%; 3.000 v 1,0%;

3.100 kcal/kg thc n v 0,85%.

2. Xc nh c nh hng ca phng thc v ma v nui g Hmng

cho sc sn xut v cht lng tht ti BSCL.

3

Chng 2: TNG QUAN TI LIU

2.1. V tr a l, kh hu v t ai ca tnh Tr Vinh

Tr Vinh l tnh nm trong khu vc Ty Nam b ca Vit Nam, pha ng

gip bin ng, pha Ty gip tnh Vnh Long, pha Nam gip tnh Sc Trng,

pha Bc gip tnh Bn Tre (Cng thng tin in t tnh Tr Vinh, 2013) [39]. Tr

Vinh thuc na Bn cu Bc, ma kh ko di t thng 10 n thng 3 nm sau

v ma ma t thng 4 n thng 9 (Wikipedia, 2013a) [242].

Din tch t nhin l 2.341 km2, c bao bc bi sng Tin v sng Hu,

c 65 km b bin. Tr Vinh nm trong vng nhit i c kh hu mt m quanh

nm, nhit trung bnh 26-270C, m trung bnh 83-85%, lng ma trung

bnh 1.500 mm, t b nh hng bi bo l. Din tch t nng nghip l 185 ngn

ha, t nng thn l 3.845 ha, t cha s dng l 900 ha. t ct ging ton

tnh chim 6,62% (Cng thng tin in t tnh Tr Vinh, 2013) [39].

Hnh 2.1: Bn a l hnh chnh ca tnh Tr Vinh

Nh vy, vi din tch t ging ct chim 6,62% v t nng nghip chim

t l ln nn vic pht trin g th vn theo phng thc chn th hoc bn chn

th trn a bn tnh l hon ton c th.

2.2 Tnh hnh chn nui g th vn BSCL

Nui g chn th pht trin khp mi vng nng thn v n g th vn

chim 65-70% tng n g c nc (L Hng Mn, 2002) [120]. Ging g th

vn c nui bng 3 phng thc nh nui th hon ton, nui bn chn th v

nui nht hon ton (Dng Thanh Lim, 2003) [62]. Kt qu phn tch ca

Nguyn Quc Nghi v ctv. (2011) [162] cho thy nui g th vn bn cng

4

nghip BSCL mang li hiu qu kinh t kh cao cho ngi nui v cn m

rng qui m sn xut tng thu nhp cho nng h.

Ging g th vn c nui ph bin BSCL bao gm g Tu Vng, g

Ni, g c, g Tre, g Tam Hong, g Lng Phng, trong ging g Ni

c ngi dn nui nhiu nht (Nguyn Vn Quyn, 2008c) [170]. Nhng h

nui bn chn th vi qui m nh chn mua con ging ti a phng, cn h

nui vi qui m ln th chn con ging ti cc Trung tm sn xut con ging

(Nguyn Quc Nghi v ctv., 2011) [162]. Mt trong cc ging g bn a c

chn nui theo phng thc th vn cc a phng min Bc l g H'mng.

G Hmng cha gen qu v tht c gi tr dinh dng cao v ngt nh hm

lng axit amin cao (Lng Th Hng v ctv., 2007) [129].

Nm 2000, Chu Khi (2010) [36] cho bit kinh ph ca d n "Bo tn cc

ging vt nui c vn gen qu him ti Vit Nam", TS. V Vn S ch tr

ti v Vin Chn nui nui thch nghi thnh cng ging g Hmng ti H

Ni. Nm 2003 B Nng nghip - Pht trin nng thn giao Vin Chn nui

thc hin d n Hon thin quy trnh cng ngh chn nui vt Bu Qu v g

Hmng, sau ging g Hmng c lit vo danh sch nui gi ging gc.

X C Ni (huyn Ht Lt - Sn La) nhn t Vin Chn nui 1.000 con ging

g Hmng, a vo chn nui theo hng hng ho. Cng ty Ging vt nui qu

him H Khnh (thn Thi Thng, x Vnh Thi, thnh ph Nha Trang) ang lin

kt vi nng dn Nha Trang, chn nui bao tiu sn phm ging g Hmng,

vi quy m n hin ti 70.000 con. Cng ty TNHH Lc Ho (x Tin Xun,

Lng Sn, Ho Bnh) hin lin kt vi 20 h nng dn nui g H'mng, quy m

n 30 ngn con. Mi h nng dn chn nui gia cng cho Cng ty 1.000 - 2.000

con. Ti BSCL, g Hmng c nui t nm 2010 ti tnh Tin Giang v Vnh

Long, g d nui v t l hao ht thp (Trn Trng Trung, 2011) [226] v sau

lan dn sang nhiu tnh khc. Nh vy, g Hmng hin nay c nui rng ri t

Bc vo Nam.

Thc n c s dng nui g th vn ti BSCL c 3 ngun nh thc n

nguyn liu ca a phng, thc n cng nghip v thc n c sn trong vn.

Thc n c sn trong vn gm cc loi ht, cc loi c ti, cc loi su b v

cn trng (Nguyn Hu Tnh, 1999) [160]. Tm go c nng h s dng

nui g Ni con v la nguyn ht c dng nui g gi, g trng thnh v

g sinh sn (Nguyn Vn Quyn, 2008c) [170]. Kt qu nghin cu ca V

5

Anh Khoa v Nguyn Minh Thng (2012) [66] cho thy hu ht thc n cng

nghip ang c ngoi th trng u p ng nhu cu dinh dng cho g Tu

Vng giai on m, t l nui sng ca g 1-4 tun tui vi cc loi thc n cng

nghip khng khc bit v t t l 97,92%.

T l nhim bnh trn g nui th hon ton l 75%, cao hn g nui bn

chn th 69,23% v nui nht hon ton 36,57%. Nguyn nhn g nui th hon

ton mc bnh cao l do g c th t kim thc n nn nguy c nhim mm

bnh t mi trng bn ngoi cao (H Th Vit Thu, 2012) [91]. Mt trong nhng

loi bnh nguy him l bnh Newcastle, bnh ny c lu hnh t lu v sut t

Bc n Nam (Nguyn Vnh Phc v ctv., 1978) [172]. Mt s nghin cu

BSCL cng cho thy t l mc bnh Newcastle nhng n g khng c tim

phng l rt cao: 58% An Giang (Mai Hong Vit, 1998) [132] v 47,4%

ng Thp (Dng Ngha Quc, 2007) [60].

G c nui th vn chim khong 70% trong ngnh chn nui g v n

ng gp ln vo pht trin kinh t ca t nc. Hn na, g th vn ca Vit

Nam c ngun gen a dng v tht g th vn p ng c th hiu ca ngi

tiu dng v ph hp vi m thc ca ngi Vit. Trong khi chi ph thc n

chim 60-90% tng chi ph sn xut g th vn (Gunaratne et al., 1992) [78]. V

vy nng cao hiu qu nui g th vn ti BSCL cn phi gim chi ph thc

n bng nhiu cch khc nhau nh: (1) Tn dng thc n c sn trong vn nh

cn trng, cc loi ht v cy c. ng thi th g vi mt thch hp m

bo ngun thc n c sn trong vn c th ti sinh. Tng cng trng cy n tri

to bng mt cho g v trng thm rau v c lm thc n xanh. Hn na, to

h thc vt phong ph s to iu kin tt cho cn trng v cc ng vt khc

pht trin. (2) B sung axit amin tng hp vo khu phn t cc ngun thc n c

sn ca a phng nhm nng cao hiu qu s dng protein th ca khu phn,

qua nng cao hiu sut s dng thc n ca g v gim chi ph.

2.3 c im v kh nng sn xut ca g Hmng

G Hmng thuc ging g th vn ni a, c ngun gc vng ni pha

Bc, c nui theo phng thc truyn thng v chim t l 13-14% trong c

cu n g ti cc huyn vng ni ca tnh H Giang (Trn Thanh Vn v ctv.,

2006) [222]. G thuc nhm g da, tht v xng en (V Quang Ninh, 2001

[233]; o L Hng, 2001 [64]; Dng Th Anh o v ctv., 2011 [63]). Hn

na, tht g Hmng c gi tr dinh dng cao v ngt nh hm lng axit amin

6

cao (Lng Th Hng v ctv., 2007) [129]. Bn cnh , g Hmng cn cha

gen qu ca ging g bn a v hin nay c Vin Chn nui nui gi qu gen

v sn xut ging a xung vng ng bng nui tp trung cung cp thc

phm cho con ngi.

G Hmng mi n c 4 mu lng chnh l en tuyn, tro, vng rm v

trng (Dng Th Anh o v ctv., 2011) [63]. Lc trng thnh g c mu sc

a dng, trong mu lng xm chim t l 34,1%, mu en 16,6% v mu vng

rm 3,4%, khi lng c th lc 12 tun tui l 942 g/con v lc 24 tun t

1.820 g/con trng v 1.400 g/con mi (Trn Thanh Vn v ctv., 2006) [222]. Theo

Dng Th Anh o v ctv. (2011) [63] cho bit g trng thnh khi nui trn 12

thng th con trng c tm vc cao to, dng hng dng, nhanh nhn v khi lng

c th t trn 3 kg, cn g mi c tm vc trung bnh, khi lng t 2,5-2,6 kg;

100% g c mo c, mu en hoc thm; chn en chim trn 90%, chn vng

chim 5-10%; chn c 4 ngn chim 98%, mt s t c 5 ngn, chn c lng

chim 5-10%; b lng dy, mt, mu sc lng a dng, ui di v vnh.

Tiu tn thc n cho 1 kg tng khi lng c th l 3,3 kg, t l nui sng

trn 92%, thch nghi tt vi iu kin kh hu ca Vit Nam v tui trng u

tin khong 135-140 ngy (Dng Th Anh o v ctv., 2011) [63]. G H'mng

lng en nui nht 3 tun u sau nui th cho thy g thch nghi vi iu

kin nui bn chn th ti nng h, sau 12 tun tui t l nui sng t 85,84%,

c tnh sinh dc th cp hot ng sm, khi lng c th t 1.206 g v tiu

tn thc n/kg tng khi lng c th l 3,54 kg (Trn Thanh Vn, 2005) [221].

G Hmng rt hu n, bn tnh chm ch v chu kh bi tm thc n; khi

ng g rt c, u chi xung, bng p xung nn v 2 cnh khp; hiu ng v

nhy cm, c bit nhy cm vi tn hiu m thanh v mu sc, g hung d v

hiu chin (Dng Th Anh o v ctv., 2011 [63]; o L Hng, 2001 [64]).

Hnh vi tranh ginh con mi, gh mi, cng hot ng sinh dc v trng

din ra vo cc thi im khc nhau trong ngy, nhng biu hin i p ca g

Hmng khng cao (Dng Th Anh o v ctv., 2011) [63].

G Hmng c nui min Nam t nhng nm 2007 ly tht cung cp

cho con ngi. y l ging g thch nghi lu i ti vng ni cao, nhng c

Vin Chn nui Quc gia nh gi l c kh nng thch nghi tt ti vng ng

bng pha Bc v pht trin c cc tnh min ng v min Ty Nam B.

Tuy nhin, vic nghin cu v nh hng ca nng lng trao i v axit amin

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ln kh nng sinh trng v sn xut ca g Hmng v vic nh gi kh nng

sinh trng v cht lng tht g Hmng vi cc phng thc nui v ma v ti

vng BSCL cn hn ch. Hn na, nng lng trao i v hm lng mt s

axit amin thit yu trong khu phn c nh gi l nh hng n kh nng

sinh trng v cht lng thn tht ca ging g cng nghip. V vy, nghin cu

ny nhm lm r hn s nh hng ca nng lng trao i v mt s axit amin

thit yu khc nhau trong khu phn ln kh nng sinh trng v cht lng thn

tht ca g Hmng.

2.4 nh hng ca nng lng trao i v axit amin khu phn ln

sinh trng v cht lng tht g

2.4.1 nh hng ca nng lng khu phn ln tiu th thc n ca g

Nng lng cn thit cho cc hot ng sng ca c th g bao gm nng

lng phc v cho cc hot ng tiu ha, tun hon, h hp, hot ng sinh sn,

bi tit v qu trnh trao i cht. C th g cn nng lng t protein, lipid v

carbohydrate trong thc n duy tr s sng v tch ly li trong c th, trong

carbohydrate cung cp nng lng chim t l 40-60% (V B Th, 1996) [231].

Khi xy dng khu phn cho g th mc nng lng trong khu phn l yu

t c quan tm u tin, v n nh hng trc tip n s tiu th thc n. Hn

na, cng phi ch n t l gia nng lng v protein hoc t l gia nng

lng v axit amin. Theo Dng Thanh Lim (2003) [62] cho bit vic t hp

khu phn thc n cho g nu tha protein hoc mt cn i axit amin u dn

n s khai thc nng lng trong thc n khng hiu qu. Ngoi ra, vic xc

nh mc nng lng trao i ti thiu trong khu phn thc n ca g cng c

cn c vo tc sinh trng ca chng v c trnh by Bng 2.1.

Bng 2.1: Nhu cu nng lng trao i ca g theo tc sinh trng

Tc sinh trng Mc nng lng trao i ti thiu, kcal/kg thc n

Nng lng trao i Nng lng tiu ha

Mc cao 3.000 3.200

Mc trung bnh 2.750-3.000 2.970-3.200

Mc thp 2.750 2.970

nng sut g t ti u trn lng thc n c tiu th, th nhu cu

nng lng trao i cho g tht cng nghip cc giai on theo tiu chun NRC

8

(1984) [154] l 3.011 kcal/kg thc n. Tuy nhin, i vi g Ni nui tht cc

giai on tui th nhu cu nng lng trao i cho tng trng ti u l 2.900

kcal/kg thc n (Nguyn Vn Quyn v V Vn Sn, 2008a [168]; 2008b [169]).

Lng n vo ca g tng quan nghch vi mc nng lng trao i khu

phn, chng hn g s tiu th nhiu thc n hn vi khu phn thp nng lng,

ngc li g tiu th t thc n hn vi khu phn cao nng lng (Summers,

2000) [212]. Kt qu nghin cu ca Brue and Latshaw (1985) [28] cng cho

thy g gi nui tht tiu th nhiu nng lng hn khi n khu phn nng lng

cao so vi g c nui bng khu phn nng lng t thp ti va. Bn cnh ,

g c th t iu chnh nng lng n vo nhng khng chnh xc, nn khi n

khu phn cao nng lng g s tch ly m trong c th, t lng n vo

gim dn n thiu dng cht v gim tng trng (NRC, 1994) [155]. Theo Bi

c Lng v L Hng Mn (2001) [30] cho bit nng lng khng b bi thi ra

ngoi khi lng tiu th ca g d tha m nng lng c tch ly vo c th.

Tuy nhin g tht iu ha lng n vo chnh xc hn khi c nui bng khu

phn nng lng thp (Latshaw et al., 1990) [117].

Khu phn ca g nui tht chn th vn theo khuyn co ca Trn Cng

Xun v ctv (1999) [220] th mc nng lng trao i l 3.100 kcal/kg thc n

cho nng sut tt nht. ng thi, tc gi Nguyn B Thuyn (1998) [158]

ngh s dng khu phn c hm lng dinh dng cho g Ta Vng nui thnh

ph H Ch Minh vi nng lng trao i l 3.000 kcal/kg thc n. Do , vic

nghin cu mc nng lng trao i trong khu phn ca g Hmng nui tht t

3.000 kcal/kg thc n tr ln l iu cn thit.

2.4.2 nh hng ca axit amin thit yu ln sinh trng v cht lng

tht g

2.4.2.1 Axit amin thit yu

Axit amin l acid hu c, n v nh nht tng hp nn protein v c

cu to bi carbon, hydro, oxy, nit, mt s axit amin cn cha lu hunh v

selen (Fuller, 2004) [75]. C 20 loi axit amin tham gia vo qu trnh sinh tng

hp protein trong c th g v v chc nng sinh l th tt c u quan trng. Tuy

nhin, cc loi axit amin ny c chia thnh 2 nhm l axit amin thit yu v

axit amin khng thit yu. Axit amin thit yu l cc axit amin phi c cung

cp t thc n, cn axit amin khng thit yu l axit amin m c th c th tng

9

hp t cc axit amin khc (DMello, 2003a) [56]. Ngoi ra, cc axit amin thit

yu c trong thc n vi t l so vi nhu cu thp nht bn cnh cc axit amin

thit yu khc, n quyt nh mc tng hp protein trong c th g l axit

amin gii hn (Dng Thanh Lim v ctv., 2002) [61]. V vy khi xy dng khu

phn cho g phi m bo cung cp y v cn i cc axit amin thit yu.

C th g cn 12 axit amin thit yu, trong lysine l axit amin thit yu

c quan tm u tin (Dng Thanh Lim v ctv., 2002) [61]. Mt s axit amin

thit yu c th chuyn ha cho nhau nh methionine c th chuyn ha thnh

cystein v cystin nhng khng th chuyn ha ngc li (Baker, 1976) [14]. Do

nhu cu methionine ch c tha mn bng methionine v methionine ti

thiu phi chim 40-60% so vi tng s methionine + cystin (Dng Thanh Lim

v ctv., 2002) [61]. Ngoi ra, phenylalanin c th chuyn ha thnh tyrosine

(Sasse and Baker, 1972) [193], nhng s chuyn ha ngc li chim t l rt nh

(Ishibashi, 1972) [98]. Theo Dng Thanh Lim v ctv. (2002) [61] th tyrosine

phi chim 46% tng s ca phenylalanin + tyrosin.

2.4.2.2 Bng axit amin l tng v nhu cu axit amin ca g tht

Hin nay, bng axit amin l tng theo lysine c s dng xy dng

cng thc khu phn cho g (Baker and Han, 1994 [15]; NRC, 1994 [155]; Baker,

1997 [16]; Emmert and Baker, 1997 [69]; Mack et al., 1999 [131]; Baker et al.,

2002 [18]). Bng axit amin l tng khng phi l nhu cu axit amin, m l t l

axit amin khng thay i khi protein trong khu phn thay i. V vy, khi nhu

cu axit amin ca g thay i th phi tun theo bng axit amin l tng lysine.

Theo Mack et al. (1999) [131] xc nh bng axit amin l tng chnh

xc cn lu : th nghim phi s dng khu phn c bn ging nhau, g v giai

on th nghim ging nhau; bit kh nng tiu ha axit amin thc s ca khu

phn c bn; phn loi axit amin r rng gii hn axit amin c nghin cu;

mc tiu v qui trnh r rng d on nhu cu mi axit amin. Bng axit amin

l tng theo lysine xy dng khu phn cho g c trnh by Bng 2.2.

Bng axit amin l tng theo lysine ca Baker (1997) [16] c hiu chnh

mt phn t kt qu ca Baker and Han (1994) [15], t l ny c so snh vi

kt qu ca NRC (1994) [155] v mt s t l da vo s liu ca Han and

Baker (1994) [82]. Tuy nhin, nu cn c vo bng axit amin l tng ny th nhu

cu lysine duy tr cao hn so vi cc kt qu trc ca Edwards and Baker

10

(1999) [68]. Emmert and Baker (1997) [69] ngh khng thay i t l

tryptophan v axit amin c gc lu hunh i vi g tht tun 6, 8 hay 10 v t l

threonine:lysine ny tng nh khi g ln dn. Tuy nhin, kt qu nghin cu ca

Salehifar et al. (2012) [191] cho thy tng trng ca g tht giai on 29-42 ngy

tui tng khi t l cc axit amin so vi lysine tng mc nh leucine:lysine

(144:100), isoleucine:lysine (75:100), methionine:lysine (48:100), valin:lysine

(85:100) v met+cys:lys (81:100). Tng t, Mack et al. (1999) [131] yu cu t

l methionine+cystin so vi lysine cho g tht thp nht l 77:100.

Bng 2.2: Bng axit amin l tng theo lysine trong khu phn ca g

Axit amin Baker (1997) [16]

NRC (1994) [155]

Mack et al. (1999) [131]

Baker et al. (2002) [18]

Lysine 100 100 100 100

Methionine 36 42 - -

Cystine 36 33 - -

SAA 72 75 70 -

Threonine 67 67 59 56

Valine 77 75 76 78

Isoleucin 67 67 66 61

Leucine 109 100 - -

Tryptophan 16 17 17 17

Arginin 105 104 104 105

Histidine 35 29 - -

Phe + tyr 105 112 - -

Ch thch: SAA: axit amin cha lu hunh; Phe + tyr: phenylalanin + tyrosine.

Nhu cu axit amin duy tr khc vi nhu cu axit amin cho tng trng ti u

g tht. Nhu cu axit amin cho duy tr hng ngy thp giai on g con, sau

nhu cu ny tng dn khi g tht ln dn ln. Hn na, mi dng g tht c t l

tng trng v thnh phn thn tht khc nhau th nhu cu axit amin cng khc

nhau. Nhu cu lysine ca g tht theo khuyn co ca NRC (1994) [155] giai

on 0-3; 3-6 v 6-8 tun tui ln lt l 11; 10 v 8,5g/kg thc n. Tuy nhin

hm lng axit amin trong khu phn nui g tht trong nhng nm gn y

c nng ln v c trnh by Bng 2.3.

11

Bng 2.3: Hm lng axit amin trong khu phn g tht t nm 2001 n 2006

Hm lng protein th v axit amin

Nm CP (%) Lys (%) Met (%) Met+Cys (%) Thr (%)

Giai on g m

2001 22,4 1,20 0,51 0,87 0,83

2002 22,3 1,23 0,53 0,90 0,83

2003 22,0 1,26 0,53 0,88 0,83

2004 22,0 1,26 0,53 0,88 0,83

2005 22,3 1,28 0,54 0,89 0,85

2006 22,2 1,29 0,55 0,9 0,86

Giai on g gi

2001 20,9 1,12 0,50 0,86 0,76

2002 20,8 1,12 0,50 0,85 0,76

2003 20,2 1,12 0,48 0,84 0,75

2004 20,4 1,15 0,48 0,82 0,76

2005 20,6 1,17 0,50 0,84 0,77

2006 20,4 1,16 0,49 0,83 0,77

Giai on v bo

2001 19,8 1,02 0,42 0,77 0,73

2002 19,7 1,06 0,46 0,82 0,73

2003 19,2 1,06 0,46 0,80 0,71

2004 19,7 1,10 0,44 0,78 0,73

2005 19,8 1,10 0,48 0,81 0,73

2006 20,2 1,13 0,49 0,81 0,77

Ngun: Petri and Lemme (2007) [181].

Nhm nng cao hiu qu s dng thc n v kh nng sinh trng ca g

tht th vic cn bng axit amin trong khu phn s dng theo bng l tng

ca lysine. V vy, g Hmng s dng thc n hiu qu v cho nng sut cao

th vic cn bng axit amin trong khu phn cng tun theo t l lysine. Hn na,

hm lng lysine trong khu phn c th nghim mc s dng cho g cng

nghip nui tht theo di kh nng sinh trng ca g Hmng.

12

2.4.2.3 nh hng ca lysine trong khu phn ln thn tht v chuyn

ha thc n ca g tht

Lysine l axit amin thit yu v cng l axit amin gii hn u tin ca khu

phn g nn phi c cung cp t thc n (Wikipedia, 2013b) [243]. Hn na,

lysine c dng tnh theo bng axit amin l tng nn vic xc nh nhu cu

lysine phi c thc hin u tin v chnh xc (Baker, 2003) [19].

B sung lysine vo khu phn mc thp hay cao hn nhu cu u nh

hng n cht lng tht v h s chuyn ha thc n ca g. Chng hn khi b

sung lysine cao hn mc nhu cu s lm g ln nhanh hn (Leclercq, 1997) [125]

v c bit l nng sut tht c ca g tng (Hickling et al., 1990 [88]; Moran and

Bilgili, 1990 [148]). Tng t, Leclercq (1997) [125] cho bit b sung lysine 13

g/kg thc n trong khu phn cho g tht t 21-49 ngy tui lm gim h s

chuyn ha thc n cn 2,05 v lng m bng gim cn 26,7 g/kg thn tht. Tuy

nhin, g tht t 3-6 tun tui tng trng tt nht v m thp nht th nhu cu

lysine tng ng l 10,14 v 10,6 g/kg thc n (Han and Baker, 1994) [82].

Tesseraud et al. (1996) [217] cho bit khi gim lysine xung 7,7 g/kg thc n dn

n si c IIb gim do tng s phn gii ca loi c ny, tri li vi mc lysine

10,1 g/kg thc n th c I v IIb s t nh hng hn g 2, 3 v 4 tun tui. nh

hng ca vic b sung lysine ln nng sut v thnh phn thn tht ca g trng

tht 20-40 ngy tui c trnh by Bng 2.4.

Bng 2.4: nh hng ca vic b sung lysine ln nng sut v thnh phn

thn tht ca g trng tht 20-40 ngy tui

Lysine (g/kg TA)

Chuyn ha TA (g TA/1.000g TT)

Tht c (g/kg KLCT) M bng (g/kg KLCT)

8,0 1.982a 148,7a 25,4c

8,9 1.846b 159,5b 24,3bc

9,8 1.755cd 169,0c 22,4ab

10,7 1.796c 171,3c 20,4a

11,6 1.719cd 168,1c 20,4a

12,5 1.710d 170,3c 19,4a

Ngun: Leclercq (1997) [125]; Ch thch: TA: thc n, TT: tng trng, KLCT: khi lng c th.

Khi thiu lysine th tng trng ca g tht gim, nhng h s chuyn ha

thc n tng (Leclercq, 1997) [125], tri li khi tng lysine trong khu phn th

13

gim h s chuyn ha thc n do gim s tch ly m. Kt qu nghin cu ca

Leclercq (1997) [125] nu c nhu cu lysine cho g tht t 21-49 ngy tui

h s chuyn ha thc n t 2,03 l 10,07 g/kg khi lng c th tng thm.

Trong khi, nhu cu lysine ca g tht t 3-6 tun tui cho h s chuyn ha thc

n tt nht theo Han and Baker (1994) [82] l 11,55 g/kg. Theo phn tch ca

Leclercq (1997) [125] cho thy nhu cu lysine g tht t tng trng tt l 9,69

g/kg, nhng h s chuyn ha thc n gim th nhu cu lysine trong khu phn

l 11,84 g/kg thc n, nh vy nhu cu lysine ca g tht gim h s chuyn

ha thc n cao hn nhu cu lysine tng tng trng.

Trong khi g Hmng thuc nhm ging g th vn ca a phng,

nhng c nui ly tht, i hi tng trng nhanh v thn tht t cht lng

cao. Do c th s dng nhu cu lysine trong khu phn ca cc ging g

chuyn tht thm d trn ging g Hmng.

2.4.2.4 nh hng ca methionine v cystine trong khu phn ln thn

tht v chuyn ha thc n ca g tht

Methionine v cystine l axit amin thit yu c cha gc lu hunh, tham

gia vo qu trnh tng hp protein, ngoi ra methionine cn l axit amin cho

nhm metyl trong qu trnh trao i cht (DMello, 2003b) [57]. Nhu cu

methionine+cystine cho g tht giai on 0-3 tun tui l 9 g/kg thc n theo

NRC, (1994) [155] v Wadroup et al. (1979) [234]. i vi g tht giai on 3-6

tun tui th nhu cu methionine+cystine l 7,2g/kg thc n, giai on 6-8 tun

tui l 6 g/kg thc n (NRC, 1994) [155], cao hn mc ngh ca Boogaardt

and Baker (1973b) [25] v nhu cu methionine+cystine cho g tht giai on 6-8

tun tui l 5,1 g/kg thc n.

Kt qu nghin cu ca Dilger and Baker (2008) [49] cho bit khi b sung

0,8 g DL-methionine vo khu phn thiu methionine lm tng lng n vo t

15,7 g/ngy ln 27,6 g/ngy, t ci thin tng trng t 5,9 g/ngy ln 17,2

g/ngy g con cng nghip. B sung methionine vi cc mc 3,2; 3,8; 4,4 v 5

g/kg thc n ln g Ross 308 giai on 0-3 tun tui, mc d khng lm nh

hng n tng trng nhng chuyn ha thc n c ci thin khi methionine

tng dn (Kalinowski et al., 2003) [104]. Hn na, chuyn ha thc n c ci

thin r rt khi tng methionine trong khu phn n 5 g/kg thc n i vi g

Ross 308 giai on 3-6 tun tui. Schutte and Pack (1995a [197]; 1995b [198])

cng cho bit vi mc methionine 5 g/kg thc n trong khu phn lm hiu

14

qu s dng thc n v nng sut tht c tt nht g cng tui c nui

bng khu phn cha methionine thp hn.

Mc d methionine trong khu phn c th lm thay i s thy phn m

bng do enzym (Takahashi and Akiba, 1995) [215], nhng vic b sung y

axit amin cha lu hunh cho thy methionine nh hng ln hn s tc ng

ca enzym (Jensen et al., 1989 [101]; Mendonca and Jensen, 1989 [143]; Moran,

1994 [150]; Jeroch and Pack, 1995 [102]; Schutte and Pack, 1995a [197]). Hn

na, vic b sung methionine p ng nhu cu axit amin cha gc lu hunh

cho thy ci thin nng sut tht c cho g tht lc 6 tun tui (Hickling et al.,

1990 [88]; Schutte and Pack, 1995a [197]; b [198]; Huyghebaert and Pack, 1996

[97]). Kt qu nghin cu ca Kalinowski et al. (2003) [104] cho thy b sung

methionine 4,6 g/kg thc n lm cht lng tht g t 3-6 tun tui t ti u.

2.4.2.5 nh hng ca threonine trong khu phn ln thn tht v

chuyn ha thc n ca g tht

Threonine l axit amin gii hn th 3 sau lysine v methionine ca c th g

(Han et al., 1992 [81]; Fernandez et al., 1994 [74]; Kidd et al., 1997 [107]). Nhu

cu threonine ca g tht t 0-3 tun tui phn ln u thng nht l 8 g/kg thc

n (NRC, 1994) [155], cao hn nhu cu threonine theo cch tnh ca Baker

(2003) [19] mc 6,85 g/kg thc n v cng cao hn kt qu nghin cu ca

Kidd et al. (1997) [107]. M t threonine:lysine l tng theo Baker et al. (2002)

[18] l 56:100, thp hn kt qu c xc nh trc ca Baker (1997) [16]

l 67:100 v ca Mack et al. (1999) [131] l 59:100 i vi g t 20-40 ngy tui.

Do m t t l l tng ca threonine:lysine c ngh l di 60:100 cho

g tht t 0-40 ngy tui (Mack et al., 1999) [131].

G c b sung threonine lc 21-42 ngy tui mc 7,3-8,7 g/kg thc n

cho lng n vo v tng trng hng ngy cao hn khi ch b sung mc 5,2-6,6

g/kg thc n (Kidd et al., 2004) [112], ng thi chuyn ha thc n gim mc

threonine 6,6-8,7 g/kg thc n so vi mc threonine 5,2-5,9 g/kg thc n. Ngoi

ra, g c nui vi khu phn 7,3 g threonine/kg thc n cho khi lng tht c

v thn tht cao hn so vi khu phn cha threonine 5,2-6,6 g/kg thc n. Tuy

nhin, khi lng thn tht v tht c tng khi threonine khu phn tng t 5,2

ln 5,6 g/kg thc n. tng trng tt th threonine c b sung vo khu phn

mc 5,9 g/kg theo Mack et al. (1999) 131], mc 7 g/kg thc n theo Webel et

al. (1996) [239], Kidd and Kerr (1997) [108] v Penz et al. (1997) [178]. Trong

15

khi Kidd and Kerr (1997) [108] cho bit khi lng tht c tng dn vi mc

threonine t 7,8 g/kg thc n tr ln g 30-42 ngy tui. Tuy nhin, g 42-56

ngy tui th nhu cu threoninee cho tht c tt cao hn nhu cu threoninee cho

tng trng tt (Dozier et al., 2006) [58], trong khi Kidd et al. (1999) [110] v

Kidd et al. (2003) [111] khng ng vi nhn nh ny. Theo nghin cu ca

Kidd and Kerr (1997) [108] v Kidd et al., (1999) [110] cho thy nhu cu

threonine to m bng thp nht thp hn nhu cu threonine cho tng trng

cao nht. Hn na, i vi 2 khu phn u thiu threonine, nu khu phn no

c protein th thp th lng m bng ca g c nui bng khu phn thp

hn (Kidd et al., 1999) [110]. Kidd et al. (1999) [110] cn cho bit threonine l

axit amin ti hn cho s pht trin c c i vi g t 54 ngy tui tr ln.

2.4.3 Cc yu t nh hng n s p ng axit amin

S p ng axit amin ring bit ca g ang tng trng b nh hng bi

nhiu yu t bao gm nhit mi trng, stress, gii tnh, tui, ging g v

khu phn nui dng.

Hiu qu s dng lysine ca g trng t khi nui nhit 31,1C gim so

vi g nui nhit 20C (March and Biely, 1972) [134]. Hn na, phn ln g

con c nui nhit 31,1C tiu th thc n gim, do khu phn phi c

hm lng lysine cao hn b p cho lng n vo gim. i vi g 8-22

ngy tui, khi b stress nhit s lm tng trng v lng n vo gim khong 22%

v nhu cu lysine ca g mi tng nhng nhu cu ca g trng khng tng. G tht

21-42 ngy tui, khi nui nhit 25-33oC lm tng trng, lng n vo, tht

c v nng sut tht i gim, nhng h s chuyn ha thc n tng so vi g nui

nhit 21,1oC; tri li nu g nui nhit di 21,1oC lm tng lng n

vo v tng t l cht (Mendes et al., 1997) [142].

Ngoi ra, nhu cu lysine v axit amin c gc lu hunh ca g gi gim dn

sau khi g c tim khng nguyn theo kt qu nghin cu ca Klasing and

Barnes (1988) [113] nh: nhu cu lysine ca g c tim nc mui l 9,5 g/kg

thc n, trong khi g c tim khng nguyn th nhu cu lysine ch cn 7-9,5

g/kg thc n. Tuy nhin, nhu cu axit amin cho tng trng v hiu qu s dng

thc n khng th xc nh t nh hng ca stress min dch (Swain and Johri,

2000) [213]. Thiu axit amin s lm gim kh nng min dch ca g con nui

tht v khi a axit amin vo c th g s lm nh hng n p ng min dch

ch khng phi l nhu cu (Konashi et al., 2000) [114].

16

Lng axit amin trong khu phn ca g tht gim dn theo tui (NRC,

1994) [155], ph hp vi vi nhu cu axit amin ca g tht cng gim dn theo

tui (Behrends and Waibel, 1980) [23]. Tuy nhin, nhu cu lysine cho tng trng

cao nht l 4,62 g/kg protein g 14-28 v 42-56 ngy tui, nhng nhu cu axit

amin cha gc lu hunh gim t 3,05 g/kg protein g 14-28 ngy tui xung

2,56 g/kg protein g 42-56 ngy. Kt qu ca DMello (1983) [54] cho thy nhu

cu axit amin cha gc lu hunh ging g ty cng khc nhau theo tui.

nhng ging g khc nhau th nhu cu axit amin cng khc nhau, c bit

l nhu cu arginin ca g con nui tht l 12,5 g/kg thc n, cn g ty l 16 g/kg

thc n (NRC, 1994) [155]. S dng nhu cu arginin khc nhau cc ging t

c gii thch v thng c chp nhn theo qui lut chung (Nesheim, 1968)

[156]. Tuy nhin, nhu cu arginin nhng ging g tht thng phm khng khc

nhau (Wilburn and Fuller, 1975) [241]. T kt qu so snh nhu cu axit amin g

con nui tht v g ty con, DMello (1979) [53] cng ghi nhn c nhu cu axit

amin nhng ging g khc nhau l khc nhau. Tuy nhin nhu cu isoleucin v

valin g ty v g con ging nhau (DMello, 1975) [51] v nhu cu axit amin

cha gc lu hunh cng ging nhau 2 ging g ny (DMello, 1976) [52]. Bn

cnh , theo kt qu nghin cu ca Leclercq et al. (1997) [125] cho thy khng

phn bit c nhu cu axit amin gc lu hunh ca g tht t m v g tht nhiu

m, nhng g tht tch ly m t chuyn ha axit amin ny thnh protein hiu

qu hn v tng trng l yu t nh gi hiu qu ca axit amin cha gc lu

hunh c n vo. Hn na, nhu cu threonine l rt ging nhau 2 nhm g

ny (Alleman et al., 1999) [9], nhng lysine c s dng hiu qu hn nhm

g tht m thp (Tesseraud et al., 1996) [217].

Nng lng trao i l yu t iu ha lng n vo ca g tht ang sinh

trng. Kt qu nghin cu ca Boomgaardt and Baker (1973a) [24] cho thy

tng trng ca g tht thay i tng ng vi 3 mc nng lng trao i trong

khu phn, nhng hiu qu s dng axit amin cha gc lu hunh ca g khng

b nh hng bi nng lng trao i ca khu phn. Tht ra, nng lng trao i

khu phn ch nh hng thng qua s thay i lng n vo, m khng nh

hng n kh nng s dng axit amin (Boomgaardt and Baker, 1973a) [24].

Khu phn cn bng axit amin s lm gim lng n vo, trong khi hiu qu

s dng axit amin khng thay i (Harper and Rogers, 1965) [85]. Tuy nhin,

quan im trn vn cn nhiu tc gi nh Morris et al. (1987) [151]; Mendonca

17

and Jensen (1989) [143]; Abebe and Morris (1990) [2] cha chp nhn. Bi v khi

protein th trong khu phn tng t 140 g ln 280 g/kg thc n th hiu qu s

dng lysine gim, c bit khu phn cha hm lng protein th cao (260 g v

280 g/kg thc n). Ngoi ra, Abebe and Morris (1990) [2] cn cho rng y l

nh hng ca cn bng chung do axit amin c hp thu vt tri khi tiu ha

khu phn cha protein cao. Tuy nhin, nng sut sinh trng ca g con gim

thp khi c nui vi khu phn thiu lysine (DMello, 1990) [55], bn cnh

lng lysine n vo v tng trng c mi quan h tuyn tnh dng vi nhau.

2.4.4 nh hng ca axit amin tng hp ln nng sut g tht

Vic tn dng ngun thc n a phng pht trin g th vn l iu

cn thit, nhng thc n ny thng khim khuyt mt s axit amin thit yu, do

cn b sung axit amin tng hp vo khu phn ci thin hiu qu s dng

protein. Hn na, axit amin tng hp c gi tr sinh hc cao hn khi cc axit amin

c lin kt vi nhau (Izquierdo et al., 1988 [99]; Han et al., 1990 [79]; Chung

and Baker, 1992 [37]; Ciftci and Ceylan, 2004 [38]). Do , Izquierdo et al.

(1988) [99] v Chung and Baker (1992) [37] cho bit axit amin tng hp theo l

thuyt l c hp thu vo rut 100%. Han and Lee (2000) [84] cho bit axit

amin tng hp nh hng n tng trng ca g v ng vai tr quan trng trong

giai on 3-6 tun tui. Hn na, nui g bng khu phn cha axit amin thit

yu cn bng v y s lm gim lng nit tiu th/con/ngy (Han, 1996)

[83]. Hn na, nng sut g tht khng b nh hng bi hm lng protein th

ca khu phn khi b sung y lysine v methionine (Han and Lee, 2000) [84]

v b sung thm 0,1% lysine trong khu phn c th gim 2% lng protein th.

Theo Cho et al. (1996) [35], c th gim 3% lng protein th bng cch b sung

cho mi axit amin lysine, methionine, threonine v tryptophan vo khu phn

0,1%, s lm tng trng v hiu qu thc n c ci thin 1,6% v 15,6% giai

on 0-3 tun tui v giai on 3-6 tun tui l 2,1% v 0,4%. Nng sut g tht

tng t khi nui bng khu phn 22% hoc 18% protein th v c b sung

0,03% lysine v 0,13% methionine tng hp (Fancher and Jensen, 1989a [71];

1989b [72]). Trong khi , b sung methionine tng hp c th gim 2% protein

th khu phn (Summers et al., 1992) [211] v b sung lysine v methionine tng

hp th protein th c th c gim 4% (Summers and Leeson, 1984) [209].

Kt qu nghin cu ca Abdel-Maksoud et al. (2010) [1] cho thy protein

th trong khu phn l 21% c b sung axit amin tng hp thit yu t

18

protein th (21,68%), cho tng trng cao hn v hiu qu s dng thc n tt hn

khi nui g bng khu phn cha 23% protein th giai on 0-18 ngy tui. Kt

qu tng t, khi nui g bng khu phn cha 19% c b sung axit amin thit

yu t 21,4% protein th (Waldroup et al., 2005) [236] v nhiu nghin cu

cng cho kt qu tng t (Summers and Leeson, 1985 [210]; Schutte, 1987

[196]; Stillborn and Waldroup, 1989 [208]; Parr and Summers, 1991 [174]; Han

et al., 1992 [81]; Moran et al., 1992 [149]; Descherpper and de Groote, 1995

[48]). Ciftci and Ceylan (2004) [38] chng minh khi s dng khu phn (i

chng) c protein th 21,3% th nng sut g thu c giai on m thp hn

nui g bng khu phn vi protein th (19,13% v 17,97%) c b sung axit

amin tng hp protein th t bng vi khu phn i chng. Vic b sung

axit amin tng hp vo khu phn 21% protein th cho kt qu tt hn khu phn

23% protein th l do axit amin dng t do c trao i v hp thu tt hn

dng peptid (Bregendahl et al., 2002) [26].

Tiu th thc n ca g con c nui bng khu phn 23% protein th thp

hn so vi khu phn thp protein th c b sung axit amin tng hp (Parsons

and Baker, 1982 [175]; Nakhata and Anderson, 1982 [153]; Pesti and Fletcher,

1984 [180]; Fancher and Jensen, 1989b [72]; Aletor et al., 2000 [7]; Sklan and

Plavnik, 2002 [204]). Hn na, nui g bng khu phn thp protein c b sung

axit amin tng hp cho thy lng n vo tng (Aletor et al., 2000 [7];

Rosebrough and McMurtry, 1993 [190]; Fancher and Jensen, 1989a [71], 1989b

[72]; Rosebrough and Steele, 1985 [189]). Ngoi ra, tng tc gia protein th v

lysine khu phn cha 23% protein th v lysine cao lm tng khi lng c th

v hiu qu thc n giai on g m (Sterling, 2002) [207]. Nh vy, khi thm

axit amin tng hp vo khu phn thp protein th cho hiu qu cao hn khi b

sung protein cn bng axit amin trong khu phn (Hurwitz et al., 1998) [95].

Tuy nhin, Parsons and Baker (1982) [175]; Bregendahl et al. (2002) [26];

Si et al. (2004) [201]; Jiang et al. (2005) [103]; Waldroup et al. (2005) [236] cho

rng tng trng v hiu qu s dng thc n ca g gim khi n khu phn thp

protein th c b sung axit amin tng hp. iu ny, Aftab et al. (2006) [5] cho

rng khi b sung nhiu axit amin t do trong khu phn thp protein th lm tng

qu trnh d ha axit amin c. Do , axit amin tng hp ch c th thay th cho

protein th mc nht nh (Pinchasov et al., 1990) [184], trng hp protein

th qu thp th axit amin tng hp khng th b p cho khu phn. Vic b

19

sung axit amin tng hp vo khu phn chn nui g tht cho thy nng sut c

nng ln v c ng dng rng ri trn cc ging g nng sut cao. Tuy nhin

ti BSCL, vic nghin cu b sung axit amin tng hp thit yu trn cc ging

g th vn cn rt hn ch. Do , vic nghin cu b sung axit amin tng hp

thit yu vo khu phn nui g Hmng nhm nng cao nng sut sinh trng v

cht lng tht l cn thit.

2.4.5 nh hng ca nng lng trao i v axit amin khu phn ln

sinh trng v cht lng tht g

Nng lng trao i trong khu phn l yu t iu ha lng n vo

(Leeson et al., 1996 [127]; Dozier et al., 2006 [58]), nn mc nng lng trao i

trong khu phn s c nh hng n kh nng sinh trng ca g tht. Lng n

vo ca g gim sau khi thu nhn nhu cu nng lng. ng thi, g c kh

nng iu chnh lng n vo b p s thay i nng lng khu phn

(Dozier et al., 2006 [58]; Leeson et al., 1996 [127]).

Nhu cu nng lng ca g tht trn 44 ngy tui l trn 3.200 kcal ME/kg,

v khi nng lng khu phn mc 3.400-3.600 kcal/kg th lng n vo cng

tng (Arajo et al., 2005 [11]). Khi g c nui bng khu phn nng lng

thp (3.300 kcal nng lng trao i/kg thc n) cho tng trng thp, mc d

hiu qu chuyn ha ca nng lng vo c th cao hn (Summers and Leeson,

1984) [209]. Hn na, lng n vo ca g tht giai on v bo gim, nhng

chuyn ha thc n c ci thin khi nng lng trao i ca khu phn tng t

2.700 ln 3.300 kcal nng lng trao i/kg thc n (Leeson et al., 1996) [127].

Tng t, nng sut g tht khng nh hng khi tng nng lng khu phn t

2.600 ln 3.200 kcal/kg, mc d lng n vo gim nhng khi nng lng tng

ln ci thin chuyn ha thc n (Waldroup et al., 1990) [235]. Holsheimer

and Veerkamp (1992) [92] cho rng g tng trng cao hn 4,2% v chuyn ha

thc n ci thin 12,1% khi tng nng lng trao i. ng thi, nng sut g tht

trong giai on v bo tng tuyn tnh vi cc mc nng lng trong khu phn

3.200, 3.400 v 3.600 kcal nng lng trao i/kg (Pesti et al., 1983) [179].

Nghin cu ca Deaton et al. (1983) [47] v Holsheimer and Veerkamp

(1992) [92] cho thy khi tng nng lng trong khu phn th nng sut cc

phn thn tht khng tng, nhng t l m bng tng. Trong khi Jackson et al.

(1982) [100] cho rng tng nng lng trong khu phn dn n lng m bng

tng, nhng kt qu ca Griffiths et al. (1977) [77] cho thy lng m bng

20

khng tng. Leeson et al. (1996) [127] cho rng g tiu th nng lng thp hn

c khuynh hng tch ly m trong thn tht t hn. Mabray and Waldroup (1981)

[130] gii thch rng lng m cao l do t l nng lng so vi protein trong

khu phn l cao, mt cn bng axit amin v loi m c dng trong khu phn.

Nng lng trao i ca khu phn tng t 3.175 ln 3.310 kcal/kg lm

gim lng n vo v chuyn ha thc n g 30-59 ngy tui (Dozier et al.,

2006) [58], nhng khi lng c th, tng trng v t l sng st khng b nh

hng. Ngoi ra, nng lng trao i trong khu phn tng t 3.175 ln 3.220

kcal/kg khng lm nh hng n m bng hay nng sut tht c, nhng nng

lng tng t 3.220 ln 3.310 kcal/kg lm nh hng xu n nng sut tht c

(Dozier et al., 2006) [58]. Nui g tht bng khu phn nng lng trao i cao

ci thin c s chuyn ha thc n (Hidalgo et al., 2004 [89]; Leeson et al.,

1996 [127]; Cheng et al., 1997 [34]; Proudfoot and Hulan, 1987 [186];

McNaughton and Reece, 1982 [139], 1984 [140]; Griffiths et al., 1977 [77];

Sinurat and Balnave, 1985 [202]; Dale and Fuller, 1980 [45]). Tuy nhin, nui g

tht bng khu phn cha nng lng trao i 3.220 kcal/kg mang li hiu qu

kinh t (Dozier et al., 2006) [58].

Cho g tht n khu phn cao nng lng s gip nhit c th cao lm ci

thin nng sut (McNaughton and Reece, 1984 [140]; Dale and Fuller, 1980

[45]). Do , nhu cu nng lng trao i duy tr hot ng c th cn b nh

hng bi nhit mi trng (Hurwitz et al., 1980) [94]. Theo May and Lott

(2001) [136] th nhit ti u cho tng trng v chuyn ha thc n ca g

trng Ross 308 khi lng c th 2,5-3,0 kg l 16C.

Axit amin l n v nh nht gn kt vi nhau to thnh protein v protein l

c s c s dng xy dng khu phn (Fuller, 2004) [75]. Hm lng axit

amin trong khu phn khng nh hng hon ton ln thnh phn ha hc ca c

th g tht (DMello, 2003b) [57]. Tuy nhin hm lng isoleucin trong khu

phn tng ln dn n 6g/kg thc n lm lng m ca c th tng (Velu et

al., 1972) [229], nhng tc gi Burnham et al. (1992) [31] cho bit hm lng

isoleucin ca khu phn t 4g/kg thc n tr ln lm lng m c th gim lc

3 tun tui. Trong khi khi b sung lysine vo khu phn mc 5g/kg thc n

tr ln lm hm lng m c th gim lc 3 tun tui (Velu et al., 1972 [229];

Gous and Morris 1985 [76]). Nh vy, hm lng isoleucin hay lysine mc qu

thp lm lng m c th thp, nhng khi tng dn 2 axit amin ny lm cho

21

lng m c th tng ln, iu ny l do thiu ht axit amin t lng n vo thp.

Tuy nhin khi b sung thm axit amin dn n gim lng m c th, do

quan im cho rng lng m c th tng tng quan dng vi axit amin n vo

l khng c c s (DMello, 2003b) [57]. Ngoi ra, nghin cu ca Seaton et al.

(1978) [199] cho thy b sung lysine 7,2-16,8 g/kg thc n g lc 3 tun tui,

khng nh hng n hm lng m trong c th g.

Khi nui g trng tht 3-6 tun tui bng khu phn cha protein th

153g/kg thc n lm gim lng n vo v h s chuyn ha thc n tng so vi

g c nui bng khu phn protein th cao hn (Aletor et al., 2000) [7] v khi

g tht c nui bng khu phn thp protein th lm lng m c th tng.

Nng sut ca g trng tht 0-55 ngy tui khng thay i khi b sung lysine

trong khu phn 3 mc (9,5; 10,5 v 11,5 g/kg thc n) (Arajo et al., 2005)

[11], lng n vo v chuyn ha thc n gim khi lysine trong khu phn tng.

Han and Baker (1991) [80] cho bit khi tng lysine trong khu phn c th lm

gim lng n vo nhng tng trng khng gim, dn n h s chuyn ha thc

n gim. Tuy nhin, Parr and Summers (1991) [174] cho bit b sung lysine vt

10% so vi nhu cu bnh thng thu c nng sut khng i, nhng Kidd et al.

(1997) [107] cho rng b sung lysine vt 105% nhu cu lysine theo Skinner et

al. (1992) [203] cho thy tng trng v chuyn ha thc n tt hn.

Bng 2.5: nh hng ca nng lng trao i v lysine ln t l thn tht,

tht c v m bng ca g

Cc ch tiu Nng lng trao i (kcal/kg) Lysine (g/kg thc n) CV

(%) 3.200 3.400 3.600 9,5 10,5 11,5

Khi lng (g) 2.700c 2.775b 2.886a 2.793 2.767 2.800 0,98

T l thn tht (%) 82,81c 83,71b 84,71a 83,45 83,61 84,16 0,84

T l tht c (%) 23,44c 24,43b 25,21a 24,16b 24,32ab 24,60a 1,43

T l m bng (%) 1,72 1,77 1,83 1,7 1,79 1,82 8,84

Ngun: Arajo et al. (2005) [11]; Ch thch: a, b cc gi tr cng hng mang t nht mt ch k

hiu chung khng sai khc nhau P = 0,05.

Tng lysine trong khu phn dn n nng sut v t l cc phn thn tht

c ci thin (Han and Baker, 1991) [80], nhng nng sut tht khng nh

hng bi tng lysine trong khu phn giai on v bo. M bng thp hn v

nng sut tht c cao hn khi tng lysine trong khu phn (Acar et al., 1991 [4];

22

Holsheimer and Veerkamp, 1992 [92]). Mc khc, khu phn thiu lysine lm

gim 45% tng trng so vi khu phn cha lysine mc bnh thng (Tesseraud

et al., 1996) [217] v protein sinh hc lm g tng trng cao hn protein tng

hp. nh hng ca nng lng trao i v lysine ln t l thn tht, tht c v m

bng ca g theo Arajo et al. (2005) [11] c trnh by Bng 2.5.

Thc n nui g tht c protein th thp lm gim nng sut tht (Moran et

al., 1992) [149] v lm tng tch ly m (Moran et al., 1992 [149]; Bartov, 1996

[20]). Tuy nhin, b sung protein th v axit amin (Met, Lys v Thr) trong khu

phn vt mc trung bnh lm nng sut tht c tng (Bartov and Plavnik, 1998

[21]; Han and Baker, 1994 [82]; Schutte and Pack, 1995a [197], b [198]; Kidd

and Kerr, 1997 [108]). B sung lysine vo khu phn mc 12,2 g/kg thc n

khng nh hng n sc khe hay kh nng sng st ca g con nui tht (Corzo

et al., 2005) [42], nhng b sung lysine trn 13,9 g/kg thc n lm nh hng n

sc khe g con nui tht (Kidd et al., 1998 [109]; Latshaw, 1993 [118]).

Bng 2.6: nh hng ca axit amin ln h s chuyn ha thc n, khi

lng c th, t l thn tht v tht c

Mc axit amin FCR Khi lng (kg) T l thn tht (%) T l tht c (%)

Thiu axit amin 1,8a 2,55c 68,5 19,51b

Thp axit amin 1,75b 2,63bc 68,9 19,86ab

Cao axit amin 1,69c 2,7ab 68,3 20,14a

Tha axit amin 1,65d 2,73a 68,7 20,23a

SEM 0,01 0,04 0,24 0,01

P

23

n g t khi lng cao nht v h s chuyn ha thc n gim (Lilly et al.,

2011) [128] v c trnh by Bng 2.6.

Khi g c nui bng khu phn thp axit amin lm gim tng trng v

tng h s chuyn ha thc n (Kidd et al., 2004 [112]; Corzo et al., 2005 [42]),

nhng g c nui bng khu phn cao axit amin cho kt qu tng trng, nng

sut tht, khi lng c th t cc i v lm gim ng k h s chuyn ha

thc n (Kidd et al., 2004 [112]; Corzo et al., 2005 [42]; Dozier et al., 2008 [59]).

Tuy nhin, nui g tht bng khu phn cao axit amin ci thin nng sut th

lm tng chi ph thc n, tri li thc n thp axit amin th lm gim hiu qu sn

xut v tht c v nng sut tht gim nhng h s chuyn ha thc n cao (Kidd

et al., 2004) [112]. Bng 2.7 trnh by nh hng ca axit amin khu phn ln

thnh phn ha hc ca tht i v c.

Bng 2.7: nh hng ca axit amin khu phn ln thnh phn ha hc ca

tht i v c (% ca tht ti)

Mc axit amin

Tht i Tht c

Nc, %

Protein, %

M, %

Nc, %

Protein, %

M, %

pH 24 gi

Thiu axit amin 71,5b 19,1b 7,6a 74,1 23,1 1,0 5,9

Thp axit amin 72,3a 19,3ab 6,4b 73,9 23,4 0,9 5,9

Cao axit amin 72,4a 19,6a 6,4b 74,1 23,2 0,9 5,9

Tha axit amin 72,6a 19,7a 6,0b 74,1 23,3 1,1 5,9

SEM 0,26 0,16 0,38 0,11 0,19 0,1 0,02

P

24

nhng cao hn so vi kt qu ca (Corzo et al., 2009 [43]; Schilling et al., 2010

[195]) vi mt nc sau khi nu l 20%. Kh nng chp nhn ca ngi tiu

dng i vi tht g c nui vi cc mc axit amin khc nhau u ging nhau

(Lilly et al., 2011) [128]. Nng lng trao i, lysine v methionine+cystin trong

khu phn g tht nm 1957 v 2001 c trnh by Bng 2.8.

Bng 2.8: Nng lng trao i, lysine v methionine+cystin trong khu

phn g tht nm 1957 v 2001

Khu phn nm 1957 Khu phn nm 2001

Nng lng v axit amin G con G gi G con G gi

Nng lng trao i (kcal/kg) 2.895 2.930 3.200 3.150

Lysine (%) 1,18 0,90 1,25 1,10

Met+Cys (%) 0,75 0,65 0,91 0,87

Ngun: Havenstein et al. (2003a) [86],( b) [87].

Bn cnh , g thay i lng n vo khng ch l thuc vo nng lng

khu phn m cn b nh hng bi t l gia nng lng v protein hoc axit

amin (Thomas et al., 1986) [218]. Do , nu khu phn nui khng thiu axit

amin th s sinh trng ca g s p ng tt nht vi nng lng n vo (Leeson

and Summers, 1989) [126]. Aletor et al. (2000) [7] cn cho rng t l nng

lng/protein trong khu phn thp protein th lm nng lng tiu th ca g

tng, dn n axit amin tiu th tng. Havenstein et al. (2003a [86]; b [87]) cho

bit hm lng nng lng v axit amin trong khu phn thay i lin tc

trong thi gian di t nm 1957 n 2001.

Tm li, nng lng trao i v axit amin trong khu phn nh hng ln

n sinh trng v cht lng tht g. S thay i nng lng trong khu phn

tng ng vi tng mc axit amin lm nng sut ca g thay i khc

nhau. i vi nng sut ca g th vn cng b nh hng bi nng lng v

axit amin, nn vic nghin cu nhng mc axit amin ng vi cc mc nng lng

tm ra nng sut tt nht ca g Hmng l cn thit.

2.4.6 nh hng ca dinh dng v thc n ln cht lng tht g

Dinh dng trong thc n nh hng trc tip n s thay i c, xng v

m trong c th g, do n nh hng trc tip n cht lng tht (Mead,

2004) [141]. Trong s thay i c th c c chim t l cao v c nh gi l

25

quan trng nht (Mead, 2004) [141]. Ngoi ra, t l nng lng/protein trong khu

phn cng nh hng n cht lng tht (Mead, 2004) [141], v nng lng khu

phn nh hng n thc n v protein th n vo.

Khi nng lng khu phn cao hn nhu cu protein ti u th m c th tng

v tht c gim (Mead, 2004) [141], tri li khi protein vt tri hn nng lng

th m gim v tht c tng. Hn na, m bng tng hay gim u l thuc vo t

l nng lng/protein. Theo Basker et al. (1987) [22] nui g tht bng khu phn

c t l nng lng/protein tng th cht lng tht c nh gi cao nht khu

phn giai on m c 136kcal/100gprotein v gim ng k khi nng lng tng

n 150kcal i vi g trng. V vy, t l nng lng/protein c th duy tr,

nhng nng lng v protein c th thay i gim chi ph thc n (Mead,

2004) [141]. Khi khu phn c duy tr t l nng lng/protein theo nhu cu

NRC (1994) [155] v gim nng lng di 3.200 kcal/kg (Moran, 1980) [147],

dn n khi lng c th gim, nhng tht c gim t so vi m c th. Tri li,

khu phn t cht bo nhng nng lng cao th tng trng, nng sut tht v m

gim nhng khi lng c th vn duy tr (Skinner et al., 1992) [203].

Ngoi ra, khi lng c th v cht lng tht b nh hng bi cn bng

axit amin l tng nh khi cung cp y lysine v threonine lm cho lng

tht v m ph hp, nhng cung cp thiu lysine v threoninee dn n t l

tht/m khng p ng nhu cu ngi tiu dng (Mead, 2004) [141]. Lysine di

mc gii hn lm gim c c v khi nng lng tha cho qu trnh tng hp

protein lm m gim phn gii v tng d tr (Mead, 2004) [141]. Nh vy

cht lng tht g chu nh hng phn ln bi dng cht trong thc n, do

vic tm ra khu phn nui g cn i l cn thit.

2.5 nh hng ca phng thc nui ln sinh trng v cht lng tht g

Cc ging g th vn ca Vit Nam c nui vi 3 phng thc nh nui

th rng, nui bn thm canh v nui thm canh (Dng Thanh Lim, 2003) [62].

Trong , ging g a phng c nui th l ph hp nht (Alemu and

Tadelle, 1997) [6]. Kh nng sinh trng v cht lng tht g b nh hng bi

phng thc chn nui. Tng trng v chuyn ha thc n khng i gia g

nui nht v nui th, nhng g nui th th manh trng di hn v gan nng hn

so vi nui nht (Nguyen Thi Kim Khang and Ogle, 2004) [165].

26

T l thn tht ca g nui nht v th ging nhau, nhng khi lng gan v

m g nui nht cao hn g nui th, v da g nui nht c mu vng m

hn da g nui th (Nguyen Thi Thuy and Ogle, 2007) [167]. Trong khi kt qu

ca Minh and Ogle (2005) [145] cho thy t l tht i, tht c v thn tht ca g

nui th cao hn nui nht. Ngoi ra, t l m bng v h s chuyn ha thc n

ca g nui th thp hn g nui nht (Minh and Ogle, 2005) [145]. Bn cnh ,

g Ross nui th c t l tht i v c, kh nng gi nc cao hn g nui nht,

nhng m bng thp (Castellini et al., 2002) [32]. G c nui nht tch ly m

nhiu hn g c nui th (Castellini et al., 2002 [32]; Wang et al., 2009 [238]).

Ngoi ra, tng trng ca g a phng v g Leghorn c nui th khng

khc nhau (Solomon, 2003) [206] v khi b sung thc n cho g nui th th nng

sut ca g Leghorn cao hn g a phng c iu kin nui th v nht. Theo

Teketel (1986) [216] th kh nng sinh trng v khi lng thn tht ca g a

phng nui nht ch t 61-64% so vi g Leghorn c nui cng iu kin

lc 6 thng tui; thp hn kt qu ca Abebe (1992) [3] t 72%. Trong khi kt

qu ca Solomon (2003) [206] cho thy g a phng nui nht lc 5 thng tui

c kh nng sinh trng v khi lng thn tht t 81% so vi g Leghorn.

Kh nng tng trng ca g nui th gim so vi g nui nht (Baeza et al.,

2001 [13]; Pavlovski et al., 2009 [177]; Skomorucha et al., 2008 [205]; Santos et

al., 2005 [192]; Ponte et al., 2008 [185]). Tuy nhin t l tht c v i g nui

th cao hn nui nht lc 49 ngy tui (Castellini et al., 2002) [32], tri li g

Cobb nui nht c tht c cao hn nui th (Skomorucha et al., 2008) [205].

Ngoi ra, t l tht c, i ging nhau nui nht v th (Wang et al., 2009) [239].

n tht g nui th t nhin tt hn n tht g c nui nht (Fanatico et

al., 2006 [70]; Pavlovski et al., 2009 [177]). G nui th c tht dai hn tht g

nui nht (Castellini et al., 2002) [32]. Husak et al. (2008) [96] cho rng tht c v

i ca g nui nht mm hn tht c v i g nui th. Tng t, Farmer et al.

(1997) [73] cng cho rng tht g nui th dai hn tht g nui nht. Tuy nhin,

Fanatico et al. (2006) [70] cho rng dai ca tht ging g ln nhanh phng

thc nui nht v th u ging nhau; kt qu tng t trn ging g tng trng

chm (Wang et al., 2009 [239]; Ponte et al., 2008 [185]). Fanatico et al. (2006)

[70] ch ra tht g Cobb 56 ngy tui nui nht mm hn nui th.

Phng php nui nht hay nui th khng nh hng n mu sc tht

(Fanatico et al., 2006) [70], nhng Fanatico et al. (2006) [70] cho rng tht g nui

27

nht c mu nht hn tht g nui th, tri li mu sc tht ging g c tc

ln nhanh khng b nh hng bi phng thc nui. Trong khi , Castellini et

al. (2002) [32] cho rng g nui th lm sng ca tht tng ln v Husak et al.

(2008) [96] cho bit tht g nui th c mu hn tht g nui nht.

Khi quan st kh nng mt nc ca tht g sau 24 gi th Katarzyna and

Joanna (2011) [105] cho bit c c v i ca g nui nht l 38,1% v nui th

l 21,3%. Tng t, kh nng gi nc ca tht g nui nht cng km hn tht

g nui th (Muriel and Pascual, 1995) [152], tri li kh nng gi nc ca tht

c ging nhau gia g nui nht v th (Brown et al., 2008 [27]; Wang et al.,

2009 [239]). pH24 ca tht c g nui nht l 6 v nui th l 6,19 (Katarzyna and

Joanna, 2011) [105], tng t Wang et al. (2009) [239] v Fanatico et al. (2006)

[70] cng cho rng pH tht g nui nht thp hn tht g nui th.

Tm li, phng thc chn nui nh hng khng nh n cht lng tht

g, c bit l tht c v tht i. Trong g c nui bng phng thc chn

th cho tht cht lng tt hn v p ng c th hiu ngi tiu dng. Hn

na ti BSCL th g c nui bng phng thc chn th chim t l cao, v

vy ngoi vic nghin cu tm ra khu phn cn i th cn nn nh gi cht

lng tht trong iu kin chn th v nht.

2.6 S lc v thc n th nghim

2.6.1 Bp

Bp l loi ng cc quan trng, ng th hai sau la m v la go Vit

Nam, nhng sn lng vn khng p ng nhu cu nn hng nm Vit Nam phi

nhp khu (Bi Ch Bu, 2012) [29]. Ht bp cha zein v glutelin, thiu lysin v

tryptophan (L Vn Knh, 2003) [115]. Bp cha khong 8,5% v khng cn i

tt axit amin v thng b gii hn lysine, threonine, isoleucine v tryptophan.

Bp c t l tiu ha tinh bt cao, x thp v nng lng trao i cao 3.200-

3.300kcal/kg (Vin Chn nui Quc gia, 1995) [230], nhng bp d b nhim

nm mc khi m trn 15% (Bi c Lng v L Hng Mn, 2001) [30].

Trong khu phn n cho g bp thng c dng n 60-70%, nhng cht bo

trong bp cha nhiu acid bo khng no lm gim cht lng m, nn s dng

mc thp hn k nui v bo (L Vn Knh, 2003) [115].

Do gi bp thng xuyn tng nn trong khu phn nui g th vn th bp

thng c thay th bi cc nguyn liu a phng c gi r hn. Chng hn,

28

bp c thay th bng m c Tra v bt khoai m lt trong khu phn nui g

Tu Vng (Chu Th Ngc Dung, 2003) [33], kt qu cho thy thay th 6,6% bp

trong khu phn bng khoai m lt lm chi ph thc n nui g Tu Vng 4-7

tun tui thp nht m vn p ng cho tng trng ca g.

2.6.2 Tm cm

Tm go l ph phm c to ra vi s lng ln khi ch bin go xut

khu. Tm l thc n ngon ming, giu nng lng v t x nn c gi tr trong

khu phn nui g gi (Nguyn Th Hng Nhn, 2001) [163]. Thnh phn ha

hc v gi tr dinh dng ca tm tng ng vi go, nng lng trao i

3.340 kcal/kg, protein th khong 6,73-12,49% v cht x thp 0,9% (L Vn

Knh, 2003) [115]. Ngoi ra, cc h chn nui s dng tm go lm thc n

chnh cho g Ni con (Nguyn Vn Quyn, 2008c) [170]. Hn na, tm go v

bo tm c dng thay th u nnh nui g Tu Vng th vn cho

tng trng tng, h s chuyn ha thc n gim v chi ph thc n gim (Nguyen

Thi Kim Khang and Ogle, 2004) [165].

Cm go cng l ph phm ca ht la trong ch bin go v thng chim

khong 10% so vi trng lng la. T l protein th trong cm mn c th t

12-14%, cht bo 13-14%, cht x khong 7-8% v nng lng trao i 2.600-

2.700 kcal/kg (Vin Chn nui Quc gia, 1995) [230]. Nng lng trao i ca

cm lau l 3.335 kcal/kg (Ali and Leeson, 1995) [8] v cm go cha lng cht

bo khng no cao nn d b oxy ha v lm gim gi tr dinh dng. C th b

sung cm go trong khu phn g tht n 10% (McNab, 1987) [138], n 22,5%

(Torki and Falahati, 2006) [219] v n 25% (Nguyn Th Hng Nhn, 2001)

[163]. Tuy nhin, Ali and Leeson (1995) [8] cho bit khi s dng cm vi mc

cao trong khu phn cng vi bp v kh du nnh s gii hn tng trng ca g.

2.6.3 Kh du nnh

Kh du nnh l ngun protein tt s dng trong thc n chn nui g

(Cromwell, 1999) [44] cha y axit amin tr methionine b gii hn. Kh du

nnh loi tch v c protein th, axit amin v nng lng trao i cao hn loi

kh du nnh khng tch v (NRC, 1994) [155]. Hm lng protein th kh du

nnh t 45,2% n 50,6%, vi hm lng lysine theo protein th t 5,51 n

6,26% (De Coca-Sinova et al., 2008) [46]. Baker et al. (2011) [17] cho bit kh

29

du nnh cao protein c protein th v lysine ln lt 54,86% v 3,56% so vi

kh du nnh truyn thng c protein th v lysine l 47,47% v 3,14%.

Hn na, kh du nnh c gi tr dinh dng cao v cn i thng c

dng trong khu phn thc n g vi s lng ln. Protein ca ht u nnh v

kh du ca n cha y axit amin thit yu v giu nng lng. Ht u nnh

c protein th 36-39%, cht bo 14%, cht x 3,7%, nng lng trao i 3.380-

3.400 kcal/kg (Bi c Lng v L Hng Mn, 2001) [30]. Theo Vin Chn nui

Quc gia (1995) [230] th thnh phn ha hc ca u nnh l 41-43% protein

th, cht bo 16-18% v nng lng trao i 3.600-3.700 kcal/kg vt cht kh.

Khi kh du nnh c x l nhit qu cao lm gim hm lng v kh nng

tiu ha lysine v cystine do s hnh thnh cc lin kt (Mauron, 1981 [135];

Sherr et al., 1989 [200]; Dillis, 1993 [50]), t dn n lysine b ngn cn hp

thu do glycosylate (Sherr et al., 1989) [200]. Ngoi ra, hm lng cysteine trong

kh du nnh cng gim do ch bin qu nhit (Parsons et al., 1991) [176].

Bp v kh du nnh l thc n tt cho chn nui g nhng phn ln phi

nhp khu, do gim nhp khu thc n chn nui th cn thay th cc loi

thc n sn c ca a phng v to s a dng v nguyn liu thc n cho g.

2.6.4 Bt c

Bt c cha protein c gi tr sinh hc ng u trong thc n ngun gc

ng vt (Bi c Lng v L Hng Mn, 2001) [30] v c th s dng trong

khu phn nui g. Bt c cha 60% protein th, nhng c th thay i t 57 n

77% ty vo loi c c ch bin (Miles et al., 1997) [144]. Protein bt c cha

hm lng cc axit amin thit yu y v n nh nh lysine 7,5%, methionine

3% v cystin 0,6-0,8%. Ngoi ra, dinh dng ca bt c ph thuc vo loi bt

c, cng ngh v ni sn xut (Bi c Lng v L Hng Mn, 2001) [30].

Ngoi ra, s dng bt c trong khu phn c th b sung tt cc axit amin cha

gc lu hunh (Miles et al., 1997) [144]. Nng lng ca bt c 2.500-3.200

kcal/kg v c mi quan h vi t l protein v cht bo (Richard et al., 2009)

[188]. Theo Bi c Lng v L Hng Mn (2001) [30] th bt c c nng lng

trao i 2.850-2.900 kcal/kg vt cht kh, 19,6-34,5% khong v Ca chim 5%.

Hn na, bt c l ngun cung cp tt calci v phospho cho g, ng thi calci v

phospho c tnh hu dng cao (Miles et al., 1997) [144].

30

BSCL l vng nui c tra v basa ch bin xut khu, nn to ra

ngun ph phm rt ln, sn lng nm 2011 l trn 1 triu tn v nm 2012 t

1,2 triu tn. Thnh phn dinh dng ca bt c tra v protein th 50-59%, cht

bo 1 -14%, khong 22-28%, mui 2-3% (Cng ty TNHH Hip Quang, 2012)

[40]. Vic s dng bt c vo khu phn nui g Hmng tht l bc u to

tin cho cc nghin cu tip theo v s dng bt c tra lm thc n cho g

trc tnh hnh gi thc n nhp khu tng cao.

31

Chng 3: I TNG V PHNG PHP NGHIN CU

3.1 a im v thi gian thc hin th nghim

Cc th nghim c thc hin ti tri chn nui ca nng h thuc x Kim

Ha, huyn Cu Ngang, tnh Tr Vinh.

Thi gian tin hnh t thng 7/2011 n thng 5/2013.

3.2 Thnh phn ha hc ca thc n v tnh nng lng trao i

Bp, tm v cm go, kh du nnh v bt c c mua ti Ca hng Thc

n gia sc Hng Phc - TP. Cn Th. Du nnh c sn xut t Cng ty

TNHH du thc vt Ci Ln. Axit amin c sn xut t Cng ty TNHH Hubei

provincial Bafeng Pharmaceuticals & Chemicals Share, Trung Quc. Premix

c sn xut t Cng ty Vemedim Vit Nam. Cc nguyn liu c xc nh

thnh phn ha hc trc khi phi hp khu phn.

Thnh phn ha hc ca nguyn liu thc n (DM, CP, EE, CF, NFE, Ca v

P) c xc nh theo phng php phng nh Weende (AOAC, 1990) [10] ti

phng Th nghim Thc n gia sc thuc khoa Nng nghip v Sinh hc ng

dng - Trng i hc Cn Th. Axit amin ca nguyn liu thc n c xc

nh ti phng th nghim Dinh dng ng vt - Vin Khoa hc K thut Nng

nghip Min Nam. Acid bo bo ha v khng bo ha ca du nnh c phn

tch ti Cng ty TNHH Intertek Vit Nam - Chi nhnh Cn Th v nng lng

trao i ca du nnh c tnh bng cng thc ca Ketels and DeGroote (1989)

[106], ME = 8.227 - 10.318[-1,168(t l acid bo khng bo ha : acid bo bo ha)]. Nng lng

trao i ca cc nguyn liu thc n c tnh theo cng thc ca L Vn Knh

(2003) [115]:

Bp: ME (kcal/kg thc n) = 19,0 + 37,5CP + 78,5EE + 11,2CF + 37,7NFE

Kh du nnh: ME (kcal/kg thc n) = -2,7 + 35,1CP + 96,7EE - 4,2CF +

28,6NFE

Tm go: ME (kcal/kg thc n) = -6,5 + 37,9CP + 86,1EE - 9,48CF +

38,3NFE

Cm go: ME (kcal/kg thc n) = -77 + 49,6CP + 71,8EE - 20,4CF +

28,1NFE

Bt c: ME (kcal/kg thc n) = -348 + 44,7CP + 72,3EE + 4,17CF + 37NFE

32

Bng 3.1: Thnh phn ha hc ca nguyn liu thc n

Nguyn liu TA

DM (%)

Thnh phn ha hc ca nguyn liu thc n (tnh theo % ca TA)

CP ME

(kcal/kg)

EE CF Lys Met+

cys

Thr Trp Ca P

Bp 86,90 7,59 3.236 3,31 4,84 0,21 0,28 0,25 0,05 0,63 0,29

Tm go 87,41 7,98 3.345 1,82 1,23 0,28 0,26 0,62 0,09 0,50 0,13

Cm go 88,00 12,64 2.667 14,72 8,34 0,63 0,23 1,16 0,18 0,37 1,58

KDN 87,50 42,74 2.512 2,35 7,35 2,23 1,14 1,51 0,52 0,63 0,67

Bt c 90,77 53,91 2.891 8,48 0,73 3,17 2,08 2,06 0,92 5,30 2,76

Du nnh - - 8.227 - - - - - - - -

DCP - - - - - - - - - 24,11 19,29

Bt s - - - - - - - - - 29,22 -

Ch thch: DM: vt cht kh, ME: nng lng trao i, EE: cht bo, CF: x th, KDN: kh du

nnh, DCP: dicalci phosphate; TA: thc n.

3.3 B tr th nghim 1: nh hng ca cc mc nng lng trao i v

lysine trong khu phn ln sc sn xut ca g Hmng

3.3.1 Phng php b tr

Mc tiu th nghim l xc nh nh hng ca cc mc nng lng trao i

v lysine ln sc sn xut tht ca g Hmng qua tng giai on sinh trng.

Th nghim c b tr theo th thc tha s 2 nhn t (3*3) qua 3 giai

on, vi 4 ln lp li v mi n v th nghim gm 6 con. Khi lng trung

bnh ca g u cc giai on 0-4; 5-9; 10-14 tun tui ln lt l 28,4 0,44g;

195 3,13g; 568 20,5g.

Nhn t 1 gm 3 mc nng lng trao i (3.000; 3.100 v 3.200 kcal/kg

thc n) cho c 3 giai on (0-4; 5-9 v 10-14 tun tui) v nhn t 2 gm 3 mc

lysine (0,9; 1 v 1,1%) cho giai on 0-4 tun tui, 3 mc lysine (0,81; 0,9 v

1%) cho giai on 5-9 tun tui v 3 mc lysine (0,69; 0,76 v 0,85%) cho giai

on 10-14 tun tui. T l methionine+cystin, threonine v tryptophan t ti

thiu theo bng axit amin l tng ca Baker (1997) [16].

3.3.2 S b tr

S b tr th nghim c trnh by qua Bng 3.2.

33

Bng 3.2: S b tr th nghim

ME (kcal/kg TA) 3.000 3.100 3.200

Tun tui Lysine (%)

0-4 0,9 1,0 1,1 0,9 1,0 1,1 0,9 1,0 1,1

5-9 0,81 0,9 1,0 0,81 0,9 1,0 0,81 0,9 1,0

10-14 0,69 0,76 0,85 0,69 0,76 0,85 0,69 0,76 0,85

3.3.3 Ging g v phng php chn g th nghim

G th nghim c ngun gc t H Ni, c mua qua trung gian ca tri

nui g tht ti tnh Tr Vinh.

u mi giai on th nghim, g c trn u sau c chn ngu

nhin c s d, v m bo khi lng c th trung bnh ca g cc n v th

nghim ng u nhau. S g d chn la u mi giai on l g c nui

song song vi g th nghim. G giai on 5-14 tun tui c chn la vi t l

trng mi bng nhau.

3.3.4 Chung tri v cch cho g n

G c nui nht hon ton trn chung sn tre c lt li vi din tch

1m2/6con, xung quanh v pha trn chung c lm bng tre v li. G giai

on 0-4 tun tui c nui 2 tun u trn nn tru v 2 tun sau nui trn sn.

Mng n v mng ung c lp t ring bit ly s liu cho tng n

v th nghim. G c n ung t do c ngy m. tng giai on th nghim,

g c b tr v ly s liu ring bit.

3.3.5 Khu phn v gi tr dinh dng khu phn

Cc khu phn v gi tr dinh dng ca khu phn 3 giai on nui g

Hmng c trnh by Bng 3.3, Bng 3.4 v Bng 3.5.

34

Bng 3.3: Khu phn v gi tr dinh dng khu phn ca g Hmng giai

on 0-4 tun tui

Thc liu (kg)

ME 3.000 kcal ME 3.100 kcal ME 3.200 kcal

Lysine 0,9%

Lysine 1%

Lysine 1,1%

Lysine 0,9%

Lysine 1%

Lysine 1,1%

Lysine 0,9%

Lysine 1%

Lysine 1,1%

Bp 56,18 55,81 56,06 54,49 53,25 53,52 54,17 53,40 52,99

KDN 38,45 38,6 38,03 37,97 38,9 38,36 36,56 36,99 37,00

Du nnh 2,48 2,58 2,65 4,5 4,71 4,77 6,24 6,42 6,57

L-Lysine-HCl - 0,03 0,14 - 0,03 0,14 - 0,10 0,17

DL-Methionine 0,06 0,13 0,20 0,06 0,13 0,20 0,09 0,15 0,22

L-Threonine - - 0,03 - - 0,03 - - 0,05

DCP 2,00 2,02 2,02 2,15 2,15 2,15 2,11 2,11 2,17

Bt s 0,10 0,10 0,14 0,10 0,10 0,10 0,10 0,10 0,10

Premix 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 2.987 2.987 2.987 3.087 3.087 3.087 3.185 3.185 3.185

CP 20,76 20,89 20,88 20,42 20,82 20,83 19,83 20,11 20,77

EE 5,24 5,33 5,40 7,20 7,38 7,44 8,89 9,05 9,19

CF 5,55 5,54 5,51 5,43 5,44 5,41 5,31 5,30 5,28

Ca 1,10 1,11 1,12 1,13 1,12 1,12 1,11 1,10 1,11

P 0,81 0,81 0,81 0,83 0,83 0,83 0,81 0,81 0,82

Lysine 0,90 1,00 1,10 0,90 1,00 1,10 0,90 1,00 1,10

Met-cys 0,65 0,72 0,79 0,65 0,72 0,79 0,65 0,72 0,79

Threonine 0,72 0,72 0,74 0,71 0,72 0,74 0,68 0,69 0,74

Tryptophan 0,22 0,23 0,20 0,22 0,23 0,22 0,22 0,22 0,22

Ghi ch: KDN: kh du nnh; DCP: dicalci phosphate; ME: nng lng trao i; TA: thc n; CP: protein th; EE: cht bo; CF: x th.

35


on 5-9 tun tui

Thc liu (kg)


Lysine 0,81%

Lysine 0,9%

Lysine 1%

Lysine 0,81%

Lysine 0,9%

Lysine 1%

Lysine 0,81%

Lysine 0,9%

Lysine 1%

Bp 65,94 66,05 66,51 63,75 63,92 64,22 61,48 61,6 62,04

KDN 30,34 30 29,2 30,73 30,36 29,7 31,20 30,81 30,08

Du nnh 1,19 1,25 1,32 2,98 3,03 3,11 4,77 4,85 4,90

L-Lysine-HCl - 0,10 0,22 - 0,09 0,21 - 0,09 0,21

DL-Methionine 0,05 0,12 0,20 0,14 0,12 0,21 0,06 0,12 0,21

L-Threonine - - 0,07 - - 0,07 - - 0,07

DCP 1,65 1,65 1,65 1,65 1,65 1,65 1,66 1,70 1,66

Bt s 0,10 0,10 0,10 0,10 0,10 0,10 0,10 0,10 0,10

Premix 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 2.994 2.994 2.994 3.080 3.080 3.080 3.166 3.166 3.166

CP 18,02 18,06 18,02 18,03 18,04 18,06 18,06 18,05 18,06

EE 4,10 4,14 4,21 5,81 5,86 5,93 7,54 7,61 7,66

CF 5,42 5,40 5,37 5,34 5,33 5,29 5,27 5,25 5,21

Ca 1,03 1,03 1,03 1,02 1,02 1,01 1,01 1,02 1,01

P 0,72 0,71 0,71 0,71 0,71 0,71 0,71 0,72 0,71

Lysine 0,81 0,90 1,01 0,81 0,90 1,01 0,81 0,90 1,01

Met-cys 0,58 0,65 0,72 0,59 0,65 0,72 0,58 0,65 0,72

Threonine 0,62 0,62 0,68 0,62 0,62 0,68 0,62 0,62 0,68

Tryptophan 0,19 0,19 0,19 0,19 0,19 0,19 0,19 0,19 0,19

Ghi ch: KDN: kh du nnh; DCP: dicalci phosphate; ME: nng lng trao i; TA: thc n;

CP: protein th; EE: cht bo; CF: x th.

36


on 10-14 tun tui

Thc liu (kg)


Lysine 0,69%

Lysine 0,76%

Lysine 0,85%

Lysine 0,69%

Lysine 0,76%

Lysine 0,85%

Lysine 0,69%

Lysine 0,76%

Lysine 0,85%

Bp 75,96 76,18 76,22 73,68 73,82 74,12 71,32 71,59 71,80

KDN 21,4 20,99 20,62 21,86 21,50 20,90 22,40 21,90 21,40

Du nnh 0,06 0,10 0,20 1,88 1,93 2,00 3,69 3,73 3,80

L-Lysine-HCl 0,06 0,14 0,23 0,05 0,13 0,23 0,04 0,13 0,22

DL-Methionine 0,04 0,10 0,17 0,04 0,10 0,17 0,04 0,11 0,17

L-Threonine - 0,01 0,06 - 0,01 0,06 - 0,01 0,06

DCP 1,75 1,75 1,77 1,76 1,78 1,79 1,78 1,80 1,82

Premix 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 3.000 3.000 3.000 3.088 3.088 3.088 3.174 3.174 3.174

CP 15,01 15,00 15,06 15,03 15,03 15,02 15,07 15,04 15,05

EE 3,08 3,11 3,21 4,83 4,88 4,94 6,58 6,61 6,68

CF 5,23 5,21 5,18 5,16 5,13 5,10 5,08 5,05 5,02

Ca 1,03 1,03 1,03 1,02 1,03 1,03 1,02 1,02 1,02

P 0,71 0,70 0,70 0,70 0,71 0,70 0,70 0,71 0,71

Lysine 0,69 0,76 0,85 0,69 0,76 0,85 0,69 0,76 0,85

Met-cys 0,50 0,55 0,62 0,50 0,55 0,61 0,50 0,55 0,61

Threonine 0,51 0,52 0,56 0,51 0,52 0,56 0,52 0,52 0,56

Tryptophan 0,15 0,15 0,15 0,15 0,15 0,15 0,15 0,15 0,15



3.3.6 Cc ch tiu theo di

Nng lng trao i, protein th, lysine v thc n tiu th; tng khi lng

c th v h s chuyn ha thc n.

37

3.4 B tr th nghim 2: nh hng ca khu phn thc n khc nhau

ln sc sn xut v cht lng tht g Hmng

3.4.1 Phng php b tr

Mc tiu th nghim l xc nh nh hng ca cc khu phn thc n khc

nhau ln sc sn xut v cht lng tht g Hmng.

S dng gi tr dinh dng theo khu phn th nghim 1 cho g sinh

trng tt nht thay i mt phn bp v kh du nnh bng tm cm v bt c

nhm lm a dng ha nguyn liu dng lm thc n cho g Hmng.

Th nghim c b tr hon ton ngu nhin vi 5 nghim thc, 4 ln lp

li, mi n v th nghim gm 6 con v c tin hnh qua 3 giai on: 0-4; 5-9;

10-14 tun tui. Nguyn liu c s dng trong khu phn gm bp, tm v cm

go, kh du nnh v bt c. Khi lng trung bnh ca g u cc giai on 0-

4; 5-9; 10-14 tun tui ln lt l 28,4 0,33g; 213 1,30g; 696 4,61g.

Giai on 0-4 tun tui g c nui bng khu phn cha nng lng trao

i l 2.987 kcal/kg thc n, protein th 20,88% v 1,1% lysine.

Giai on 5-9 tun tui g c nui bng khu phn cha nng lng trao

i l 2.994 kcal/kg thc n, protein th 18,02% v lysine 1%.

Giai on 10-14 tun tui g c nui bng khu phn cha nng lng

trao i l 3.088 kcal/kg thc n, protein th 15,02% v lysine 0,85%.

G kt thc th nghim lc 14 tun tui, m kho st 8 con/nghim thc

so snh cht lng tht ca g nhng khu phn thc n khc nhau. G m kho

st c chn la ng u nhau mi nghim thc.


Ging nh mc 3.3.3


Ging nh mc 3.3.4


Cc khu phn v gi tr dinh dng ca khu phn nui dng g Hmng

3 giai on c trnh by Bng 3.6, Bng 3.7 v Bng 3.8.

38


on 0-4 tun tui

Thc liu (kg)

Cc nghim thc

TC0BC0 TC14BC5 TC14BC8 TC28BC5 TC29BC8

Bp 56,06 46,70 48,18 32,49 33,48

Tm - 12,07 12,55 24,81 25,69

Cm - 2,46 2,22 3,74 4,30

KDN 38,03 29,60 26,18 29,38 26,02

Bt c - 5,78 8,37 5,83 8,12

Du nnh 2,65 1,18 0,62 1,22 0,51

L-Lysine-HCl 0,14 0,11 0,10 0,10 0,10

DL-Methionine 0,20 0,17 0,15 0,17 0,15

L-Threonine 0,03 - - - -

DCP 2,02 1,10 0,90 1,53 0,90

Bt s 0,14 0,10 - - -

Premix 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 2.987 2.987 2.987 2.987 2.987

CP 20,88 20,87 20,89 20,88 20,88

EE 5,40 4,89 4,10 4,48 4,02

CF 5,51 4,79 4,59 4,35 4,21

Lysine 1,10 1,10 1,10 1,10 1,10

Met+cys 0,79 0,79 0,79 0,79 0,79

Threonine 0,74 0,78 0,79 0,84 0,85

Tryptophan 0,22 0,24 0,25 0,25 0,25

Ca 1,12 1,15 1,20 1,20 1,16

P 0,81 0,76 0,77 0,84 0,77



39


on 5-9 tun tui

Thc liu (kg)

Cc nghim thc


Bp 66,51 55,03 56,22 37,50 40,69

Tm - 10,96 11,38 28,91 24,80

Cm - 4,20 4,05 4,22 6,45

KDN 29,20 22,44 19,96 22,09 19,76

Bt c - 4,60 6,41 4,70 6,22

Du nnh 1,32 0,47 - 0,13 -

L-Lysine-HCl 0,22 0,20 0,19 0,18 0,17

DL-Methionine 0,20 0,17 0,16 0,18 0,17


DCP 1,65 1,10 0,90 1,36 1,01

Bt s 0,10 0,10 - - -

Premix 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 2.994 2.994 2.994 2.994 2.994

CP 18,02 18,02 18,02 18,02 18,02

EE 4,21 4,03 3,68 3,44 3,74

CF 5,37 4,80 4,67 4,15 4,27

Lysine 1,00 1,00 1,00 1,00 1,00

Met+cys 0,72 0,72 0,72 0,72 0,72

Threonine 0,67 0,68 0,69 0,75 0,75

Tryptophan 0,19 0,20 0,21 0,21 0,21

Ca 1,03 1,09 1,10 1,10 1,10

P 0,71 0,73 0,73 0,75 0,75


40


on 10-14 tun tui

Thc liu (kg)

Cc nghim thc


Bp 74,12 60,68 61,40 40,74 41,62

Tm - 11,25 11,50 32,30 32,10

Cm - 5,00 5,00 4,24 4,61

KDN 20,90 15,77 14,10 15,82 13,92

Bt c - 3,30 4,50 3,14 4,49

Du nnh 2,00 1,50 1,20 1,07 0,80

L-Lysine-HCl 0,23 0,21 0,20 0,20 0,19

DL-Methionine 0,17 0,16 0,15 0,16 0,15


DCP 1,79 1,40 1,20 1,60 1,39

Premix 0,25 0,25 0,25 0,25 0,25

Mui n 0,48 0,48 0,48 0,48 0,48

Tng cng 100 100 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 3.088 3.088 3.088 3.088 3.088

CP 15,02 15,02 15,02 15,02 15,02

EE 4,94 5,10 4,89 4,27 4,15

CF 5,12 4,65 4,57 3,88 3,82

Lysine 0,85 0,85 0,85 0,85 0,85

Met+cys 0,61 0,61 0,61 0,61 0,61

Threonine 0,56 0,58 0,58 0,65 0,66

Tryptophan 0,15 0,16 0,16 0,16 0,17

Ca 1,03 1,06 1,07 1,08 1,09

P 0,70 0,74 0,73 0,73 0,72


41


Nng lng trao i, protein th, lysine v thc n tiu th; tng khi lng

c th v h s chuyn ha thc n; t l cc phn thn tht; pH15, thnh phn

ha hc, r dch v t l mt nc sau nu ca tht c.

3.5 B tr th nghim 3: nh hng ca phng thc v ma v nui

ln sc sn xut v cht lng tht g Hmng

3.5.1 Phng php b tr

Mc tiu th nghim l xc nh nh hng ca phng thc v ma v nui

ln sc sn xut v cht lng tht g Hmng.

Th nghim c b tr theo th thc tha s 2 nhn t (3*2), 4 ln lp li v

mi n v th nghim gm 12 con (6 trng v 6 mi). Nhn t 1 gm 3 phng

thc nui (nht hon ton trn chung sn, th 6 gi/ngy v th hon ton) v

nhn t 2 l ma ma (thng 6 n thng 9) v ma nng (thng 12 n thng 3

nm sau). G c theo di v ly s liu t 5 n 14 tun tui v c chia

thnh 2 giai on ring bit. Khi lng trung bnh ca g u giai on 5-9 v

10-14 tun tui ln lt l 196 8,08g; 670 4,30g. tt c phng thc v

ma v nui th g c cho n bng khu phn ging nhau.

G c m kho st 48 con (8 con/nghim thc) lc 14 tun tui so

snh cht lng tht nhng phng thc v ma v nui khc nhau. G m

kho st c chn la ng u nhau mi nghim thc.


Ging mc 3.3.3, nhng g c trn u trong cng phng thc nui.


Phng thc nui nht ging nh mc 3.3.4. phng thc th 6 gi/ngy

v th hon ton, g c th trn nn t vi din tch 4-5m2/con, nhng u c

chung g tr ma v ng. phng thc th 6 gi/ngy th g c th t 6

n 12 gi ging nhau c 2 ma, sau c nht vo chung.

Thc n ca g nui th hon ton v th 6 gi/ngy khng t ma.


Khu phn v gi tr dinh dng ca khu phn c trnh by Bng 3.9.

42

Bng 3.9: Khu phn v gi tr dinh dng khu phn

Khu phn th nghim ca cc giai on

Thc liu (kg) 0-4 tun tui 5-9 tun tui 10-14 tun tui

Bp 32,49 37,50 40,74

Tm 24,81 28,91 32,30

Cm 3,74 4,22 4,24

KDN 29,38 22,09 15,82

Bt c 5,83 4,70 3,14

Du nnh 1,22 0,13 1,07

L-Lysine-HCl 0,10 0,18 0,20

DL-Methionine 0,17 0,18 0,16

DCP 1,53 1,36 1,60

Premix 0,25 0,25 0,25

Mui n 0,48 0,48 0,48

Tng cng 100 100 100

Gi tr dinh dng (%)

ME (kcal/kg TA) 2.987 2.994 3.088

CP 20,88 18,02 15,02

EE 4,48 3,44 4,27

CF 4,35 4,15 3,88

Lysine 1,10 1,00 0,85

Met+cys 0,79 0,72 0,61

Threonine 0,84 0,75 0,65

Tryptophan 0,25 0,21 0,17

Ca 1,20 1,11 1,08

P 0,84 0,75 0,73 Ghi ch: KDN: kh du nnh; DCP: dicalci phosphate; ME: nng lng trao i; TA: thc n; CP: protein th; EE: cht bo; CF: x th.


Ging mc 3.4.5.

43

3.6 Qui trnh s dng vc xin cho g c 3 th nghim

G c tim phng theo qui trnh ca V Vn S v Phm Cng Thiu

(2010) [232] Bng 3.10.

Bng 3.10: Qui trnh tim phng bng vc xin trn g Hmng

Ngy tui Loi vacxin v cch s dng Phng bnh

5 Lasota ln 1 (Nh mt v mi) Newcastle

7 Gumboro ln 1 (Nh mt v mi); u g (xin cnh) Gumboro v u g

21 Gumboro ln 2 (Nh mt v mi) Gumboro

28 Lasota ln 2 (Pha nc cho ung trong 1 gi) Newcastle

3.7 Phng php thu thp s liu

3.7.1 Xc nh tng khi lng c th v lng n vo c 3 th nghim

Xc nh tng khi lng c th g hng tun bng cch cn tt c g vo

lc 6 gi sng trc khi cho n. G c cn chung tng n v th nghim lc 0-

4 tun tui, nhng g t 5 tun tui v sau c cn ring bit tng con bng cn

ng h c phn ti thiu 1 gram v ti a l 500 g; phn ti thiu 2 gram

v ti a l 1.000 g; phn ti thiu 5 gram v ti a l 2.000 g. Khi lng

trung bnh ca tng n v th nghim c tnh t khi lng g cn. Tng

khi lng c th ca g c tnh bng cng thc:

Tng khi lng c th hng tun (g/con) = khi lng c th cui tun

(g/con) - khi lng c th u tun (g/con).

Tng khi lng c th tch ly (g/con) = tng tng khi lng c th ca

g cc tun (g/con).

Lng thc n tiu th c xc nh hng ngy bng cch cn khi lng

thc n a vo v thc n tha bng cn ng h c phn chia nh nht l 1 g

v cao nht l 500 g. Lng thc n tiu th c xc nh bng cng thc:

Lng thc n tiu th hng ngy (g/con) = tng lng thc n a vo

trong ngy (g/con) - lng thc n tha ca ngy (g/con).

Lng thc n tiu th hng tun (g/con) = tng lng thc n tiu th cc

ngy trong tun (g/con).

44

Lng thc n tiu th c k (g/con) = tng lng thc n tiu th ca cc

tun (g/con).

H s chuyn ha thc n (FCR) = lng thc n tiu th (g)/tng khi

lng c th (g).

3.7.2 Xc nh t l cc phn thn tht

Xc nh t l thn tht, tht c v tht i theo phng php c tham kho

t L Th Thy v ctv (2010) [124].

a. T l thn tht

Cn khi lng g trc khi git m, sau b tit, lng, lng, u v chn

gi l thn tht,

T l thn tht (%) = 100*khi lng thn tht/khi lng g trc git m.

b. T l tht c

Lc bn tri tht c sau nhn i l khi lng tht c,

T l tht c (%) = 100*khi lng tht c/khi lng thn tht.

c. T l tht i

Lc ly ton b tht i bn tri sau nhn i l khi lng tht i,

T l tht i (%) = 100*khi lng tht i/khi lng thn tht.

3.7.3 Xc nh thnh phn ha hc tht c

Xc nh vt cht kh, protein th, cht bo v cht khong ca tht c g ti

phng Th nghim Thc n Gia sc, thuc khoa Nng nghip v Sinh hc ng

dng - Trng i hc Cn Th bng phng php phng nh Weende (AOAC,

1990) [10]. Axit amin ca tht c g Hmng th nghim 2 c phn tch ti

phng Phn tch Thc n v Sn phm Chn nui - Vin Chn nui Quc gia.

3.7.4 Xc nh pH15 v kh nng gi nc ca tht c

Xc nh pH15 theo phng php ca WHO (1955) [240] bng cch ct ly

10 g tht c, sau bm nhuyn, cho vo 100ml nc ct un si ngui trong

thi gian 15 pht v o bng my o pH - Data line pH meter, Winlab.

Xc nh r dch sau bo qun bng phng php ca Honikel (1987)

[93] bng cch lc ly 1 bn c ngc, cn khi lng (khi lng tht trc bo

45

qun) sau cho vo ti nha kn v bo qun nhit 2-4oC trong 24 gi. Sau

mu c lm ro nc bng giy thm v cn li khi lng (khi lng tht

sau bo qun) v c tnh bng cng thc:

r dch (%) = 100*(khi lng tht trc bo qun - khi lng tht sau

bo qun)/khi lng tht trc bo qun.

Xc nh t l mt nc sau nu bng phng php ca Honikel (1987) [93]

bng cch cn khi lng tht c (khi lng tht trc nu) sau nu 10 pht

trong nc si. Tht nu chn c treo kh nc trong khng kh sau cn li

(khi lng tht sau nu) v c tnh bng cng thc:

T l mt nc sau nu (%) = 100*(khi lng tht trc nu - khi lng

tht sau nu)/khi lng tht trc nu.

3.8 X l s liu

S liu th c tnh ton v x l s b trn Excel v phn tch thng k

theo m hnh tuyn tnh tng qut (General Linear Model) trn Minitab (Minitab

Release 13.2, 2000) [146]. khc bit ngha ca cc gi tr trung bnh trong

v gia cc nghim thc c xc nh theo Tukey, vi alpha < 0,05.

M hnh th nghim 1 v 3:

Yijk = + i + j + i*j + eijk

Trong : - : trung bnh chung

- i: nh hng ca nhn t A mc i

- j: nh hng ca nhn t B mc j

- i*j: nh hng ca nhn t A tng tc vi nhn t B

- Yijk: tr quan st lp th k ca n v th j ca nghim thc th i.

M hnh th nghim 2:

Yij = + ti + eij

Trong : - : trung bnh chung

- ti: nh hng nghim thc

- eij: nh hng sai s

- Yij: gi tr quan st th j ca nghim thc i.

46

Hnh 3.1: G Hmng lc 1 ngy tui

Hnh 3.2: G Hmng lc 9 tun tui

Hnh 3.3: Du nnh th nghim

Hnh 3.4: M kho st g Hmng

Hnh 3.5: M kho st g Hmng

Hnh 3.6: o pH tht g

47

Chng 4: KT QU V THO LUN

4.1 Th nghim 1: nh hng ca cc mc nng lng trao i v

lysine trong khu phn ln sc sn xut ca g Hmng

4.1.1 Tng khi lng c th, tiu th v h s chuyn ha thc n ca

g Hmng 0-4 tun tui

4.1.1.1 nh hng ca nng lng trao i ln tng khi lng c th,

tiu th v h s chuyn ha thc n ca g Hmng

Kt qu Bng 4.1 cho thy vi 3 mc nng lng trao i khc nhau trong

khu phn lm cho lng thc n tiu th ca g Hmng giai on 0-4 tun

tui khc bit c ngha (P

48

nng lng trao i 45,04 kcal/con/ngy khu phn cha nng lng trao i

3.000 kcal/kg thc n, thp hn so vi khu phn cha nng lng trao i

3.100 kcal/kg v 3.200 kcal/kg thc n t 46,88 kcal v 46,63 kcal/con/ngy. G

Hmng tiu th thc n khu phn cha nng lng trao i 3.000 kcal/kg

thc n cao hn, nhng nng lng trao i c tiu th li thp hn nng lng

trao i c g tiu th khu phn cha nng lng trao i 3.100 v 3.200

kcal/kg thc n l do s chch lch nng lng trao i trong khu phn. iu

ny ph hp vi kt qu ca Leeson et al. (1996) [127] cho rng g c kh nng

cn bng nng lng tiu th theo mc nng lng trao i trong khu phn v c

kh nng iu chnh lng thc n tiu th b p cho s thay i nng lng

trao i trong khu phn. ng thi cng ph hp vi kt qu nghin cu ca

Nguyn Hu Li (2009) [159] cho thy g c tiu th nng lng cao hn

khu phn cha nng lng trao i cao v nguyn nhn l do s chch lch v

nng lng trao i trong khu phn. Tuy nhin, tiu th nng lng trao i ca

g Hmng 45,04-46,88 kcal/con/ngy, thp hn mc tiu th nng lng trao i

ca g Ai Cp theo nghin cu ca Trn Vn Tm (2008) [227] mc 53,7-55,5

kcal/con/ngy.

Tuy nhin, Dozier et al. (2006) [58] cho rng mc nng lng trao i c

g tiu th khng khc nhau khi nng lng trao i khu phn tng ln v g tht

cng nghip c th iu chnh s tiu th thc n t mc nng lng tiu th

ging nhau khi cung cp khu phn c nng lng trao i thay i. V vy, g

tiu th nng lng cho n v tng khi lng c th s gim khi nng lng

trao i khu phn tng nhng nng lng tiu th trn n v tht khng b nh

hng bi cc mc nng lng trao i trong khu phn (Dozier et al., 2006)

[58]. Trong th nghim ny cng cho thy g Hmng t iu chnh lng thc

n tiu th khu phn cha nng lng trao i khc nhau cn bng nng

lng c tiu th, nhng s iu chnh ch l tng i nn mc nng lng

trao i c tiu th ca g Hmng khng ging nhau.

Lng protein th c g Hmng tiu th Bng 4.1 th hin s khc

bit c ngha (P

49

Hmng tiu th lng thc n gim khu phn cha nng lng trao i cao

th s lm gim lng protein th tiu th. Lng protein th g Hmng tiu th

hng ngy thp hn lng protein th g Ai Cp tiu th hng ngy mc 3,9-

4,02 g/con/ngy theo nghin cu ca Trn Vn Tm (2008) [227].

Bng 4.1: nh hng ca nng lng trao i ln tng khi lng c th,

tiu th v h s chuyn ha thc n ca g Hmng giai on 0-4 tun tui

Cc ch tiu

Cc mc ME (kcal/kg thc n)

SEM P 3.000 (n=12)

3.100 (n=12)

3.200 (n=12)

Tiu th TA (g/con) 422a 425a 410b 2,47 0,001

Tiu th TA hng ngy (g/con) 15,08a 15,19a 14,64b 0,09 0,001

Tiu th ME (kcal/con) 1.261b 1.313a 1.306a 7,57 0,001

Tiu th ME hng ngy (kcal/con) 45,04b 46,88a 46,63a 0,27 0,001

Tiu th CP (g/con) 88,0a 88,0a 82,3b 0,51 0,001

Tiu th CP hng ngy (g/con) 3,14a 3,14a 2,94b 0,02 0,001

Tiu th lysine (g/con) 4,25a 4,28a 4,13b 0,03 0,001

Tiu th lysine hng ngy (g/con) 0,152a 0,153a 0,147b 0,001 0,001

T l lysine/ME tiu th (g/mcal) 3,370 3,261 3,161 - -

KLCT u G (g/con)* 28,37 28,40 28,37 0,14 0,98

KLCT cui G (g/con)* 193a 190b 182c 0,67 0,001

Tng KLCT (g/con)* 165a 162b 154c 0,69 0,001

Tng KLCT hng ngy (g/con)* 5,90a 5,77b 5,48c 0,03 0,001

FCR 2,44b 2,50a 2,49a 0,01 0,001

Ghi ch: a, b v c: nhng s trung bnh cng hng mang ch s m khc nhau sai khc c ngha

(P

50

ng thi, Bng 4.1 cn cho thy vi 3 mc nng lng trao i khc nhau

trong khu phn th s tng khi lng c th ca g Hmng giai on 0-4 tun

tui khc bit c ngha (P

51

3,37 g/mcal cao hn t l lysine/nng lng trao i mc nng lng trao i

3.100 v 3.200 kcal/kg thc n nn tng khi lng c th ca g cao nht.

Tuy nhin Waldroup et al. (1990) [235] cho rng khi nui g tht cng

nghip vi khu phn tng nng lng trao i ln t 2.600 n 3.200 kcal/kg

thc n khng nh hng n nng sut. Hn na, Holsheimer and Veerkamp

(1992) [92] cho rng g tng khi lng c th cao h

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