anh hucjng cua nhiet do, am do, chi so am nhiet -thi

VIEN C H A N NUOI - Tgp chi Khoa hgc Cdng nghi Chdn nudi - S6 4 C h d n g 2-2007)

ANH HUCJNG CUA NHIET DO, AM DO, CHI SO AM NHIET -THI (TEMPERATURE HUMIDITY INDEX) DEN LUONG NUOC UONG, LUONG THLTC AN AN VAO VA NANG SUAT, CHAT LUONG S0A CUA BO LAI F„ F,

NUOI TAI BA v i TRONG MUA HE

Vuong Tudn Thuc', Vu Chi Cuang^, Nguyin Thgc Hod' vd Nguyin Thien Trudng Giang^

'Trung tam Nghien curu bo va dong co Ba Vi, Vien Chan nuoi; ; J :.^

^Bg mdn Nghien ciru bo; ^Bg mdn Sinh ly Sinh hoa, Vien Chan nudi ,t

Tac gia d^ lien he: TS. Vu Chi Cuong, Phd Vien trudng Vien Chan nudi .^. ,.. •,,,; ,i^

DT: 0912121506, Email: vccuong@nemam.vn , , . , ^ ,

ABSTRACT . , o .

Effects of temperature, humidity and THI on water consumption, feed intake, milk yield and milk quality of F„ F2 dairy cross breed lactating cow in summer at BaVi Cattle and Forage Research Centre

i i

One experiment with 20 dairy crossbred cows, namely F, and F, rearing in small holders farms in Bavi was conducted to investigate the possible effects of temperature, relative humidity and THI on feed intake, water consumption and milk yield of cows during summer time. It was found that the temperature, relative humidity and THI had negative effects on water consumption, dry matter intake of roughage, milk yield of dairy cows in the summer time. These effects were more serious in F2 cows than those in F,. However, no effect of temperature, relative humidity and THI on milk compositions was found.

Key words: Cows: THI; Water; Feed intake; Milk yield

DAT VAN D ^ wi Nhidt do mdi trudmg va do dm Id yd'u td ehinh anh hudng dd'n san xudt sOa, dac bidt Id bd

siia nang sudt cao (Kadzere vd cpng su., 2002), vi chiing anh hudng ea lugng thiic an an vdo va lugng nhidt san xudt ra trong qua trinh trao ddi ehdt. Cac nghidn eiiu ve bd sita da tap trung rdt nhieu vdo cai tid'n di truyen va dinh dudng de nang cao nang sudt siia, nhung lai ed rdt it ede nghidn eiiu vd kha nang dieu hod nhidt cua bd sira hidn nay (Kadzere vd cpng su, 2002). Tang nang sudt sira ed nghia Id tang lugng thiic an an vdo vd tang san xudt nhidt do trao ddi chat. Bd sira thich hgp nhdt vdi khoang nhidt do tit 5 dd'n 25°C, day Id vimg nhidt do trung tinh (Roenfeldt, 1998). Khi nhidt do > 26°C, bd sira dat tdi diem, md tai dd chiing khdng cdn kha nang ldm mdt co the dugc niia va roi vdo trang thdi stress nhidt. Stress nhidt dugc dac trung bdi tang nhip thd va nhidt do true trang, trao ddi chdt siit kem, gidm lugng thiic an an vdo ndn nang sudt sira, sinh san giam (Bandaranayaka va Holmes, 1976).

Vdi mue dich budc ddu xdc dinh anh hudng cua nhidt do, am do trong miia he dd'n lugng nudc udng, lugng thiic an an vao, nang sudt va chat lugng sira cua bd lai F,, F2 giai doan dang khai thdc sira de tai nay da dugc tid'n hanh.

VAT LIEU VA PHl/ONG PHAP NGHIEN ClTU Ddi tugng nghien cicu thdi gian vd dia diem

De tai duge thuc hidn tir 1/5/2005 va kdi thiic vao 31/7/2005 trdn 20 bd lai hudng sOfa

VUONG TUAN THl/C - Anh hicdng ciia nhiet do, dm do. chisddm nhiet - THT . .

tai Trung tam Nghien cim bd va ddng cd Ba Vi trong mua he. Bd dugc nudi nhdt tai cdc ndng hd, cd do ddng deu vd: Iiia vdt sua (Iiia 3- 5), thdng vdt sua (tir thdng thii 2 - 4) va nang sudt sita.

Phuang phdp nghien citu

Anh hicdng cua nhiet dp, dm dp, chi sd nhiet dm (THI) den lugng thdc dn thu nhdn, lugng niCdc tieu thu hdng ngdy vd ndng sudt, chdt lugng sita a bd sica

Didn bid'n nhidt do, dm do mdi trudng duge tdng hgp tii sd lieu eua Tram khi tugng thuy van ddng tai Trung tam Nghidn ciiu bd va ddng cd Ba Vi. Didn bid'n nhidt do, dm do chudng nudi dugc do bdng mdy tu ddng Sato (do Nhat Ban san xudt) vdo 3 thdi diem: sdng (7 gid), trua (13 gid), chieu (17 gid). Chi sd nhidt dm THI (Temperamre Humidity Index) ciia tiing ngdy, timg thdi diem trong ngdy tinh theo cdng thiic ciia Frank Wiersma (1990):

THI = Nhidt do ben khd (°C) + (0,36 x Nhidt do bdn udt (°C)) + 41,2

Lugng thiic an thu nhan ciia bd sira, dugc theo ddi tumg cd the bdng phucmg phdp can lugng thiic an cho an va thiie an thira hang ngdy. Lugng ehdt khd an vao (CKAV) (kg/con/ngdy) = [(lugng thiic an cho an) x (ham lugng vat ehdt khd cua thirc an cho an)] - [(lugng thiic an thira) x ham lugng vat ehdt khd eua thiic an thira)]. Lugng nude tidu thu duge theo ddi timg cd the bdng pbuemg phap can, do (lit/con/ngdy). Lugng nudc tidu thu (lit/con/ngdy) = (lugng nude cho vao xd) - (lugng nudc edn lai trong xd).

Nang sudt sira dugc xdc dinh bdng phuang phap can true tid'p lugng sira hang ngay tai thdi didm vdt siia. Cde thdnh phdn ciia sira dugc xdc dinh bdng mdy Lactor Star ciia Dire.

Cdc sd lieu thu dugc duge xii ly trdn mdy tinh vdi phdn mim Excel va Minitab, bdng cac thuat todn: phan tich phucmg sai (ANOVA), tuong quan, hdi quy tuyen tinh bac nhdt vdi md binb thdng kd Y= a -f- bx d^ lugng hod quan he giira nhidt dd, dm do, THI cua mdi trudng vd chudng nudi vdi lugng nudc udng, lugng thii'c an an vao va nang sudt sira eiia bd lai F, , F2 nudi tai Ba Vi trong miia he.

KfiT QUA VA THAO LUAN

Anh hudng cua thay ddi nhiet dp, dm dp vd THI trong miia he den lugng thicc dn dn vdo, lugng nudc udng a bo F„ F^

Khdng cd sai khac \6 CKAV giira bd F, va F2 (P > 0,05), nhung bd F2 udng nhieu nudc ban bd F, (P < 0,05) (Bang 1).

Bang 1. Lugng thiic an an vao, lugng nudc udng cua bd F,, F2

F, (n=504 Idn quan sat) F2 (n=3"0 Idn quan sat) Chi tieu Min Max Mean ± SE Min Max Mean ± SE Thirc an an vdo KgVCK) 13,4 10,0 l l , r ± 0 , l 15,48 9,49 12,14" ±0,05 Nudc udng (lit) 41,3 38,1 39,0'±0,2 90,00 20,00 48,64'± 0,57

VIEN CHAN NUOI - Tap chi Khoa hgc Cdng nghi Chdn nudi - So 4 (Thang 2-2007)

Phdn tich mdi quan hd giiia vat chdt khd thtic an thd an vao trung binh (VCKTATHOTB), lugng nudc tieu thii hang ngay (NUTB) ctia bd F„ F2 nudi tai cac ndng hd d Ba vi vdi nhidt do chudng nudi trung binh (NDCNTB), dm do chudng nudi trung binh (ADCNTB), THI chudng nudi trung bmh (THICNTB), THI mdi trudng 17h (THIMT17h), THI mdi trudng trung binh (THIMTTB) chiing tdi cd kdi qua d Bang 2 va Do thi 1.

Bang 2: He sd tuomg quan giiia vat chat khd thiic an thd an vdo, lugng nudc tidu thu hang ngdy cua bd F,, Fj vdi cdc chi tidu nhiet do, dm do va THI

NDCNTB NDCNTB ADCNTB ADCNTB THICNTB THICNTB THIMT17 h THIMT17 h THIMTTB THIMTTB

F,

F2

F,

F2

F,

F2

F, F2 Fl F2

VCKTATHOTB r

- 0,032 - 0,339 - 0.257 - 0,291 -0.174 - 0,220 -0,218 -0,170

P 0,855 0,050 0,130 0,090 0,310 0,200 0,200 0,320

r 0,351 0,697

-

0,556 0,271 0,481

-

-

NUTB P 0,036 0,000

-

0,000 0,110 0,003

- - -

Nhidt do, dm do, THI ciia mdi trudng va chudng nudi anh hudng dd'n vat chdt khd thiie an thd an vao eiia bd F, it ban bd F2 (Bang 2). Trong 8 he sd tuang quan tinh dugc giiia cdc chi tidu nhidt do, dm do, THI ciia mdi trudng va chudng nudi vdi vat chdt khd thiic an thd an vdo ciia bd, cd tdi 5 he sd tuong quan thudc ve F2, va chi cd ba he sd tuong quan thudc ve F, (Bang 2).

Cudng do ciia he so tucmg quan va do tin cay cua he so tuomg quan cho thay la nhidt do, am do, THI ciia mdi trudng va chudng nudi anh hudng dd'n vat chdt khd thiic an thd an vao eua bd F2 vdi cudng do manh ban d bd F, (Bang 2). Trong khi VCKTATHOTB ciia bd F, chi ed 3 tucmg quan am yd'u vd khdng ddng tin cay ve mat thdng kd vdi NDCNTB, ADCNTB va THICNTB (r = - 0,032 de'n - 0,257, P = 0,130 dd'n 0,855) thi VCKTATHOTB cua bd F2 cd 5 tuong quan dm vdi cudng do cao ban chut it tir (r = - 0,170 den - 0,339) va dang tin cdy hem (P

= 0,05 de'n 0,32) vdi NDCNTB, ADCNTB, THICNTB, THIMT17h vd THIMTTB (Bang 2). Tdt ca ede tuomg quan deu Id tucmg quan am thdy stress nhidt d bd sira da ldm giam lugng thiie an an vao d bd siia.

Lugng nudc udng hdng ngay cua bd ciing didn bie'n theo mdt khuynh hudng tucmg tu nhung theo chieu ngugc lai. Nhidt do, am do, THI cua mdi trudng va chudng nudi anh hudng dd'n lugng nude udng hang ngay cua bd Fi ft bom bd F2. Trong 5 he sd tucmg quan tinh dugc giiia cac chi tieu nhiet do, dm do, THI ciia mdi trudmg va chudng nudi vdi lugng nudc udng hang ngay cua bd, cd tdi 3 he sd tucmg quan thudc ve Fj, va 2 he sd tuang quan thudc \6 F, (Bang 2).^

Cudng do cua he sd tuomg quan va do tin cdy ciia he sd tucmg quan cho thd'y rd la nhidt

VUONG TUAN THUC - Anh hudng ciia nhiit dd. dm dd. chi sd dm nhiet • TW. . .

eiia bd F2 vdi cudng do manh hem d bd F, (bang 2). Trong khi NUTB hang ngdy eiia bd F, ed 2 tuong quan duong yd'u va khdng dang tin cay ve mat thdng kd vdi NDCNTB va THICNTB (r = 0,271 dd'n 0,351, P = 0,036 dd'n 0,110) thi NUTB hang ngdy eua bd F2 ed 3 tuong quan duong vdi cudng do khd eao (r = 0,481 dd'n 0,697) va dang tin cay vd mat thdng kd (P = 0,003 dd'n 0,001 tlie la < 0,05) vdi NDCNTB, ADCNTB, THI THICNTB (Bang 2). 6 day, ede tuong quan deu la tucmg quan ducmg eho thdy khi bi stress nhidt bd siia tang lugng nude udng vao.

Quan he giira NUTB hang ngdy cua bd Fj va NDCNTB Id quan he hdi qui tuydn tinh bae nhdt, dang tin cay ve mat thdng kd (P < 0,001) vdi cudng do tucmg trung binh (r = 0,46) {Do thi 1). Theo Umberto va es., (2002): miia he lugng thiie an an vao d bd sua thdp hem 19,8%, edn theo Allan va Dan (2005) bd siia bi stress nhidt giam 10-15% lugng thiic an an vao. Lugng thire an an vdo eua bd dang vdt siia thudng giam khi nhidt do mdi trudng 25-26"C va giam manh d nhidt do 30 'C, d 40 "C lugng thiie an an vdo giam 40% hoae ban (NRC, 1989). Khi nhidt dg tang tir 25 ldn 30 va tir 35 ldn 40 "C lugng thiie an an vao giam tuong iing 18,1; 17,6;

16,8; 16,6; 10,1kg va nudc tidu thu tang tir 68,0; 73,7; 79,0; 119,8; 105,8 lit (NRC, 1981).

1

30 31 32

NDCNTB

D6 thj 1: H6i qui tuyd'n tinh bac nhdt giir NUTB hang ngay ciia bo F2 vai NDCNTB Stress nhidt d bd sira lam giam lugng thiie an an vdo cua thiire an thd rdt manh, va giam nhai lai (Collier va cs., 1982). Giam tinh ngon mieng trong didu kidn stress nhidt la do nhidt do CO thd' tang cao va cd the lidn quan dd'n siie chiia eiia da day (Silanikove, 1992). Theo Scott va es., (1983) cd quan he nghich giua lugng thirc an an vao (FI) (kg/ngay) vdi THI va nhidt do d nhidt ke khd tinh bdng "C. Cdn theo Mc Dowell va es., (1976) yd'u td mdi trudng tao ra gdn 40% bidn ddng ve lugng thiic an thu nhan trong miia he. Bd sira nang sudt eao trong didu kidn stress nhidt tang lugng nudc tidu thu vi chiing ed tdc do mdt nude eao hem (Maltz va es., 1984). Richards (1998) cdng bd bd sira khi gap dieu kidn ndng vao ban ngdy ehiing udng nhieu nudc vi ehiing nhd nudc du trii nhidt de ban ddm khi trdi mdt thai ra ngoai mdi trudng gid'ng nhu lac da (Schmidt-Nielsen, 1964). Co sd khoa hgc cua vide giam thu nhan thire an la stress nhidt da lam cho trung tdm lam lanh d phdn ddu Hypothalamus kich thich trung tam dieu khidn su no (no, ddi) trung tam nay iire chd' trung tam dieu khien su ngon mieng d bdn canh, kdi qua la lugng thire an thu nhan giam di va lugng sira giam (Albright va Allinson,

1972).

59

•J£.

Vi:-N CHAN NUOI - Tgp chi Khoa hgc Cdng nghi Chdn nudi - So 4 Chang 2-2007) Anh hudng cua thay ddi nhiet dp, dm dp trong miia he den ndng sudt vd chdt lugng sUa d bdF„F, • . • . .:

Ndng sudt sica cua bd thi nghiem

Nang sudt (NS) siia ciia bd F,, F2 nudi tai cde ndng hd d Trung tam Nghien curu bd va ddng ed Ba Vi, va quan he giiia NS siia va THI chudng nudi trong thdi gian thi nghidm duge trinh bay d Bang 3 va Dd thi 2. NS sira trung binh trong thdi gian theo ddi d F, vd F2 tuong irng Id: 10,7 ± 0,1 va 10,89 ± 0,09kg/con/ngay. NS sira ciia bd F, va F2khdngsai khde ve mat thdng kd (P > 0,05) chiing td bd Fj da bi anh hudng cua stress nhidt nang hom ndn NS giam chi cdn bdng NS ciia b o F , .

Chi tidu NS sua (kg)

Bang 3. Nang suat sira cua bd F,, F2

Fl(n=504 Idn quan sdt) ' ' F2 (n=370 Idn quan sdt)

Min Max Mean ± SE Cv% Min Max Mean ± SE Cv%

11,8 9,8 10,7 ±0,1 5,09 15,10 6,00 10,89 ±0,09 16,23 Dd thi 2 eho thdy mdt khuynh hudng ehung la NS sira ciia bd F, F2 chiu anh hudng ciia THI chudng nudi, khi THI trung binh cua chudng nudi tang ldn NS siia giam di va ngugc lai.

Chdt lucmg siia cua bd thi nghiem.

Kdi qua theo ddi ehdt lugng siia cua bd F,, F2 nudi tai cdc ndng hd d Trung tam Nghidn ciiu bd va ddng ed Ba Vi trong thdi gian thi nghidm dugc trinh bay d Bang 4 cho tha'y: ty Id md siia d F, Id: 4,1 ± 0 , 1 % (budi sdng), 4,1 ± 0 , 1 % (budi chidu); ty Id md sira d F2 Id: 3,70 ± 0,10% (budi sdng), 3,88 ± 0,08% (budi chieu). Cdc gid tri protein tuong iing cua F, la: 3,30 ± 0,0% (budi sdng), 3,2 ± 0,0% (budi chieu); vd F2 la: 3,13 ± 0,03% (budi sdng), 3,13 ± 0,03% (budi chieu). Cde gid tri vat chat khd (VCK) khdng md eiia F, la: 8,7

± 0 , 1 % (budi sdng), 8,4 ± 0 , 1 % (budi chieu); vd F2 la: 8,27 ± 0,07% (budi sdng), 8,20 ± 0,07% (budi chieu).

NSS 12 11.5

11 10.5 10 95 9

Ngay

THI chuong nudi va nang suat siira Fl, F2

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THI

]THITB -•-NSsi}aF2 -NSSOaFl

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D6 thi 2: Anh hudng ciia THI chudng nuOi dd'n nang sudt sira bd F,, F2

VUONG TUAN THUC - Anh hicdng ciia nhiet dd, dm do, chisddm nhiet - THI. . .

Mae dil ehdt lugng siia eua budi sang, budi chidu ciia cung mdt gid'ng khong cd sai khac cd y nghia thdng kd (P > 0,05), ehdt lugng sira eiia F, (md vd VCK khdng md) cd sai khae ed y nghia thdng kd (P < 0,05) vdi ehdt lugng sira eiia Fj (md va VCK khdng md).

Bang 4: Chdt lugng sira eua bd F, va Fj

Chi tidu Bd n (Ian) Sang

Mean ± SE

Chidu Mean ± SE Mo'

Md Protein Protein

VCK khdng md VCK khdng md

F, Fa F, F2 F, F2

84 55 84 55 84 55

4,10^ ±0,10 3,70" ±0,10 3,30 ± 0,00 3,13 ±0,03 8,70^ ±0,10 8,20" ± 0,07

4,10^ ±0,10 3,88 "±0,08 3,20 ± 0,00 3,13 ±0,03 8,40" ±0,10 8,27 "±0,07 Nhidu kdi qua phan tieh chdt lugng siia trudc day cho thay chat lugng sira eua bd lai F, eao hon bd lai Fj, bd lai F3 va bd siia HF thuan nudi tai Viet Nam. Kdi qua eua ehiing toi eho thdy F2 gdn tuong duong vdi kdi qua phan tich eua eiia Nguydn Kim Ninh va es, (1997), khi phan tieh sua cua bd F, d Ba Vi: (md 4,32 ± 0,01% protein 3,54 ± 0,01%) vd bd F2: (md 3,98 ± 0,01%, protein 3,46 ± 0,01%).

Khdng tha'y ed su thay ddi vd ehdt lugng siia d nhirng ngay phan tieh ehiing td chdt lugng sira cua bd F, , Fj khdng hoae rdt it chiu anh hudng eiia mdi trudng. Trong nhimg ngay phan tieh sii'a, gia tri THI chudng nudi bid'n ddng rdt ldn va d mirc cao (tir 82,5 dd'n 89,6), nhung chdt lugng sua: md (TB Fat), protein (TBprotein), va chdt kho khdng kd md (TBSNF) khdng thdy cd su bid'n ddng nao dang ke.

Anh hudng cua moi trUdng din ndng sudt sita ciia bo F,, F2

Phan tieh mdi quan he giira NS va ehdt lugng sira cua bd F,, Fj nudi tai cac nong hg d Ba Vi vdi ede ehi tidu nhidt do, dm do va THI chung tdi cd kdi qua d Bang 5.

NDCNTB, ADCNTB, THICNTB, NDMTTB, ADMTTB, TH1MT13 h, THIMT17 h, THIMTTB cd anh hudng dd'n NS sira ciia bd F, vd F2, nhung miie do anh hudng la khae nhau.

Nhidt do, am do, THI ciia mdi trudng va chudng nuoi anh hudng dd'n NS sira eiia bd F, it ban bd F2. Trong 10 bd sd tuong quan tinh duge giira cde ehi tidu nhidt do, am do, THI eiia moi trudng va chudng nudi vdi NS siia eiia bd, ed 5 he sd tuong quan thudc ve F,, va 5 he sd tuong quan thudc ve F2 (Bang 5). Cudng do eiia he sd tuang quan va do tin cay eiia he sd tuang quan cho thdy nhiet do, am do, THI eua mdi trudng va chudng nudi anh hudng dd'n NS sira ciia bd Fj vdi cudng do manh hem d bd F, (Bang 5).

Trong khi NS sua trung binh eiia bd F, ehi cd 5 tuang quan am rat yd'u va khdng dang tin cdy vd mat thdng kd vdi NDCNTB, ADCNTB va THICNTB, ADMTTB va THIMTTB (r = - 0,015 dd'n - 0.249, P = 0,143 dd'n 0.931) thi NS sua trung binh eiia bd F2 ed 5 tuong quan am vdi cudng dd eao ban chiit it tir (tha'p dd'n trung binh) (r = - 0,153 dd'n - 0,402) va dang tin eay ban (P = 0,37 dd'n 0,02) vdi ADCNTB, NDMTTB, THIMT13 h, THIMT17 h va THIMTTB (Bang 5). Hdu hdi eae tuong quan deu la tuong quan am chimg td stress nhidt da lam giam NS 61

VIEN C H A N NUOI - Tgp chi Khoa hgc Cdng nghi Chdn nudi - So 4 Chang 2-2007) siia cua bd siia. Trong sd cdc tucmg quan tinh dugc tuong quan giiia NS sira trung binh eua bd F2 va NDMTTB d miie trung binh vd ddng tin cdy ve mat thdng kd (r = - 0,402, P < 0,05) cho thdy nhidt do mdi trudmg cd anh hudng de'n 40% ede dao ddng ve NS siia ciia bd F2 nudi tai cdc ndng hd d Ba vi. Ha tdy. -

Bang 5: He sd tUcmg quan giiia nang suat sira ngay (kg) ciia bd F,, Fj vdi cdc chi tidu nhidt dd, dm dd va THI

Chi tieu Bo Nang sudt siia trung binh

r P NDCNTB

NDCNTB ADCNTB ADCNTB THICNTB THICNTB NDMTTB NDMTTB ADMTTB ADMTTB THIMT13 h THIMT13 h THIMT17 h THIMT17 h THIMTTB THIMTTB

F»

F2 F, F2 F, F2 Fx F2 F, F2 F|

F2 F, F2 F.

0,056 0,015 0,197 0,077

- 0,402 0,077

- 0,348 - 0,307 - 0,249 -0,153

0,747 0,931 !.; A'

0,25 0,657

;/i . 1 ; ^

0,02 ^ /M.' 0,656 ^ .s

0,04 0,07 0,143

0,37

' 3: r ' tr;

Phan tich mdi quan he giiia vat chdt khd thiic an thd an vdo (VCKTATHOAV) vd nang sudt siia chiing tdi thdy: nang sudt sira cd quan he kieu mdt ham bac hai (parabon) vdi vat chdt khd thtic an thd an vao (r = 0,6542; P < 0,001)

10.0-1 40

1 —

50 1 —

60 VCKTATHOAV

1 — 70

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VUONG TUAN THUC - Anh hudng cita nhiet do. dm do. chi sd dm nhiet - THI. . .

Theo Mc Dowell vd es., (1976) yd'u td mdi trudng tao ra 50% bid'n ddng ve NS sira trong miia he va bd se eho sira it hem trong dieu kidn stress nhidt (16,5 lit so vdi 20 lit) (P < 0,01) (Schneider va cs., 1988). Su giam NS sua xdy ra khi nhidt do mdi trudng qua 80'F (26,7°C) hoac ehi sd stress nhidt vugt qud 72 (Collier va cs., 1982). Theo Beede va es., (1985) trong miia he, NS siia ciia bd giam 10 - 20%, bd giam ea sd ngay eho sira va san lucmg sira. San lugng miia he sira thdp hem 10% so vdi mua xuan (P < 0,01) (Umberto va cs., 2002). Theo Schneider va es., (1988) trong didu kidn stress nhidt bd eho siia it hem (P < 0,01). Ddi vdi bd dang vdt siia, nhidt do trdn 25"C lam giam lugng thiic an an vdo do dd giam san lugng siia va tdc do trao ddi ehdt (Berman, 1968). Tdt cd cdc ddp ting nay la de giam nhidt do co thd (Beede va Collier, 1986).

Thdng thudng Bd Bos Taurus ddp iing kem hem bd Bos Indicus, bd Zebu trong mdi trudng ndng dm (Kadzere va es., 2002). Bd Bos Indicus it mdn cam ban Bos Taurus, Jersey it mdn cam bon Holstein (Sharma va es., 1983). Cd le day la ly do tai sao NS siia eiia bd Fj (25% mdu Bos indicus) bi anh hudng bdi stress nhidt nhidu hem va nang hem NS sira ciia bd Fi (50% mdu Bos indicus). • f ; /

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, , , KET LUAN VA DE NGHI Kit ludn

Khdng cd sai khac ve CKAV giira bd F, vd F2 (P > 0,05), tuy nhidn bd F2 udng nhieu nude ban bd F, (P < 0,05).

Cde yd'u td mdi trudng anh hudng dd'n VCKTATHOAV eiia bd F, it ban bd Fj.

VCKTATHOAV ciia bd F2 cd 5 tuomg quan am vd- cudng dd cao ban vdi TBNDCN, TBADCN, TBTHICN, TBTHIMT17h va TBTHIMT cho thdy stress nhidt d bd sua da lam giam lugng thiirc an an vdo d bd sua F2.

Cdc yd'u to mdi trudng anh budng dd'n NUTB bang ngay cua bd F, it hem bd Fj. NUTB hang ngay eiia bd F2 ed 3 tuong quan duong vdi cudng do kha eao vdi TBNDCN, TBADCN, TBTHICN cho thdy khi bi stress nhidt bd sua Fj tang lugng nudc udng vao.

Nang sudt sira trung binh trong thdi gian theo ddi d F, va F2 tuong img la 10,7 ± 0,01 va 10,89 ± 0,09kg/eon/ngay. Nang sudt sira eiia bd F, va F2 trong thdi gian tbi nghidm khdng sai khac ve mat thdng kd (P > 0,05) Chat lugng sira cua F, (md va VCK khdng md) sai khae ed y nghia thdng kd (P < 0,05) vdi ehdt lugng siia cua Fj (md va VCK khdng md).

Cac yd'u td mdi trudng anh hudng dd'n nang sudt siia eiia bd F, it hem vd vdi cudng do nhe hem anh hudng nay d bd F2. Nang sudt sira eua bd Fj cd 5 tuong quan am vdi cudng do eao ban vdi TBADCN, TBNDMT, TBTHIMT 13h, TBTHIMT 17b vd TBTHIMT eho thdy stress nhidt d bd sira da ldm giam nang sudt sira ciia bd sira F2. Giira nang sudt sua eiia bd F2 va trung binh nhidt dd rndi trudng (TBNDMT) ed tuong quan d miie trung binh va dang tin eay vd mat thdng kd (r = - 0,402, P < 0,05) eho thdy nhidt do mdi trudng ed anh hudng dd'n 40% eae dao ddng vd nang sudt sira eiia bd F2. Chdt lugng sita eiia bd F,, Fj lai khdng chiu anh hudng eiia stress nhidt. ;, j > v .£ , .y y. ) / ; -

De nghi

Do stress nhidt ed nhirng anh hudng tidu cue va lau dai dd'n bd sira trong miia he ma nghidn eiiu nay mdi chi thuc hidn trong mdt thdi gian ngdn, edn ed nhirng nghidn eiru tidp dd khdng dinh eae kdi qua ban ddu va md rdng sang cdc nhdm gid'ng bd sira khae. Nhirng nghien

VIEN CHAN NUOI - Tgp chi Khoa hgc Cdng nghi Chdn nudi - S6 4 C h a n g 2-2007)

eiiu tie'p theo ndn tid'n hanh xem xet anh hudng cua stress nhiet dd'n sinh san va dua ra cdc giai phap (dinh dudng, chudng nudi, gid'ng,...) lam giam stress nhidt cho cdc loai bd siia nudi tai nudc ta.

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TAI LIEU THAM KHAO

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J. Anim. Sci. 32 (1972), pp. 566-577.

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Beede, D.K. and R.J. Collier. 1986 - Potential nutritional strategies for intensively managed cattle during thermal stress. J. Anim. Sci. 62 (1986), pp. 543-554.

Beede, D.K. Beede, R.J. Collier, C.J. Wilcox and W.W. Thatcher. 1985 - Effects of warm chmates on milk yield and composition (shortterm effects). In: A.J. Smith, Editor, Milk Production in Developing Countries, University of Edinburgh, Scotland (1985), pp. 322-347.

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19(1968), pp. 181-188.

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Livestock production Science. Vol: 77, Issue 1, pp; 59-91

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Biochem. Physiol. 77A (1984), pp. 79-84.

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NRC (1981). National Research Council. Nutrient Requirements of Dairy Cattle, (6th Revised Edition Update ed),.National Academy Press. Washington, DC .

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Washington, DC National Academy Press, Washington, DC (1989).

Richard.S.Adams. 1998 - Reducing heat stress on Dairy cows. ' '

hltp://www.penpages.psu.edupenpagesreference/28902/28902123HTML. Pagel of 3 ' •' ;'•

Roenfeldt S.. 1998 - You can't afford to ignore heat stress. Dairy Manage. 25 5 (1998). Pp. 6-12.

Scheneider P. L., Beede D. K. and Wilcox C. J.. 1988 - Nycterohemeral patterns of acid-base status, mineral conventrations and digestive function of lactating cows in natural or chamber heat stress environments. J.

Anim. Sci. 66 (1988). Pp. 112-125.

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