D,;.I HQC Qu6c GIA - TP. HCM
TRUONG D,;.I HQC KHOA HQC TV NHIEN
L Y THJ THANH LOAN
"
,
",,"
A1...
NGHIEN CUU MOT SO VI KHUAN VA VIRUS
GA Y B~NH TREN TOM SU (Penaeus monodon)
"
A1
NUOI THU<1NGPHAM
{j DONG BANG SONG cifu LONG
CHUYEN NGANH : VI SINH
MA SO: 1.05.12
TOM TA T LU!N AN TIEN si SINH HOC
TP. HO CHI MINH - 2003
J>-L
tONG TRiNHaliOC HoANTHANHT41
VleN NGHIENcl1u NUOITRaNGTHUYSANII
Ngllirihll(fngdin khoahoc:
1. PGS.TS.PH4MTHANHHO
2~ TS. NGUYEN
VANHAO
Phin bien1: .PGS.TS.BiJiLai...................
,
..
Phin bien 2: PGS.TS. Tran Linh Thuoc.....................
.............................................................................
Phin bien3: .TS.TrinhTruongGiang...................................
"..,.,...,.........................
Lu~nan se duQcbaav~ truDcHOidongcha'mlu~nan ca'pnhanuDc
hop t~i
TruOngE>~ihoc Khaahoc TI,lnhien
,
,
...D(,lihoc Quac gia - Tp.Ho ChI Minh ...............................
vaohoi ,09.giCJ00 ngay30 thang..01..nam2004...
Coth~tim hi~ulu~nant~i thuvi~nKhoahocTOnghOpva
thuvi~nTruOng
E>~ihocKhoahocTI,lnhien- TP.HoChiMinh
Lu4n an "Nghien cztu m(}t so'vi khudn va virus gay b~nh tren tom su
(Penaeus monodon) nuoi thlldng phdm d'D8ng Bang Song Cau Long"
Chu'dng 1: MO E>AU
1.1. Tinh c6p thiet cua luin an
Trong nhung th4p Bien g~n day, nu6i tr6ng tMy san c1khu vf!c CMu
A n6i chung va Vi~t Nam n6i rieng dang tren da phat tri~n, nha'tla
ngM nu6i t6m bi~n c1nhung vung veil bi~n, cii'a s6ng. Tuy nhien, mQt
trC1ng~i ldn anh hu'C1ng
de'n Dang sua't va san 1u'<;1ng
la va'n d~ djch b~nh
bUng n6 trong qua trlnh nu6i cling vdi sf! suy thoai m6i tru'<1ng.
Vi the', va'n d~ ca'p bach hi~n nay la pMi xac djnh nguyen nMn gay
che't t6m nu6i, cac ye'u t6 m6i tru'<1ng,mua vt,lxua't hi~n b~nh d~ giam
nhung thi~t h~;ddo ~nh t6m gay ra h~u c6 th~ mC1rQng va phat trieD
ngh~ nu6i Wm biln mQtcach Mn vung (j Vi~t Nam, ct,lth~ la cac dnh
D6ng B?ingS6ng Cii'uLong (DBSCL).
1.2. Ml,lcti~u cua luin an
D~ tai du'<;1c
thf!Chi~n nhiim xac djnh vi sinh v4t (vi khua'n va virus)
gay b~nh; hta tu6i nhi~m va th<1idilm xua't hi~n mQt s6 b~nh thu'<1ng
g~p tren t6m su nu6i c1cac m6 hinh nu6i cM ytu: quang canh (QC),
ban tham canh (BTC), "Tom - Lua" va tham canh (TC) - nu6i c6ng
nghi~p (CN) d DBSCL d~ lam cd Sc1khoa hQc cho vi~c d~ xua't cac
giai phap phOng tq thfch h<;1p.
1.3. NQidung cua luin an
- Nghien cU'u~m ~nh vi khua'n, cM ye'u nh6m Vibrio tren t6m su
nu6i tren m6 hinh BTC va "Tom -Lua".
-
Nghien cU'u~m
b~nh virus (MBV va WSSV) tren t6m su va cac
loai thuQc hQ t6m he tren m6 hinh BTC, "T6m - Lua" va QC ("Tom r
Rang" va "Rang-Tom").
'
"-""-'"
"--"
f
II:)H.
V.i-LTt! NHi
,! .
,., t'iI
1 p'r' r,\..' !
U U'
. n \lJ \.'; ~1::'1\4 !
!f
!
!
l
"""":-"'\
.
j
2
- Nghien cti'u va
M th6ng
cac b~nh thu<'1ngg~p tren tom su nuoi
thudng phGm (Penaeus monodon) d mo hinh nuoi TC.
1.4. Net md! cua lu,n an
- Lu~n an la mQt trong nhii'ng oong trinh d~u tieD d Vi~t Nam nghien
cti'u c6 M th6ng cac vi sinh v~t gay b~nh quail trQng: nh6m Vibrio,
MBV, WSSV tren tom su nuoi d cac roOhinh khac nhau (QC, BTC va
TC) t~i cac dnh BBSCL.
-
Lu4n an ding la mQt trong nhung cong trinh dAu tieD nghien cau va
tdng hqp cac b~nh thu<'1ngg~p tren tOm su d cac giai do~n phat tri€n
khac nhau tren mo hinh nuM TC.
Y nghiii khoa h{Jc
Hinh thanh cd sd khoa hQc cho vi~c xac dinh nguyen nhan gay che't
tom nuoi d BBSCL va
Y nghia
M xua't cac
giiii phap phOng tranh.
tht/c ti5n
- Giup Dong db
c6 th€ phong ngita b~nh tren tom trong chu ky nuoi
thong qua vi~c qUail 19 sac khOe tom nuoi cung vdi cac giiHphap do
lu4n an d~ xua't.
- Ke't qua cua lu~n an giup cd quail qm\n 19 Nha nudc c6 duqc cd si'1
khoa hQCva cac thong tin c~n thie't v~ nguyen nhan gay che't tom nuoi
d BBSCL, nh~m ph\lc V\lchie'n luqc phOng tri b~nh tren tom nuoi thich
hqp.
Chuang 2: TONGQUANTAl LieU
G6m 6 d~ m\lc:
D~ IIlQCd~u tieD Hi gidi thi~u sd net v~ tinh hinh nuoi va dich ~nh
tom teen the' gidi. San d6 khao sat v~ tinh hinh nuoi tom su va nhung
thi~t h~i do dich ~nh tom gay fa d Vi~t Nam.
D~ m\lc 2: thai quat v~ cae roOhinh nuoi tom phd bien d B6ng B~ng
Song Cii'uLong (DBSCL): BTC, "Tom -Lila" , QC ("Tom -
3
Rung", "Rung - Tom") va TC (nuMcongnghi~p).
E>~m\lc 3 va 4: gidi thi~u cac ~nh thu'<'1ng
g~p tren tom so.nuoi va cac
vi sinh v~t g~y ~nh chinh tren tom so. nhu' b~nh do virus (MBV,
WSSV, YHCV); b~nh nhi~m khu~n (nh6m Vibrio).
E>~m\lc 5: gidi thi~u mQt vai phu'dng phap nghien cU'uvi sinh v~t g~y
b~nh tren tom so. va cac loai thuQc h~m\le 6: sd net v~ tinh hlnh nghien eU'u~nh vi sinh v~t (virus va vi
khu~n) tren tom so. va cac loai tom he tren the' gidi va
a Vi~t
Nam.
Chlidng 3: V4T lieU vA PHUONG PHAp NGHIEN CUU
3.1. Nghi6n cuu mSm btnh vi khuin tr6n tom nuoi is eaSCl
3.1.1. Thai gian, dla di~m, IliQng miu phan trch
Thiti wan
02/1994 - 03/95
02/97 - 05/97
Dia diim
S61u'nl! m u thu
Cae tinh f>BSCL
Cn f>u"deLong An
256 mu
102 mu
Mcj hlob
Ban tham eanh
"Tom-Lila"
3.1.2. Phlidng philp
- Phan l~p tae nhan g~y ~nh
tir cae milu tOmbhng phu'dng phap nuoi
c{{ytruy~n th6ng va dinh daub vi khu~n theo Bergey, 1994.
- G~y nhi~m nhan ~o
d~ xac dinh kba mlng g~y b~nh cua cae loai vi
khu~n phan l~p tir cae milu tom bhng phu'dng phap ngam va tiem.
- T~o khang huye't thanh cua V. harveyi tren ca tai tu'<;1ng
va thii' 1i'ng
d\lng trong ch~n doan nhanh vi khu~n g~y ~nh tren tom (theo phu'dng
phap eua cae tae ghl J.A. Plum va P.R. Bowser (1982); Grimes va etv.
(1987); Yii va etv (1997).
4
3.1.3. XU'IVs61i~u
Ap d\mgcac ph~nm~mtrongchu'dngtrinhSPSSde xii'19s6lic$u.
Dung phep rinh th6ng ke mo ta de rinh cac gia tIi: gia tIi trung biBb
(mean), dQlc$chchu~n (SD),M s6 tu'dngquaDPearson va phu'dngsai
ANOVA de tim cac m6i tu'dngquaD.
3.2. Nghi6n ct1u mim b~nh virus: virus g6y b~nh col (MBV)va
virus g6y hoi chang d6m trAng (WSSV)tr6n t6m su va cae loai is
hQt6m he
3.2.1. ThCligian, dla (liim, htC1ngmiu ph6n tfch
ThO'iIdan
to'0205/1997
to'0307/1998
to' 06/97 -
Dia diim
Cn Dude Long An (*)
Duyen Hili Tri'iVinh (*)
Ci'iMau (**)
05/98
S6miuthu
108 mfiu
91 mfiu
Me) hlnh
"TOm-LUa"
BTC
72 mfiu: TOmgitfng
"Tom-Rimgn,
216 mfiu: TOm trwng thanh
"Rimg-Tom"
Ghi eM: (*): phdn tfchMBVva WSSV bdng phllang phdp mo hqc truy€n tMng.
(**): phlin rich MBV bdng phllang phdp mo hqc truyin tMng; WSSV bdng
phllang phap nW hqe va PCR.
3.2.2.
Phu'dng phap
- Phltdng phdp M6 hqc: m§u tom du'<;1c
thu ph~n gall tl}.yva mang (m§u
tOm gi6ng thu nguyen con) c6 djnh trong dung djeh Davidson. Xii' 19,
duc trong parafin, cAthit vdi dQ day 5 - 6 J1m;nhuQmvdi Hematoxylin
va Eosin. 8ge ke't qua theo Lightner (1996a).
- Phltdng phdp PCR: mall thu pMn mang (mau tom gi6ng thu nguyen
con) c6 djnh trong cdn 95%, du'<;1c
nghi~n vdi dung djeh SDS (Sodium
Dodecyl Sulphate) 0,0025% va NaOH 0,005N de ly trieh DNA. San d6
tie'n hanh pban 6'ng PCR theo quy trinh cda Kim (1998). - Phltdng phap
phdn rich cae chi tieu chtlt Iltqng nltoc: pH, 00, dQtrang, dQm~n du<;1e
de djnh theo cae phu'dng phap thong thu'<7ngcua phong thi nghic$m
thuy h6a.
5
3.2.3. XU'IV soU,u
Ap d~ng cae ph~n m~m trong chu'dng trlnh SPSS d~ xii' ly s6lic$u.
3.3. H, thong mQt so b,nh thuC1ngg4p tr~n t6m su Csm6 hlnh
nu6iTC
3.3.1. ThC1igian, dla diim, so ao nghh!n euu
Thiti gian
1999-2000
Dia di~m
I
1 Long
Hlidng
(Bi!
D~e di~m
S6 ao
I
n2hi~n eU'u
2 ao
Ria - VfingTau
1999-2000 I C6nC6ng
(Tien Gian.
4 ao
B<;1e
Li~u
1999-2000 VinhH~u
03-07/2001 Trai Thlien hiem
22 ao
2 ao
Vung da't cao trieu, yen
bi€n Nam 86m!.Hau
3.3.2. Phuong phap nghi6n euu
- Quan sat da'u hic$ubc$nhtich va bi~u hic$nlam sang cae bc$nh:
+ Lien quaD de'n ye'u t6 moi tru'C1ng:bc$nhmang barn, b~nh
nhiem khuei'n,bc$nhden mang, hQich6'ng tom n6i d~u.
+ Cae bc$nhdo virus: bc$nhMBV, bc$nhd6m trilng (WSD).
- Quan trilc cae ye'u t6 moi tru'C1ng:
+ Nhic$tdQ,pH, oxy bOa tan (sang va chi~u).
+ Do NH3-N, COD, de)~n: 2 tu~nll~n.
- Thu m§u tOm: 10 ngayllftn, kiSm tra mftm b<$nh WSSV va
MBV.
Chuang
4: KET QUA
- THAo Lu4N
4.1. Nghi6n euu mim b,nh vi khu§n tr6n t6m nu6i CseBSCL
4.1.1. Tin so xuat hi,n ella cae loi:ti Vibrio e6 kha n4ng gay b,nh
tr6n t6m nu6i Csm6 hlnh BTC
6
Klt qua ghi nh~n c6 Sf!.sai khae y nghla (p <0,05) v~ ~t
giira cln so' xu!t hi~n cia
th6ng k~
cae loai vi khua'n g;iy ~nh:
V.
parahaemolyticus, V.alginolyticus, V.harveyi tr~n cae mill t6m e6 ddu
hi~u b~nh d~u caDhdn cae mill kh6ng c6 ddu hi~u ~nh.
Bang 4.1.1 T~ns6 xua'thi~n cda cae loai vi khuln tren eae mAll
tom nuoi- Mo hlnhBTC41icae tInhDBSCL
Loai vi khudn
Vibrio so.
V. oaraheamolvticus
V. alfdnolvticus
V. anf!uillarum
V. cholerae non 01
V.harvevi
V. oelafdus
V.metschnikovii
V.fluivalis I
Pseudomonas so.
Enterococcus
Tan s6 xucft hien (%)
TrJmco dt1uhiu
TrJmkMng co dt1uhifU
(n 24])
benh (n 15)
100
100
0
2282
0
224
0
39,8
200
9.90
4.1
0
236
15
0
866
58
600
481
666
1,2
=
=
nh
n: s6 milu kilm Ira
4.1.2. Tin 66 cua cae loBI Vibrioco kha Ding gay btnh t~n t6m 6U
nu61 iJ m6 hinh "T6m Lua"
-
Bang 4.1.2 T~n s6 cda eae 10Mvi khu~n Wn cac m§u tom nudi
Md hinh "T8m - Laa" ta i C~n Dltdc LongAn
Loai vi khulin
TAnslf xulft hi2n (%)
Mdu nh (n =41 )
Mdu dink IcY(n =41)
Vibrio so.
100
100
V. alrdnolvticus
26.83
17.07
V. anf!uillarum
26.83
2.43
V. cholerae
26.83
4.87
V. harvevi
2683
12.19
V. vulnitfcus
0
31.70
V. camobelli
34.15
29.26
V. mimicus
0
78.04
V. fluivalis I
55,65
14,63
-
Ghi eM: n: s6 mdu kitm Ira
-
7
Ke't qua khao sat cae m~u t6m tho t~i C~n Dude -Long An, ghi nh~n
cae loai vi khu~n g~y b~nh hi~n di~n trong cae m~u tho d<;Jtdieh b~nh
eho ke't qua eao hdn cae m~u tho dinh ky. xU' 19th6ng ke eho tha'y e6
sf/.sai khae
9 nghia
(p < 0,05) d6i vdi cae loai V. harveyi, V. cholerae,
V. anguillarum gitYacae m~u tho dinh ky va tho Ilk dieh ~nh.
4.1.3. Xac dlnh kha n4ng gay b,nh cua cae lOBi Vibrio tren t6m
- Ke't qua gay nhi~m ghi nMn khci Dang gay ~nh eua cae loai Vibrio
g~y nhi~m tren t6m, dii ehti'ng minh c6 m6i tudng quaD gitYacae loai
Vibrio g~y ~nh vdi cae m~u t6m c6 bilu hi~n b~nh deh dii tho du'<;Je
tren cae ao nu6i nhu': do than, phdng v~y r~u, ehan du6i, ho~i tU'cae
pMn ph~.
- Ke't qua gay nhi~m ghi nMn
ty l~ t6m ehe't b?1ngphu'dng phap tiem
eao hdn phu'dng phap ngam. Di~u nay eho phep ghi nh~n t6m nhi~m
khu~n huye't (nhi~m khu~n toau th~n) thi g~y tae h~i hdn t6m bi nhi~m
khu~n e~e bQ.
Bang 4.1.3 TY11$
tOmche'ttrungblnhsan khi g~y nhi6m 168gio (7 ngay)
Loai vi khu4n
V. harveyi
V. parahaemolyticus
V. alginolyticus
V. anguillarum
V. vulnificus
D6i chang
Phddng ph8p gay
nhim
nf1;m
tiem
nj!;m
tiem
nJ!.m
tiem
ndm
tiem
ngm
tiem
ngiim
tiem
Ty I tm
nh va chtt
saD 168 fliit (7 nflAy)
70,00 :t 0,70 %
100,00:t 0%
66,67 :t 6,67%
100,00:t 0%
46,70:t 14,53%
73,33 :t 3,33 %
30,00:t 11,54
30,OO:t5,77%
13,83:t 8,82%
16,70:t 5,77%
0
0
8
4.1.4. Nghi~n cl1u chi t4o khang huyit thanh V. harveyl dg phat
hi,n nhanh vi khu§n nay tr6n tom
Thi nghi~m du'6[114]. Khi m~t dQ nh6m Vibrio khdng g~y b~nh trong mdi
tntCJngao nudi giam thi b!'y giCJnh6m Vibrio g~y ~nh ehie'm u'u the',
d6 rung Ia Iue cae ~m ~nh khae c6 thi xu!'t hi~n [82].
-
Cae vi khu§n g~y ~nh (V. parahaemolyticus, V. harvey, V.
alginolyticus, ...) chi xu!'t hi~n tren cae m~u tdm c6 ~nh tich nhu':
ffiQts6 d6t tren th~n bi do. phdng v§y riu, eMn dudi, ndi bi phdng c6
10
man hdng nh1;ltd6n hdng s~m va ho1;litit K6t qua kbao sat nay phil
h<;1pvdi nghien cU'utht1cnghil$mcua Eleonor , V. Alapide- Tendencia
va ctv. (1997), ghi nMn vdi V. parahaemolyticus tom bi6n man qua 4
giai do1;ln:vang, vang hdng, hdng d6n do. Theo Lightner va Redman
(1985) tom bi bi6n do lit do sActo' astaxantin hil$ndil$n tren cae loai
giap xac, khi co V.parahaemolyticus xam nMp thl astaxantin theo M
lympho d6n khu trU t1;ligall t1;J.y
va cae mo khac. MQt so' tac gia khac
thl cho rAngbl$nhdo hay hQi chd'ng do tren tom su bao gdm nhi~u hie
nhan, trong do co ca v. alginolyticus [64, 90].
- V. vulnificus hil$n dil$n tren cae mftu tom tii' 23,60% d6n 31,70%.
Theo Paul, T. Smith (2000) thl vi khuan nay du'<;1c
t1mtha'y tren tom su
nuoi bi ho1;litd' C1mAt[126].
4.1.6. Kit lucjn
- T~n
so' cua nhOm Vibrio gay bl$nh (V. parahaemolyticus,
V. alginolyticus,
V. harveyi,
...) chi6m u'u th6 trong cae mftu tom co da'u hil$u bl$nh
nhu': do than, phdng vay ran, chaD duoi, ho1;litd' ph1;J.bQ,
'"
- K6t qua gay nhi~m da xac dinh kba Dang gay bl$nhcua cae loai
Vibrio gay bl$nhpMn l~p du'<;1e
tii'cae mftu tom bl$nh.Cac mftu tom san
khi gay nhi~m d~u c6 da'u hil$ubl$nhnhu'cae mftu dii thu t1;liao nuoi.
- Co m6i tu'dng quail giii'a st1hil$n dil$n cua cae loai Vibrio gay bl$nh
vdi da'u hil$ubl$nhtren tom.
- Khang
huy6t thanh du'<;1ct~o ra tii' ca tai tu'<;1ngc6 hil$u gia khang the
cao va tinh dijc hil$u cao, c6 the d'ng d1;J.ngde eh£n doan nhanh cae
bl$nhdo vi khuan.
4.2. Nghl6n cuu mam b,nh virus (MBV, WSSV) tr@nt6m su va
cac loai thuQc hQt6m he
.
4.2.1. Ty I, nhi6m MBVtr6n t6m nu6i
4.2.1.1. TyI, nhi6mMBVtr6nt6mnu6i- M6hinh "Tom- Lua"
11
Ty I~ nhi~m MBV !ren tdm sli nudi d IDQng Ilia kM cao
(75,57 :i:19,47%),c1f(1ngdQnhi~m nh~ chi~m da s6 (32,70%) va c1f(1ng
dQ nhi~m n~ng chi~m ty I~ thtp nhtt (15,90%)
,-..
-
~
35
30
ImMBvl
t;I? 25
~
,;:.,
20
.
15
10
5
0
~ 1)
~
~'c.-.
'\c.-.
~
~-2
~~
!f~
"'.sl.
'"
~
Cdling dO nbi~m
Biiu dd 4.2.1.1. Ty I~ nhi~m MBV tr~n t6m nu6i
M6 hlnh "Tom Lila"
-
4.2.1.2.
TV" nhlim MBVtr6n t6m sti
.
- M6hlnh ban thctmcanh
(BTC)
IDGiU'a chu ky
IBThu hooch
DDjch ~nh
~
:2'
.;:.,
....
~i]I
111
~~
~~i
~i/!}r;
Bi6u d6 4.2.1.2.
CU'i'lng dQ nhi€m
4'Jij,~
~ '% \\'6, f!Q)
II;;
~
'1/6
TY 11%
nhi~m MBV tren tom nnoi
-
Mo h1nhBTC ~i Tr8 Vinh
Tr~n md hlnh BTC t~i Tra Vinh ty I~ nhi~m MBV tren tdm la
30,66 :i:6,26%, C1f(1ngdQ nhi~m n~ng chi hi~n di~n trong d<;Jtthu m~u
giii'a chu ky nhttng ding chi vdi t<1ns6 thtp (2,30%) va chie'm da s6
vAn Iii c1f(1ngdQ nhi~m nh~: 13,60% vito d<;Jtgifi'achu ky; d<;Jtcu6i chu
ky Iii 17,20% vii d<;Jtdjch ~nh
Iii 22,7%.~
"--""--""
;~"
!!,i!..! t,(H TtfN!-\IENi
! ,," ,'. ..'
!, ,J t~.'"
",)~,
, ','.,'
.
i
"I~~-"'l
I
'" I ojif" r!:\ i
},~-,,~~~~:~=~._.{
\
1
12
HJnb4.6. va4.7. It baGganIllY cua16msli bi nhi8mmlm bfnhMBV- (X100)
4.2.1.3.TyI. nhlim MBVtren
cae loaf t6m nu61- M6 hlnh
"T6m- Rting" va "Rting- T6m"
Bang 4.2.1.3.3
TY l~ nhi€m MBV (*)tren cac loai t6m nu6i
T I nhi~m MBV (%
M6 hlnh "TomM6 hloh "RitngTom"
Ritn "
(1) 34,37 ::I:8,35 &
(2)13,75::I:6,25 &
LoAiWm
T6m gi6ng & T6m the
n = 24
T6m gi6ng & T6m b!!c
n = 24
!
45,83::1:
8,98
r=O,OO' > 005
41,67::1:
6,30
r= 0,25; > 0,05
54,17:t: 7,91
13,75::1:6,25&
45,16 ::1:7,35
I34,37::1:8,35 &
I
r = 0,18' > 0,05 r = 0,34; > 0,05
Tom gi6ng & T6m da't
n = 24
T6m the & Tom b!!c
n=24
I34,37::1:8,35 &
37,50:t: 8,64
I
r =0,00; > o 05
45,83:t: 8,98 &
54,17:t:7,91
1
13,75 ::I:6,25 &
38,91 ::I:6,09
r = 0,37;. > 0,05
41,67::1:6,30 &
45,16::1:7,35
r = o40; < 0,05 r = 0,34; > 0,05
T6m the & T6m dar-.
n 24
45,83:t: 8,98 &
41,67::1:6,30 &
37,50:t: 8,64
38,91::1:6,09
r= 0,44; <0,05 r= 0,73; <0,05
54,17::1:7,91 &
45,16 ::1:7,35
&
Tom b!!c & T6m da't
n = 24
37,50:t: 8,64
38,91 :t:6,09
r=0,56;
<0,05 r=0,58;
<0,05
Ghi chu: (1)va (2):kick th:mJctt5mgi6ng: 1,67::1:0,39
va 2,lO::l:O,37cmJcon;
(*)Phll(/1tgphdp Mt5fu;Jctruyin tMng
=
.
I
1
13
Bang 4.2.1.3(a) cho IDly:
- Tomgiong: ty I~ nhi~m MBV tr~n tdm gi6ng a rod
hinh "Tom
-
Rilng" cao hdn "Rang -Tom". Di~u nay c6 th~ do kich thtidc tdm
gi6ng a rod hinh "Tom- Rang" (l,67:t:O,39cm/con)
nho hdn kich thtidc
tdm gi6ng a md hinh "Rilng-Tom "(2,1O::I:0,37cm/con).
Nhi~u hie gia
da chrtngminh ty l~ nhi~mMBVtr~n tdm ty I~ nghjchvdi Dch thtidc
(ttidngrtngvdi s6 ngay tu6i) cua t6m, ty I~ nhi~mcao nh(t Ia giai do~n
postlarvae(kichthtidc< 2cm/con)[96, 112, 122].
- Tom trztJng thanh (the, b~c, dlt): ty I~ nhi~m MBV gifi'acac Ioai
tdm trtiang thanh vdi nhau clingghi nMn tr~n mo hinh "Tom - Rang"
va tr~n mo hinh "Rang- Tom" chi c6 tdm b~c vdi t6m d(t va the vdi
d(t c6 sl/ ttidng quaD y nghla (p< 0,05)
Ktt qua khao sat nay da chrtngminh, mi~unay dii giiH
thich du'<;1cvi saD ty l~ nhi~m MBV nen m6 hinh "Tom
- Lua"
l~i qu~
caD(75,57%), e6 thi vi ao nu6i la ruQng lua, thu'<1ngnhm san trong nQi
ddng n~n vi~e thay, ci'p nu'de vao ao nuM d6i khi la mQt vi'n d~ Dan
gitH.
-
Ghi eM: (1): mo kInk "Tom -RttnK"; (2): mo mnh "RttnR Tom"
Ngu'<;1e
l~i tr~n cae ao nu6i BTC ~i Tra Vinh, ty l~ nhi~mMBV gitim
-
theo th<'1 Ghi eM: (1): m6 kInk "T6m -RttnK"; (2): mo kInk "RttnK T6m"
III
ky nu6i). E>i~unay eho thi'y trong di~u ki~n m6i tru'<1ngao nu6i du'<;1c
cai thi~n thi ty l~ nhi~m MBV c6 thi giam d~n trong qua trlnh nu6i.
[96, 112].
MQt s6 tac gia khac ding dii c6ng b6 ty 1~ nhi~m MBV thi ty 1~
nghieh vdi kfch thu'de 16m gi6ng, Ramasamy et aI., (1995) dii chti'ng
minh ty l~ nhi~m MBV se giam rhea giai do~n pMt triin cua tudi 16m
[122,123]. Vi the' kich thu'dc t6m gi6ng va ty 1~nhi~m MBV nen t6m
gi6ng c6 81/tu'dngquaD nghich vdi nhau. Chung t6i ding ghi nh4n du'<;1e
c6 s1/ tu'dng quaD mQt each c6
y nghia
(p < 0,05) khi so sanh ty
1~
nbi~m MBV giil'a cae loai (t6m the, b"c va 16m di't) vdi nhau tr~n ca
hai m6 binh "Tom
- Rilng" va "Rilng - Tom".
M~c du ktt qua khao sat cho thi'y m~m ~nh MBV nen t6m gi6ng
kh6ng tu'dng quaD y nghia vdi t6m tru'dng thanh, my nhi~n cfing c6 thi
gbi nh~n kha Dang du'<;1c
truy~n theo chi~u dQc,tU'16m gi6ng sang t6m
tru'dng thanh va ding du'<;1c
truy~n theo chi~u ngang, giil'acae loai (t6m
the, b~c, di't) vdi nhau. E>i~unay ding dii du'<;1c
nhi~u tac gill rong b6
[96, 112, 122].
15
Ty l~ nhi8m va cu'Clngdl) nhi8m MBV ~p trung cao nh(t vao nhii'ng
thang trong mila mu'a - cu6i mila mu'a d:iu mila khd. Ke't qua ghi nh;}.n
du'c;Jccfing trilng hc;Jpvdi ke't qua nghi~n cU'ucua Natividad, J.M. va
Lightner, D.V. (1992).
4.2.2.
Ty I, nhiim WSSV tf'n cae loal tom nu61 is BBSCL
4.2.2.1. Ty I, nhtim
-M6 hinh
WSSV tr'n tom nuol
"T6m
- Lus"
va ban thAm canh (BTC)
2S
20
tIS
S
P
10
5
B(1Ilhumiu
~"
, , ,
9.'\;
t),
Q~,
t),
t),
Bi/n d6 4.2.2.1. TY it nhiim wssv
tr~n tllm nulli
Mil hlob "TOm. Lthl" lJGIn Dti"c .Long An.
- Tren roOhinh "Tom - LUa" ~i C~n Du'dc- Long An, ty l~ nhi8m
WSSV tr~n tdm tang d:in trong qua trinh nodi va cao nhR"tvao dc;Jtgiii'a
chu ky nodi, diy cling la dc;Jtxiiy ra djch ~nh. Ke't qua nhu'sau: d:iu
chu ky la 17,85%; giii'a chu kY la 22,00% va cu6i chu ky la 10,76%;
trung binh la 16,87:J:3,28% (Bi~u dd 4.2.2.1).
3S
30
2S
!
20
~
IS
10
Dqt tho m
~
q.
<-
~ltfp
h
~;
~
~
0,05). D~t thu ~u
djch b~nh ty 1~nhi~m WSSV ~n tOmcao nh(t (Biiu dd 4.2.2.2.). Ty
1~nhi~m trung blnh C1cae dc;ftthu mlu chi (Jmti'cth(p: 15,77 :f:6,44%.
,
Hinh 4.8. Mang cua t6m sO bi
nhiem WSSV (X40)
.
Hinh 4.10. NhAn t~ baa mang
t6m cht1a WSSV . (X 20.000)
Himh 4.9. Mang cua t6m sO bl
nhiim WSSV. (X100)
Hinh 4.11. NhAn tf baa mang
t6m cht1aWSSV (X 60.000)
.
Thaoluqn
Mo hlnh "Tom - Lua" rung chinh 130mo hinh BTC n~n ty 1~ nhi~m
WSSV tr~n tom nuoi (j ca hai mo hinh nuoi nay dc!u tang ~n theo
thCJigian nuoi, cao nh(t 130vao giU'achu ky nuoi. Dic!unay c6 thi 19
17
giii do mD hinh noDiHiBTC n~n khdng c6 ao trii'Mng (V30thlfi di~m
khio s~t) d~ xtr 19 nu'de trttde khi ea'p V30 ao nudi, khOng kh6ng eh€
du'm1e
-Long An), e~e y€u
to': m~t dQ con gi6ng khi ilia, ngu6n g6e con gi6ng, thli'c an sd' d~ng
trong qua trlnh nudi,
... hoan loan khdng c6 tu'dng quaD mQt e~eh c6 9
nghia vdi 81!xu!t hic$n~m bc$OO
WSSV tr~n tom (p > 0,05).
4.2.2.2. Ty Ii nhiim WSSV ("")tr6n t6m tlj nhlin CJm6 hinh "T6mRang"va
"Rang - T6m"
Bang 4.2.2.2 (8) Tu'dng quaD va tY l~ nhi~m wssv !ren ba loai Wm tI!
nhien vdi tom gi6ng - MohInh "Rilng T 15m"(1,2)va "Tt5m- Rilng" (1,2)
-
Tv l nhim
LoBi tl)m
Tom gi60g & Tom
the
0=24
Tom gi60g & Tom
bc
0=24
WSSV (%)
Ml) hinh "RilngMl) hlnh "Tom
Rilng"
Tom"
19,44 j;;6,92 &
28,12 j;;6,87 &
39,58 j;;7,18
32,94 j;;5,92
-
r = 0,21
19,44j;; 6,92 &
43,75 :t 7,56
r=O.lO
19,44 j;;6,92 &
50,00 :t 6,02
r = 0,25
28,12 :t 6,87 &
40,33 j;;7,96
r = 0 12
28,12 j;;6,87 &
31,67 j;;6,24
r=OJ4
32,94 j;;5,92 &
40,33 j;;7,96
Tom gi60g & Tom
d(t
0=24
Tom the & Tom bc
0=24
39,58:t 7,18 &
43,75 j; 7,56
Tom the & Tom d(t
0=24
39,58 j;;7,18 &
50,00 :t 6,02
r = 0,37
r = 0.56*
Tom bc & Tom d(t
0=24
43,75 j;;7,56 &
50,00 :I:6,02
40,33 j;;7,96 &
31,67 j;;6,24
r = 0.07
r
=0,24
r = 0 59*
r
= 0,43*
32,94:t 5,92 &
31,67 :1:6,24
r = 0.50*
Ghi eM: (*):v < 0.05: (1,2): PhlJdnJ! vhdv mt5 hoc va vhlldnJ! vluiv PCR
18
- Bang 4.2.2.2 (a) ghi nMn ty l~ nhi~m WSSV tr~n cae loai tom tlf
nhi~n (the, b~c, d!t) giiJ'a cae loai tom vdi nhau tr~n ea hai mo hinh
"Tom -Ritng" va "Rung -Tom" Hi tttdng quaD
y nghla
(p < 0,05).
Bang 4.2.2.2 (b) T~n sO'xua't hi~n cua m~m b~nh WSSV tIen t6m nuoi
M6 bloh "Tom - Rang" va "Rang - Tom"
TMng
6'"
7
8
9
10
Gki eM: (1) : Mo kink "Tom
11
12
198
-
2
3
4
5
33,3
8,3
0
0
0
0
50
0
0
16,6
50
0
100
25
100
0
0
50
50
25
0
25
50
0
0
25
0
0
50
25
0
0
- Rang" (2): Mo JUnk"Rang -
Tom"
- Bang 4.2.2.2(b)eho th!y: m~m ~nh WSSV hi~n di~n tr~n tom gi6ng
va cae loai tom the, b~e, d!t c6 ty 11$nhi~m va eu'<1ngdQ nhi~m eao
~p trung nhi~u nh!t vao nhiJ'ngthang eu6i mua mu'a d~u mila kho ~n
ea hai roO hinh "Tom - Ritng" va "Rung - Tom". Ri~ng d6i vdi mo
hinh "Tom - Rung" ~m bl$nh WSSV hoan toAn vAng m~t ~n tOm
gi6ng trong su6t nhiJ'ng thang mua kho (thang 3 d6n thang 5). Ty 11$
nhi~m va t~n sO'xu!t hi~n giiJ'ahai mo hinh la sai khae khong y nghla
(p > 0,05).
4.2.2.3. Tu'cmgquan glfta tY I, nhiem WSSV tran cae loal t6m tv
nhi'n vdl mot val yiu t6 thuy h6a chfnh
- DO hi~n dil$nvdi mU'eth!p nh!t la 2,95 mg/l;eao nh!t la 6,22mg/l;
(~o hinh "Ritng
-Tom "); 2,90
mg/l va 5,55 mg/l tr~n "Tom
-
Ritng" .
- Xem thêm -