KHOA HOC C O N G NGHE
PHAIV TICH HIEU QUA CUA CHE PHAM SlIXJH HOC S U DUIVG TROIMG CAC AO IMUOl TOM S U QUAIVG CAIVH CAI TIEIM
Nguyin Trung Hidu\ Nguydn Van Phiing\ Phan Thanh Lim^
T6MTAT
Nghien ciiu dugrc thuc hien nham dd danh gia didn bidn chat lirgmg nuoc va nang suat tom nuoi bang each bd sung che pham sinh hoc trong cac ao nu6i torn sii quang canh cai tien (QCCT) tai huyen Dam Doi, tinh Ca Mau. Thi nghiem dupe bd tri gdm 2 nghiem thuc voi 3 lan lap lai, sir dung 6 ao va mdi ao cd di§n tich la 2 ha; tuong ung voi 3 ao thi nghidm co su dung chd pham smh hoc va 3 ao doi chimg khong sir dyng che pham sinh hoc. Yeu td do mSn pH, DO, TAN, N-NO.^, P-PO4, H^S, duoc theo ddi ti-ong sudt 20 dgt thu m&u tu thtog 10 nam 2018 den thang 7 nam 2019. Ket qua nghien cuu cho thay rang yeu td nhi6t dd va dp man bi^n ddng Ion trong nam la do ydu td miia vu, che dp trieu va didu ki$n canh tac cua nong ho. Nghiem thitc thir nghidm duy tri cac yeu td chat luong nuoc nhu: TAN, N-NO2, P-PO„ HjS va mat dp Vibrio spp. tdt hon so voi nghi&m thiic ddi chiing va khong anh huong den hoat dpng tang trudng cua torn nuoi. Nghien ciiu cung cho thay rang, nghiem thiic thu nghiem co kdt qua ty le sdng va nang suat trung binh la 14,67 ± 0,48%
va 420,47 ± 25,01 kg/ha/nam cao hon nghiem thirc ddi chiing (10,28 ± 0,83% va 304,63 ± 38,88 kg/ha/nam), khac bi^t c6 y nghia thdng k6 (p<0,05). Nhu v^y viec ap dung bo sung chd pham sinh hoc giiip duy tri dn dinh ch^t lupng nuoc va gop phan nang cao ty le sdng va on dinh nang suat tdm nudi.
Tir khda: Chat luong nuoc, ch^pham sinh hoc, quang canh cai tiSn.
I.GMnTTHEU
Nudi tdm nude lo chiem vi tri d i e biet quan frong frong chidn luoc phat tndn kinh te nganh thuy san Vidt Nam hon 10 nam qua. Cung vdi qua trinh chuyen ddi co e^u cay frdng vat nudi va ehuyen ddi dat ndng nghiep, dat lam mudi nang suat thap sang nudi tdm d cae tinh ven bien, nhd vay m i nganh tdm cd su tang trudng vuot bac ca vd didn tich, s i n lupng va gia tin xuat khau. Nam 2018, tdng dien tich nudi tdm ntrdc Ip' d^t 736.000 ha, frong dd tdm su chiem 632.000 ha; didn tich nudi tdm sii tap trung chu ydu d mien Nam, chiem 95,5% didn tich nudi tom sii ea nude; tdm sii quang eanh cai tien (QCCT) chidm gan 60% tdng dien tich nudi tdm sii (Tdng cue Thuy sin, 2018).
Vdi nhiing Igi thd ve dieu kien tu nhien va tiem nang dien ti'ch, nghe nudi tdm sti da ed nhiing budc phat tiien k h i manh v i da dang ve phirong thiic nudi khac nhau. Md hinh nudi tdm sii QCCT vdi dac didm dau tu vdn it, than thien vdi mdi trudng do it sii dung thiic an va hda chat va kha nang thu hdi vdn cao do dd dupe nhidu ndng hd ap dung phd bien d cac tinh ven bien. Nhu tnrde day nghd nudi tdm su vdi phuong thirc nudi tdm quang eanh tmyen thdng cho kdt qua ning suat thap, thi gan day hinh thuc nudi QCCT ed nhung tien ho dang ke. Vdi mat do nudi
Vien Nghien ciiu Nuoi trong Thiiy san 2 Email: [email protected]
thap va thdi gian nudi dii fren 6 thang tdm thu hoach vdi kich cd Idn (>50 g/con), nang suat tdm tir 50-500 kg/ha/nam (Ronnback, 2001; FAO, 2017).
Mac dii, md hinh nudi tdm su QCCT mang lai hieu qua va thu nhap cho dai bd phan ngudi dan sdng trong khu vuc ven bien; tuy nhien, theo nhirng nghien ciiu ctru gan day cho rang vdi dieu kien didn tich ao Idn va khdng giii dupe nude, tha gidng khdng dupe kiem soat mat dp va chat lirpng con gidng v i viec ti-ao doi nude thtrdng xuydn theo thuy trieu la nguyen nhan dd nhidm bdnh cho tdm nudi. Do do, md hinh nudi tdm sii QCCT cd ning suat khdng dn dinh CThidu Lu va cdng su., 2010; Nguydn Thanh Phuong va Dang Thi Hoang Oanh, 2012). Ben canh dd, hien nay md hinh nudi nay dang ddi mat nhieu thach thiic nhu: tmh frang d nhidm ngudn nude cap do su biing no nudi tdm tham canh va sieu tham canh, su bien ddi khi hau,... din den dich benh va nguy CO mat nang suat anh hudng true tiep ddn sinh ke hang trieu ngudi dan.
De han che su xam nhap eua mam benh thi viec ban che thay nude tiiudng xuydn theo thiiy tneu va cai thidn cic yeu td mdi truong nude frong ao nudi l i mot frong nhiing giai phap can thidt eua md hinh nudi niy frong bdi cinh hidn nay. Gan day, tidm nang ling dung chd pham sinh hpc de phdng benh v i cai thien mdi trudng nuoc frong qua trinh nudi tdm da dupe nhidu nghidn cuu chiing minh. Vi khuan cd lpi thude gidng Bacillus dupe su dung rong rai frong
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
55KHOA HOC C O N G NGHE
nudi frdng thuy san v i cd kha nang eii thidn chat lugng nude va nen day ao tdm (Gatesoupe, 1999), Moriarty (1998) cho ring su dung BacUIus spp. cd k h i nang giam ty le Vibrio spp. frong ao nudi tdm, die biet la frong bun diy ao.
Xuat phat tir thuc tidn fren, nghien ciiu nay nham danh gii anh huong su dung che pham sinh hpc den cae ydu td mdi trudng nude va nang suat, tii do dd ed giai phap ky thuat giam thidu inh hudng den tdm nudi frong md hinh nudi tdm sii QCCT.
2 . V0T UBJ VA PHUDNG PHAP NGHIBU CIJU 2.LBd til thi nghidm
Hinh 1. Bin do vi tri thu miu Nghidn cihi dtrpc thuc hien frong thdi gian tir thing 10 nam 2018 den thing 7 nim 2019 tai Hgp tic xa Tan Long, xa Tan Duydt, huyen Dim Dm, tinh Ca Mau.
Thi nghiem gdm 2 nghidm thuc va 3 lin lap lai/nghiem thiic, tdng cdng cd 6 ao nudi cd dien tich 2 ha/ao/ndng hd:
- Nghidm thiie thi nghidm (TN): Su dung vi sinh nhdm Bacillus spp. va Thiobacillus dinh ky 2 tuin/lan frong sudt thdi gian 10 thing nudi. Che pham vi sinh dupe boat hda va tang sinh khdi vdi cae loai eo chat (mat ri dudng, cam gao va khoing vi lupng) dupe u ky khi 24 gid tnrde khi dua xudng ao.
Mat do tha tdm ca nam la 8 con/m^ vdi sd lin tha 4 dpt/nam, mdi dpt thi 2 hoac 3 con, tiiy thudc vao miia vu frong nam. Chd dp thay nude dupe kiem soat bang each ban chd thay nude frong hai thing diu tidn tinh ti> liic chuydn tdm gidng tii ao uong sang ao nudi, cae thing tiep theo se thay nude theo 2 con
nuoc ed dinh tridu cao nhat tii ngiy li' ""^ ™ ^^
O^a muoi) i m hch. Mdi dpt thay lien me tii 3 4 ngiy.
- Nghidm thiic ddi chiing (DC): khdng bd sung chd pham vi sinh frong sudt qua trinh nudi. Mat dd t h i ea nim la 10 con/m^ sd lin thi 5 dpt/nim, mdi dpt tha 2 hoic 3 con. tiiy thudc vio raiia vu frong nam. Chd dp thay nude, khdng kiem soat lugng nimc thay, thay tiitrdng xuydn theo chd dp thuy tridu hing thing tinh tii liic tdm gidng chuydn ttr ao uong sang ao nudi.
- Qui trinh ky thuat: ao nudi dupe dam nen bdao xung quanh dd franh rd ri va tien hinh cai tao vi s^n vet bim diy tai cac muong bao, vi bdn vdi vdi lidu lugng 500 kg/ha. Dau vu nudi tidn hanh diet tap va sau do lay nude giy mau nude trude khi tha tdm gidng vao ao uong. Gidng t h i dupe kidm tra sach benh va uong tdm gidng trude khi thi ra ao nudi QCCT. Bd sung thiic an cdng nghidp cd dp dam 38- 42% frong thdi gian uong tdm. Cho tdm an 34 lan/ngiy. Lupng thiie i n tinh tir ngiy dau tidn li 50 g/10.000 tdm Post Cic ngay tidp theo lugng thiic an tang tii 5-10%. Khi tdm gidng tir 20-30 ngay till udc lupng ty 1§ sdng va sang ra ao nudi QCCT.
2.2. Phuong p h i p phin tich mHu v i : ^ ly sd lidu Cac chi tieu chat lupng nude dugc theo d6i:
nhidt dd, pH, DO, dp man, dp kiem dupe kiem ba t^
hien trudng ao nudi vao thdi gian 7-8 gid sang bang may do chuyen dimg. Cac chi tieu cdn lai HjS, P-PO4, N-NO2, TAN va Vibrio spp. frong nude dugc phan tich tai Vidn Nghidn cuu Nudi frdng Thuy san II. Tan suat thu miu dinh ky 2 tuan/lan. Cac chi tieu pH, nhiet dp, DO, do kiem duoe do bang miy do HANNA HI 98196; do man dugc do bang Khiic xa kd; P-PO4 phan tich bang phuong phip TCVN 6202-2008; HjS phin tich bang phuong phap Methylene blue; N-NHj phin tich bang phuong phap SMEWW 4500-NHrF;
va N-NO2 phan tich bing phuong phip SMEWW 45OO-NO2-B. Chi tieu Vibrio spp. frong nude dugc phan tich bing phucmg phap TCVN 6831-1:2010.
Chi tieu ket qua sin xuat ty le sdng, nSng suat kich ed thu hoach dupe theo ddi thdng qua sd nhat ky ciia timg ndng hd tham gia thi nghiem.
Sd beu dupe luu trii va phin tich bang phan mdm MS Excel 2010, SPSS 16.0, va so sinh su khk biet ciia hai nghiem thiic bang kiem dmh bidn ddc lipT(p<0,05).
56 N O N G NGHIEP VA PHAT TRIEN N O N G THON - KY 2 - THANG 3/2020
KHOA HOC CdNG NGHl
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3.1. DiSn bifa chit linmg nu6c trong mfl hinh nuftittmsiiQCCT
3.1.1. Nhidt do
31.5 31,0 030,5
?^30,0
A ^B,5
^ 28,0
^
D(rt D D D B D D D D 9 D D D D D D D D D D B
^ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Hinh 2. Diin bidn nhidt dg b hai nghidm thiic Nhiet dp b hai nghiem thiie thi nghidm dao ddng khoing 27,3-32,0'*C, tuy nhien khdng cd su chdnh Ideh Idn qua cic dpt thu miu. Nhiet dd nude cac ao c6 xu hudng ting dan theo thdi gian nudi va dat cao nhat b giiia thing 5 la 32,0°C. Ngupc lai, nhiet dp dat gii tri thap nhat vio thdi gian thing 12 l i 27,3°C (Hinh 2). Su bien ddng niy ciing phu hpp vdi nhip miia vu frong nam va khdng anh hudng den su tang trudng ciia tdm nudi. Theo Boyd va Tucker (1998) thi tdm sii phat trien tdt frong khoing nhiet dp tii 25- SO^C, nhiet dd qui thip hay qua cao se anh hudng ddn sinh trudng v i phit tndn cua tdm va tdm nudi se dd mic bdnh hon. Vdi md hinh nudi QCCT, eac dam nudi dd bi that thoat nude do he thdng bd bao xay dung thd so, khdng thudng xuyen dupe gia cd; nen dam nudi tdm dd hi tham lau. Dp sau miie nude fren hang va ty le muong bao cd vai frd quan frong la noi till In cho ddi tiipng nudi, dac biet khi nhiet dp fren m$t tiing ao tang cao vao giiia trua (Vd Nam Son va cdng su., 2018).
3.1.2 Do m$n
2^5
= 20
- T N . - D C
B ^ D D O O O O O O O O O O D D O B O O D D , 1 , ' , 1 2 3 4 5 6 1 8 9 10 11 1 2 1 3 1 4 15 1617 1819 20
Hinh 3. Didn bidn dd min b hai nghidm thiic
Bien ddng do min d hai nghidm thiic thi nghiem qua cic dot khio sit frong nam la tuong ddi Idn. Tir thing 12/2018 (dot 8) den thing 5/2019 (dot 16) vio thdi diem mua khd, dp man cd khuynh hudng tang dan va dat gia tri cao nhat l i 35%o b nghidm thiic doi chimg (Hinh 3). Tuy nhidn, ket qui ghi nhin, dd man d nghidm thiie thii nghidm ip dung vi smh v i han che thay nude cd xu hudng ed dp man thip hon so vdi nghiem thiic ddi chiing.
Chanratehakool etal. (2003) cho ring tdm nudi cd do man cao hon 30%o thudng hi bdnh ddm tring va dau ving, tdm sii cd thd nudi d dd man tiiap thi bdnh it xiy ra nhung dp man khdng nhd hon 7%o.
Tdm lai, do man ed su bidn ddng theo mua, miia khd cd dp man cao hon miia mua va vao tiidi didm thing 4 ddn tiling 5/2018 cao hon 30%o cd the anh hudng den tang trudng tdm.
3.1.3. Do kiem
D 9 t O D O B D D O O O D O O O e O O D D O O t h u ] 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Hinh 4. Didn bidn dd kidm b hai nghidm thiic Dp kiem d nghiem thuc thu nghiem v i ddi chiing cd xu hudng bidn ddng tuong tu nhau va dao ddng tii 111-180 mg CaCOs/L (Hinh 4). Dp kidm cd vai frd l i he dem frong nude giir pH nude dn dinh.
Dp kiem ly tuong cho tdm nudi ting trudng v i phit trien l i 80-120 mg CaCOs/L (Chanratehakool et al, 2003). Nhu vay dp kidm frong hai nghiem thiic qua cac dpt khio sat thich hpp eho sy ting trudng cua tdm su.
31.4. DopH
Chi sd pH frong ao QCCT giiia hai nghidm thiic cd xu hudng bidn ddng tuong tir, dao ddng tii 7,1-8,6 (Hinh 5). Md hinh nudi QCCT, bidn ddng pH tang v i giam theo thdi gian nudi phu thudc phan Idn vio mua vu. Nhin ehung, pH d eac ao tdm QCCT cd gii tri Ion hon 7 vi pH cd xu hudng tang len cao tii dot thu miu thii 14 ddn 17. Nguyen nhin niy cd the do vio miia khd, do man vi nhidt do tang cao tao didu
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
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kien cho tao phit trien manh nen lam tang pH. Chi sd pH la mdt frong nhiing chi tieu rat quan frong frong vide quan ly chat lupng nude ao nudi va anh hudng true tiep hoae gian tidp den tdm nudi. Theo nghien eiiu cua Vu The Tru (2001) cho ring khoang pH thich hgp frong nudi tdm su la 7,5-8,5. Nhin chung, g i i tii pH d 2 nghiem thiic khdng i n h hudng Idn ddn q u i trinh sinh trudng.
_*-TN - ^ D C
phap can thift de giiip dam bao ham liwng oxy h6a tan de torn tang trufag va phat trien. Whetstone etal.
(2002) cho rang ham luong oxy hoa tan trong ao nuoi cua t6m sii voi pham vi chiu dung la 3-11 mg/L v4 thich hop la >5 mg/L.
3.1.6. Ham lucmg TAN (NH/NH:)
Bin B B D B B D B B B B B B B B D D a B B B (ho 1 2 3 4 5 6 7 8 91011121314151617181920 Hinh 5. DiJn b i & dO pH nii6c hai nghidm thiic 3.1.5. Haw lucmg oxy hda tan (DO)
O D O O O D O O O O O O O O O D C O O O 1 2 3 4 5 6 7 8 9 1011 121314 151617131920 Hinh 6. Di&i biSn h i m lu(mg DO a hai nghifan thiic
Ket qua nghiSn ciiu cho thay ham luong oxy hoa tan (DO) a hai nghidm thiic dao ddng tir 3,6 den 6,5 mg/L trong snot thoi gian nghien ciiu (Hinh 6).
Trong d6, nghiem thiic thu nghiem (TN) co ham luong DO tir (3,6-5,2 mg/L) thap hon so voi nghiem thiic doi chiing (4,0-6,5 mg/L). Mo hinh nuoi QCCT, nguon cung cap ham lupng DO chu yeu den tir hai nguon chinh la qua trinh quang hpp cua tao va qua trinh khuech tan oxy tir khong khi vao nuoc. Voi cac ao CO mat dp tha gi6ng cao va sinh khoi tao cao, tai mot s6 thdi Aitm nhat dinh lui^ng oxy co the bi thiSu n^n can phai dupe bo sung them bang bien phap sue khi. Do do, ddi vol hinh thiic QCCT. nguoi nuoi can luu y d^n mat do tha va kiem soat mat dp tao la giai
Dfft thu
O O D O D D O D D O B D O O D O D D O e 1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20
Hinh 7. DiSn bi^n him lupng TAN 6r hai nghiftn thiic Ham lupng TAN on dinh trong khoang dpt thu mSu lan dau hen d^n dot 12 va co xu huong tang cao vao giai doan miia kho tir thang 2 iia thang 5 (dpt 13 den 17). Ham lupng TAN o nghi$m thiic co bo sung che pham vi sinh dao dpng frong khoang (0,050,95 mg/L) cao hon so voi doi chiing (Hmh 7). So di co su khac biet nay la do nghiem thiic doi chiing co chf do canh tie thay nuoc thu6ng xuyen theo ch^ il>
tneu, dieu nay giiip giam dang k^ ham lupng TAN qua cac dpt khao s a t Trong khi do, voi nghiSm thiic thi nghiem, ham lupng TAN tang nhanh trong giai doan miia nang la do cac chat hiiu co tii rong, tao tin va tich luy xudng n^n day ao, da thiic day qua hinh hoat dpng cua nhdm vi khuan nitrate hda frong ao.
RUay va Kutty (2005) cho rang gia tri ciia pH cd th^
gay stress hoac gay chet cac loai thiiy san, tuy nhi&n khong cd tac dpng true hep ma cdn phu thupc boi cac ydu td nhu; can bang axit va kiem frcng cpt nude hay mdi tuong quan giiia ndng do NH3-N, NH^-N va N-NO2 vdi pH. Ham lupng TAN dao ddng tir 0,2-2,0 mg/L se dam bao tdt cho su phat trien ciia torn (Whestone etal., 2002). Dieu nay cho thay rang, vi§c ap dung dinh ky ch^ pham vi sinh 2 tuan/lan da giiip duy tri ham lupng TAN d miic an tcan cho sinh trudng cua tom frong sudt chu ky nuoi.
3.1.7. N-NO 2
Ham lupng N-NO3 co chieu huong tang dan theo thdi gian d hai nghidm thiic thi nghiem va dat gi4 tri
<0,5 mg/L frong sudt thdi gian thu mSu. Theo Pillay va Kutty (2005) khuyen cao rang frong nudi frdng
58
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thuy sin him lupng N-NO^ dudi 1 m g / L H i m lupng N-NO2 dat miic 1,45 mg/L va d dp man tiiip vi NH3 cao thi ddc tinh N-NOj se inh hudng ddn tdm nudi (Whestone e^a/, 2002).
= 0,3 0 0,2
0,0
D f f l O O O O e D O D D O O D e O O O O O O O t h u 1 2 3 4 5 6 7 8 9 101112 1314 1516 1718 !9 20 Hinh 8. Didn bidn h i m luong N-NO2 b hai nghidm
thiic 3.1.8. P-PO4
0,20
n . ^ O D D O D O O O G O O e O G O O O D O O
" ^ 1 2 3 4 5 6 7 8 9 101112 1314 151617 181920 thu
Hmh 9. Didn bidn h i m lugng P-PO4 or hai nghidm thiic
Him luong P-PO4 bien ddng tuong tu h i m lugng TAN giua hai nghiem thiic (Hinh 9). Tuy nhien, nghidm thiie cd bd sung che phim vi sinh cd h i m lupng P-PO4 (0,01-0,08 mg/L) thap hon so vdi nghiem tiiiic ddi chung (0,01-0,15 mg/L). 6 hinh thiic QCCT, viec cung cap thiie an bd sung hang ngay cho tdm rat it dupe ndng hd quan tim, phan Idn su ting trudng cua tdm dua vio ngudn thiic i n tu nhidn (Thidu Lu v i cdng su., 2010). Vao miia khd khi dp m§n tang Idn ket hpp nhiet dp cao l i dieu kidn tao diy phit trien vi su tin lui rong, rdu din den h i m lupng dmh dirong ting eao trong md hinh nudi QCCT. Kdt q u i niy eho thay bidn ddng h i m luong P- PO4 cung tuong tu vdi nghidn ctru cua Nguydn Tlii Ngoc Anh v i cdng su (2017). Nhu vay nghiem thiic su diing chd phim vi smh duy tri ham lupng P-PO4
tot hon so vdi ddi chiing va khdng anh hudng den tang truong tdm nudi.
3.1.9. HS 0,07
3-0,05 sb
= 0,04
fifft G D D 0 O O D 0 O D 0 O O D 0 9 D D 0 O t h u 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Hinh 10. Didn bidn h i m lugfng HgS 6 hai nghidm thiic
Ham lupng HjS giira hai nghidm thiic thi nghidm cd su khic biet Idn trong sudt 20 dpt thu miu.
Chanratchakkol et al. (2003) cho ring h i m lupng HgS thich hpp cho ao tdm phii nhd hon 0,03 mg/L. O nghiem thirc thi nghiem cd nhimg thdi diem him lupng H2S trong nude >0,03 mg/L sau dd giam din v i on dinh theo thdi gian nudi. Trong khi do, nghiem thiie ddi chiing him luong H2S bidn ddng k h i Idn (0,02-0,065 mg/L), cd thd su bidn ddng nay la do ao nudi dupe thay nude thudng xuyen tiieo dinh tridu cao nhat trong thing. 6 md hinh nudi tdm QCCT, ngudn sinh ra HgS chu yen tir qui trinh phan hiiy hdn hpp cac chat hiiu co nhu xic ba thuc vat (rong, tao) v i ngudn yem khi tren ndn dat phen. Nguydn Thi Ngpc Anh vi cdng su (2017), d md hinh nudi QCCT, rong l i mdt trong nhirng nguyen nhin gay khi rong tin lui, h i m lupng N-NO2 v i H2S ting len rat cao lin lugt la 4,87±1,70 mg/L vi 0,03+0,02 mg/L va thudng giy hai tdm nudi. Cao Phuong Nam (2008) cho ring rong tin lui lim pH v i DO giam se din den mdi trudng sdng cua tdm rat bat Ioi thuong giy chet tdm hang loat. Boyd va Tucker (1998) cho ring ddc tinh cua H^S phu thudc vao nhiet dp, Oxy v i pH cua nude, su ket hpp 3 yeu td pH thap, nhiet dp tang eao va ham luong Oxy thap se giy nguy hiem eho tdm nudi. Nhu vay trong dieu kidn thi nghiem, ao ed bd sung VI sinh gop phan giira him lupng huu c o v i duy tri h i m lupng HgS tdt hon v i it inh hudng den ting tnrdng cua tdm so vdi ddi ehiing.
3.2. Bidn ddng m i t dO vi k h u i i Vibrio spp.
Hinh 11 cho thay mat dp vi khuan Vibrio spp.
trong nuoc 0 nghiem thiic TN dao ddng trong khoang 1,20 xlO^ - 6,63 x 10^ CFU/mL, eon nghidm
NdNG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
59KHOA HOC C O N G N G H £ thiic DC dao ddng ti-ong khoing 1,24 x 10^-6,63 x 10^
CFU/mL, cdn nghiem thiic DC dao ddng trong khoang 1,24 x 10^ - 1,13 x 10^ CFU/mL. Nhm ehung, mit dp Vibrio spp. trong nude d nghiem thiic TN ed bd sung che pham sinh hoc thap hon va it bien ddng hon so vdi nghiem thiic DC. Trong giai doan miia mua khi dp min giam dan, m i t dp Vibrio spp. ed xu hudng giam dan d hai nghiem thiic thi nghidm. Vio giai doan mua khd tir thing 2 den thing 6 duong lich tir dot thu miu thii 13 ddn 17, d nghidm thiie DC va TN ed mat dp Vibrio spp. ed khuynh hudng tang eao v i dat gii tri cao nhat lin lupt li 1,13 x 10^ CFU/mL v i 6,63 X 10^ CFU/mL Nhu vay, b hinh thuc nudi QCCT nhiet dp v i dp man cd the inh hudng den bidn ddng mit dd vi khuan Vibrio spp. Nghidn ciiu cua Anderson (1993) cho ring d mdi tnrdng nude sach cd mat dp vi khuan Vibrio spp. <10^ CFU/mL, trong khi dd ndu mat dp vi khuan vugt qua 10'^
CFU/mL se cd hai cho tdm, c i nudi v i mdi trudng trd ndn ban. Theo Gatesoupe (1999) thi viec bd sung che pham sinh hpc chiia ddng Bacillus spp. se giiip cho tdm phat tridn tdt hon, it benh vi lim giam dupe mit do Vibrio spp. trong nude vi chung vi sinh niy cd tinh ddi khang vdi tie nhan gay bdnh.
1200
D d O D O D D D O O O O O O O O O O D D O O Jll'u 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1920 Hinh 11. Bidn ddng m i t dd vi khuSn Vibrio spp. d hai
nghidm thiic 3.3. Kdt q u i ning suit tdm
Kdt qui phin tich bing 1 cho thay, kich cd tdm thu hoach giiia nghidm thu-c CTN) va ^ C ) khdng chdnh lech nhieu va khic biet khdng cd y nghia thdng ke (p>0,05), vdi kich cd lan lupt l i 29,33 + 1,15 con/kg vi 28,66 + 1,50 con/kg. Ty le sdng d nghiem thue TN eao hon va khic biet cd y nghia thdng ke (p<0,05) so vdi nghiem thiic DC, lin lupt li 14,67 + 0,48%, 10,28 + 0,83%. N^ng suit cua tdm sii khi su dung ehe pham sinh hpc dat 420,47 ± 25,00 k g / h a / n i m cao hon cd y nghia thdng ke (p<0,05) so vdi nghidm thiic DC khdng su dung chd pham sinh
hoc (304.63 ± 38.88kg/ha/n3m). Ket qua niy thap hon so vdi nghidn ciiu cua Vd Nam Som v i cdng sy (2018) vd dinh gii hieu q u i ky thuat va tai chinh cua md hinh nudi tdm QCCT v i tdm lua tai huydn Thdi Bmh tinh C i Mau, nSng suit li 558,40±113,01 kg/ha/nam. Tuong ti/ vdi ket q u i ciia Lim Ngpc Biiu (2010) khi dieu b-a md hmh nghidn ciiu kha nang su dung eay Nang tupng de xu ly nude thii nuoi tdm sii, nang suit tdm sii dao ddng tii 380421 kg/ha/nam. Nghien ciiu nay eho ket qua cao hon so vdi nghidn ciiu cua Nguydn Thi Ngpc Anh vi cdng su (2017) vdi nang suit md hinh nudi QCCT dao dpng 120-350 kg/ha/nam v i Le Quoc Vidt v i Trin Ngpc Hai (2016) thu dupe nang suit md hinh tdm riing 196 kg/ha/nam.
Vide ning suit v i ty Id sdng ting len thi lpi nhuin eiia nghiem thiic TN cd sii dung chd phdm sinh hpc ciing ting theo v i khic biet cd y nghia thdng kd (p<0,05). Lpi nhuin dat dupe cua nghidm thiic TN la 40,11+1,87 tiidu ddng/ha/nim; ti-ong khi, lpi nhuin ciia nghidm thiic DC dat 29,72+7,31 hidu ddng/ha/nam.
Bang 1. Ning su^t v i hidu q u i kinh td cHa tdm s i d aoQCCT
Thong sd Tylesdng(%) Kich CO torn thu hoach (con/kg) Chi phi cd dinh (trieu ddng /ha/nam) Chi phi bien ddi (trieu ddng/ha/nam) Tdng chi (trifeu ddng /ha/nam) Gia ban (ngan ddng/kg) Tdng thu (tri§u ddng/ha/nam) Loi nhuan (tri^u ddng/ha/nam)
TN 420,47 ± 25,00'
14,67 ±0,48' 29,33 ± 1,15'
1,70+1,51
27,48 ± 0,00"
29,18 ±0,18"
165,00 + 5,00 69,29 + 2,04' 40,11 + 1,87'
DC 304,63 ±38,88*
10,28 ±0,83' 28,66 ±1,50"
1,53 + 1,62
19,08 ±0,11'
20,63 +0,15' 165,00 ±5,00 50,35±7,34' 29,72 ±7,3l' Ghi chu: Cac gia bi (IB±BLC) trdn cung 1 hing cd chd cai Ichdc nhau thi khac biet cd y nghia thdng Ice (p<0,05)
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NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
KHOA HQC CONG N G H l
Ning suit v i hidu q u i nudi tdm chiu anh hudng cua nhidu yeu td khic nhau: mit dp giong, thiic in cdng nghiep, thiic i n tuoi, kinh nghidm sin xuit, v.v... Mdt sd tdng kdt d Bangladesh, An dp. Thai Lan va PhiUppine eho thay tiiy theo miic dp dau tu, hidu bidt vi kinh nghidm cae hd nudi ed thd dat ning suit cao hon tir 150-1.100 kg/ha/nam. Nhiing cai tidn trong nudi QCCT bao gdm thidt ke cdng cap va thoit rieng, sd lupng cdng cap vi thoit tuy theo dien tich ao dam, cd muong phu v i siu >40-60 cm, dd sau eiia ti^ang >40 cm, bdn phin hmi co giy rain, chon nude ben ngoai tdt de thay nude, thudng xuydn diet ca tap trong sudt vu nudi, bo sung thiic an tir bdn ngoai nhu cim gao, khd binh dau, c i tap, nhuydn thd v i ca thiic an vidn (Kungvankij el al., 1990). Theo nghidn ciiu cda Thieu Lu v i cdng su (2010), Nguydn Thanh Phuong v i Ding Thi Hoang Oanh (2012) eho ring vdi dieu kidn didn tich ao Idn va khdng giir dupe nude, tha gidng khdng dupe kiem soit mat dp v i trao ddi nude thudng xuydn theo thuy trieu ben ngoii dd nhidm benh do dd md hinh niy nang suat khdng dn dinh.
4.KfrLUANVilOEXUAT 4.1. Kdt luin
Nghiem thirc ed su dung che pham vi smh dinh ky trong sudt qui trinh nudi da cd tie dung cai thien va giiip dn dinh chit lupng nude dam bao cic thdng so mdi tiiidng n h u pH, TAN, N-NOg, P-P04 va HaS ddu thich hpp ti-ong ao nudi tdm QCCT, han che su d nhidm xay ra trong sudt mua vu so vdi ddi chiing.
Bdn canh dd, giiip han chd viec thay nude thuong xuydn ti-ong hd thdng ao QCCT khi ma bdi canh ngudn nude cap ngay cang bi d nhidm. Ngoai ra, tdng vi khuan Vibrio cua nghidm thiie bd sung chd pham vi sinh ludn thap hon nghidm thiie ddi chiing.
Viec su dung che pham sinh hpc cd anh hudng tich ci^ ddn hidu qua eiia md hinh nudi v i ning cao ty le sdng vi nang suit tdm tudi.
4.2. Dd xuit
Mic dii ty le sdng vi nang suit d nghidm thue TN cao hon nghiem thiie DC, tuy nhidn vin cdn thip. De cai thien ty Id sdng va nang suat can uong tdm gidng ed Idn chia 3 giai doan nudi vi thiet ke lai didn tich ao nhd hon dd quan ly cham sdc tdt hon.
Nghien cuu cdn mat han che la eac ao ddi chiing tiiay nude thudng xuyen do dd can ed thi nghiem so sanh vdi cac ao khdng thay nude de thay rd tie dung.
hieu q u i ciia dung ehe pham vi smh d dieu kien khd khin ve ngudn nude.
TAIUEUTHAMKHAO
1. Cao Phuong Nam, 2008. Khao sat didn bidn HgS d Idp nude diy, nude trong bun diy trdn eac md hinh nudi tdm su vimg dat phen hoat ddng b Ca Mau.
Tap chi Khoa hpc Ky thuit Thiiy loi va Mdi trudng 22,3-1L
2. Lim Ngpc Buu, 2010. Nghidn ciiu kha ning sii dung ciy nan tupng {Schpus Uttorahs) de xu ly nude thai nudi tdm sii {Penaeus monodon). Luin van tdt nghiep Cao hpc chuydn nganh Nudi trdng thuy sin, Trudng Dai hpc Can Tlio. 89 trang.
3. Le Quoc Viet Va Tran Ngpc Hai, 2016. Khia canh ky thuat v i hidu q u i kinh te cua md hinh nudi tdm-rimg d huyen Nam Can, tinh C i Mau. Tap chi Khoa hpc vi Cdng nghe Bien. T i p 16, sd 1; 2016: 99- 105.
4. Nguydn Thi Ngpc Anh, Dinh Thanh Hdng va Nguydn Thanh Phuong, 2017. Khao sat sinh lupng va tie ddng cua rong xanh (Cladophoraceae) trong dim quing eanh cai tien d tinh Bac Lieu va Ca Mau. Tap chi Khoa hoc - Trudng Dai hoc Can Tho. Tip 51, phan B (2017) :95-105.
5. Nguydn Thanh Phuong vi Dang Thi Hoang Oanh, 2012. Cac benh nguy hiem trdn tdm bien va tdm cang xanh nudi d DBSCL. Tap chi Khoa hpc - Trudng Dai hpc Cin Tho, 22e, 106-118.
6. Thidu Lu, Trinh Trung Phi, Nguydn Cdng Thanh, Dd Van Hoang, Ngd Minh Ly, Tran Quoc Binh, Nguydn Trpng Nghia, 2010. Nghien ciiu mdt sd giai phap phit trien ben viing cac md hinh nudi tdm trdn viing chuyen doi tai huydn Dam Doi, tinh C i Mau. Bao cao khoa hoe, Vien Nghien ciiu Nudi trdng Thuy san 2.103 trang.
7. Tdng cue Thiiy sin, 2018. Bao tong kdt nganh hang tdm nam 2018 va trien khai ke hoach nim 2019.
8. Vd Nam Son, Binh Van Nhin, Ly Van Khanh, Tran Ngoc Hai, Nguydn Tbanh Phuong, 2018. Dinh gii hidu qua ky thuat v i tii chinh ciia md hinh nudi tdm su quing canh cai hdn vi tdm - lua tai huyen Thdi Binh, tinh Ca Mau. Tap chi Khoa hpc - Trudng Dai hpc Cin TTio. Tip 54, sd 3B (2018): 164-176.
9. Vu The Tru, 2001. Thiet lap v i dieu hanh ti-ai sin xuat tdm gidng tai Viet Nam. Nha xuat ban Ndng nghidp. Trang 33-46.
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
KHOA HOC C6NG NGHl 10. Anderson, 1., 1993. The veterinary approach
to mabne prawns. In: Aquaculture for veterinanans:
fish husbandry and medicine (Editor Brown L ) , pp.
271-296.
11. Boyd, C. E. and Tucker, C. S., 1998. Pond Aquaculhire Water Quality Management Huwer Academic Publishuig, Boston, MA USA 700 pp.
12. Chanratehakool, P., J. F. TumbuU, S.J.
Funge-Smith, 1. H. Macrae and C. limsuwan, 2003.
Quan ly sue khde tom trong ao nudi. Tai ban lan thir 4. Ngudi dich: Nguyin Anh Tuan, Nguydn Thanh Phuong, Dang Thi Hoang Oanh, Tran Ngoc Hai.
DANIDA-Bg Thiiy san 2003.153 p.
13. FAO, 2017. A world overview o( species of interest to fisheries. Penaeus monodon. FIGIS Species Fact Sheets. Text by SIDP-Species Identification and Data Programme in: FAO Fisheries and Aquaculture Department [online].
Rome. Updated. [Cited 17 March 2017].
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62
THE EFnCIENCY OF APPUCATION PROBIOTICS IN THE IMPROVED-EXTENSIVE BLACK TIGER SHRIMP CULTURE PONDS
Nguyen Trung Hieu, Nguyen Van Phung, Phan Thanh Lam Summary
The study was canned to evaluate changes in water quality and productivity of shnmp by adding probioUcs m the improved extensive black tiger shnmp culture ponds in Dam Doi district, Ca Mau province. The experiment was designed with two treatments and three replications of each treatment at six ponds and each pond area was 2 hectares; three experimental ponds were probioUcs ponds and three were control ponds without probiotics use. The parameters of water qualily such as temperature, salinity, DO, TAN, N- NOa, P-PO4, H2S were monitored during 20 sampling periods Irom October 2018 to July 2019. The results showed that temperature and salinity were high variation duruig the year due to seasonal factor, tidal cycles and farming conditions. The experimental ponds helped maintain water quality factors such as TAN, N-NO2, P-PO^, H^S and densities of Vibno spp. better than that of the contiol ponds, and did not affect the growth performance of shrimp. The study also showed that the experimental ponds had an average survival and shnmp yield (14.67 + 0.48% and 420.47 ± 25.01 kg/ha/year) were higher than that of the control ponds (10.28 ± 0.83% and 304.63 ± 38.88 kg/ha/year), there was a significant difference (p<0.05). Therefore, Ore addition of probiotics helps maintain water quality and contributing to increasing the survival rate as well as stabilizing the productivity of farmed shnmp.
Keywords: improved-extensive shnmp culture, probiotics, water quality.
Ngudi phin bif n: TS. Phiun Anh TuSn Ngiy nh|n bii: 20/12/2019 Ngiy thdng qua phin bi&: 20/01/2020 Ngiy duy«t ding: 30/01/2020
