^Anh hudng<br />
c u a viec bo sunq EROpSAN<br />
v a o khau phan a n<br />
len tdc dp tang tri/dng<br />
vd ty le song c a tra<br />
• Phan Phrf(jng Loan<br />
Trrfdng DHAG<br />
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Trong nhrfng nam gan day nghe nuoi ca tra (Pangasianodon hypophthalmus) d Ddng bang sdng Cufu<br />
Long phat trien nhanh chdng. Trong dd. An Giang la mot trong nhrfng tinh cd nghd nuoi thiiy san phat trien<br />
manh nhat. De viec nudi ca tra thrfdng pham dat Meu qua cao phu thuoc vao nhieu yeu td'trong do chat Irfdng<br />
con gidng la mot trong nhrfng khau quyet dinh. Con gidng td't tM se lam giam gia thanh san pham; con gidng<br />
cd sach benh, srfc de khang td't, tdc dp tang trrfdng nhanh tM se thuan Idi hdn trong qua trinh nudi thrfdng<br />
pham. Giai doan ca tra trf ca hrfdng len ca gidng la giai doan de cam nMem mam benh dac biet la benh nhiem<br />
khuan, do he mien dich chrfa hoan chinh nen srfc de khang vdi benh kem. Mat khac, tren thrfc te ndng dan<br />
rfdng ca vdi mat dp cao hdn rS't nMlu vdi mat dp drfdc khuyen cao, quan 1^ mdi trrfdng kem hieu qua nen dich<br />
benh d i phat sinh va ISy lan nhanh chdng. Hdn nrfa Meu qua dieu tri benh ngay cang kem la do vi khuan<br />
khang thuoc, each diing chrfa phu hdp, benh chrfa xac dinh drfdc nguyen nhan. Dac biet, trong giai doan rfdng<br />
ca gio'ng thi ngrfdi nudi suf dung thud'c vdi Ueu cao lam anh hrfdng xau de'n chat Irfdng con gid'ng va viec didu<br />
tri benh cho ca giai doan nudi thit cang trd nen kem Meu qua, ma cd the vi khuan da khang vdi nhieu loai<br />
khang sinh suf dung trrfdc dd (Nguyen Diic Hien, 2008). CMnh vi vay ma cdng tac phong benh la rat quan<br />
trpng, trong do nang cao srfc de khang cua vat nudi la giai phap hrfu hieu va trien vpng nhat trong trfdng lai<br />
nham han che'va dan loai bd khang sinh trong thuy san. Day cung la mot trong nhrfng vrfdng mac Idn nhat ma<br />
nganh thuy san Viet Nam phai nhanh chdng thao gd neu mud'n di tiep tren con drfdng hdi nhap va khang dinh<br />
vi the nganh cua nrfdc nha.<br />
Theo dan Ueu trf http://www.spaquaculture.com; Ergosan vdi thanh phan la Algme lam tang crfdng he<br />
thd'ng bao ve trfnMdn d ca, giup hoat dpng hap thu va trao ddi oxy qua mang tebao tich erfc, cho phep tebao<br />
Mm viec d tdc dp trao ddi chat cao, bang each nay lam cho chung thrfc Men vai trd ciia minh hieu qua hdn. Vi<br />
vay se lam tang td'c dp tang trrfdng cua ca, tang srfc de khang cua ca vdi benh nMem trung, cd kha nang phuc<br />
hdi md bi tdn thrfdng va giiip dap rfng td'irfuvdi viec tiem vaccme. Thanh phan hoat hda cua Ergosan cdn lam<br />
tang hoat ddng trao ddi chat va srf phat tridn cua te'bao lympho, dai thrfc bao, sd'Irfdng lysozym va cytokme.<br />
Ket qua lam tang hoat ddng cua toan bp te bao bao bpc ben ngoai va Irftfng chat nhay. Vi vay lam tang crfdng<br />
he thdng bao ve, giam kha nang bpc phat benh.<br />
Trf nhrfng dan Ueu tren, nghien crfu "Anh hrfdng cua viec bd sung Ergosan vao Idiau phan an len td'c dp<br />
tang trrfdng va ty le sd'ng cua ca tra" drfdc thrfc Men nham danh gia td'c dp tang trrfdng va ty le sdng ciia ca tra<br />
kM bd sung Ergosan vao khau phan an.<br />
1. v a t lieu<br />
- Thdi gian ngMen crfu keo dai trf thang 4/2009 den thang 6/2009. Tai ap Binh Hda 2, xa My Khanh, thanh<br />
phd Long Xuyen, tinh An Giang.<br />
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19<br />
- Vat Ueu nghien crfu: ca tra (Pangasianodon hypophthalmus); thrfc an cdng nghiep: UP. T502S, UP.<br />
T502, UP. T503S ciia cdng ty TNHH UM - Presedent Viet Nam; che pham Ergosan cua cdng ty Schering-<br />
Plough Animal Health; test kiem tra: pH, NH^/NH^, DO; NO^; veo Irfdi kich thrfdc 1,8m x Im x 2m va cac loai<br />
dung cu khac nhrf nMet ke, thrfdc, giay ke d U, can dien tuf, than, vdt, xudng, Irfdi..<br />
2. Phrfofng phap ngW§n citu<br />
2.1 Bo tri thi nghiem<br />
TM ngMem drfdc bd' tri theo kieu hoan toan ngSu nhien vdi 4 ngMem thrfc va 3 lan lap lai. Cac veo tM<br />
nghiem drfdc dat trong cung mot ao. Mat dp ca tha la 300 con/veo.<br />
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NTHI 1 NTI 2 NTDC 2 NTH 1 NTni_3<br />
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NTDC 1 NTH 2 NTHI 2 NTI 3 NTn_3<br />
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I- 2<br />
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Hinh 1: Sa do bo tri cac veo trong qua trinh thi nghiem<br />
Nghiem thrfc dd'i chrfng: khong trpn Ergosan trong suot thdi gian thii nghiem.<br />
NgMem thrfc 1: bd sung 5g, 4g va 2g Ergosan/kg thrfc an lan Irfdt theo trfng thdi diem (ngay thrf 1 - 10,21<br />
- 30, ngay 41 - 50) cac ngay cdn lai khong bd sung Ergosan.<br />
Nghiem thrfc 2: bd sung 3g, 2g va Ig Ergosan/kg thrfc an lan Irfdt theo trfng thdi diem (ngay thrf 1 - 10,21<br />
- 30, ngay 41 - 50) cac ngay cdn lai. khong bd sung Ergosan.<br />
Nghiem thrfc 3: bd sung 2g, 2g va Ig Ergosan/kg thrfc an lan Irfdt theo trfng thdi diem (ngay thrf 1 - 10,21<br />
- 30, ngay 41 - 50) cac ngay cdn lai. khong bd sung Ergosan.<br />
Sau khi bd' tri ca vao veo 3 ngay de ca dn dinh trrfdc khi cho ca an tien hanh can do ngau nhien moi veo<br />
30 con de xac dinh chieu dai va khd'i Irfdng ban dau.<br />
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Hinh 2. Trgn Ergosan vao thiic dn<br />
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20<br />
2.2 ThUc dn vd cho dn<br />
Trf ngay 1 - 15 sii dung thrfc an cdng nghiep UP. T502S dang hat, 40% dam, cho an 8 - 10% khd'i Irfdng<br />
than, cho an 2 lan/ngay. ' ' '"<br />
Trf ngay 15 - 45 sii dung thrfc an cdng nghiep UP. T502 dang vien, 40% dam, cho an 4 - 5% khd'i Irfdng<br />
than, cho an 2 lan/ngay.<br />
Trf ngay 45 - 60 sii dung thrfc an cdng ngMep UP. T503S dang vien, 30% dam, cho an 3 - 5% khd'i Irfdng<br />
than, cho an 2 lan/ngay.<br />
Sau khi tha ca vao veo, de 3 ngay cho ca dn dinh. Cac be thuf nghiem bat dau bd sung Ergosan theo cac<br />
Ueu Irfdng drfdc trinh bay d bang 1. •<br />
Bang 1: Lich trinh bd sung Ergosan<br />
Thcfi gian tM' NgW§m thrfc Nghiem thtfc I NgMem thitc II NgMgm thuTc III<br />
nghiem dd'i chtfng<br />
Trf ngay thrf Khong trpn Trpn 5g Ergosan Trpn 3g Ergosan Trpn 2g Ergosan<br />
1 - 10 Ergosan /kg thrfc an /kg thrfc an /kg thrfc an<br />
Trf ngay thrf Khong trpn Trpn 4g Ergosan Trpn 2g Ergosan Trpn 2g Ergosan<br />
21-30 Ergosan /kg thrfc an /kg thrfc an /kg thrfc an<br />
Trf ngay thrf Khong trpn Trpn 2g Ergosan Trpn Ig Ergosan Trpn Ig Ergosan<br />
41-50 Ergosan /kg thrfc an /kg thrfc an /kg thrfc an<br />
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3. Ket qua va thao luan<br />
3.1 Cac yeu to'moi trUdng<br />
3.1.1 Nhiet do<br />
NMet dp trung binh trong qua trinh thi ngMem nam trong khoang 29,92 - 32,40°C. NMet dp tMch hdp<br />
cho srf phat trien cua ca, tdm nam trong khoang 25 - 32°C (Truang Qud'c Phii, 2004). Nhrf vay, vdi khoang<br />
nhiet dp tren la phu hdp cho sii sinh trrfdng cua ca tra.<br />
3.1.2 pH<br />
Theo Trrfdng Qud'c Phu va VQ Ngpc Ut (2006), pH tMch hdp cho thuy sinh vat la 6,5 - 9. Khi pH ciia mdi<br />
trrfdng qua cao hay qua thap deu khong thuan Idi cho qua trinh phat trien ciia thuy sinh vat. Trong qua trinh tM<br />
ngMem pH dao ddng trong khoang trf 7,1 - 8,5. Cho thay pH nam trong khoang thich hdp cho hoat ddng sinh<br />
ly binh thrfdng, sinh trrfdng va phat trien cua ca.<br />
3.1.3 Oxy hoa tan (DO)<br />
Ham Irfdng DO dao ddng trf 2 - 5 mg/1, tuy gidi han drfdi khdng nam trong idioang tMch hdp cho sinh<br />
trrfdng va phat trien chung cua cac loai ca, nhrfhg theo Drfdng Thuy Yen (2003), ngrfdng oxy drfdi cua ca tra<br />
la 1,88 ± 0,07 mg/1 va theo Drfdng Nhrft Long (2003) ca tra cd kha nang sdng td't trong dieu kien ao tu nrfdc<br />
dpng, nMeu chat hiiu cd, oxy hda tan thap va cd the nudi vdi mat dp rat cao. Hdn nrfa ndng dp oxy thap deu<br />
rdi vao budi sang trf 6 - 7 gid vao budi chidu ndng dp oxy thrfdng 3 - 4 mg/1. Vi vay, vdi khoang oxy hda tan<br />
trong qua trinh tM ngMem la thich hdp cho sinh trrfdng ciia ca tra.<br />
3.1.4 NO^<br />
Theo Trrfdng Qude Phu (2000) thi ham Irfdng NO^^ cho phep trong cac ao nudi ca la trf 0,01 - 1 mg/1;<br />
ndng dp tMch hdp nhat la 0,01 - 0,1 mg/1 (Li NhuXudn & ctv,1994). Vi vay, trong sud't thdi gian tM nghiem<br />
ndng dp NO^ khdng anh hrfdng dd'n qua trinh sinh trrfdng va phat trien cua ca.<br />
3.1.5 NH/NH^^<br />
Theo Trrfdng Qud'c Phu va Vu Ngpc Ut (2006) thi ham Irfdng NH3 gay ddc ddi vdi ca la 0,6 - 2 mg/1. Nong<br />
dp NH3 drfdc coi la an toan cho ao nudi la > 0,13 mg/1. Ham Irfdng NHj/NH^ trong sud't thdi gian thi ngMem<br />
dao ddng trf 0,03 - 0,7 mg/1 hoan toan tMch hdp cho tang trrfdng cua ca nudi.<br />
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3.2 Kit qua tdc do tdng trudng ve chieu ddi vd khdi lugng<br />
Khd'i Irfdng va cMeu dai cua ca bat dau thi ngMem girfa cac ngMem thrfc khdng cd srf khac biet cd y ngMa<br />
thdng ke (P>0,05). Dieu nay cho thay ca drfa vao tM nghiem cd kIch cd ddng deu nhau.<br />
Sau 60 ngay thi ngMem td'c dp tang trrfdng ve khdi Irfdng theo ng^y (DWG, g/ngay) girfa cac ngMem thrfc<br />
cd srf khac biet cd ^ nghia thd'ng ke (P