KHOA HOC CdNG N G H |
IMGHIEIXI CIJU T A O D A B O I T R £ | \ 1 CA R O P H I v A l \ ] {OREaCHROMIS MILOTICUS LIIXIIVAEUS 1 7 5 B )
Ngd Phii Thda', Nguyen Hthi NinhS Ph^m Hdng Nh§t', Nguydn Vin D?i', Nguydn Thj Ld' T6MTAT
Ca r6 phi vin don tinh dye da va dang la mOt trong nhung ddi tugng nu6i quan trpng b nude ta. C6ng ngh^
xii ly gioi tinh ca bing ho6c mon 17a-Methyl testosteron c6 thd c6 nhung nguy co tidm In khong tdt ddi voi m6i truong, chit lupng thjt ci vi siic khoe ngu-M ti^u diing, Cfing ngh^ tgo ci r6 phi tam b$i (3n) bang phuong phap sdc nhiet hoSc lai tgo giua ci r6 phi tu bpi (4n) vi ci r6 phi nhj bpi (2n) dupe bidt ddn nhu mpt giai phap huu hi§u nhim ki^m soit mit dp va ning cao hidu qua kinh td ddi v6i trang trgi nuoi ci r6 phi thuang phim. Nghidn ciiu kich thich sinh san nhin tao \h, mOt trong nhung y^u td tidn dd cho cic nghien citu vd tgo da bOi trdn ca r6 phi. Nghidn ciiu nay xic djnh anh huong cua cic loai kich dye td (HCG, LHRHa vi DOM) voi lidu lupng khic nhau trong kich thich sinh sin nhin t^o vi bu6c diu thii nghidm phuong phap soc nhi§t n6ng (xic djnh nhi§t dp, thdi gian sdc nhi^O tao da bOi thd trdn ci r6 phi vin. Sau khi tning thu tinh 65 phut, tidn hinh thi nghiem sdc nhi^t b 3 niirc nhi$t dp (40''C, 41''C vi 42°C) voi 3 thdi luong sdc nhidt li 2 phiit, 3 phut va 5 phiiL Ket qua thi nghidm cho thiy sii dung kich due td HCG voi hdu luong 3000 - 3500 UIAg cho ty Id ci dd tir 61,11 - 65,56%, tiidi gian hidu ling tiiudc tii 17-31 gid. Phuong phap sdc nhiet nong d 42^'C, thdi didm sdc nhi^t 65 phiit sau khi trimg thy tinh, thoi gian sdc 2 phiit cho ^ le da bpi trung binh dat 58,15 ± 2,75%.
Tir khda; Ci rd phi vin. Oreochromis niloticus, kich due td, kich kich sinh san, sdc nbi$t ndng, da b^i.
LBATVJJiNflt
Ci ro phi l i ddi tuong c i kinh td voi didn tich v i sin lupng e i ro phi khdng ngimg ting ldn trong nhung nam qua do vide i p dung khoa hpc e6ng nghd. Trong dd, sii dung hodc mon 17a-Methyl testosteron de tao c i ro phi don tinh due l i cong nghd dang dupe ^ dung pho bien hidn nay 6 hau het cic trai sin xuat gidng. Tuy nhidn, mpt sd nghidn ciiu chi ra rang vide sii dung hodc mdn trong nuoi trong thuy san tidm an nhieu nguy co bat lpi tdi moi tnrong sinh thai (Barel-Cohen etal., 2006; Kidd etal., 2010). Thdm vio dd, nhidu thi truong kho tinh (eic nude chiu Au v i My) quan ngai vd anh huong bat lpi ciia vide sir dung hodc mon trong nuoi trong thuy sin vi du lupng hooc mon trong thit c i ro phi ddn mdi trudng v i sue khoe con ngudi. Nudi c i ro phi tam bdi (3n) dupe tao ra bling phuong phip sdc nhidt hoac lai tao giiia ca the tii bOi (4n) v i nhj bpi (2n)) se giiip kidm soit mat do va t i n dung nhiing uu thd ciia thd da bOi. Thd tam boi v i hi bpi cd thd dupe tao ra nhd tic ddng gay sdc (nhidt do, i p suit, tia cue tim hoic hoa chat) 6 thdi didm thich hpp (Cassani, Caton, 1986; Chourrout, 1984; Thorgaard, 1986).
Nhidu nghidn ciiu tao da bdi trdn cic ddi tupng thuy
sin da thinh cdng nhu c i hdi (Solar etal., 1984), c i trim cd (Cassani, Caton, 1986), c i me Vinh (Koedprang, Na-Nakom, 2000), c i Chep (Dunham, 2004; Recoubratsky etal., 1992). Tuy nhien mdi ehi ed mdt sd tic gia nghidn eiiu tao da bOi trdn e i ro phi CTebaldi. Junior. 2009; Herbst, 2002; Abdel-Rahman et al., 1999). Do vay, diy l i hudng di moi nhim phit huy tinh uu vidt cua thd da bOi, giam thieu tic dpng bat lpi ciia hodc mdn ddn mdi truong huong tdi phit tridn nudi trdng thuy sin ben viing.
L PHUONG PHAP NGHEN CUU 1. Ddi tirpng v i so dd nghidn cuu
- Nghidn ciiu dupe tiiuc hidn ti-dn c i ro phi vin (Oreochromis niloticus). Cic thi nghiem dupe ti-idn khai tai Vidn Nghidn ciiu Nudi trong Thuy san 1 theo so dd gdm cie bude nhu hinh 1.
2. Tuydn chpn c i bd m?
Ci rd phi vki bd m? kich cd 500-800 g/con da dupe nuoi vd thinh thuc theo quy trinh ciia Vidn Nghidn ciiu Nudi trdng Thuy san 1.
Lira chpn c i bd me ttiinh thuc: (1) C i cii ed 16 sinh due loi, cd miu hdng nhat; (2) ca d i ^ cd miu sic s i c so v i c6 s? mau ti"^ due khi vuot nh? p h ^ 16 sinh due.
' Vi^n Nghien ciru Nudi trong Thijy san 1
N C N G NGHIEP VA PHAT TRIEN NONG THON • KY 2 - THANG 12/2012
73
KHOA HQC C d N O N O H t
Tuyen chgn ca bo Thi nghi$m loji lieu lu<?ng kicii d\ic to
S t o p l i a m sinli dye, thy tinh
Lay mau mau, do kich thuoc nhan te bao hong cau xac djnh
the da bpi
Xac djnh ty 1$ de, thai gian hi?u img
thuoc
Xac dinh phuong phip 1510 da bpi loi
uu Hinh 1: Sa dA b^ Iri thi nghidm t^o c4 rfl phi da b^i 3. Thi nghidm xic djnh loiii vi Uia lupng kich
due t^ phu hop
Thi nghidm sii dyng cic loai kich due t6 bao gom HCG va LHRHa k^t h<n) vtn DOM * cic li^u lupng khic nhau v i ddi chung (khdng ti^m kich due to) (Bang 2).
Ddi v « kich dye td LHRHa kdt h w voi DOM;
Tidm lim 2 lidu, lidu khoi ddng bing 1/4 tdng liSu v4 tnrfk: lidu tidm quydt dinh 6 gid. Tidm c i due 1 Ian ciing thdi didm tidm hdu quydt djnh cho c i cii.
Ddi v<n kich dye td HCG: Tidm 1 lin cho ci ci due vi c i cii.
V) tri tidm: Gdc viy nguc.
STT 1
2
3
Loai kich due td HCG
LHRHa + DOM
Khdng tidm
Bing 2: Loai v i lidu lupng kich dye td thi nghidm Lidu tidm cho c i cii (kg"')
Cdng thuc 1: HCG 2500 UI Cdng thuc 2: HCG 3000 UI Cdng thuc 3: HCG 3500 UI Cdng thuc 4: 30 mg LHRHa + lOmg DOM
Cdng thuc 5: 45 mg LHRHa + 15 mgDOM
Lidu tidm cho e i dye Lidu tidm bang 1/3 lidu tidm c i cii Lidu tidm bang 1/3 lieu tidm ca cii
Khdng tidm
Sd lin ISp 3
3
3 Ty Id c i tham gia de la co so dd lira chpn lo^i v i
hdu lupng kich due td phii hpp cho kich thich sinh sin nhan tao e i ro phi vin.
4. Thi nghidm sdc nhidt t ^ c i r6 phi da bdi Cic thi nghidm dupe tidn hinh nham x i c dinh nhidt do v i thdi lupng sdc nhidt phii hpp cho tgo da bdi ti-dn e i rd phi vin, cu thd: Nhidt dp sdc 40"C, 41°C va 42°C; thoi diem sdc nhidt 65 phut sau thu tmh;
thdi lupng sdc nhidt 2 phiit, 3 phiit v i 5 phiit; Im^ng tning ihii tinh dem sdc 10 ml tning/l6 thi nghidm;
cic 16 thi nghidm dupe bd tri l$p lai 3 lan. Ty Id no, ty Id ra hot, ty Id sdng v i ty Id c i da bpi li co so- cho vide lua chpn nhidt dO, thdi didm v i thoi lupng sdc nhidt phii hpp cho tao c i ro phi da bOi.
5. Phuong p h ^ thu tinh v i ip tning Sau khi tidm kich due td, ca bd m? dupe nhdt ridng, ddn thoi ddm c i cii rung trimg thi tidn hinh vuot tning, cung vdi do vuot sf ciia c i due dd thu tinh nhan tao. Tning sau khi thti tinh dirpc chia ra ip
b cic khay ridng rd (10 ml tning/khay) cd nude chay lidn tuc trong qua trinh ip. Nhidt dp nuoc ^p tning duy tri trong khoang 25-28^C. Djnh ky theo dOi vi ve sinh c$n bin trong khay ip.
6. Phuong phip thu t h | p sd lidu a. Xic dfnh cic chi tidu sinh san
Xic djnh sd lupng tning dem sdc theo cdng thiic: N - a x V .
Trong dd: a l i sd tiling c6 trong 1 ml tning da thu tinh; V l i thd tich tning thi nghidm (10 ml).
Thdi gian hidu ling thudc li khoang thdi gian tinh tij khi tidm kich di^c td cho ddn khi c i thd dau tidn de t?i mpt khoang nhidt dO nude nhat dinh.
Sd c i dd tning T y l d c i d e ( % ) - x 100
Tong sd c i cii thi nghidm Sd ^u triing mdi no Ty Id nb (%) x 100
Sd tning thy tinh
74 NONG NGHIfP VA PHAT TRIEN N 6 N G T H 6 N - K t 2 - THANG 12/2012
KHOA H9C C 6 N 0 NCHt
Tyldrabdt(%)=- Sd c i hot Tdng sd au trung no
aoo
Khi ca hdt noin hoang, ddm sd e i bpt v i chuydn ra uong nudi ridng ri trong giai vdi mit dp 100 con/m^ thiic i n sii dung l i bdt c i min. Tidn hinh kiem tra ty Id sdng sau 4 tuin uong nudi.
Sd e i thu dugc Ty Id sdng (*) = x loO
Tdng sd c i t h i b. Xac dinh ci thi da bdi
Khi ci dat khdi lupng tir 40-50 g / c i thd thi tidn hinh thu mau miu eiia 30 e i thd ngiu nhidn, nhupm miu bing Giemsa theo phuong phip eiia Romanopxki. Soi tidu ban khd trdn kinh hidn vi dp phdng dai 40x dd do kich thuoc nhin nhin te bio hong eiu xic dinh thd da bdi (do ngiu nhidn kich thuoc ciia 30 nhin te bao hdng cdu / mau). Theo Beck vi Biggers (1983) the tich nhin td bio hdng cau (V) dupe xic dinh theo cdng thiic:
V-4*T|abV3 (um")
Trong do: a l i nua tryc chinh (ym); b Ii nua true phu (ym).
Ci thd da bdi (3n ho^c 4n) duoc xac dinh la nhung ci thd cd the tich trung binh ciia nhan td bio hdng cau Idn hon hoac bing 1,5 lin so vdi the tich tnmg binh eua nhin td bao hdng can a Id ddi chiing (2n) Oohnson et al.. 1984: Chourrout et al., 1986;
Quillet, Gaignon, 1990; Child, Watkins, 1994).
7. Phin tich v i ' x i 1)> sd lidu
Sd lidu dupe thu thip, tdng hpp, xu ly thdng kd md ta v i phin tich trdn Microsoft Excel 2007.
Cic sd li^u Ii ty 1$ phin trim dupe chuydn ddi (areos) vd dang phin phdi chuin trudc khi dua vio phin tich. Phin mdm SPSS 17.0, so sanh Turkey vdi miic y nghia a - 0,05 dupe sir dpng dd phin tich sd lidu.
•.KCTQlMVAniAOLUAN
i. Kich thich sinh sin sii dyng kich dye td Kdt q u i nghidn eiiu cho thay, ty 1^ de cua c i ro phi vin a cie cdng thiic thi nghidm tidm kich due td ddu cao hon so voi cdng thiic ddi chiing. Tuy nhi^n, ddi vdi e i due thi ty 1$ e i vuot dupe se d cdng thiic ddi chiing lai cao gap tir 2 den 3 lin so vdi cic cdng thiic thii nghidm kich dye td (P<0,05).
Ty 1^ de cua ca cii thap nhit 6 cdng thiic ddi chiing khdng tidm kich dye td, chi dat 6,67 ± 1,67%.
Trong khi dd, ty Id c i de cao nhat, lin luot l i 61,11 ± 3,36% v i 65,56 ± 4,98% khi sii dung kich dye td Ii HCG vdi lidu lupng 3000 Ul/kg (CT2) vi 3500 lU/kg (CT3). Ty Id e i de d hai cdng thiic niy eao hon so vdi ty Id de d cie cdng thiic thi nghidm khie (P<0,05). Su sai khie ve ty Id e i de cr cdng thiic 2 v i cdng thiic 3 khdng cd y nghia thdng kd (P>0,05).
Thdi gian hieu ling nhanh nhat li 17 gid den 20 gid (trung binh 18,44 ± 0,48 gid) d cdng fliiic tiem HCG vdi lidu lupng 3500 UI (P< 0,05). Tidp theo den CT2, thdi gian hieu ling trung binh li 27,89 ± 0,95 gid khi tiem HCG vdi Udu lupng 3000 Ul/kg (P<0,05).
Cac cdng thiic thi nghidm khic cho thdi gian hieu ling tir 31 - 36 gio. Ddi vdi c i dye, ty Id ca vudt dupe se trung binh dao ddng trong khoing 18,89 - 62,22%, ty Id niy cao nhat p cdng thiic ddi chiing khdng tidm kich due td(P<0,05).
Bing 3: Kdt q u i sir duni? kich due td kich thich sinh sin nhin tao c i rd phi vin Cdng thuc
CTl CT2 CT3 CT4 CT5 Ddi chime
Ty Id ca cai de trung (%) 23,33 ±4,41°
61,11 ±3,36"
65,56 ±4,98*
12,22 ± 4 , 6 5 "
7,78 ±2,61' 6,67 ±1,67'
Thdi gian hidu ling (gip) Trung binh
33,67 ±0,58*
27,89 ± 0,95°
18,44 ±0,48°
32,11 ±0,22' 33,44 ±0,78'
-
B« dau 32 25 17 31 32
Ket thdc 36 31 20 34 35
-
Ty 1? ca dye vudt dupe s? (%) 28,89± 6,76°
31,11 ±6,33°
34,44 ±5,30°
22,22 ±7,03°
18,89±5,39°
62,22 ±6,41*
Ghi chii: Cic si hiu (%) diroc chuyin doi (areas) vi phin phii chuin trudc khi dua vio phin tich. Cic gii tii (tivng binhi SE) trong cimg mdt cdt cd ky lu ma (a, b, c.) khic nhau tiii khic nhau cd y nghia tiling ki
<P<0,05).
NONG NGHIfP VA PHAT TRIEN NONG T H 6 N - KY 2 - THANG 12/2012 75
KHOA HPC C 6 N 0 NOHt
Thdi gian hidu ling nhanh nhit Ii 17 gid ddn 20 gid (tiung binh 18,44 ± 0,48 gid) d' cdng thiic Udm HCG vdi lidu lupng 3500 UI (P< 0,05). Tidp theo ddn CT2, thdi gian hidu ling hung binh li 27,89 ± 0,95 gid khi Udm HCG vdi lidu lupng 3000 Ul/kg (P<0,05).
Cic cdng thiic thi nghidm khic cho thdi gian hidu ling til 31 - 36 gid. Ddi vdi e i due, ty Id c i vudt dupe sp trung binh dao dpng trong khoing 18,89 - 62,22%, ty Id niy cao nhit d cdng til lie ddi chiing khdng tidm kich dye td(P<0,05).
Kdt qua cho tliiy sir dyng kich due to HCG vdi lidu lupng 3000 - 3500 Ul/kg c i cii vi khdng sir dung kich due td ddi vdi c i due Ii phii hpp dd kich thich sinh sin nhim thu san phim sinh dye v i tidn hanh thy tinh. Thdi gian hidu ling thudc khi sii dyng HCG vdi hdu lupng h-dn tii 17 ddn 31 gid. Kdt qui
ddng tie gii (1994), cQng nhu ciia El-Hakim v i ddng tic gii (2005) khi kich thich sinh sin c i rd phi sii dung HCG vdi lidu lupng tir 2500-3500 Ul/kg (tj 1{
dd d?t tit 36-85%). Thinh cdng trong sir dyng kich dye td kich thich sinh s i n l i c a sd vimg chic cho vide tridn khai cic nghidn ciiu tidp theo nhim myc dich liu dii l i sin xuit c i rd phi tam bdi tii quin din bd me tii bdi v i luiing bdi.
2. Kdt q u i theo ddi mOt sd chi Udu thi nghidm sdc nhidt
Tidn hinh thir nghidm sdc nhidt cho tning sau khi dupe thy Unh 65 phiit d ba muc nhidt dp la 40"C, 41''C v i 42°C vdi ba thdi lupng khic nhau li 2 phiit, 3 phiit vi 5 phiit. Kdt q u i vd inh hudng cua nhidt dO va thin lupng sdc nhidt ddn mdt sd ehi Udu sinh san dupe trinh biy d bing 4.
niy phii hpp vdi nghidn eiiu eiia Garcia-Abiado v i
Bing 4: Anh hudng ciia nhidt dp v i thdi lupng sdc nhidt ddn mpt sd chi lieu sinh sin Nhi?l dd soc
("C) 40
41 42
Tiidi lupng sdc (phiit)
2 3 5 2 3 5 2 3 5 Ddi chiing
Ty Id nd
(%)
20.34 ±1,58°
18,65 ±1,70' 17,33 ±2,50°' 30,87 ±1,50' 26,07 ± 0,03°
15,03 ±0,01' 37,75 ± 2,05°
31,56 ±0,02' 13,58 ±0,02' 52,81 ±0,04"
Ty Id ra bpt
(%)
36,18 ±1,04°
34,26 ±2,19°-' 34,01 ± 1,20°' 37,45 ±1,05°
34,29 ±1,06°' 31,81 ±0.04' 45.54 ± 0.05°
41,94 ±0.01' 33,77 ± 0.03' 66,47 ± 0,03"
Ty Id sdng 47.04 ± 1.27°
(%)
42,30 ±1.45' 36,20 ±0,08' 42,28 ±1,36' 39,68 ± 0,06' 34,83 ±0,01' 60,27 ± 0.04°
54.39 ± 0.05' 35.84 ± 0,04' 72,13 ±0,01"
Ghi chu: Cac si Udu (%) duoc chuyin dii (arcos) viphin phii chuin trudc khi dua vio phin tich. Cic gia tri (tiung binh ± SE) tiong cung mot CQt c6 ky tu mu (a. b, c.) khic nhau thi khic nhau cdy nghia thing ki (F<0.05).
Kdt qua thi nghidm cho thay ty Id ncr, ty Id ra bpt vi ty 1$ sdng trung binh ciia c i rd phi vin d Id ddi chiing dat lin lupt l i 52,81 ± 0,04%, 66,47 ± 0,03% v i 72,13 ± 0,01% eao hon ty Id nd, ty Id ra bpt vi ty Id sdng cr cic Id thi nghidm (P<0,05). Do thd da bdi thudng ydu hon thd ludng bpi trong giai do^in phit hien phdi cung nhu giai doan tir c i i)dt ldn c i huong (Thorgaard; 1986; Nguydn Tuong Anh, 1999). Kdt qui nghidn ciiu cung chi ra ring trong eic cdng thiic thi nghidm kdt qui cao nhat dat dupe khi sdc nhidt
0,04 - 41,94 ± 0,01%; ty Id sdng trung binh dat ti 34,83 ±0,01-54,39 ±0,05%.
3. Kdt q u i sdc nhidt t^o c i rp phi vin da bdi thd Khi c i d^t khdi lupng hi 40-50 g / e i thd, tk hinh liy mau miu cua 30 c i thd ngiu nhidn trong mdi Id thi nghidm, nhupm mau v i do kich thuoc nhin td bio hdng cau theo phuong phip cua Beck va Biggers (1983).
Ket q u i thi nghidm (bing 5) cho thiy, thd tich nhin td b i o hdng eiu c i a c i rd phi vin d eic cdng cho UTing d 65 phiit sau khi thu Unh, nhidt dd sdc l i - - , , , . . , , 42«C h-ong thdi gian 2 phiit, vdi ty Id nd, ty Id ra bdt * * = * ' ' ^ ' ^ ^ " ' • • " ^ ''•^ " ^^•''^ t™ • ^""^ "*'"^
va ty Id sdng lin lupt dat 37,75 ± 2,05%, 45,54 ± 0,05% " * '* '°^° ^°''« "^^ ' ^ "=* ^ * * * « * ' ^ ' ' '^ T^
va 60,27 ± 0,04% (P<0,05). Cic cdng thiic thi nghidm " ^^'^^ l™'' '^^' " " ^ ^ ^ * • • * ' '^ •*"« * * ' khic cho ty Id nd himg binh dat tit 13,58 ± 0,02 - *""« ^ ^ ' ^ " * * " ^ ^^° ^^"^ "^^ * ^^^ '^'^ „ « 31,56 ± 0,02%; ty Id ra bpt tnmg bmh dat hi 31,81 ± * i nghidm d,t hi 10,60± 0 2 3 ym ddn 19,25±0,»
ym' ldn hon thd hch nhin td bio hdng eiu ttung W
76 NONG NGHIfP VA PHAT TRIEN N 6 N G T H 6 N - KV 2 - THANG 12/2012
KHOA HOC C O N O N O H t
cia c i nhi bdi (2n) d cdng thiic ddi chung (chi dat 8,79 ± 0,20 ym") (P<0,05).
Bing 5: Kdt q u i thi nghidm tjio da bdi thd bing sdc nhidt ndng Thdi didm sau
thy tinh (phut)
65
Nhidt dp (°C)
40
41
42
Thdi lupng (phut)
2 3 5 2 3 5 2 3 5 Ddi chimg (2n)
Thd tich nhan te bio hdng eiu (um^) Nhd nhit
8,62 9,35 8,75 7,63 8.15 8.65 1-1.27 9.13 8.21 6,64
Ldn nhat 16,75 15,86 16,83 18,64 19,27 19,76 24,75 21,09 17,96 13.25
Trung binh 12,45 ± 0,40°
11,27 ±0.35°' 10,95 ±0,95' 11,74 ±0,38°°
11,23 ±0,45' 10,81 ±0,29' 19.25 ±0,29"
13,03 ±0.52°
10,60 ±0.23' 8,79 ±0,20°
Ty 1§ da bpi
(%)
22,89 ±1,65°' 20,65 ± 2,55' 18,58 ±1,33' 15,56 ±2,23°
15,86 ±3,23°
6,67 ±0,01' 58,15 ±2,75"
28,89 ±4,45°
2,22 ±2,22' Ghi chd Cic SO li$u (%) dupv chuyen ddi (arcos) v4 phin phdi chuin trudc khi dua vio phin tich. Cic gii
-
Oi (trung binh ±SE) trong cung m^t cdt cd ky tir mO (a, b. c.) khic nhau thi khic nhau cdy nghia thdng kS (P<0.05).
Ty Id c i ro phi vin da bpi dat dugt tir 2,22 ± 2,22% d^n 58,15 ± 2.75% khi tidn hanh soc nhidt t^i that diem 65 phiit sau khi tning thu tinh b nhidt dO 40<'C, 41''C hoic A2K ti-ong thoi gian 2 phiit, 3 phiit hoic 5 phiit. Ty Id da boi trung binh cao nhit dat duoc trong thi nghidm niy la 58,15 ± 2,75% khi soc nhidt voi thoi lugng 2 phiit o nhidt do 42°C tai thoi diem 65 phut sau khi tning thu tinh. K^t qua nay con thap khi so sinh voi cic nghidn ciiu trdn the gioi nhu thi nghidm cua Abdel-Rahman va dong tic gia (1999) vm 100% ca tam bOi thu duoc khi tien hinh soc nong b 40- 41^0 tai thoi diem 4-6 phiit sau khi thu tinh trong thai gian 10 phiit. Nghien ciiu ciia cic tic gia trdn ciing cho thay vide soc nong 6 41''C trong thoi gian 5 phiit tai thoi diem 65 v i 80 phiit sau thu tinh cho k^t qua 85-100% ca ro phi hi bOi. Tuong tu, Tebaldi vi Junior (2009) da tao ra 100% c i ro phi tii bgi khi tien hinh soc nong o 40''C tai thoi di^m 65 phiit sau khi thu tinh tirong thai gian 2 phiit. Tuy ty 1^
da boi trong nghidn ciiu chua cao so voi cic nghidn cuu trdn the gidi nhung ket qua nay sd l i co so v i n^n tang cho cic nghidn ciiu ti^p theo v^ tao ro phi da bOi the b nuoc ta.
IV. KET LUAN
Ca ro phi vin d i thanh thuc dugc kich thich sinh san nhin tao b ^ g HCG voi li^u lugng tii 3000 - 3500 Ul/kg cho ty Id de hning binh tir 61,11 - 65,56%, thoi I gian hidu ting tir 17 d^n 31 gio a di^u kidn nhidt do nu6c tii 25 - 28''C. Ty 1^ no, ty Id ra bOt va ^ Id song
! trung binh ciia c i ro phi v^in cao nhat dat 37,75 ± I 2,05%, 45,54 ± 0,05% v i 60,27 ± 0,04% khi cho thu tinh kh6 vi thu nghidm soc nhiet ndng a thai di^m 65 s phiit sau thu tinh, nhiOt do soc 42"C trong thai gian 2
phiit Day cung li cong thiic thi nghidm cho k^t qua v^ ty Id da bOi trung binh cao nhit 58,15 ± 2,75%. Ket qui nghidn cihi li co so viing chic cho vide trien khai cic nghidn ciiu sin xuat ca ro phi tam bpi (3n) tir quan din bo me tii boi (4n) v i luong bOi (2n) trong tuong lai.
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INDUCTION OF POLYPLOIDY IN NILE TILAPIA (OREOCHROMISNlLOTTCUSUNi^AEUS 1758) Ngo Phu Thoa, Nguyen Huu Ninh, Pham Hong Nhat, Nguyen Van Dai, Nguyen Thi Le
Smnmary
All male Nile tilapia has been one of the most important species for aquaculture in Viet Nam. Appbcation of sex reserval technology by using hormone 17a-Methyl testosterone may have negative effects and risk to environment, foot safety and customer's health. Induction of triploidy (3n) by heat shock or crossing between tetraploidy (4n) and diploidy Nile tilapia is known as an essential solution to control the density and mcrease economic of tilapia in flie culture pond. Study on induced breeding is one of the initial elements m the researches on induction of polyploidy in tilapias. The present study has been earned out to investigate the suitable hormone type and dosage (HCG and a combination of LHRHa and DOM) for inducing the artificial spawning and initial research on heat shock (temperature and duration) to induce polyploidy of Nile tilapia. Three temperature levels (iCfC, AVC and 42°C) and three durations (2 minutes, 3 minutes and 5 minutes) have been tested. The results show that the effected time was from 17-31 hours when female brooder was injected with HCG and the dose of 3,000-3,500 lU/kg, and the spawning rate was 61.11 - 65.56%. The average of polyploidy rate of Nile tilapia was highest (58.15 ± 2.75%) when the heat shock applied after 65 minutes fertilization for 2 minutes duration at temperature of 42°C.
Key words: Nile tilapia, Oreochromis niloticus, hormone, induced spawing. heat shock, polyploidy.
Ngu6i phin bi^n: TS. NguySn Cdng Din Ngiy n h ^ bii: 8/11/2012
Ngiy th6ng qua phin bi$n; 6/12/2012 Ngiy duy^t ding: 12/12/2012
78 NONG NGHIfP VA PHAT TRIEN NONG T H 6 N - KY 2 - THANG 12/2012
