Giaotrinhthucangiasuc

8/7/2019 Giaotrinhthucangiasuc

1/152

TRNG I HC NNG LM HU

GIO TRNHTHC N GIA SC

PGS. TS. L c Ngoan - ch binThs. Nguyn Th Hoa LThs. D Th Thanh Hng

Nh xut bn Nng nghip, nm 2005

1


2/152

LI M U

Trong nhng nm gn y, vic i mi phng php ging dy tr nn bcthit v cp bch. Sinh vin v s l trung tm ca dy v hc. Gio trnh l khu quantrng khng th thiu c nhm gp phn thc hin tt vic i mi phng php gingdy. Quyn Gio trnh Thc n gia sc do PGS. TS. L c Ngoan, Ths Nguyn ThHoa L v Ths D Th Thanh Hng bin son nhm cung cp cho sinh vin i hcngnh Chn nui, Th y, Thy sn nhng kin thc c bn v thc n ng vt ni chungv thc n gia sc ni ring. Gio trnh dy hn 150 trang A4, bao gm 8 chng. B ccv ni dung cc chng r rng.

hon thnh tp ti liu c gi tr ny, cc tc gi tham kho rt nhiu ti liutrong v ngoi nc, v c nhng sch v ti liu mi xut bn trong nhng nm gn y(2002- 2004).

Trong khun kh thi lng ca mt mn hc Thc n gia sc vi 4 hc trnh(60 tit, bao gm c thc hnh, thc tp), cho nn ni dung sch khng th bao trm ht

nhng vn chuyn su c. Tp th tc gi mong nhn c nhng kin gp cacc thy c, cc ng nghip v cc em sinh vin ti liu hon chnh hn trong ln tibn sau.

Gio trnh Thc n gia sc c GS.TS. V Duy Ging c v gp . Chngti xin chn thnh cm n nhng ng gp c gi tr ca gio s.

Mi gp xin gi v a ch:PGS. TS. L c Ngoan, khoa Chn nui-Th y, trng i hc Nng Lm Hu.

102 Phng Hng, Hu. Tel. 054 525 439; Fax 054 524 923; E.mail:[email protected]

PGS.TS. Trn Vn MinhHiu trng, ch tch HKH-GD

Trng i hc Nng Lm Hu

2
mailto:[email protected]:[email protected]:[email protected]


3/152

MC LCCH NG I ................................................................................. 7

PHN LO I TH C N ................................................................... 7

I. NHNGHA.................................................................................................................... 7II. PHNLOITHCN...................................................................................................... 7

2.1. ngha c a phn lo i th c n gia sc ...................................... 72.2. Ph ng php phn lo i ....................................................... 7

CH NG II ............................................................................... 11

C T TRONG TH C N ............................................................ 11

I. KHI NIM C BN V CHT GY C TRONG THC N............................. 111.1. nh ngha .................................................................... 111.2. Cc tr ng thi ng c ....................................................... 11

II. PHN LOI CHT C THEO NGUN GC LY NHIM .............................. 122.1. Ch t c c s n trong nguyn li u lm th c n v trong qu trnh ch bi n 122.2. Ch t c do th c ph m b bi n ch t trong qu trnh b o qu n ........ 122.3. Ch t c do n m m c sinh ra (mycotoxin) ................................ 12

2.4. Ch t c do vi khu n gy ra ............................................... 122.5. Cc ho ch t c h i l n vo th c n ..................................... 12III. CC YU T NH HNG N MC C ............................................. 12

3.1. Li u l ng ch t c .......................................................... 123.2. Y u t gi ng, loi ng v t .................................................. 133.3. L a tu i c a ng v t ........................................................ 133.4. Tnh bi t ....................................................................... 133.5. Tnh tr ng s c kh e v ch dinh d ng ............................... 133.6. Tr ng thi v t l c a ch t c .............................................. 13

IV. CC CHT C HI C SN TRONG THC N.............................................. 134.1. Cc ch t c h i trong th c n th c v t ................................... 134.2. Axit amin phi protein (non protein amino acids)- axit amin b t th ng 184.3. Nh ng ch t terpenoide v steroide c h i ............................... 234.4. Cc ch t nh y c m quang h c (photosensitive compounds) ........... 244.5. Nhm ch t saponin ........................................................... 264.6. Ch t gossipol .................................................................. 264.7. Nhm ch t tannin ............................................................. 264.8. Nh ng ch t khng enzyme tiu ha protein (proteinase inhibitors) ... 27

V. C T NM TRONG THC N.......................................................................... 275.1. Khi ni m ...................................................................... 275.2. Nh ng tc h i do c t n m m c sinh ra ................................ 295.3. Cc giai o n v ngu n gy nhi m c t n m ......................... 315.4. M c an ton c a c t n m trong th c n ............................... 315.5. Nh ng gi i php phng ng a mycotoxin ................................. 31

CH NG III .............................................................................. 34

TH C N TH XANH V PH PH M NNG NGHI P .......................... 34

I. NHM THC N XANH.......................................................................................... 341.1. c i m dinh d ng ........................................................ 341.2. Cc y u t nh h ng n gi tr dinh d ng c a th c n xanh ...... 351.3. Nh ng i m c n ch khi s d ng ........................................ 35

II. NHM RAU BO.................................................................................................... 362.1. Rau mu ng (Ipomea aquatica) ............................................. 372.2. Thn l khoai lang (Ipomea batatas)....................................... 372.3. L s n (Manihot esculenta Cranz) ......................................... 382.4. C ha th o ................................................................... 39

3


4/152

III. NHM THC N TH.......................................................................................... 393.1. C kh ......................................................................... 393.2. R m r ......................................................................... 403.3. Ma............................................................................ 41

CH NG IV .............................................................................. 46

TH C N H T V PH PH M CC NGNH CH BI N ....................... 46I. THC N HT NG CC ......................................................................................461.1. c i m dinh d ng ........................................................ 461.2. Ng ............................................................................ 461.3. Thc............................................................................ 48

II. THC N HT B U V KH DU................................................................ 482.1. H t b u ..................................................................... 482.2. u t ng ..................................................................... 492.3. L c .............................................................................. 50

III. SN PHM PH CA CC NGNH CH BIN................................................. 503.1. S n ph m ph ngnh xay xt ............................................... 503.2. S n ph m ph ngnh chi t p d u th c v t .............................. 523.3. S n ph m ph c a ngnh n u r u bia ................................... 55

3.4. S n ph m ph c a ngnh ch bi n thu s n ............................. 57CH NG V ............................................................................... 61

TH C N H N H P .................................................................... 61

I. KHI NIM............................................................................................................... 61II.VAI TR CA THC N HN HP...................................................................... 61III. PHN LOI THC N HN HP........................................................................ 62IV. QUI TRNG CNG NGH SN XUT THC N HN HP............................. 65

4.1. Quy trnh cng ngh s n xu t th c n h n h p .......................... 654.2. Cc ch tiu ch t l ng c a th c n h n h p: ............................ 67

V. THC N HN HP DNG VIN ........................................................................685.1. u i m c a th c n vin ................................................... 685.2. Nh ng nh c i m c a th c n vin ...................................... 69

5.3. Quy trnh lm th c n vin .................................................. 69CH NG VI .............................................................................. 70

TH C N B SUNG .................................................................... 70

I. VAI TR CA THC N B SUNG .......................................................................701.1. Khi ni m ...................................................................... 701.2. Nh ng xu h ng m i s d ng th c n b sung trong chn nui ...... 70

II. THC N B SUNG PROTEIN.............................................................................. 722.1. Ch t ch a N phi protein (NPN - non protein nitrogen) ...................722.2. M t s axit amin l y u t h n ch ...................................... 772.3. Nguyn tc b sung axit amin cng nghi p ............................... 77

III. THC N B SUNG KHONG............................................................................ 773.1. B sung khong a l ng ............................................. 773.2. B sung vi khong ............................................................ 783.3. Tnh ton nhu c u khong b sung ....................................... 79

a l ng ............................................................................ 793.4. S ng c cc nguyn t vi l ng khi cho n qu li u ................. 79

IV. THC N B SUNG VITAMIN............................................................................. 81V. KHNG SINH........................................................................................................... 82

5.1. Tc d ng c a khng sinh s d ng v i m c ch dinh d ng ...........825.2. Nh ng h n ch c a vi c s d ng khng sinh ............................ 84

VI. PREMIX ................................................................................................................. 89

4


5/152

VII. CHT KCH THCH SINH TRNG V CC LOI THC N B SUNG KHC.........897.1. Enzyme........................................................................ 897.2. N m men ...................................................................... 897.3. Ch t b o qu n th c n v ch t k t dnh ...................................907.4. Ch t nh ha .................................................................. 917.5. Cc ch t t o mu, mi ....................................................... 92

CH NG VII ............................................................................. 94PH NG PHP CH BI N TH C N .............................................. 94

I. CHUA (SIL - SILAGE)........................................................................................ 941.1. Vai tr enzyme th c v t trong qu trnh chua .......................... 941.2. Vai tr vi sinh v t trong qu trnh chua .................................. 951.3. Nh ng nhn t nh h ng n qu trnh xanh .........................971.4. S m t mt trong qu trnh chua ....................................... 1001.5. nh gi th c n chua ................................................... 100

II. CH BIN THC N HT (HT CC V HT H U)................................. 1012.1. Tnh ch t v t l, ho h c c a tinh b t h t ................................ 1012.2. Bi n i v t l, ho h c c a tinh b t trong qu trnh ch bi n ........1012.3. Cc ph ng php ch bi n th c n h t ................................. 102

III. X L RM R V PH PHM X TH......................................................... 1043.1. X l v t l ................................................................... 1053.2. X l sinh h c ............................................................... 1053.3. X l ho h c ............................................................... 106

IV. CH BIN PH PHM LM THC N CHO TRU B.................................. 1104.1. X l r m kh v i ur v vi ............................................... 1104.2. R m t i v i ur ......................................................... 1114.3. Ph ng php lm bnh a dinh d ng: ................................. 112

CH NG VIII ........................................................................... 113

TIU CHU N V KH U PH N ...................................................... 113

I. KHI NIM............................................................................................................. 1131.1. Tiu chu n n ............................................................... 113

1.2. N i dung tiu chu n n .................................................... 1131.3. Kh u ph n n ................................................................ 115

II. NGUYN TC PHI HP KHU PHN............................................................. 1152.1. Nguyn t c khoa h c ....................................................... 1152.2. Nguyn t c kinh t .......................................................... 116

III. PHNG PHP XY DNG KHU PHN THC N CHO VT NUI........ 1163.1. Ph ng php tnh ton n gi n ......................................... 1163.2. S d ng ph n m m trn my vi tnh ..................................... 119

PH N PH L C ........................................................................ 120

I. TIU CHUN N CHO GIA SC NHAI LI......................................................... 120II. TIU CHUN N CHO LN................................................................................ 127III. TIU CHUN N CHO GIA CM...................................................................... 131

TI LIU THAM KHO CHNH............................................................................... 1551. NGUYNXUNBV CTV (1997). NGHINCUSDNGUREAXLRMLALMTHCNCHOTRUB. TUYNTPCNGTRNHNGHINCUKHKT & KTNN, KNIM30 NMTHNHLPTRNGIHCNNG LMHU. NHXUTBNNNG NGHIP, HNI; TR. 157-160................................................................ 155

2. HINGNGHINCUQUCGIA HOA K(2000). NHUCUDINHDNGCALN. NHXUTBNNNGNGHIP, HNI. .......................................................................................................................... 155

3. LMINHHONG (2000). CHBINTHCNHNHPCHO GIASC, GIACM. NHXUTBNVNHADNTC, HNI..................................................................................................................................155

4. VDUYGING (2001). GIOTRNHDINHDNGVTHCNGIASC. NHXUTBNNNG NGHIP, H NI.............................................................................................................................................. 155

5


6/152

5. VDUYGING, NGUYNTHLNG HNG, TNTHTSN(1999). DINHDNGVTHCNGIASC.NHXUTBNNNG NGHIP, HNI.............................................................................................. 155

6. VDUYGING (2003). NHNGXUHNGMISDNGTHCNBSUNGTRONGCHNNUI. TPCHTHCNCHNNUI. CSANKHOAHCKTHUT THCNCHNNUI. S 1 -2003. HNI................ 155

7. DNG THANH LIM, BIHUYNHPHC, DNG DUYNG (2002). THCNVDINHDNGNG VT. NHXUTBNNNGNGHIP, TP H CH MINH. ......................................................................155

8. DNG THANH LIM(2003). CTNMMC, KTHSMTCATHCNCNGNGHIP. TPCHTHCNCHNNUI; S 1 -2003................... .............. .............. .............. ............... .............. .......... 155

9. DNG THANH LIM(2004). HUQUCAVICSDNGKHNGSINHTRONGTHCNCHNNUI. TPCHTHCNCHNNUI; S 2 -2004. .............................................................................................155

10. LVNKNH(2004). PHNGPHPXYDNGKHUPHNTHCN. TPCHTHCNCHNNUI; S 2-2004..........................................................................................................................................155

11. NGUYNXUNTRCH(2004). SDNGPHPHMNUIGIASCNHAILI. NHXUTBNNNGNGHIP,HNI.........................................................................................................................................155

12. NGUYNXUNTRCH, BICLNG (2004). HTHNGNNGNGHIPVSDNGPHPHMLMTHCNGIASC. TPCHCHNNUI; S 4 (62) 2004.............................................................................. 155

13. CCKHUYN NNGV KHUYN LM, B NNG NGHIPV PTNT (2001). QUNLTHCNCHNNUICCTNH, THNHPHPHA BC, TILIUTPHUN, 26.9.2001. ......................................................... 155

14. T.R. PRESTONV R.A. LENG (1989). CCHTHNGCHNNUIGIASCNHAILIDATRNNGUNTINGUYNSNCVNGNHITIVNHITI. NGIDCH: LVITLY, LNGCDNG, NGUYNVITHI,NGUYNTINVN, LCNGOANV MVNTIN. NHXUTBNNNGNGHIPH NI , 1991.......155

15. VINCHNNUIQUCGIA (2001). THNHPHNVGITRDINHDNGTHCNGIASC, GIACMVITNAM. NHXUTBNNNGNGHIP, H NI......................................................................................155

16. SCHIERE, J.B. AND M.N.M. IBRAHIM(1989). FEEDINGOFUREA-AMMONIATREATEDRICESTRAW.15517. B.R. CHAMP, E. HIGHLEY, A.D. HOCKING, AND J.I.PITT(1991). FUNGIANDMYCOTOXINSINSTORED

PRODUCTS. ACIAR PROCEEDINGS.....................................................................................................15518. ERICSINCLAIRAND GRAHAMWHITE(1992). INSECTPESTINSTOREDGRAIN. NATIONAL RESEARCHCOUNCIL

(NRC) (1994). NUTRIENTREQUIREMENTSOFPOULTRY. NINETH REVISED. NATIONAL ACADEMYPRESS.........15619. POND, W.G., CHURCH, D.C., POND, K.R. (1995). BASICANIMAL NUTRITIONAND FEEDING. JOHN

WILEY& SONS. 4THEDITION.......................................................................................................... 15620. E. HIGHLEYAND G.J.JOHNSON (1996). MYCOTOXINCONTAMINATIONINGRAINS. ................ 15621. MICHAEL EVANS(1997). NUTRIENTCOMPOSITIONOFFEEDSTUFFSFORPIGSANDPOULTRY.... 15622. M. CHENOSTAND C. KAYOULI (1997). ROUGHAGEUTILIZATIONINWARMCLIMATES. FOODAND

AGRICULTURE ORGANIZATIONOFTHEUNITED NATIONS, ROME...............................................................15623. BO GOHL (1998). TROPICAL FEEDS. DATABASEBYANDREWSPEEDYAND NICKWALTHAM, VERSION8..15624. NATIONAL RESEARCHCOUNCIL (NRC) (1998). NUTRIENTREQUIREMENTSOFSWINE. TENTHREVISED

EDITION. NATIONAL ACADEMY PRESS. ............................................................................................... 15625. VERENIGINGVAN, NEDERLANDSEFABRIKANTEN, VANVOEDERTOEVOEGINGGEN (1998). FEED ADDITIVES:

THE ADDEDVALUETOFEED. NEFATO, NETHERLANDS...........................................................................15626. RALFG. D. ETZGEN (1998). ELIMINATIONOFAFLATOXINCONTAMINATIONINPEANUT............15627. LEDUCNGOAN (2000). EVALUATIONOFSHRIMPBY-PRODUCTSFORPIGSINCENTRAL VIETNAM.

DOCTORALTHESIS. SWEDISHUNIVERSITYOFAGRICULTURAL SCIENCES, UPPSALA, SWEDEN..........................15628. IPC LIVESTOCKBARNEVELD COLLEGE (2001). FORMULATIONOFCOMPOUNDFEEDSFORPIGS.

NETHERLANDS. ..............................................................................................................................15629. P. MCDONALD, R.A. EDWARDS, J. F. D. GREENHALGH; C. A. MORGAN (2002). ANIMAL NUTRITION.

LONGMAN. SIXTHEDITION................................................................................................................ 156

6


7/152

CHNG IPHN LOI THC N

I. NH NGHA

Trong hc phn Dinh dng gia sc, chng ta c gii thiu v khi nimcht dinh dng v thc n. gip h thng li kin thc, chng ti xin nhc limt vi khi nim tham kho. Trc ht, Pond v CTV (1995) a ra khi nim vcht dinh dng nh sau: cht dinh dng l mt nguyn t hay mt hp cht ha hcm c th gi c s sinh trng, sinh sn, cho sa mt cch bnh thng hoc duy trs sng ni chung. Theo , thc n c nh ngha l: mt vt liu c th n cnhm cung cp cht dinh dng. Wohlbien (1997) nh ngha rng tt c nhng g mcon gia sc n vo hoc c th n vo c m c tc dng tch cc i vi qu trnh trao

i cht th gi l thc n gia sc. Mt nh ngha khc cng c s chp nhn canhiu ngi l Thc n l nhng sn phm ca thc vt , ng vt, khong vt v cccht tng hp khc, m ng vt c th n, tiu ha, hp thu duy tr s sng, pht trinv to ra sn phm.

II. PHN LOI THC N

2.1. ngha ca phn loi thc n gia scVic phn loi thc n gip cho ngi chn nui bit chn v nh hng s dng

thch hp tng loi thc n cho tng i tng gia sc mang li hiu qu kinh t cao.

2.2. Phng php phn loiC nhiu phng php phn loi thc n khc nhau, cn c vo ngun gc, c

tnh dinh dng, tnh cht thc n...2.2.1 Phn loi theo ngun gcCn c vo ngun gc thc n c chia thnh cc nhm sau:+ Thc n c ngun gc t thc vt: Trong nhm ny gm cc thc n xanh, thc

n r, cu, qu, thc n ht cc sn phm ph ca ngnh ch bin nng sn: thc n x,rm r, dy lang, thn l lc, thn cy ng cc loi cm, kh du (do cc ngnh ch bindu) b bia, ru, sn phm ph. Nhn chung, loi thc n ny l ngun nng lng chyu cho ngi v gia sc, ngoi ra n cn cung cp vitamin, protein th, cc loi vikhong, khng sinh, hp cht sinh hc.

+ Thc n c ngun gc t ng vt: gm tt c cc loi sn phm ch bin tnguyn liu ng vt nh bt c, bt tm, bt tht, bt nhng tm, bt sa v bt mu.

Hu ht thc n ng vt c protein cht lng cao, c cc axit amin thit yu,cc nguyn t khong v mt s vitamin A, D, E, K, B12.., t l tiu ha v hp thu cccht dinh dng trong thc n ng vt cao hay thp ph thuc vo cch ch bin, lmthc n b sung protein quan trng trong khu phn ca gia sc gia cm.

+ Thc n ngun khong cht:Gm cc loi bt s, vi v cc mui khong khc nhm b sung cc cht

khong a v vi lng.2.2.2 Phn loi theo thnh phn cc cht dinh dng

7


8/152

Phng php ny ch yu da vo hm lng cc cht dinh dng chnh trongthc n: protein, lipit, gluxit, nc.. chia thnh cc nhm.

+ Thc n giu protein. Tt c nhng loi thc n c hm lng protein th chimtrn 20% (tnh theo vt cht kh) th c gi l nhng loi thc n giu protein.

+ Thc n giu lipit:

Gm cc loi thc n m hmlng lipit chim trn 20%. Mc chs dng thc n ny l cung cp mtlng lipit thch hp trong khu phn hm lng vt cht kh nhnggi tr nng lng cn qu thp.

+ Thc n giu gluxit: L loi thc n trong c hm lng gluxit 50% tr ln, gm cc loiht ng cc, ng, thc cm, bt khoai, bt sn. Thcn ny chim t l rt ln trong khu phn thc ngia sc d dy n, n l ngun nng lng d tiu ha, hp thu v t gy tai bin trong

qu trnh s dng m gi thnh r.+ Thc n nhiu nc: Gm cc loi thc n c hm lng nc t 70% tr ln.V d: thc n c qu, b ru, b bia, rau xanh, bo...+ Thc n nhiu x: Gm cc loi thc n m hm lng x th 18% tr ln.

Loi thc n ny l sn phm ch bin ngnh trng trt, nh rm r, dy lang, dy lc..nhng loi thc n ny t c ngha vi gia sc d dy n nhng chim t trng lntrong khu phn gia sc nhai li.

+ Thc n giu khong: gm cc loi mui khong, bt xng, mui n, bt s...+ Thc n giu vitamin: gm nhng loi vitamin hoc nhng loi thc n giu

vitamin nh: bt rau xanh, du gan c...+ Thc n b sung khc: gm cc loi thc n c ngun gc c bit nh khng

sinh, cc hp cht cha nit, cc cht chng oxy ha, cc cht kch thch sinh trng.2.2.3 Phn loi theo ng lng tinh btTheo phng php ny, ngi ta phn thc n thnh 2 loi: thc n tinh v thc

n th.+ Thc n th: bao gm cc loi thc n c ng lng tinh bt di 45% ngha

l trong 100 kg thc n c gi tr khng qu 45 n v tinh bt.+ Thc n tinh: bao gm cc loi thc n c ng lng tinh bt trn 45% (trong

vt cht kh) nh cc ht ng cc, bt c qu , cc ht kh du. Trong thc n tinh cnphn ra thc n giu protein, gluxit, lipit...

2.2.4 Phn loi theo toan tnh v kim tnhNgi ta cn c vo pH ca sn phm chuyn ha cui cng chia thc n

thnh toan hay kim. Thng nhng thc n c cha nhiu P, Cl, S th sn phm cuicng ca s chuyn ha mang tnh axit.

V d: P cho H3PO4, S, H2SO4, Cl, HCl, cn loi thc n nhiu Ca, K, Na, Mg thsn phm chuyn ha cui cng mang tnh kim.

Phng php xc nh mt loi thc n toan tnh hay kim tnh da vo cngthc:

97 62 28

50 26 43 83

P S Cl X

Ca K Na Mg

+ +=

+ + +

8

V d:

1 kg bt c loi 1 c 443 g; 1 kg bt thtc 660 g; 1 kg u tng c 374 g; kg kh dulc nhn c 409 g protein th.

V d: Vng cha 44,1% v lcnhn 46.3% lipit


9/152

Nu X > 1: Thc n thuc nhm toan tnhNu X < 1: Thc n thuc nhm kim tnh

Thay vo cng thc ta c:

97 62 28 0.2350 26 43 83

P S Cl XCa K Na Mg

+ += =

+ + +

Trng hp ny X < 1 nn thc n thuc nhm kim tnh.Nhng loi thc n kim tnh gm: thc n xanh, c qu, thc n xanh... Nhng

loi thc n ny thch hp cho gia sc sinh sn, tc dng tt i vi kch thch tit sa.Trong khi, nhng loi thc n toan tnh nh: cc loi thc n ng vt, ht h u v mtvi loi thc n giu protein li thch hp vi gia sc c, gia sc c sinh sn nht ltrong thi gian ly tinh.

M s quc t ca nguyn liu thc n chn nui:Hin nay trn th gii ngi ta phn thc n thnh tm nhm:Thc n th kh

Tt c cc loi c xanh t nhin thu ct v cc loi ph ph phm ca cy trngem phi kh c hm lng x trn 18% u l thc n th kh. Bao gm: c kh h uhoc ha tho, rm r, dy lang, dy lc v thn cy ng... phi kh. Ngoi ra cn gmv cc loi ht thc, lc, u, li v bao ng.

Thc n xanhTt c cc loi c trng, c t nhin, cc loi rau xanh cho gia sc s dng trng

thi ti, xanh bao gm: rau mung, bo hoa du, l bp ci, su ho, c t nhin, c trngnh c voi v c s, bo tm, rau da nc, rau dn, rau lp, thn l khoai lang...

Thc n chuaTt c cc loi thc n chua, cc loi c ha tho hoc thn, b ph phm ca

ngnh trng trt nh thn, l lc, b da, v chui, thn cy ng... em chua.

Thc n giu nng lngTt c cc loi thc n c hm lng protein di 20% v x th di 18%. Baogm cc loi ht ng cc nh ng, go, sn, c khoai lang, cao lng, mch, m... v phph phm ca ngnh xay xt nh cm go, cm ng, cm m, tm...nhm nguyn liuny chim t l cao nht trong cng thc thc n hn hp, thng chim 40-70% ttrng. Mt s loi du th, m th cng c dng b sung vo cng thc thc n hnhp nhng khng vt qu 4-5%. Ngoi ra cn c cc loi c, qu nh sn, khoai lang,khoai ty, b ....

Thc n giu proteinTt c cc loi thc n c hm lng protein trn 20%, x th di 18%. Thc n

giu protein c ngun gc ng vt: bt c, bt tht, sa bt, bt tht xng, bt mu,

nc sa..; thc n giu protein c ngun gc thc vt: ht tng, lc, u xanh, utriu, u nho nhe, kh tng, kh lc, kh du hng dng, kh du da, kh dubng.

Thc n b sung khongBt v s, bt , v hn, dicanxiphotphat, bt xng...Thc n b sung vitaminCc loi vitamin B1, B2, B3, D, A hoc premix vitamin.Cc loi thc n b sung khc

9

V d: Trong c kh c cha P: 2,1 g; K:19,2 g; Na: 2,46 g; S: 2,05 g; Cl: 2,17 g;Ca: 17,7 g; Mg: 2,28 g.


10/152

y l nhm thc n rt a dng. Theo bng hng dn s 70/524 ca chu u cti 14 loi ph gia thc n chn nui khc nhau:

S th t Loi ph gia S th t Loi ph gia1

234567

Cc cht khng sinh

Cht chng oxy hoCht to hng vCht phng cu trngCht nh hoCht to muCht bo qun

8

91011121314

Cc vitamin

Cc cht vi lngNhn t sinh trngCht kt dnhCht nh ho axitCc loi menSn phm vi sinh vt

S th t ca tm nhm thc n c nh s nh sau:

Tn nhm thc n S quc t ca nhm thc n- C kh, thc n th nhiu x- C ti, cc loi thc vt ti, rau

xanh- Thc n chua- Thc n giu nng lng- Thc n giu protein- Thc n b sung cht khong- Thc n b sung vitamin- Cc cht ph gia (additives)

12

345678

Trong m s quc t ca cc loi nguyn liu thc n chn nui, ch s u tincho bit loi nguyn liu thc n thuc nhm no cn nm ch s tip theo trong m

s l cc s phn bit cc nguyn liu trong cng nhm.Trong tmnhm nguyn liu trn,cc nhm nguyn liuthng s dng trongch bin thc n chnnui cng nghip lcc nhm 4, 5, 6, 7 v8 cn cc nhm 1, 2, 3thng dng cho giasc nhai li, nhm 2

cng dng cho ccnhm gia sc khc nhthc n b sung.

10

V d:- Kh du lc p c m s quc t l: 504604- Kh du lc chit ly c m s quc t: 504612- Kh du u tng p c m s quc t: 503649- Kh du u tng chit ly c m s quc t: 503650- Bt c linh lng kh 17 % protein c m s quc t l: 100023- Bt c linh lng kh 20 % protein c m s quc t l: 100024- Cm go thng c m s quc t l: 403928- Cm lau c m s quc t l: 403943


11/152

CHNG IIC T TRONG THC N

I. KHI NIM C BN V CHT GY C TRONG THC N

1.1. nh nghaCht c (poinsons)Cht c l nhng cht v c hay hu c c ngun gc trong t nhin hay docon

ngi to ra, n c nhim vo trong thc n v a vo c th n nng nht nhv gy ra s ng c, lm ri lon cc hot ng sinh l, sinh ho bnh thng ca c thv biu hin bng nhng triu chng v bnh tch khc thng.

Tu theo loi cht c, mc nhim c nng hay nh, tu theo la tui, tnhtrng sc kho ca c th m triu chng ng c nng, gy t vong hoc nh sau mtthi gian di tch lu mi gy biu hin ng c.

Cht c c sinh ra t nhiu ngun gc khc nhau: N c th l cc sn phm

trao i ca nm mc, vi sinh vt to ra m ta gi l Mycotoxin. Hoc c th ln vo thcn do nhim mi trng hoc cng c th do con ngi v tnh hay c cho thm vocc nguyn liu bo qun v tng khu v.

Nghin cu v cht c thc cht l nghin cu v bn cht ho hc, c chtc ng, phng php xc nh t c nhng bin php k thut loi tr v hn chtc hi ca n ti c th ngi v ng vt.

S ng c (toxicosis, poisoning)Lnh vc nghin cu v s ng c bao gm nhiu kha cnh khc nhau. iu ny

phc tp v c qu nhiu cht c nn rt kh phn bit. i khi cng xy ra triu chngng c thc phm m khi kim tra khng thy c c cht trong thc n, nh s ng

c cht dinh dng do n qu nhiu khng tiu, b vi khun ln men trong ng rutsinh ra c t, s ng c cht khong vi lng, s ng c vitamin.. khi s dng quliu. Tri vi iu ny, i khi ngi v ng vt n phi cht c m khng c triuchng ng c do liu lng c t qu thp hoc do sc khng ca c th ngi vng vt vi c t cao nn khng xut hin triu chng.

1.2. Cc trng thi ng c

Ng c cp tnh l trng thi ng c sau khi nhim cht c mt thi gian ngn,xut hin nhng triu chng khc thng rt nghim trng hoc gy ra t vong cho ngiv ng vt.

Ng c tch ly (cn gi l ng c trng din, ng c mn tnh) l trng thim c th nhim cht c vi liu lng thp, cha gy ra triu chng lin m phi triqua mt thi gian di cht c tch ly trong c th, lm bin i cc qa trnh sinh l,sinh ha lu di ri mi gy ra triu chng.

11


12/152

II. PHN LOI CHT C THEO NGUN GC LY NHIM

2.1. Cht c c sn trong nguyn liu lm thc n v trong qu trnh ch binTrong t nhin cc loi thc vt cng nh mt s loi ng vt c bit u c

cha mt s lng c t nht nh. l nhng cht tch ly hoc l sn phm trunggian trong qu trnh trao i cht ca chng hoc l nhng cht c sinh vt tng hp.

thc vt, nht l nhm cy h u c nhiu cht khng dinh dng (nutritionantigonist). Nhiu loi thc vt c cha nhm cht glusit c, trong mt s loi ng vtc cha nhng amit c gy d ng rt mnh cho c th.2.2. Cht c do thc phm b bin cht trong qu trnh bo qun

S tn tr nguyn liu trong kho lu ngy, do tc ng ca oxy trong khng khoxy ha hoc do enzyme trong thc phm tc ng lm bin i cc cht dinh dng trthnh cc cht c hay cht khng dinh dng.

V d: cc cht du thc vt lu ngy trong khng kh s bin thnh ccperoxyt, aldehyt c. Cc axit amin nh histidine trong tht c ti di tc ng caenzyme decarboxylase kh nhm cacboxyl tr thnh histamin c gy d ng mnh cho

c th. Mt s vitamin bi oxy ha tr thnh cht khng vitamin.2.3. Cht c do nm mc sinh ra (mycotoxin)

Cc loi thc n sau khi thu hoch v khng c lm kh v ch bin kp thitrc khi em d tr trong kho. Nu m trn 14% rt d b ln men hoc nm mcpht trin sinh ra c t. Ty theo loi c t, ty theo hm hng cao hay thp m c thgy ra c cho ngi hay ng vt.

2.4. Cht c do vi khun gy raNg c thc n do c t vi khun thng xy ra do thiu st trong cng tc

kim tra v phn ln xy ra trn thc phm c ngun gc ng vt giu protein nh thtsa, trng...

2.5. Cc ho cht c hi ln vo thc nNguyn nhn gy ra s ng c thc phm hoc khng an ton thc phm c th

do cc yu t sau y:Cho thm vo thc n bo qun, nhm ny bao gm: Cc cht st khun, cc

cht chng nm, cc cht khng sinh v cc cht chng oxy ho...Cc cht cho thm vo thc n tng khu v, hng liu ca thc n.Cc cht ty mu hoc cho vo thay i mu thc phm, lm cho dai hoc xp

thc phm.Cc loi cht kch thch t, hoc cc cht tng ng ha, tng gi nc cho gia

sc tng trng nhanh.Cc cht gy nhim mi trng bao gm kim loi nng ca nh my thi ra hp

th vo cy thc n, thuc tr chut, tr su, tr nm v virus nhim vo thc phm.III. CC YU T NH HNG N MC C

3.1. Liu lng cht cC nhiu cht liu thp th l yu t dinh dng. V d: nh cc nguyn t vi

lng, nhng liu cao th gy ra ng c.

12


13/152

3.2. Yu t ging, loi ng vtCng mt loi c t, cng mt liu lng nhim nhng c gia sc c triu chng

trng c nhng c loi li khng. V d: vi t l 10% bt l keo du th g c hintng bu c, rng lng nhng gia sc nhai li vi mc trn 30% trong khu phn thmi c triu chng ng c. Hay cng mt t l aflatoxin trong thc n th vt c biu

hin ng c trc g.3.3. La tui ca ng vt

ng vt non ni chung h thng khng, h thng kh c v thi c t rangoi ca c th pht trin cha hon thin, do sc khng vi c t ca c th giasc non cng yu hn gia sc trng thnh. Ngc li, c th gi yu s trao i chtcng gim xung, sc khng i vi c t cng gim.3.4. Tnh bit

nh hng ca c t trn gii tnh cng ch l khi nim tng i. trng thibnh thng th khng c s khc bit c ngha gia 2 loi gii tnh trn lnh vc khng vi c t. Tuy nhin khi gia sc mang thai, sinh sn hoc nui con th rt mn

cm vi c t.V d: c t nm aflatoxin c th gy cht phi t l cao; c t zearalenone (F 2,

c trong ng) do nm Furarium tit ra c th gy ra sy thai. V vy, trong thi gianmang thai cn phi c ch n k lng hn bnh thng.3.5. Tnh trng sc khe v ch dinh dng

Sc khe c th c nh hng rt ln n kh nng khng i vi c t.V d: khi c th b bnh vim gan hoc vim thn do nguyn nhn khc khng

phi c t th kh nng loi b c t ca c th rt km. V vy cng vi mt liulng ging nhau, nhng c th khe mnh c th vt qua c.

Khu phn n v ch dinh dng ca ng vt cng nh hng rt ln n sc

khng ca c th i vi c cht. V d: khi khu phn n thiu cholin hocmethiomine s gy ra hin tng tch m gan lm cho chc nng ca gan tr nn suygim, t khng vi c t cng s km. Hoc khu phn mt cn bng gia nnglng v cht m, qu d tha cht m c ngun gc ng vt, c cha nhiu cht huc purine v pirimidine m li thiu vitamin A s c nguy c pht sinh ra bnh gout lchng bnh tch urat trong c th, trong b thn lm cho chc nng lc v loi thi chtc ca c th suy yu. T c th lm cho tnh trng ng c tr nn nng n hn.

3.6. Trng thi vt l ca cht cCng mt loi cht c, cng mt liu lng, nhng cht c trng thi ho tan

c trong nc th s gy ra triu chng ng c nhanh hn, nhng n loi thi ra ngoi

cng nhanh hn. Ngc li, trng thi nh du hoc dng bt khng tan th cht chp thu chm nn gy ra triu chng ng c mun hn, nhng loi thi cht c ra khic th cng chm hn.

IV. CC CHT C HI C SN TRONG THC N

4.1. Cc cht c hi trong thc n thc vt4.1.1 Cc hp cht glucoside trong thc nXyanglucosit (HCN)

13


14/152

Bn cht ho hc l mt hp cht hu c c cu trc gm 2 phn: mt phn tng (glucose) v mt phn khng phi l ng: axeton hoc HCN. HCN c tothnh do qu trnh thu phn linamarin v linustalin do hai enzyme tng ng:linamarinase v linustalinase. Trong , linamarin chim phn ln (95%) cn rt tlinustalin (5%). Trong sn ti, cc cht ny tn ti tt c cc b phn l v c, nhng

nhiu nht lp v dy th hai (lp v mu hng), li v hai u ca c sn. Glucositph bin trong cc loi thc vt nht l cy c gn vi hoang di. Khi chn th trn ngc, nu gia suc n phi nhng thc vt c nhiu glucosit s xut hin du hiu ng c.Ty theo gc ha hc gy c hi, ngi ta chia glucosit thnh cc nhm sau y:

Cng thc cu to nh sau:

H3C CN H3C CN

C C

H3C O Glucose H3C O Glucose

O Glucose

Linamarin LinustatinXyanglucosit tn ti nhiu trong cy sn (bng 1 v 2), ht lanh v u Java.

Bng 1. Phn b HCN trong sn c

Sn ng Ph Th Hm lng HCN (mg/100g)- V ngoi mng- V trong dy- Hai u c sn- Phn rut (n c)- Phn li

7,621,616,29,7215,8

Ngun: Phm S Tip, 1998.

Bng 2. Phn b HCN trong l sn (mg/100g ti)

Cc loi l Ging n Ging chui L gi (1/2 cao thn tr xung)L bnh t (1/2 n 3/4 cao thn)L non pha trnt non

1,44 0,064,29 0,4236,48 2,2544,23 2,10

0,46 0,031,54 0,1514,75 0,1618,05 1,81

Ngun: Phm S Tip,1998.

Bng 3. nh hng ca phng php ch bin ti hm lng HCN trong l sn(mg/100g ti)

Phng php ch bin Sn n Sn chui L tiBm nh, nu chnBm nh, chua 1 tun

21,61 2,373,26 2,373,06 0,05

8,76 0,221,72 0,121,50 0,07

14


15/152

Bm nh phi kh tn btBm nh ngm nc, phi kh tn btBm, ngm nc vi, phi kh, tn bt

2,79 0,112,05 0,171,74 0,53

0,88 0,050,46 0,330,22 0,11

Ngun:Phm S Tip, Nguyn Vn ng, 1998.

Bng 4. nh hng ca phng php lm kh n hm lng HCN trong bt l sn

(ppm)Phng php ch bin Ging Thi lan Ging gn Nam bPhi nng kh nhanhPhi trong nh kh chmSy 600CSy 800CSy 1000C

12705621106990495

954280664499217

Bng 5. nh hng ca phng php ch bin n hm lng HCN trong sn c

Cch x l T l HCN cn li so ban u (%)

Bc v ngm nc 24 giLuc khng v na giLuc 2 ln ncLuc k ko di

75564231

Sn phm sn HCN (mg/100 g)C sn tiSn lt phi khBt sn

9,722,701,08

Gia sc n nhiu: liu c ti thiu 2,3 mg/kg th trng. Gc CN- khi vo c ths lin kt lin kt cht ch vi hemoglobin, c ch qu trnh vn chuyn oxy lm cho c

th thiu oxy ngt th, cc nim mc da tm bm cht rt nhanh. Vic bt gi CN-

ca Hbl phn ng t v ca c th nhm ngn chn ion CN khng lt vo bn trong cc t bo.Nu c th nhim qu nhiu ion CN th khng c kh nng phng v, khi ion CN ltvo bn trong cc t bo v lin kt cht ch vi nhn Fe ++ v Cu++ trong h thngenzyme h hp cytochrom khng cho h thng ny thc hin chc nng vn chuyn int trong chui phn ng h hp t bo. Lc ny tnh trng ng c tr nn ti t hn, khc kh nng cu cha c.

Globin Globin

N N N N

Fe + CN- Fe

N N N N

O2 CN

Hemoglobin Methemoglobin

15


16/152

S 1. Chuyn ha cyanogenesis v cyanide trong c th ngi (Hans Rosling,1994)

O CC N

CH 3

CH 3

C CHO

CH 3

-Glucosidase

Aceton cyanohydrin

N

HC N SCN-

OCN_

CyanateM etHb--CN

Cyanide

Red block cell

H C CH COOH C N-

Nhit cao, pH cao

Linamarin

S N

C

NH2

Axit amino thiazoline carboxylic Rhodanase & -S-S

Thiocyanate

C hai trng thi ng c:Ng c cp tnh: gc CN- khi vo c th s lin h cht ch vi hemoglobin. c

ch qu trnh oxygen lm cho con vt ngt th, cc nim mc da tm bm v cht rtnhanh nu n phi mt lng ln. Tr em v ng vt non trao i cht rt mnh do cn rt nhiu oxy, v vy cng l i tng rt mn cm vi HCN.

Ng c mn tnh: trng hp n vi mt lng t, thng xuyn th trong c thng vt ch yu l gan s oxy ha kh cht HCN nh vo lu hunh trong axit amin to ra cht thiocianat t c hn HCN.

- Liu gy ng c: theo ti liu ca Humphreys (1988) th liu gy ng c ti

thiu ca HCN t do trn ng vt l 2 - 2,3 mg/kg trng lng c th. Tuy vy, nu liu ny nhng gc CN nm trong cu trc glucosit th cha sc gy c m n cnph thuc nhiu yu t khc nhau. Nu nh dng glucosit trong thc n khi vo c th mgii phng nhanh HCN v c th hp thu nhanh th c th gy ng c, nu gii phngHCN chm, hp thu chm th liu ny cng cha gy triu chng ng c. Trong thctin ngi ta cn nhn thy khi ng vt n nhiu v hp thu nhanh HCN (4 mg/kg thtrng) th cht mt cch r rng. Nguyn liu lm thc n cha khong 20mgHCN/100g nguy him cho con vt. xt nghim HCN chnh xc, chng ta nn kim tra

16


17/152

hm lng HCN trong gan v cht cha trong d c ng vt. Khi gia sc b ng cHCN th trong gan ca n cha ti thiu t 1,4 mg/g tr ln, trong d c 10mg/g tr ln(Van der Walt, 1944).

Trn ngi: ng c HCN thng hay gp do n phi sn c, ngi ta cn gi lsay sn. Khi n phi sn ng ch bin khng tt s pht sinh ra triu chng ng c do

cht linamarin, mt loi glucosit c b thu phn bi enzyme sinh ra HCN, liu lnggy ng c cho mt ngi ln l 20mg HCN. Liu gy cht ngi l 1 mg/1kg thtrng. Tuy nhin, nhm glucosit rt d b phn hy bi nhit, trong cc mi trng axitv kim long. V d, hm lng HCN trong sn gim ng k khi chua, phi kh hayngm nc vi (bng 3, 4, 5 v 6).

AlkaloideAlkaloide l nhng hp cht hu c c cha Nit v c tnh kim nh, a s c

ngun gc t tho mc, ch vi mt liu tht nh cng to ra tc dng sinh hc rt mnhtrn c th. Cht alkaloide n gin c tng hp sm nht vo nm 1886 l chtconiine, gi tn ha hc l 2-propyl-piperidine (C5H 10NC3H7). y l cht m ngy xangi xu dng n u c nh trit hc v i lc by gi - ng Socrates. Hin

nay, ngi ta tm thy c trn 3000 cht alkaloide khc nhau v c khong 30 trong sny c s dng rng ri trong y hc v c ngi ta nghin cu k. V d: chtnicotine trong cy thuc l c s dng lm thuc tr su, cafein trong ht cf,Cocaine trong cy coca lm hng phn thn kinh, morphine trong nha cy phinc s dng lm thuc gim au, reserpine trong cy da cn cng lm thucgim au, atropin c tm thy trong cy belladonna (cy c dc) lm thuc ginng t (theo ti liu Encarta, McRosoft, 1997). Theo ti liu ca Petteson (1991) thalkaloide c chia ra lm 3 nhm: nhm alkaloide thc (True-alkaloides), nhmalkaloide gi (Pseudo-alkaloides) v nhm tin alkaloide (Proto-alkaloides). Nhngalkaloide c bit r nht l trong cy khoai ty v trong c lupin. Ngy nay, ngi tacng bit c trong mt s cy nhit i cng c nhiu alkaloide. V d: cy vng nem( Erythrina sp) c cha trn 60 loi alkaloide. Alkaloide c cha nhiu trong htErythrinaamericana,E.breviflora (Sotelo, 1930).

Phn c khoai ty tri ln trn mt t c v xanh v phn c khoai ty c chacht solanin. Khi thy phn n gii phng ra ng, v vy ngi ta gi n ng nghaho hc l cc glucoside cng c. Song, khi nim alkaloide l gi trn nhm cy cmnh trong v xanh ca c khoai ty, l cht solanin.

Trn ngi: hin tng ng c solanin thng xy ra do n c khoai ty mcmm. Ty theo ging khoai ty m hm lng solanin c khc nhau. Ging khoai tyRosevall Angieri c cha n 0,49g solanin/1kg rut c v 1,22g/1kg v c. Cc gingkhc c hm lng solanin thp hn, trung bnh 0,04-0,07 g/kg rut c v 0,30-0,55 g/kgv c. Khi khoai ty mc mm th solanin c th ln n 1,34g/kg c. Liu gy chtngi ca salonin t 0,2 - 0,4g/1kg th trng ngi.

Triu chng ng c trn ngi th nh l au bng, tiu chy ri sau tobn. Th nng th gin ng t v lit nh hai chn. Khi khu thn kinh b t lit dn nngng h hp, ngng tim v t vong.

Trn ng vt: Trong thc tin chn nui trn ng c chn c mt s loi thcvt h u nh c ngi sao (Lupinus) l loi cy h u hoa trng (Lupinus albus), hochoa vng (Lupinus luteus) c mt loi cht c gy bnh cho gia sc trn ng c x ni, trc y ngi ta gi tn bnh do loi c ny gy ra l lupinozis. Sau ny ngi ta

17


18/152


19/152

sc n nhiu cy h u thuc h Mimosa, c bit l cy keo du s c khuynh gy rabu c.

OOH

N

H2C CH COOH

NH2

Mimosine

NH2

COOHCHH2C

N

OH HO

N

H2C CH COOH

NH2

OH

OH

CHH2C

N

OH

2 NH2NH22

HO

N

CH

OH

HC

OH

Thyrosine

3,4 Dihydroxyphenylalanyle (DOP

Noradrenaline Dopamine

S 2. Cu trc v chuyn ho ca thyrosine to thnh noradrenaline bnh

thng trong c th ng vt (DMello,1991)

19


20/152

20


21/152

21


22/152

S 3. Chuyn ho mimosine trong d c (DMello, 1991)

4.2.2 Nhng cht ging vi arginine (arginine analogues)Cht canavanine, indospicine, homoarginineCht canavanine v nhng dn xut khc h hng vi n c trong l so a

(Sesbania grandiflora), l cy u chm ( Indigofera spicata), l st th (Gliricidiasepium) cng c cu trc gn ging vi arginine. V vy, khi gia sc n nhiu loi nygy c ch qa trnh chuyn ho arginine. Arginine ng vai tr rt quan trng trong qatrnh chuyn ho ornithine-arginin tng hp ra ur, nu chu trnh ny b canavaninthay th vo v tr ca arginine th s gy ra ri lon chuyn ho ca arginine. V th,canavanine cng c coi l mt c t khng dinh dng ca arginine.

Axit amin thit yu gn ging vi arginine l glycine, trong trng hp ny n tr

thnh yu t i khng vi canavanine. Ba loi axit amin ny thng phn b kh rngv c hm lng tng i cao trong cc loi cy h u, trong mt s loi ht h u.Canavanine d dng hp thu trong ng tiu ho ca gia sc, gia cm (Leon, 1990) vn xut hin nhanh trong vng tun hon (DMello, 1989). Nu cho gia cm n thc nc cha nhiu canavanine (3.7g/kg trong thc n ) s lm gim kh nng sinh trng, nhhng xu n s li dng m trong khu phn. Gn y vi nhiu nghin cu cho thyc mi quan h gia canavanine v s ly thc n ca ln (Enneking, 1993).

22

k

H2C CH2 NH2

N

OH

O

Mimosinamine

O

OH

N

H2C CH COOH

NH2

Mimosine

N

OH

O

H

3-Hydro-4(1H)-piridone

(3, 4 - DHP)

OH

ONH2, 3 - DHP

Thi quaphn v nc tiu

3, 4 -DHP


23/152

4.2.3 Nhm cht neurolathyrogens

y cng l hp cht axit amin bt thng (non-protein amino acid). Cng loivi nhng axit amin ny c: -cyanoalanine, axit -N-oxalyl-,- diaminopropionic(ngy nay cn gi n l BOAA, -N-oxalylamino alanine), axit -diaminobutyric v -aminopropionitril. y l nhng sn phm chuyn ho c lin quan nhau trong trao i

cht ca mt s loi thc vt nhit i. Nhng dng c Lathyrus khc nhau, hm lngBOAA cng c khc nhau (Aletor, 1994). Khi gia sc n loi thc n c cha loi hpcht ny thng xuyn s xut hin trng thi ng c. C ch gy ng c ca axitlathyrogenic l tc dng khng dinh dng i vi cc axit amin gn ging vi n. Nm1981, Roy c cng b tnh trng bnh Neurolathyrism trn ngi. Trn ng vt, ngi tacn nhn thy c 2 cht -cyanoalanine v -(N-oxalylamino) alanine gy c hi thnkinh (neurotoxic) cho gia cm ln ng vt c v, nhng gia cm mn cm hn, c bitg con 1 ngy tui (DMello, 1991).

4.2.4 Cht axit fluoroaceticy cng l hp cht th cp, c bit n c nhiu trong cy: Acasia, Oxylobium

v Gastrolobium (u l cy h u). Chng gy tn tht ln cho gia sc mt s vngca chu c (Everist, 1974) v mt s vng Nam Chu Phi (Vickery,1973). Theo tiliu ca Hamphreys (1988) th c 2 dn sut rt c, l Fluoroacetate (compound1080) v Fluoroacetamide (compound 1081), c hai u tan trong nc khng v v ctnh rt cao vi loi gm nhm v c cho ngi ln ng vt khc. S ng c trn cuc m t bi Marais (1940) Nam Chu Phi do mt loi thc vt Dichapetaumcymosum (gifblaar).

C ch gy ng c: Fluoroacetate c ch enzyme aconitase t n khng png y cc bc phn ng tip theo trong chu trnh citrat, mt chu trnh sinh ho rtph bin trong c th sinh vt -chu trnh axit tricarboxylic. Hu qa cui cng ca n ls tch t citrate trong c th m khng phn hy thot ra c dn ti ng c

(Peters,1954).S ng c v liu gy c: Fluoroacetate c c tnh cao cho tt c mi loing vt , nhng loi ng vt c v bc cao km nhy cm hn loi gm nhm. Liuc gy cht qua ng ming (mg/kg th trng): b 0.15-0.62; cu 0.25-0.50; d 0.30-0.70; nga 0.50-1.75; heo 0.30-0.40; gia cm 10-20; ch 0.096-0.20; mo 0.30-0.50.Robison (1970) thng bo liu LD50 ca sodium monoflluoracetate trn b Hereford l0.393 v 0.221 mg/kg th trng. phng tr bnh ny tt, khng nn cho gia sc n thcvt c c t v cho gia sc ung glyceryl monoacetate 0.5ml/kg th trng. Trong 5 giu, cch 30 pht cp 1 ln 0.2 ml/kg th trng (Annisonetal, 1960).

4.3. Nhng cht terpenoide v steroide c hi4.3.1 Terpenoide

N cng l sn phm th cp c tng hp bi thc vt. Terpenoide cng cnhiu dn xut khc nhau C5 (Isoprenoide) c trong cy phi lao, terpenoide bao gm hotcht sinh hc l carotenoide. Ngoi ra, n cn c C10 ,C15, C20 v C30, ngha l mchcarbon c th di ngn khc nhau. Trong cc loi terpenoide c loi mang hot tnh sinhhc nh l 1 tin vitamin, nhng cng c nhiu hp cht l c t c tc hi khc nhaun c th.

Ngi ta nhn thy 1 loi terpen c 15 cacbon (C15) gi l sesquiterpenoide tmra trong thc vt Myoporum (Myoporaceae) c v New Zealand gy thit hi ln cho

23


24/152

cu. Ngoi ra cn tm thy trong thc vt h bm bm (Ipomoea) cng c loi terpen ny,ngay c trong khoai lang, n c tc dng gy bnh trn gan.

Trong l mt loi cy thn bi Lantana camara (Werbenaceae) c cha chtLantadenes, l mt loi triterpenoide (C30) n gy c hi cho gan. c t ny gy ravim gan v rt nhy cm vi nh sng.

Nhng sn phm c cha gc porphyrin t cc chlorophyll khng phn gii, mtphn n bi tit ra c, phn khng bi tit a vo mu i n t chc ngoi bin, chtporphyrin ngoi bin nhn nng lng nh sng mt tri chuyn thnh hp cht hohc gy h hi t chc t bo v v th n cng xp vo loi c t thuc nhm cht nhycm vi nh sng , c tn gi l "hp cht nhy cm quang hc - photosensitivecomponds".

4.3.2 Cc cht steroide c hiTrong s cc steroide c hi c ngi ta ch trng nhiu nht l oestrogen

thc vt (Fitooestrogen). Loi hp cht ny c cha trong mt s loi thc vt.Triu chng ng c: khi gia sc n phi thc n c cha cht ny c th gy ra

triu chng ng dc gi, n kch thch lm cho m h sng ln, chy nc nhn, trn

heo con thng thy cc nm v sng . Gia sc c ng tc nhy chm ln nhau nhbiu hin ca s ng dc. Hu qa ca n l lm sy thai hng lot. Tuy nhin, nu nmc va phi s c tc dng tt vi gia sc tit sa, kch thch bu v pht trin, tng titsa, vi nhng gia sc b nn, si c tc dng kch thch ng dc tr li.

Cht fitooestrogen c ngi ta ch u tin l chu c, ni y khi chnth b trn ng c, n mt loi c 3 l (Trifolium subterraneum) lm cho n cu ngdc hng lot. Ngi ta tm hiu trong loi c ny c cha nhiu cht ging vioestrogen. Sau ngi ta cn tm thy nhiu loi c h u khc cng c chafitooestrogen nh: cc c alfalfa (Medicago sativa); c di nga, mt s loi c ho thov c cy bp cng c cha cht fioestrogen vi s lng ng k. Khi phi hoc sykh th cc cht ny b phn hu, nhng nu chua th n cn lu li trong thc n khnhiu.

Ngoi thc vt ra, ngy nay ngi ta cn thy loi nm fuzarium thng phttrin trn ht bp khi thu hoch b chm tr, n cng sn xut ra mt loi c t c tn lF2-toxin (Zearalenone) cng c tc dng ging nh oestrogen thc vt, n lm sng mh v sy thai ln v n cng c hi n vic sn xut tinh trng , lm gim t l thtinh g.

Fito-oestrogen c nhiu dng hp cht khc nhau: Isoflavin cumarin, stiben hoccc dn xut khc ca steroide. Cu trc ho hc n c khc vi oestron v oestradion tnhin. Hot tnh sinh hc ca oestrogen thc vt ging nh mt hormon sinh dc n.Vic xc nh bng phng php ha hc th rt kh, phi c cht chun ging nh chtkim tra m trong thin nhin th li c rt nhiu dn xut khc nhau v phi c thit bc bit nh sc k lng cao p. Ngi ta s dng phng php sinh vt hc: dng chutci infantilis (chut bch) th v tnh ra n v chut i vi fito-oestrogen.4.4. Cc cht nhy cm quang hc (photosensitive compounds)

4.4.1 Nhng pht hin c lin quan n bnh vim rp da do cht nhy cmquang hc (Vesicula dermatitis and photosensitizasion)

C ch gy c hi ca cht nhy cm quang hc :Cc cht nhy cm quang hc l nhng cht m khi gia sc n, hp thu vo mu

v ra da ni khng c sc t bo v, di tc dng ca tia nh sng mt tri n lm phn

24


25/152

hy cht nhy cm quang hc ra cc sn phm phn ng trn da lm cho da ng ln vsau vim rp da. S vim nhim ny c bit xy ra xung quanh khe mt, c, cc khp chn v cui cc chi gy ra cm gic au n cho gia sc. i vi gia cm th m, mng, tch tai v bn chn, ni khng c lng che ph. G ty thng b nng hnv phn da tip xc vi nh sng mt tri nhiu.

Nm 1994, Peckham m t bnh vim rp da m gia cm v ng chp 2hnh bnh tch trn ngan. Theo Calnek v CTV (1991) th bnh ny xy ra trn g, gty,vt, ngng v cng theo cc tc gi ny bnh c th gy t vong n 20%. Ngoi ra ncn gim s sinh trng, sc trng. Theo Peckham th nguyn nhn c lm sngt l do gia cm n mt s loi thc n c cha cht nhy cm quang hc. Cht ny cng c xc nh l n c trong mt s loi ht thc vt c tn lAmmi visnaga vAmmimajus. Th vim rp da lm gim sc sn xut v s sinh sn i vi vt mi .

4.4.2 Nguyn tc phng tr bnh tt do cht nhy cm quang hc gy ra

Mun cha tr bnh ny phi trnh khng cho gia sc trc tip di nh sng mttri hoc che chung cho ti bt, lm nh vy cho n khi c th thi ra ht cc cht nhycm quang hc mi cho con vt tr li mi trng chn th bnh thng.

Cht nhy cm quang hc c nhiu trong mt s loi c lm thc n chn nuinh: c Fagopyrum vulgare,Fagopirum esculentum (kiu mch), mt loi c trn ccng c n i. Khi ng vt n loi c ny vi s lng kh nhiu th xut hin nhngri lon trao i cht. V vy, ngi ta gi bnh ny l bnh fagopirizmus. Nu b sa nth hm lng ca n trong sa cng tng ln. Di tc dng ca tia nng mt tri cbc sng t 540-610nm lm cho da ln nh qa t chn, nu tip tc cho gia sc nloi c ny na th lm vim rp lp t bo da v tr thnh lp t bo cht trn da. Ngita thy khi cho ln n c alfalfa thng xuyn th ln Yorkshire thiu sc t da hay sinhra chng vim da cn ln da mu th li khng sao.

4.4.3 S phn b cht nhy cm trong thc n v thuc phng tr bnh cho giasc, gia cm

Nh trn trnh by, cht nhy cm quang hc phn b rt rng ri trong tnhin. Trc tin, n c nhiu trong mt s loi thc vt c th gy ra ng c cho giasc khi gia sc n phi. Ngoi ra, ngi ta cn thy n trong hm ru v nc ra caqa trnh ch tinh bt.Nu dng cc loi ny v bo cho b, ln kt hp vi cho n calfalfa v c di nga (c 3 l Trifolium repens hoc Trifolium pratense) cng xut hintriu chng vim rp da nh m t trn.

Cht olaqiundox l mt loi ho dc c ngi ta s dng lm cht kch thchtng trng v kim sot bnh tiu chy do vi khun ng rut, trc y ngi ta a nvo mt s loi premix cng c tc dng nh l mt cht nhy cm quang hc. Khi trnn vo thc n cho gia sc n th tuyt i khng cho gia sc vn ng ngoi nh sngmt tri. Nu gia sc ra nng th s c hin tng vim rp da.

Ngy nay, trn th trng c qa nhiu nhng loi ha dc phng bnh vkch thch cho gia sc tng trng. Trong s c nhng cht nhy cm quang hc rt chi cho vt nui, nht l con vt c mu da trng, rt d b vim rp da. Nu c trongthc phm ca ngi qua sn phm chn nui th cht ny tch ly lu ngy s gy ra ungth da. Chng ta nn hn ch s dng cc loi ha cht ny cho vo thc n chn nuithng xuyn.

25


26/152

4.5. Nhm cht saponinV bn cht ho hc th cht saponin c nhiu loi hp cht ho hc khc nhau.

c tnh chung ca chng l trong nc d dng to thnh cc bt nh bt x phng.Saponin c cha nhm cht Aglycone lin kt vi mt hoc nhiu phn t ng hocvi olygosaccharide (Fenwick et al.,1991).

S phn b saponin trong thc vt: c nhiu trong tri cy b kt. Nu gia sc nnhiu c tc dng bo mn nim mc. Trn ng c c nhng loi c di c cha nhiusaponin, v d: c Konkoly c hm lng saponin rt cao. C ny c ht ln trong ccloi ht ng cc. Khi gieo ht th chng cng pht trin vi ht ng cc. N c th gyng c nu s nhim ca n trong cc loi ng cc trn 0.5%. Mt s loi c h ukhc nh c alfalfa cng c mt s lng ng ch cht saponin.

Triu chng ng c: do n d to bt nn khi gia sc nhai li n nhiu ln mensinh hi, gia sc khng hi ln c, do sinh ra chng chng hi d c. Ngoi ra,ngy nay ngi ta bit c cht saponin trong c alfalfa cng l cht khng dinh dng(antinutritive). Ti Hunggary, ngi ta th nghim ch protein l vi phng phpVEPEX t nguyn liu c alfalfa vi hy vng thay th mt phn u nnh nhp khu.

Khi th nghim trn gia sc ngi ta nhn thy trong ch phm ny c cht c ch sinhtrng i vi g, ln v b. Trong dch p c alfalfa cng c cht c ch enzymee tiuho protein (antiproteinase).4.6. Cht gossipol

Bn cht ho hc ca gossipol n l mt hp cht polyphenol. Nhng dn xutca n c coi l c hi cho gia sc. Gossipol c nhiu trong kh du bng vi, n ctc dng c ch sinh trng. gia sc nhai li trng thnh, vi sinh vt d c hot ngd dng phn hy cht gossipol nn chng s dng tt kh du bng vi. Tuy nhin khicho n nhiu, c mt phn kh du i qua d c khng b ln men v c mt phngossipol c hp thu vo mu qua mng thai gy hi cho bo thai. V l , b chakhng dng kh du ny.

G mi c sc khng vi gossipol, tuy vy sau khi cho n kh du bng vivi ngy th gossipol i vo trng bin mu trng xanh nu, phn lng trng c muhng.

Gn y, ngi ta c xut phng php kh c gossipol gm 2 bc:- S dng acetone chit rt bo- Nng cao nhit

Sau khi x l nh vy, gossipol trong kh s tr nn mt tc dng c hi. Nhcim ca phng php ny l lm cho protein b bin tnh v tr nn kh tiu ha, vgim gi tr sinh vt hc.4.7. Nhm cht tannin

4.7.1 Bn cht ho hc ca tanninTannin l mt hp cht ester gia ng glucose v mt nhm cht khc, thngl mt phc hp ca axit phenolic hoc axit oxyphenolic. Nu em thy phn ra ta thuc ng glucose v mt thnh phn khc khng phi ng, l axit gallic v m-digallic, nh th ta gi l "gallotannins". Ngoi ra, ngi ta cn bit c mt loi tanninkhc gi l "ellagitannins" nu ct lin kt ra ta thu c cht axit ellagic. Theo Kumarv DMello (1995) th tannin l nhng hp cht c cha phenolic ha tan, c phn tlng >500, c kh nng kt ta vi gelatin v cc protein trong mi trng nc. Trong

26


27/152

thc vt c 2 loi tannin: mt loi tannin c kh nng thy phn gi l hydrolysabletannin (HTs) v mt loi khng c kh nng thy ha gi l condensed tannin (CTs).

4.7.2 S phn b ca tannin v nh hng ca n trn ng vtTannin phn b rt rng trong cc loi thc vt, tuy nhin c loi thc vt cha

nhiu, c loi t. Thc vt cng gi, ha g th tannin cng nhiu. Cht gallotannin c

nhiu trong l cy non cy Shin-oak (Quereus havardi) gy tn tht ln cho ng vtchn th trong ma n pht trin gia sc phi s dng loi cy ny (Pigeon et al.,1962) Bc M. Mt dn chng khc v loi c t ny gy thit hi kinh t kh ln trongchn nui, l mt loi cy chu c: Terminalia oblongata (Evereist, 1974; Payner,1975). c t ca n cn c cyAcacia salicina.

T xa, ngi ta bit s dng tannin thuc da, bo v cht m chng li sln men phn gii ca vi khun. Mt hng khc ngi ta cng s dng tannin lm senim mc rut tr cc bnh tiu chy.

C ch tc ng ca tannin trong dinh dng ng vt: phn ng vi protein gykt ta v bin tnh protein lm cho n tr nn kh tiu ha. Trong cc loi cy caolng, nhng ging nguyn thy hm lng tannin rt cao. Nhng ging cao lng ci

tin c hm lng protein kh cao (11-13%) nhng v c cha tannin nn kh nng tiuha km, protein bao bc xung quanh ht tinh bt, di tc ng ca tannin lm cho nkt ta, tiu ha km, t t l tiu ha tinh bt cng km theo. Nu cao lng c hphi hoc p dp lm kh cho gia sc n s tiu ha tt hn rt nhiu.

Tannin cn c nh hng nh mt cht khng dinh dng. S c mt ca tannintrong mt vi cy c lm thc n gia sc quan trng khng nhng lm gim kh nng tiuha, m cn lm gim tnh ngon ming ca gia sc, lm thay i trao i cht trong d cv gy hi cho ng vt.

4.8. Nhng cht khng enzyme tiu ha protein (proteinase inhibitors)Nhng yu t c ch enzyme tiu ha protein c cc nh khoa hc nghin

cu pht hin t rt lu, tuy nhin cha lm sng t c ch c ch, m mi ch ch tmti loi thc n c cht c ch v gii php x l n nhm hn ch tc hi gy ra chong vt . Ngy nay, ngi ta nhn thy l nhng cu trc phn t protein c tc dngbt kn hoc ngn cn khng cho enzyme proteinase hot ng thy phn protein. y lnhng cht c ch enzyme tiu ha ca tuyn ty. S c mt ca chng trong thc n lmgim ng k kh nng tiu ha protein ca ng vt.

Ngun thc n tm thy c cht khng enzyme tiu ha kh nhiu. Trong sa uc cht antitrypsine, n chng li s tiu ha protein ca enzyme trypsin vchymotrypsin. Nh vy, n bo v c cc cht khng th c trong sa u ca mchuyn sang con bng cch hp th trc tip qua lp nim mc rut.

V. C T NM TRONG THC N

5.1. Khi nimc t nm l cht c sinh ra t nm mc, n khng phi l hp cht c trong

nguyn liu thc n do s tng hp ca thc vt, ng vt. N xut hin trong nguynliu sau qu trnh thu hoch, bo qun v ch bin do cc loi nm mc to ra. N gy tchi rt ln cho gia sc, gia cm v c cho sc khe con ngi. V vy, khi nghin cu cccht dinh dng v khng dinh dng khng th b qua n.

27


28/152

V chng loi c t nm, ngi ta pht hin ra hn 300 loi c t. Tuy vy,trong thc t ngi ta thng gp v nhiu nht vn l cc loi c t sau y:

Aflatoxin: c 4 loi do nmAspergilus flavus, Aspergilus parasiticus sinh ra.Vitamin B1 v B2: trong nh sng cc tm (UV) ca n hng ngoi (fluoress)

pht ra mu xanh nc bin.

G1 v G2: trong nh sng UV pht ra mu xanh l cy.Gia bn loi trn th loi aflatoxin B1 chim s lng nhiu nht v cnggy tc hi nhiu nht, ph bin trong nhiu bnh.

Fusariumtoxin: do nm Fusarium tricothecenes sn xut ra, ngi ta cn gichung cc loi c t ca chng cytotoxin v tm thy nhiu trong ng.

Ochratoxin: do vi loiAspergilus vPenicilium sn xut ra trn bnh m mc.Rubratoxin: l c t ca nmPenicilium sinh ra trn bp b nhim loi nm ny.Citrinin: do nmPeniciliumcitrinin sn xut ra trn go mc.Stachybotryotoxin: do Stachybotry alternans sn sinh ra trong cht n chung.

5.1.1 c t nm do Aspergillus flavus v Aspergillus parasiticus sinh raAflatoxin: l hp cht hu c c nhn a mch vng c 16 dn xut ho hc khc

nhau, trong c 4 loi c tnh c ln nht: B1, B2, G1 v G2. C ch gy bnh caaflatoxin l do kh nng lin kt ca cht ny vi AND trong nhn t bo, s lin kt nygy c ch enzyme polymerase ca ARN lm hn ch s tng hp ARN v c chpolymerase t-ARN. y l nguyn nhn lm gim st s tng hp protein trong t bo.Ngi ta cng chng minh rng vng -, -lactone khng bo ho c trong phn taflatoxin lm cho hp cht ny c hot tnh gy ung th, ng thi vng lactone ny gyc ch tng hp AND nhn t bo, do lm ri lon s tng trng bnh thng ca tbo. Cc loi nng sn d nhim aflatoxin bao gm: ht lc, bnh kh du lc, cc ht cc(bp), ht h u, ci da, ht hng dng (bng 6 v 7). Aflatoxin gy thng tn ganv c th gy ung th. N cng lm gim kh nng trng, tit sa, sc khng chogia sc v gia cm.

Bng 6. Hm lng aflatoxin trong mt s thc n dng cho chn nui Vit Nam

Tn thc n n Hm lng trung bnhaflatoxin (ppb)

Hm lng ti aaflatoxin (ppb)

Bp htGo v tmu nnh htCm goBnh du mBnh du daBnh du u nnh

Bnh du lcBt khoai m ltThc n hn hp

25213374

29128

20522502981712

120040105

600255055105050

500040500

Ngun: Trn Vn An, 1991.

Bng 7. Hm lng aflatoxin thay i theo ma cc tnh pha Nam

Sn phm S mu(n)

Hm lng trung bnh(ppb)

Hm lng ti a (ppb)

28


29/152

Ma maKh du lcBp vngMa khKh du lc

Bp vng

1718

18

13

1520240

525

120

5000750

1160

450Ochratoxin: N c sinh ra t nm Aspergillus ochraceus trn bnh m mc.

Cc loi thc vt d nhim l go, la mch, la m, bp, cao lng, t, ht tiu, unnh, cafe. c t ny gy hi n gan, thn ng vt, vi nng ln hn 1ppm lmgim sn lng trng g , liu trn 5ppm c th gy tn hi n gan v rut, gim sc khng v gy ung th ngi.

5.1.2 c t nm do Fusarium tricinotumNhm ny gm 150 loi khc nhau, nhng c nht l: DON v F2-toxin.DON (Deoxynivalenol): Nhim nhiu trong tm go b mc, trong ng. c t

DON gy c ch tng hp AND, gim tnh ngon ming, gy nn ma cho ng vt. Do

triu trng khng c trng nh gim kh nng tiu th thc n, gim sc tng trng,gim sc khng bnh tt.. nn vic chn on v cng kh khn.F2-Toxin: c to ra t nm mc trn bp, la m mc. Anh hng ca loi

ny th hin r trn gia sc ci sinh sn: m h sng , sa trc trng v m o, hao mnv thi ho bung trng gy sy thai.

5.2. Nhng tc hi do c t nm mc sinh rac t nm gy ra nhng tc hi rt ln v hu qu v cng nghim trng cho c

th ca ngi v ng vt. Nhng tc hi ca c t nm c th tm tt nh sau:1. Gy thng tn t bo gan. Nhng trng thi bnh tch v hin tng suy

gim min dch do aflatoxin gy ra. Tt c cc trng hp xc nh s ngc aflatoxin u c bnh tch ging nhau ch gan ca gia cm u b h

hi. Ty theo mc nhim t hay nhiu, lu hay mau m bnh tch trn ganc khc nhau. Biu hin chung l: ban u gan bin thnh mu vng ti, mtsng. Sau gan sung to ln, mt cn phng v bt u ni cc mt hoi tmu trng sau cng do nhim khun m gan tr nn b ,d v (bng 8).

Bng 8. nh hng ca aflatoxin ln ln ca gan, tuyn Fabricius, tuyn c vhiu gi HI p ng min dch bnh Newcastle ca g Leughorn

Cc ch tiu Nhm khng nhimaflatoxin

Nhm nhimaflatoxin

P

S g th nghimTrng lng c th (g)

Trng lng gan (g)Trng lng ti Fabricius (g)Trng lng tuyn c (g)Hiu gi HI (Newcastle)

20223

11,21,22,5

1/264

20112

19,00,61,11/38


30/152

Thi k nhim nng, gan vimThi k chuyn tip (ngng bnh du lc)Thi k gan phc hi bnh thng

39,13518,11948,669

16,0030,6480,38

2. Thn cng b sng to lm cho vic bi thi cht c ra khi c th cng trnn ht sc kh khn. T lm cho triu chng ng c tr nn trm trng.

3. Lm gim kh nng khng ca ng vt. c ch h thng sinh khng th .4. Bo mn nim mc ca ng tiu ha do lp t bo nim mc b cht i bong ra

v b kh li lm cn tr s vn chuyn thc n trong ng tiu ha. i khicng thy cc tn thng ming, lm cho gia sc kh ly thc n. Do ngtiu ha b tn thng nn lm gim kh nng tiu cc cht dinh dng trongthc n.

Bng 10. nh hng ca c t aflatoxin n t l p n ca g Isabrow

Giai on nhim aflatoxin S trng p T l n (%)Giai on u nhim aflatoxin (3 thng)Giai on nhim nng (3 thng)

Giai on thay th thc n khng nhim (2thng)Giai on phc hi vi thc n khng nhim (3thng)

100,00039,135

18,11948,669

63,616,0

30,680,4

5. Lm thay i hot ng sinh l bnh thng, gy ri lon sinh sn. gia scci mang thai c th gy ra cht thai, kh thai hoc gy ra sy thai. i vi giacm gy ra t l cht phi giai on u rt cao, t l n rt thp (bng 9 v10).

6. Lm gim tnh ngon ming i vi thc n do s pht trin ca nm mc lmmt mi ca thc n. T lm cho s sinh trng chm li, s li dngchuyn ha thc n tr nn km.

7. Lm h hi cc vitamin trong thc n do s ln men phn gii ca nm mc.8. c bit l aflatoxin rt c, c khuynh hng gy ung th gan (bng 11). N

gy thit hi kh ln trong chn nui. V vy cng c ngi ta quan tmhng u.

Bng 11. Kt qu thc nghim trn chut v kh nng gy ung th ca aflatoxin

L NG AFLATOXIN TRONG TH C N (MG AFLATOX IN/KG TH TR NG CHU T)

Thi gian n(ngy)

T l chut b ungth

5,03,51,0

1,00,20,10,005

370340294

223360361384

14/1511/155/9

8/152/101/100/10

9. Ngoi cc tc hi gy ra cho c th, khi nm mc pht trin trong thc n, lnmen phn gii cc ngun dng cht nh glucid, protein, axit amin, viatmin..lm cho thc n b gim gi tr nghim trng, lm mt mi t nhin, chuynsang mi hi mc, gia sc khng thch n.

30


31/152

10. Hu qu cui cng l lm gim thp s sinh trng, sc sn xut trng sa,gim cng chc ca xng.

5.3. Cc giai on v ngun gy nhim c t nm

Trong thc t sn xut c 3 ngun nhim quan trng.5.3.1 Nhim ngoi ng lc thu hoch

iu ny c nhn bit r nht l bp. Mun khc phc tnh trng ny th khi thuhoch khng nn lu ngoi ng m em v sy, phi kh lin.

5.3.2 Nhim trong kho trong khi ch bin, bo qun, d tr thc nNguyn nhn ch yu l do m trong thc n cn cao (>14%) em d tr

hoc do m khng kh trong kho cao hp thu vo nguyn liu, do chnh lch nhit ngy m lm cho nc ngng t b mt lp thc n gy ra hin tng m cc b, toiu kin tt cho nm pht trin.

5.3.3 Nhim trong chung khi cho nTrong thc t nui dng gia sc gia cm nu thc n ri nhiu xung nn

chung, hoc thc n b m ng li trong mng lu ngy l mi trng thun li chonm mc pht trin sinh ra c t. Nu cho th qa i khi tin hnh hn ch thc n,

th s n li thc n ny vi s lng nhiu c th gy ra tnh trng ng c.5.4. Mc an ton ca c t nm trong thc n

Mc an ton ca c t nm hay kh nng chu ng c t nm (aflatoxin) cagia sc. Mi loi gia sc c sc khng mt lng aflatoxin nht nh; kh nng khng ny ty thuc vo giai on tui, sc sn xut, tnh trng sc khe. Ni chung, cnhiu yu t nh hng n kh nng chu ng c c t ca c th (bng 12). Vvy, s khng c mc aflatoxin an ton qui nh no ng n c. Theo thng bo caFAO (1979) th nhng qui nh mc ti a nh hng trong thc n hn hp ty theo loigia sc v tnh hnh v sinh nguyn liu mi nc.

Bng 12. Liu gy cht LD50 ca aflatoxin trn ng vt th nghim

Cc loi ng vt Liu LD-50 mg/kg trnglng

Th 0,30Vt con 0,33Heo con 0,60Chut lang 1,40G con 8,00Chut nht 10,00

5.5. Nhng gii php phng nga mycotoxin5.5.1 Phi thc hin vic tr thc n trn c s khoa hc

C 3 ni dung quan trng v n gin cn thc hin khi tin hnh d tr nh sau:a. Kim tra nh gi tnh trng nguyn liu trc khi d tr. Gim thiu ti atnh trng h hp ca ht v mm vi sinh vt c trong nguyn liu d tr.

b. Ni d tr phi c cu trc hp l duy tr mi trng n nh v phingn chn khng cho cn trng, su mt, cc loi gm nhm xm nhp vokho.

c. Ht d tr trong kho qua mt thi gian, nu cn thit phi x l thm nhit duy tr tnh trng tt vi s cung thm nhit v ht m.

31


32/152

C s lin quan gia nm v su mt. Nu su mt pht trin va lm tn thtcht dinh dng, va lm tng m nguyn liu v va nang mm vi sinh nh bo tnm gy lan truyn nm mc rt mau l, t sn sinh ra c t gy hi cho ngi vng vt.

1. Kim tra, khng ch m v nhit thch hp. Phi sy kh nguyn liu

trc khi a vo kho d tr. m v nhit c lin quan nhau. Mun ginguyn liu tt ta cn c qui nh tnh trng ht trong iu kin d tr c th.C s cn i gia m khng kh v m nguyn liu, v ph thuc vonhit mi trng (bng 13).

Bng 13. S cn i m nguyn liu v m khng kh (70%) nhit 270C

Nguyn liu S cn i m nguyn liu mkhng kh 70%

Ng 13,5La 15,0Go 13,0

u 15,0Lc bc v 7,0

Lng nc trong nguyn liu c 2 dng: dng kt hp, lin kt cht vi cht huc, khong trong nguyn liu v dng nc t do d dng bay ra hoc hp thu vonguyn liu, ta gi l nc hot ng (free water hay active water). Chnh lng ncnay c th gy ra tnh trng m cc b cho nguyn liu, to iu kin thun li cho nmmc pht trin.

2. Kim sot v tr kh cn trng, su mt trong kho bi . Ngi ta nhn thy cmi lin h gia s ph hoi ca su mt, cn trng trong nguyn liu v spht trin nm mc. iu ny c th gii thch bi 2 l do sau y.a. Hot ng trao i cht ca cn trng s dng cht hu c trong nguyn

liu, h hp sinh ra nc lm cho mi trng tr thc n ngy cng m thm, to iukin thun li cho nm mc pht trin.

b. Cn trng su mt di chuyn trong nguyn liu mang trn mnh n nhngbo t nm pht tn nhanh trong nguyn liu. Theo ti liu ca FAO (1979) th cntrng su mt c th lm tng s pht trin ca nm mc ln t 10-30%.

Chnh v vy ta cn phi kim tra nhim cn trng c bin php kim tra nhim cn trng.

3. S dng ha cht. Ngi ta s dng nhiu loi ha cht nh Aureofugin,Thiramtan, cc axit: propionic, lactic, sorbic, benzoic v axetic trn vothc n khng ch nhim c nm. Ty tng loi nm v ngun ly nhim m

s dng ha cht cho hp l. V d, nmAspergillus flavus nhim trn ng htc th b khng ch bi ammonia 2% hay axit propionic 1%.

4. Bin php vt l. Nhiu phng php vt l loi tr nm mycotoxin trongthc n nh loi b ht b nhim s dng ht khng nhim; loi baflatoxin trong du. Ngy nay, ngi ta ch ra h thng lc hp ph tchaflatoxin ra khi du 95-100%.

5. Lm mt hiu lc aflatoxin.

32


33/152

Lm mt hiu lc aflatoxin bi nhit : nguyn l ca phng php l bini thnh phn ha hc ca aflatoxin hoc thay i nhm hot ng trong phn taflatoxin.

n , ngi ta thy khi em go nhim aflatoxin nu di p sut hi nc cn gn 70% aflatoxin b ph hy. Phng php nhit nh rang, nng nh nhit cao

c th lm gim aflatoxin.Lm mt hiu lc aflatoxin bi nh sng: Anh sng cng c dng phhy aflatoxin. Nh vy nh sng mt tri c tc dng tt ph hy aflatoxin.

Lm mt hiu lc aflatoxin bi NH3: Di p sut mc d cn mt s im linquan n kh nng gy bin tnh ca sn phm cha c lm r, song n c coi lmt phng php thc t r rng thnh cng c s dng mc cng nghip vinhng m bo cn thit.

Lm mt hiu lc aflatoxin bi cht hp ph b mt:Ngi ta chn cc chthp ph aflatoxin trong ng tiu ha, lm cho n khng hp thu c vo c th mtheo phn thi ra ngoi, t khng gy tc hi cho c th.

Mt tri ca cht hp ph b mt l nu khng chn lc k th cht hp ph c th

gy ra s hp ph vitamin v mt s hot cht sinh hc khc cun ra ngoi.

33


34/152

V d: Thn l h u: 2-25%; l bpci, su ho: 10-15%; l sn: 25-30%; lkeo du: 20-25%; c styl: 20-25% v lkhoai lang 20-30% protein th tnh theocht kh.

CHNG IIITHC N TH XANH V PH PHM NNG NGHIP

I. NHM THC N XANH

Thc n th xanh nc ta rt a dng v phong ph, bao gm thn l ca mt scy, c trng hoc mc t nhin trn cn hoc di nc v l ngun cung cp thc nquan trng cho gia sc nc ta, nht l cc nng h. Loi thc n ny cha hu ht cccht dinh dng m vt nui cn nh protein, cc vitamin, khong a lng v vi lngthit yu v cc cht c hot tnh sinh hc cao...

Thc n xanh l loi thc n m ngi v gia sc u s dng trng thi ti,chim t l cao trong khu phn ca loi nhai li. Thc n xanh c th chia thnh 2 nhmchnh gm: cy c t nhin v gieo trng. Nhm cy ha tho nh c bi chn, ctrng, thn l cy ng... Nhm cy h u nh c styl, cy in thanh, cy keo du...Cc loi thc n xanh khc nh rau lp, bo ci, bo Nht Bn, thn chui, rau mung....

1.1. c im dinh dng

Thc n xanh cha nhiu nc, nhiu cht x, t l nc trung bnh 80 - 90%, tl x th trung bnh giai on non l 2-3%, trng thnh 6 - 8% so vi thc n ti.Thc n xanh cha nhiu nc v nhiu x nn vt nui cn lng ln mi tha mn nhucu nhng do hn ch dung tch ng tiu ha nn con vt khng n c nhiu.

Thc n xanh d tiu ha, c tnh ngon ming cao, t l tiu ha i vi loi nhaili l 75 - 80%, i vi ln 60 - 70%, l loi thc n d trng v cho nng sut cao. Vd: 1 ha rau mung cho 50 - 70 tn, 1 ha bo du cho 350 tn, 1 ha c voi cho 150-300tn cht xanh...

Thc n xanh giu vitamin: nhiu nht l caroten, vitamin B c bit l vitaminB2, v vitamin E c hm lng thp. C mc tc kh c 0,15mg B 1 v 0,45mg B2/100g;c ti c 0,25mg B1 v 0,4mg B2/100g vt cht kh.

Hm lng cc cht dinh dng trongthc n xanh rt thp v v vy gi tr dinhdng thp (bng 14), tr mt s loi thn lcy b u c hm lng protein kh cao, mts loi c giu axit amin nh arginine, axitglutamic v lysine. Nu tnh theo trng thi khmt s loi thc n xanh c hm lng proteincao hn c cm go.

Bng 14. Hm lng mt s cht dinh dng trong thc n xanh so vi cm (%thc n nguyn dng)

Cm loi I C voi C ghi-n Rau mungVt cht kh 87,6 20 23,3 10,6Protein 13,0 1,9 2,5 2,1X th 7,8 7,2 7,3 1,6Lipit 12,0 0,4 0,5 0,7

Hm lng lipit c trong thc n xanh di 4% tnh theo vt cht kh, ch yu lcc axit bo cha no. Khong trong thc n xanh thay i ty theo loi thc n, tnh cht

34


35/152

t ai, ch bn phn v thi gian thu hoch. Ni chung, thn l h u c hm lngcanxi, magi v coban cao hn cc loi h ha tho (bng 15).

Bng 15. Hm lng ca mt s cht khong ca c chn (% vt cht kh)

Cht dinh dng Thp Trung bnh Cao

NatriCanxi < 1,0< 0,3 1,2 - 2,80,4 - 1,0 > 3,0> 1,2Photpho < 0,2 0,2 - 0,35 > 0,4Magi < 0,1 0,12 - 0,25 > 0,3St < 45 50 - 150 > 200Mangan < 30 40 - 200 > 250ng < 3,0 4 - 8 > 10Km < 10 15 - 50 > 75Coban < 0,08 0,08 - 0,25 > 0,30Molypden < 0,40 0,5 - 3,0 > 5,0

1.2. Cc yu t nh hng n gi tr dinh dng ca thc n xanh

Ging cy trng: s khc nhau v gi tr dinh dng gi cc ging v nhm cythc n xanh c th hin r (bng 16). Nhm cy trn cn c hm lng vt cht kh(10-30%) ln hn nhm cy thu sinh (1-10%), trong khi h ho tho (2-10% proteinth so vi vt cht kh) c hm lng protein th thp hn b u (10-30%).1.3. Nhng im cn ch khi s dng

Cn thu hoch ng thi v m bo gi tr dinh dng cao. Nu thu hochsm t x, nhiu nc, hm lng vt cht kh thp. Ngc li nu thu hoch qu munhm lng nc gim, vt cht kh tng nhng ch yu tng cht x, cn lipit v proteingim. Thi gian thch hp thu hoch cc loi rau xanh ni chung l sau khi trng 1 -1,5 thng, thn l cy ng trc khi tr c, thn l h u: thi gian ngm n trc khi ra

hoa. Rau mung, rau lp sau khi trng 20 - 25 ngy thu hoch la 1, sau 15 ngy thuhoch la tip theo. phng mt s cht c sn trong thc n: l sn, cy cao lng, cXu ng.. c c t HCN. Hm lng HCN thng cao giai on cn non v gim dn giai on trng thnh. V vy, s dng cc loi thc n ny giai on chn sp hocnu chn l tt nht. C Medicago (Medicago sativa; Luzec), cy b u, in thanh ccht saponin, nu cho con vt n nhiu s mc chng chng bng y hi, nn dng vis lng va phi v trn vi cc loi thc n khc. Mt s loi cy thuc h thp t nhci bp, ci ba l trng cha kch t thc vt fito-oestrogen, nu con vt n va phi s ctc dng tt cho sinh sn nh: kich thch tng trng, bu v pht trin, sa nhiu. Nu nnhiu d sy thai hay sa t cung sau khi . Ngoi ra, trong thc n xanh thng chaNO3 di dng KNO3 khong 1 - 1,5%. Nu hm lng NO3 qu cao s lm cho con vt

ng c v cht. Triu chng ng c l con vt th gp, run ry, si bt mp, kh th,mu c mu thm, hm lng NO2 trong nc tiu tng. Bin php gii c: dng dungdch xanh methylen 2 - 4% tim vo tnh mch con vt.

35


36/152

Bng 16. Thnh phn ho hc ca mt s cy thc n xanh ph bin mc di ncv trn cn, v b u v ho tho

VCKProtein

th M th X th DSK Khong Ca

Cy mc di nc:Bo tm 8.5 18.8 2.4 5.9 58.8 14.1 0.8 0.6

Rau mung trng 11.0 16.4 6.4 14.5 40.0 13.6 1.3 0.5

Rau mung 8.4 22.6 8.3 16.7 39.3 13.1 1.1 0.5

Cy mc trn cn:

L dm bt 18.5 18.9 2.2 13.5 53.5 11.9 1.4 0.3

L du 30.2 24.8 2.3 9.9 52.0 10.9 0.3 0.2

L mt 43.0 17.2 4.4 21.2 46.3 10.9 1.7 0.1

Thn l khoai 10.6 19.3 2.3 16.4 51.7 10.6 0.8 0.3

Cy b u:

Thn l lc 25.4 12.6 4.2 28.7 43.4 11.2 1.4 0.2

L c styl 2.1 20.4 2.0 16.4 5.3 8.0 2.0 0.2

Cy u xanh 17.1 14.6 3.4 31.5 40.6 10.5 1.8 0.3

Cy ho tho:

Thn l ng non 13.1 10.8 3.1 26.2 51.5 9.2 0.6 0.2

C Ghi n 23.3 10.6 2.2 31.3 45.6 10.3 0.6 0.1

C Ruzi 22.4 13.0 1.4 31.7 47.9 6.1 0.5 0.3

C voi 15.8 12.7 2.5 32.9 39.2 12.7 0.5 0.3Nn m bo t l thch hp thc n xanh trong khu phn:- Ln: 20 - 30% tnh theo n v khu phn- Tru b (cao sn): 70 - 80% tnh theo n v khu phn- Tru bo (thp sn):100% tnh theo n v khu phn- Gia cm ln: 5 - 10% tnh theo n v khu phn (dng ti)- G tht: 2% tnh theo n v khu phn (dng bt)- Gia cm khc: 4 - 6% tnh theo n v khu phn (dng bt)

II. NHM RAU BO

L nhm thc n ph bin vng nhit i. Nc ta c nhiu sng ngi, ao h,thun li cho s pht trin cc loi rau, bo, rong to.. Ngun thc n c s dng rngri trong chn nui nc ta. Hm lng protein trong nhm rau bo nhn chung l thp,nhng tng i cn i cc thnh phn axit amin c bit cc axit amin thit yu. ngthi nhm thc n ny kh nhiu vitamin cn thit nh: caroten, vitamin B, C.., giu cckhong a lng nh kali, canxi, mt s khong vi lng nh mangan, st... Mt s raubo, rong to c kh nng tch t nhiu khong cht t mi trng, trong s c mt skim loi nng c hi. Do vy, cn lu khi s dng rau bo sinh trng trn cc ngunnc thi cng nghip, nc thi sinh hot c cha nhiu nguyn t c hi. Nhc imchung ca rau bo l cha nhiu nc (90-94%) nn kh ch bin v bo qun, gi tri

36


37/152

nng lng thp khng th s dng vi t l cao trong khu phn vt nui c nng sutcao.2.1. Rau mung (Ipomea aquatica)

c trng v s dng rng ri nhiu vng v gi tr dinh dng v nng sutcao. C th trng trn nhiu loi t khc nhau: t t kh, m n snh ly hay ngp

nc.. Thn l rau mung tng i giu protein, t x hn co ha tho (bng 17). cbit trong rau mung cha nhiu ng nn gia sc, c bit ln rt thch n. Trung bnh1 kg cht kh cha 180-280 g protein th, 150-200 g ng, 140-150 g x v cung cpn 2500-2600 kcal nng lng trao i i vi ln. Nu cho ln n nhiu rau mung sc hin tng i phn lng.

Bng 17. Thnh phn dinh dng ca mt s loi rau mung trn th gii (%)

Chtkh

Protein X th Khong M DSK Ca P

Cy ti, Niger* 18.8 20.9 18.2 2.1 40.0 0.71 0.32L ti, Chu Phi** 15.0 24.0 12.7 13.3 2.7 47.3 1.20 0.28

L ti, Malaysia*** 7.5 28.0 12.7 18.7 2.7 38.6 1.24 0.41Ngun:* Bartha, 1970; **: FAO,1968; *** Lim, 1967); DSK: dn sut khng m

2.2. Thn l khoai lang (Ipomea batatas)

Khoai lang ngoi mc ch trng ly c l chnh cn c th trng cung cpthc n th xanh cho vt nui. Khoai lang nu c chm sc tt c kh nng ti sinhnhanh. Thu ct c nhiu ln trong nm v cho nng sut cao. Thn l khoai lang chahm lng cacbon hydrat thp nhng hm lng protein v x cao, v cha phn ln ccaxit amin (bng 18 v 19). Protein trung bnh 18% (tnh theo vt cht kh), hm lng xth t 16-17% thp hn nhiu so vi c ha tho. Trong c khoai, cacbon hydrat chim80-90% vt cht kh nhng tinh bt ca c cn ti kh b amylaza thy phn. Hmlng cc cht khng tryxin trong c ti lm gim t l tiu ha protein trong khu phnc c khoai. Thn l khoai khng cha nhiu cc cht ny. Gi tr dinh dng ch yuca thn l khoai lang l protein v vitamin. y l ngun thc n rt tt vi gia sc nhaili v ngay c d dy n.

Bng 18. Thnh phn ha hc ca thn l khoai lang

THNH PH N % theo vt cht kh

Vt cht kh (VCK)Protein thKhong tng sADF (x axit)

NDF (x trung tnh)LigninNng lng th, MJ/kg VCK

1518,512,523,5

26,25,714,4

Ngun: Dominguez,1990.

37


38/152


39/152

L sn cng l ngun cung cp khong a lung nh Ca, Mg v khong vi lng nh Mnv Zn (bng 20). ng thi cng l ngun cung cp vitamin A, riboflavin v axitascorbic.

Tuy rt giu protein nhng li thiu ht axit amin thit yu l methionine (bng21) v nhc im ln nht ca l sn l cha nhiu glucosit linamarin. Linamarin

di tc dng ca enzyme linamarase to thnh axit cyanhydric (HCN) l cht c ivi gia sc. Tuy nhin, thng qua cc phng php ch bin nh nu chn, phi kh hay chua u lm gim ng k nng axit ny.

Bng 21. Thnh phn axit amin ca c v l sn (% theo protein)

Arg Cys Gly His Ils Leu Lys Met Phe Thr Try Tyr ValL - - - - 5,2 10,5 7,1 1,0 3,6 5,1 1,0 3,3 6,8C 7,7 - - 1,5 5,3 5,6 6,2 0,6 3,5 3,8 0,5 - 4,5

Ngun: Bo Gohl, 1998.2.4. C ha tho

iu kin kh hu nc ta thun li cho s pht trin cy c ha tho nhit i.

Nu m bo y phn bn, ti nc nht l trong ma kh, c ha tho pht trintt quanh nm v t nng sut rt cao. Nhn chung, gi tr dinh dng ca c ha thothp hn c h u. Hm lng protein chim khong 9-10%, x th 30-32% (theo vtcht kh). Tuy nhin, nu bn phn y , ng k thut v thu hoch giai on cn non(khong cch gia 2 la ct 25-30 ngy) th protein th c th t 14-15% x th gimcn 27-28% v c th dng lm thc n cho ln. Hin nay, mt s ging c ha thonng sut cao ang c s dng pht trin chn nui b thm canh, c bit l b sanh c voi (Pennisetum purpureum), c s (Panicum maximum)...

III. NHM THC N TH

Tt c cc loi c xanh t nhin hoc trng thu ct v phi kh, v cc loi ph

ph phm ca cy trng em phi kh c hm lng x trn 18% u gi l thc n thkh. Bao gm: c kh h u hoc ha tho, rm r, dy lang, dy lc v thn cy ng...phi kh. Ngoi ra cn gm v cc loi ht thc, lc, u, li v bao ng.3.1. C kh

Phng php c truyn ca vic d tr thc thc n xanh l ch bin c kh. Chtlng c kh ph thuc vo thi im ta chn ch bin v thi tit thch hp khi thuhoch. Bi v lm c kh ch yu l phi di nh nng mt tri. Mc ch chnh l lmgim m trong c xanh n mc thp km hm s hot ng ca cc enzymec sn trong cy c hay ca vi sinh vt. C khi thu hoch cha 650-850g nc trong 1 kgti. Khi mun d tr c xanh phi c lm gim t l nc xung cn 150-200 g/1 kg.

Trong iu kin thi tit thun li, c sau khi thu hoch v s c nhanh chng

lm kh nn mt mt dinh dng thp. Cht dinh dng b mt ch yu l do s bin ica cacbohydrat v cc hp cht cha nit. Khi phi kh, fructan b thy phn thnhng fructose, ng thi ng hectose b mt mt. Mt s cc ng n nh glucosecng b oxy ha to thnh CO2, H2O v ta nhit. Chnh v s mt mt cc hp chtcacbohydrat d tan nn lm tng tng i hm lng x. S mt mt protein l doenzyme protease ca thc vt phn hy protein thnh cc peptit v cc axit amin. Khiphi kh, caroten v cc hp cht tng t mt i ng k. Hm lng caroten gim ihng chc ln sau khi phi kh (ch cn 2-20 mg/kg cht kh). Nu gp thi tit khng

39


40/152

thun li, caroten b mt hu ht ng thi km theo c s mt khong, ng ha tan vcc hp cht c nit. m trong c kh cao l iu kin thun li cho cc hot ngca vi sinh vt lm tng cng s phn hy cc cht dinh dng c sn trong c kh vng thi cng to c hi cho nm mc pht trin. V vy, c sau khi thu hoch nn lmkh cng nhanh cng tt, m cng thp th cht lng dinh dng ca c cng c

bo tn.Gi tr dinh dng ca c kh trong iu kin phi tt trung bnh cha 96gprotein, 563g cht hu c tiu ha, nng lng trao i 8,5MJ, hm lng x cao: 335gcho 1 kg cht kh. Trong thc t, c kh l ngun thc n quan trng cc nc n icng nh cc nc nhit i. C kh c s dng phi hp vi thc n chua, thc ntinh, thc n c qu, r mt v cc sn phm ph ca cng nghip ch bin rau qu (bda, v chui..) em li hiu qu tt.3.2. Rm r

Rm l sn phm ph ca cy ng cc hay cy h u. Ng, la m v la nc lba cy lng thc chnh ca th gii. Rm cha nhiu x, chim 350-400 g/kg cht khch yu l lignin, c gi tr dinh dng thp. Hm lng protein trong rm la t 25-40

g/1kg cht kh.Rm la c hm lng lignin tng i cao, chim 60-70g/kg cht kh, hm

lng khong rt cao 170g/kg cht kh, trong ch yu l silic, v vy h s tiu haca rm la rt thp. T l tiu ha ca rm s c tng ln nu thng qua x l rm rbng phng php kim ha, axit ha hay amoniac ha....

Thnh phn ha hc c bn ca rm r ph thuc nhiu n c tnh sinh l, thiim thu hoch, thnh thc ca cy trng v ch dinh dng ca t ... Nhng nhnchung cc thnh phn chnh bao gm:

- T l cao ca cacbonhydrat thnh vch t bo nh cellulose, hemicellulose vlignin chim 60-80% tng vt cht hu c ca cy trng.

Cellulose l thnh phn cu trc chnh ca thnh t bo thc vt, chim vokhong t 32-47% trong tng vt cht kh ca thc vt. Bao gm chui homosaccharitc to thnh bi cc lin kt -1-4-glucose gi l xellobiose, thng qua cc cu nimicro-fibres. Cellulose c th tiu ha c bi gia sc nhai li.

Hemicellulose, khc vi cellulose, hemicellulose c to thnh t hetero-polymers khng c hnh dng nht nh bao gm tt c cc ng pentose nh xylose,arabinose. Chui i phn t ca hemicellulose th ngn hn cellulose. Chng to thnhmt ci khung polysaccharit lin kt vi phenol bao quanh si cellulose. Hemicellulosech tiu ha c mt phn.

Lignin l mt hetero-polyme phenol n gn vi hemicellulose. Mi lin kt gialignin v hemicellulose cho n nay vn cha c hiu mt cch chnh xc. T chc cacc tiu phn x ca xellulose to thnh hng ro chn c hc chc chn. V vy,lignin khng c tiu ha v cn lm cn tr s tiu ha ca cc gluxit khc. T llignin trong cy trng c tng ln cng vi tui ca cy trng v t l nghch vi t ltiu ha ca gia sc.

40


41/152

S 4. S v s tiu ha ca cc thnh phn mng t bo (Van Soest v Wine,1967)

T l tiu ha (%)0 50 100

Lignin

Cellulose

Xylanes

Arabanes

Pectins

- Ngho nit: Thc n rm r c t l protein rt thp, chim vo khong 2-5%.T l cht dinh dng ny gim mnh theo tui. Mt khc enzymee ca vi sinh vt d cli kh tip cn vi azot ca thc n th v s cn tr ca mng t bo lignin ha.

- Ngho khong v vitamin: trong thc t loi thc n ny thiu hu ht ccnguyn t khong a lng nh Ca, P, Na v cc nguyn t khong vi lng. ng thichng cng thiu ht cc vitamin nh vitamin A, v D3.

- Kh thoi bin trong d c: Mng t bo lignin ha mt mt cn tr vi sinh vtchui vo bn trong t bo, t cn tr enzyme phn gii cht x, mt mt to s bncht cho t bo, cn tr s chia ct trong qu trnh nhai li (bng 22). Thc n phi lu lilu trong d c t lm gim lng n vo.

Bng 22. T l tiu ha v lng rm n vo ca bLoi rm T l tiu ha cht hu c,% Lng n vo, g cht kh/kgW0,75

Rm la 35-55 26-65Rm mch 45-48 35-51

Rm m 35-46 25-35

3.3. MaMa l loi cy trng t c nng sut sinh khi ti a trn mt n v din tch.

Tuy vy s dng n lm thc n gia sc mt cch ti u, ma phi c p tch thnhcc thnh phn ha tan v thnh vch t bo khng ha tan.

Ngn ma

Ngn ma l thc n truyn thng cho gia sc d dy kp ch yu cho tru b cyko, trong ma thu hoch ma. Vic s dng ngn ma cho gia sc lm vic cn chac nghin cu nhiu. B vn duy tr c th trng v vn lm vic hng hi trong khin mt khu phn ton ngn ma. iu chng t rng qu trnh ln men ca ngn matrong d c cung cp dinh dng cho duy tr v lao tc mc thp. Tuy nhin vikhu phn n iu ch c ngn ma ko di v khng c b sung cc loi thc n khcnh r mt, cm.. th sc lm vic s b gim st tnh trng ny cng ko di s lm chocon vt gim trng lng c th. Chnh v vy ngn ma khng c s dng rng ri.

41


42/152

Tuy vy khi ngi ta s dng ngn ma nui gia sc dng ur v b sung cm snng cao t l tiu ha x v nng cao gi tr dinh dng lm thc n ca loi thc nny. Ngn ma gm ba phn: l, cung v bc (b l) v phn ngn non. Thnh phn hahc (bng 23) ca ngn ma rt khc nhau, n ph thuc vo tui, iu kin trng v cchchm sc qun l...nhng gi tr trung bnh vo khong 5 tn vt cht kh/ha, nu tnh

theo l thuyt th lng ny cung cp cho mt con b c khi lng 500 kg.Ngn ma c th c chua ti thi im thu hoch ma trc khi dng. Bngcch bm nh ngn ma 3-4 cm ri ym kh vi r mt, hay cm v 1% amn sulphat.Tuy nhin, qu trnh vn t kt qu tt m khng cn b sung thm cht ph gia vo.C th bng cc khi nh khong 5 tn ngn, nui 2 con b trong mt thng. Lma cng c th c km ngn nhng kh nng tiu ha rt thp v kh nng la chnloi thc n ny cng rt khc nhau, a s b thch la chn phn b l hay phn mngnuc cn rt t n phn l xanh. Nu cho n t do b c th n ti 90 kg/con/ngy phnngn non.

Bng 23. Thnh phn ha hc ca cc thnh phn ngn ma (%)

Ch tiu Li thn V thn NgnVt cht khProtein thMng tng sXKhong tng sLu hunh

221,40,246451,90,2

393,21,024703,10,3

272,70,827575,30,4

B ma

B ma l sn

phm ph cn li caqu trnh ch bin ncma. Cht lng ca phn b cn li phthuc vo cng ng chbin th cng hay hini nhung nhn chungphn b cn li sau khithu nc ma c 1,5-4%l ng sucrose. Phn b ma s dng chn

nui tru b t c hiuqu bi l do kh nngtiu ha thp. Hmlng lignin cao, chimvo khong >20% v rtngho protein (bng 24).

42

Ma cy (144kg)

Thu hochThn (100kg) Ngn (28kg) + L bi (16kg)

p

Nc ma th B ma ti (29kg)

Gia nhit

Nc c c Lc Vng bt

Ly tm

ng tinh (11kg) R mt A (3kg)

S 5. S ch bin ng theo phng php cngnghip (Preston, 1983)


43/152

Bng 24. Thnh phn ha hc ca b ma

Thnh phn ha hc % theo vt cht khVt cht khProtein thX th

Khong tng sCht chitDn sut khng m

99,21,050,1

2,50,346,1

R mtR mt l ph phm ca sn xut ng kt tinh (s 4). Ty theo cc giai on

ca qu trnh chit tinh ng m c nhiu loi r mt. R mt A l l sn phm phu tin khi ly tm trch ly ng cho ra ng th, v chim vo khong gn 77% so vitng s. ng th l phn nc ma c gn lc v c c v kt tinh. R mt "A" lphn ph phm ca qu trnh to ng "A", ng u tin ca s ch bin cha 80-85% vt cht kh. R mt "B" l r mt th hai ca qu trnh gn lc cho ra 12% ng

th (ng B). R mt cui cng c bit n l r mt "C", l phn thu c t qutrnh kt tinh phn cht lng c snh v r mt "B", m sau khi nu v ly tm cho rang C v r mt C. Ngay c khi r mt C c lc k v l sn phm ph cui cngca nh my ng th r mt ny vn cha mt lng ng sucrose (vo khong 32-42%) v n cng khng c lc li ln na tn thu ng cn li. R mt C lun cmt trn th trng.

R mt l ngun m c cacbohydrat c kh nng ln men, l cht cao nnglng, hm lng protein thp (2-4%), ch yu nit di dng nit phi protein. R mtc s dng vo cc mc ch cho chn nui sau y:

- L c s v bo b nui thm canh- L cht mang ur, khong v cc cht dinh dng khc ci thin hiu qu s

dng khu phn ngho nit (ph thi hoa mau, ma, ph phm nng nghip)- Cht ph gi

Documents

Giaotrinhthucangiasuc