vens cappell 1984 aquacultural engineering

7/28/2019 Vens Cappell 1984 Aquacultural Engineering

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Aquacul rura l Engineer ing 3 ( 1 9 8 4 ) 7 1 - 8 9

T h e E f fe c t s o f E x t r u s i o n a n d P e l le t in g o f F e e d f o r T r o u to n t h e D i g e s t ib i l i ty o f P r o t e i n , A m i n o A c i d s a n d E n e r g ya n d o n F e e d C o n v e r s i o nBernhard Vens-Cappel l*

Te ichw irtsch aft l ic her Beisp ie lsbetr ieb, 848 2 W6Uershof. Bavaria,Fede ra l R e p u b li c o f G e r m a n y

A B S T R A C TO n e f e e d i n g a n d t w o d i g e st io n e x p e r i m e n t s w e r e p e r f o r m e d i n o r d e r t os t u d y t h e e f f e c t o f e e d p ro c e s si n g b y e x t ru s i o n a n d p e l le t in g o n f e e d c o n-vers ion and on the d iges t i b i l it y o f energy , pro t e in and am bto acMs. F eedc o n v e r s io n w a s 1 . 2 4 w h e n t r o u t w a s r e a r ed o n a n e x t r u d e d d i e t a s c o m -p a r e d w i t h 1 .6 1 w h e n r e a r e d o n t h e s a m e b u t p e l l e t e d d i et . T h e sp e c if icg r o w t h r a te s o f 1 . 5 6 a n d 1 - 5 5% , r es p e c t& e l y , a t t a in e d w i t h b o t h d i e ts ,w e r e a l m o s t M e n t i c a l d u e t o a d e p r e s s i o n o f v o l u n t a r y i n t a k e o f t h e e x -t r u d e d d i e t. T h e e f f e c t o f d i f fe r e n t d a i l y f e e d i n ta k e s in p e r c e n t a g e o fb o d y w e i g h t ( N I , % ) o n t h e d i g e s t ib i l it y o f e n e r g y ( D , % c o u M b e d e s c r ib e dus ing the f o l l o win g l i near regress ion equat ions : D(% ) = 78 .3 - 5 . 9 NI (% )f o r t h e p e ll e t e d d i e t a n d D (% ) = 8 7 . 5 - - 3 . 9 N I ( % ) f o r t h e e x t r u d e d d ie t.T h o u g h c o n v e r s io n o f t h e e x t r u d e d a n d p e l l e t e d d i e t s d i f fe r e d sig nifi-can t l y t he d iges t ib l e ene rgy n eed ed to pro duc e I kg o f ga in was near l y tt les am e , 1 7 3 7 0 k J a n d 1 7 5 8 0 k J r e sp e c ti v el y , in d ic a ti ng t h a t d if fe r e n ce s inconvers ion were due t o t h e d iges ti b l e energy con ten t . The d iges ti on co-e f f ic i e n t s o f t h e p r o t e i n a n d a m i n o a c M s w e r e n o t i n f l u e n c e d s i g n i fi c a n tl y( p < 0 .05 ) by a change in t he f ee d process , b u t d i f f e ren t d iges t i on coe f fi -c i e t 't s f o r i nd i v idua l am ino ac ids w ere observed . The use o f d iges ti b l ec a r b o h y d r a t e f o r t r o u t n u t r # i o n is li m i t e d b y r ite i n c id e n c e o f l iv e rdegenera t ion .

[ N T R O D U C T I O NA s t h e t r o u t is a c a r n i v o r o u s a n i m a l i t h a s b u t l i t t le i n t e s t in a l a m y l a s ea c t iv i t y ( K i t a m i k a d o a n d T a c h i n o , 1 9 6 0 ) . T h e r e f o r e , n a t iv e s t a rc h is* P resen t addres s: Dorp s fe lde 4 , D2 000 Ham burg 54 , Federa l Repu bl ic o f Germ any .

71Aquacul tura l Engineer ing 0 1 4 4 - 8 6 0 9 / 8 4 / $ 0 3 . 0 0 - E l s e v i e r A p plie d S cie nc ePubl i she rs L td , En gland , 1984 . P r in ted in Grea t B r i ta in


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72 B . V e n s - C a p p e l lpoorly utilized by it. The digestibility of native corn, wheat or potatostarch is only 20-30% (Inaba e t a l . , 1963; Singh and Nose, 1967;Smith, 1971). These authors demonst rated, however, that the digesti-bility of starch could be improved by cooking. Bergot and Br~que(1983) demonstrated recently that the digestibility of starch dependson feed processing as well as on feed intake. In their study the digesti-bility of native corn starch ranged from 38% at high level intake to 55%at low level intake and could be improved by gelatinization to 87% and90% respectively. Accordingly improved feed utilization of an experi-mental diet was observed after replacing native with cooked corn starch(Tiews e t a l . , 1972).

Up to now the use of gelatinized starch in commercial trout nutri-tion has been restricted by its relatively high cost. For instance,digestible energy f rom pota to starch is two to three times as expensive asthat derived from marine fish oil. Additional criteria have to be takeninto consideration when justifying the use of gelatinized starch in com-mercial feeds for trout. The development of floating water-stable troutfeeds has opened additional perspectives for the use of starch containingfeedstuffs in trout nutrition. Floating feed pellets are processed byextrusion. The physical and some physiological properties of such anextruded trout feed have been described by Hilton e t a l . ( 1981 ).

From a practical point of view the expected advantages of extruded,water-stable, floating, trout feeds are fewer losses of feed and lessleaching of nutrients during feeding, and thus less pollution of waterespecially under conditions of intensive fish culture. From a strictlyphysiological point of view the advantage of extrusion processing ascompared with the conventional pelleting process is: the higher pressureand temperature during extrusion will result in a better getatinization ofthe starch which will thus increase the digestibility of the starch bytrout. Some negative effects of extrusion also have to be taken intoconsideration however:

1. The stability of vitamins, especially' that of ascorbic acid, is poorerduring extrusion as compared with steam pelleting (Slinger e t a l . ,1979).

2. Due to the higher tempera ture , humid ity and the presence ofcarbohydra tes, Maillard-type reactions could reduce the availabilityof amino acids and protein utilization as Hilton e t a l . (198t)assumed. This reaction starts with a condensation of the aldehyde


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C o m p a r i s o n o f e f f e c t s o f e x t r u s i o n a n d p e l le r in g o n t r o u t f e e d 7 3g r o u p o f an a l d o s e w i t h t h e a m i n o g r o u p o f an a m i n o a c id i n t o aS c h i f f ' s b a se , w h i c h is t h e n t r a n s f o r m e d i n t o a n N - s u b s t i t u t e d1 - a m i n o - l - d e o x y - ] - k e t o s e . A m o n g t h e e s se n t ia l a m i n o a c id s l y si n eis t h e o n e m o s t r e a c t i v e t o t h is r e a c t i o n ( H e H ia a an n , 1 9 6 6 ) .

T h e p r e s e n t s t u d y w a s c a rr ie d o u t i n o r d e r t o c o m p a r e t h e n u t r it i o n a le f f e c t s o f t w o m e t h o d s o f f i s h f e e d p r o c e s s i n g , e x t r u s i o n a n d p e l l e t i n g( w i t h o u t s t e a m ) o n t h e d ig e s t ib i l it y o f p r o t e i n , a m i n o a c i d s a n d e n er g y ,a n d o n f e e d c o n v e r s i o n . I n a d d i t i o n , t h e l i m i t a t i o n s o f th e u s e o f c a r b o -h y d r a t e in t r o u t n u t r i t i o n , d u e t o p h y s i o l o g i c a l , e c o n o m i c a l a n d t e c h -n i c a l e x i g e n c e s , s h a l l b e d i s c u s s e d .

M E T H O D S A N D M A T E R I A L SF e e d p r e p a r a t i o nT h e f o r m u l a t i o n o f t h e e x p e r i m e n t a l d i e t is g i ve n i n T a b l e 1. 5 0 0 k g o ft h is f o r m u l a t i o n w e r e m i x e d . A n a l i q u o t o f 1 0 0 k g w a s p e l l e t e d i n top e l le t s 3 m m in d i a m e t e r u s i n g a H e e s e n p r es s ( m o d e l V 3 7 5 , p r o d u c t i o nc a p a c i t y 5 t o n s h -~ ). D u r i n g t h e p e l l e t i n g p r o c e s s , w h i c h o n l y t o o ka b o u t 5 s , t h e t e m p e r a t u r e d i d n o t r is e a b o v e 6 0 C . T h e r e m a i n i n g4 0 0 k g o f t h e m i x t u r e w e r e p r o c e ss e d b y e x t r u s i o n u s in g an A n d e r s o ne x t r u d e r ( c o n d i t i o n c h a m b e r 8 in d i a m e t e r , p r o d u c t i o n c a p a c i t y 1-5t o n s h -a ). B r i ef ly t h e e x t r u s i o n p r o c e d u r e c o n s i s t e d o f t h e f o l l o w i n gs t e p s: t h e fe e d m i x t u r e w a s m o v e d w i t h i n a b o u t 5 0 s t h r o u g h a c y l in -d r ic a l c o n d i t i o n i n g c h a m b e r . P r e s s u r i z e d s t e a m a t 1 3 0 C u n d e r a p r e s -s u re o f 2 - 3 k p c m -2 w a s a d d e d a n d t h e f e e d m a t e r i a l a b s o r b e d a p p r o x i -m a t e l y 2 0 % m o i s t u r e . T h e h e a t e d m i x t u r e w a s f u r t h e r c o m p r e s s e dm e c h a n i c a l l y t o a p r e s su r e o f 1 2 0 - 1 3 0 k p c m -2. I t w a s t h e n e j e c t e dt h r o u g h h o l e s 4 m m in d i a m e t e r a n d c u t i n t o p e l l et s a p p r o x i m a t e l yI 0 m m l o n g b y a r o t a ti n g k n i fe . T h e s u d d e n d r o p i n p r e s s u r e c a u s e de x p a n s i o n o f t h e p e l le t s a n d i n c lu s i o n o f ai r b u b b l e s r e s u l te d i n t h ef l o a t a b i l i t y o f t h e p e l l e ts . F i n a l l y t h e p e l l e t s w e r e d r i e d a n d c o o l e d b yv e n t i l a ti o n w i t h in 4 0 m i n . T h e w a t e r c o n t e n t o f t h e d r i ed p e l le t s w a sa b o u t 7 %. A s t h e q u a n t i t y o f th e e x p e r i m e n t a l m i x t u r e t o b e e x t r u d e dw a s n o t s u f f i c i e n t t o a t t a in a s t e a d y s t a t e i n t h e e x t r u d i n g p r o c e s s , t h ep r o c e s s w a s i n i t i a t e d u s i n g c o r n m e a l u n t i l a c o n s t a n t c o n d i t i o n i n gt e m p e r a t u r e a n d p r e ss u r e w e re a t ta i n e d . T h e n t h e e x p e r i m e n t a l m i x t u r e


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7 4 B. Vens-CappellT A B L E 1

F o rm u l a t i o n o f t h e P e l le t ed a n d E x t ru d e dE x p e r i m e n t a l D i et

Ingredients %Herr ing mea l 64 a 41 .6Corn mea l ~ 47 .7S p ra y d r ie d b l o o d m e a lc 4.5Anim al carcass meal a 5-0V i t a m i n p r e m i x e 0.2Trace mine ra l s p remix / . 0 .2C h r o m i u m o x i d e 0 .8a 6 4 % C ru d e p ro t e i n , 12 % e t h e r e x tr a c t ,12% ash.b 9 % C ru d e p ro t e i n , 2 . 8 % e t h e r e x t r a c t ,1 .5% f ib re , 73-6% n i t rogen f ree ex t rac t .c 85% C rude pro te in , 90% wate r so lub le .a 5 0 % C ru d e p ro t e i n , 1 2% e t h e r e x t r a c t .(P rox imate ana lys i s o f ingred ien ts dec la redb y t h e p ro d u c e r s . )e R o v i m i x 3 2 4 H o f fm a n -L a R o c h e s u p p l e-me nted wi th 5 mg fo l ic ac id kg t feed , 300mg m - inos i to l kg 1 t eed and 5 00 m g ascorb icacid kg ~ feed. 2 g P re m ix ( = 1 kg f e e d ) c o n t a i n e d : 1 - 6gMgO, 190 mg MnCO3, I00 mg FeSO4, 90 nagZnCO3, 5 m g K O, 5 nag COC12, 10 m g CuS O4.

w a s a d d e d . A b o u t 3 0 0 k g o f t h e e x t r u d e d p o r t i o n w a s r e j e c te d a t f i r s ti n o r d e r to a v o i d a d u l t e r a t i o n b y c o r n m e a l .

F o r c o m p a r i s o n , t w o c o m m e r c i a l l y a v a il ab l e f ee d s w e r e u s ed , w h i c hh a d p r e v i o u s l y b e e n s h o w n as su p e r i o r t o th e o t h e r s ( V e n s- C a p p e ll ,1 9 8 0 ) . T h e i r p r o x i m a t e a n a l y s is is g i v en in T a b l e 2 .R e a r i n g a n d e x p e r i m e n t a l c o n d i t i o n s

T h r e e s et s o f e x p e r i m e n t s h a v e b e e n p e r f o r m e d in o r d e r t o s t u d y t h ep h y s i o l o g i c a l p r o p e r t i e s o f th e e x p e r i m e n t a l d ie t s .


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TABLE2

PomaeAmlys~nFC

oohxu

aPeeE

meaDeaoTwoCmmecaF

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.

C~

Epmenade

Commecaed

Exrud

Peed

K477

K5

~

Cupoen(%)

33

30

48

55

Lpd(%)

49

48

88

78

Ah(%)

10

99

81

10

Goeg(kk-~

15

11

12

~

"~

9

-

Sawgb(g

J0I-+06

38-+05

35+07

38+06

~

_

_

"

)3

Fnwgb(g

76-+02

79+19

88+37

88+_8

~

Gn(g

47-+7

41+15

53+30

5018

F~(g

51+08"~

66+23

67+20

61+07

~

L

(%)

15

15

0

0

N

Fc

o"a(egn

12

0

1600

11-00

)

1I2LOO4)~

S

iegowtraea(%)

15-+0

15-+0

18-+00(

19-+00(

o

Dyfena(%ob

wg)

19

24

21

21

aVdemaefonapeoe

me(BzaldVe

C

1

I~Meoforecesa

ddao

cMeoforece-+sa

deo

aMewhnanwihsmesu

psnsgcydee{ 2 t /5with Swithin2 ~--- r e s i d u e v a r i a n c e , r = n u m b e r o f r e p l i c a t e s , q = s t a n d -a r d i z e d c r it i ca l w i d t h o f v a r ia t i o n d e p e n d i n g o n p = p r o t e c t i o n l ev e l,s = n u m b e r o f t r e a t m e n t s a n d f = d e g re e s o f f r e e d o m t P e ar so n a n dH a r t l e y , 1 9 6 6 ) .

B e c a u s e o f t h e i n h o m o g e n e i t y o f v a r ia n c e s, p a r a m e t r i c t e st s w e r e n o ta p p l i c a b l e f o r d e t e c t i n g s i g n i f ic a n t d i f f e r e n c e s i n re l a ti v e l iv e r a n dv i sc e ra w e i g h ts . T h e r e f o r e , t h e r a n k t e s t a c c o r d i n g t o N e m e n y i h a s b e e na p p l i e d , a s d e s c r i b e d b y S a c h s ( 1 9 7 4 ) . T h e d i f f e r e n c e s in ra n k s u m se x c e e d i n g

D = W [ n ( n k ) " ( n k + 1) /12 ] v2w h e r e [,V = t a b u l a t e d v a l u e s d e p e n d i n g o n p r o t e c t i o n l ev e l ( P e a r s o na n d H a r t l e y , 1 9 6 6 ) , n = n u m b e r o f re p l i c at e s a n d k = n u m b e r o f t re a t-m e n t s , a re s i g n i fi c an t . T h e d e p e n d e n c e o f d i g e s t ib i l it y o n f e e d i n t a k ew a s d e s c r i b e d u s i n g l i n e a r r e g r e s s i o n e q u a t i o n s .


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80 B. Vens-Cappell

RESULTSFeeding experimentA comparison of the nutritive value of the experimental diets with thatof the two commercial feeds is given in Table 2. The best feed conver-sion (feed/gain = 1-12) was observed feeding the commercial feedK50. The conversion of the other commercial feed K47/7 was 1.15but was insignificantly (p > 0.05) worse. The commercial feeds wereboth significantly (p


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C o m p a r i s o n o f e f f e c t s o f e x t r u s i o n a n d p e l le t in g o n t r o u t f e e d 81

following linear regression equations can be calculated:D (%) = 78.5 -- 5-9 - NI (%) for the pelleted feed

andD (%) = 87-7 -- 3-8 NI (%) for the ex truded feed

The digestion coefficients of energy determined in the first digestiontrial (b) at a constant feed intake of 1.5% of body weight a day fittedwell with those values estimated by the regression equations. Thereforeit was assumed that the influence of the different experimental condi-tions in both experiments could be neglected, and the data of bothexperiments were pooled, thus winning two degrees of freedom. Thenewly calculated regression equations were almost identical with thosecalculated for digestion trial (c) alone:

D (%) = 78-3-- 5.9 (- 0-5 standard deviation) NI (%)and

D (%) = 87.5 -- 3-9 (+- 1-0 standard deviation) x NI (%)During the feeding trial the daily intakes of the extruded and pelleteddiets were quite different : i-9% and 2-49% of the body weight, respec-tively. Using the regression equations, digestion coefficients for thisfeeding trial of 80.0% and 63.6% can be estimated for the extruded andpelleted feeds, respectively. Thus, it can be calculated, l kg of theextruded diet contained 14010 kJ (3346 kcal) digestible energy, while1 kg of the pelleted diet contained 10920 kJ (2608 kcal) digestibleenergy (Table 4). Though the extruded and the pelleted experimentaldiets had quite different feed conversions, Table 4 shows that thedigestible energy values for 1 kg weight gain were almost the same.When trout were reared on the extruded diet 17370 kJ (4149 kcal)digestible energy was expended for 1 kg weight gain as compared with17 580 kJ (4200 kcal) for pelleted feed. The digestible energy contentfor the commercial feed K50 had been determined previously (Butz andVens-Cappell, 1982). Using this value it can be est imated that 17 060 kJ(4076 kcal) digestible energy was expended to produce 1 kg weight gain.

The protein efficiency ratio (PER) is a good relative measure ofprotein utilization as the portion of the weight gain due to protein ismore or less constant (Tiews e t a l . , 1973; Pfeffer and Potthast, 1977).Using this cri terion the pelleted experimental diet (PER = 1.78) was as


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82 B. Vens-CappellTABLE 4Expen se of Digestible Energy fo r Gain and Protein Efficiency R atio

Exper imenta l d ie t Commercial feed sExrn lded Pe lleted K4 7 /7 K5 0

kJ digestible energykg feed

kJ digestible energykg gain

kg gainPER kg protein intake

14 01 0 10 92 0 -- 15 240 a

1 7 3 7 0 1 7 5 8 0 -- 1 7 0 6 0

2.28(i ) 1.7 8( ii , i i) 1-82 (ii) 1 . 7 0 ( i i i )a Value estimated from a previous experiment (Butz and Vens-Cappell, 1982).b Differences betw een m eans with sam e subsc ripts not significant (p < 0-05).e f f i c ie n t a s t h e c o m m e r c i a l f e e d K 4 7 / 7 ( P E R = 1 . 8 2 ) a n d w a s s ig n if i-c a n t l y ( p < 0 . 0 5 ) b e t t e r th a n t h e c o m m e r c i a l f e e d K 5 0 ( P E R = 1 . 70 ) ,a s ca n b e c o n c l u d e d f r o m T a b l e 4 . T h e P E R o f 2 .2 8 f o r t h e e x t r u d e dd i e t w a s s i g n i f i c a n t ly ( p < 0 . 0 5 ) b e t t e r t h a n t h a t o f all t h e o t h e r d ie t s .F i s h c a r c a s s c o m p o s i t i o nT h e r a ti o o f t h e w e i g h t o f v i s ce r a w i t h o u t l i v er t o t o t a l b o d y w e i g h t,r an g in g b e t w e e n 7 . 9 a n d 8 -1 % , d i d n o t d i f f e r s i g n i fi c a n t ly ( p > 0 . 0 5 )b e t w e e n t h e g r o u p s f e d t h e e x p e r i m e n t a l a n d c o m m e r c i a l f ee d s. T h er a ti o o f l iv e r w e i g h t t o b o d y w e i g h t w a s g r e a t es t w h e n t h e e x t r u d e de x p e r i m e n t a l d i e t w a s f e d ( 4 .5 % - + 1 .1 % s t a n d a r d d e v i a t i o n ) . T h e r e la t iv el i v e r w e i g h t s f o r t h e p e l l e t e d d i e t a n d c o m m e r c i a l d i e t s K 4 7 / 7 a n d K 5 0w e r e 1 .3 % (-+ 0 - 3 % s t a n d a r d d e v i a t i o n ) , 1 .0 % ( - 0 . 2 % s t a n d a r d d e v i a t i o n )a n d 1 .3 % ( + 0 . 3 % s t a n d a r d d e v i a t i o n ) , r e s p e c t i v e l y , i .e . w e r e s i g n i f i c a n t l y( p < 0 . 0 5 ) l e s s.C o n t e n t a n d d i g e s t i b i l i t y o f a m i n o a c id s

V a l u e s o f a m i n o a c id c o m p o s i t i o n a n d t h e a p p a r e n t d i g e s ti b i li t y o f i nd i-v i d u a l a m i n o a c i d s a n d p r o t e i n a r e g i v e n i n T a b l e 5 . W i t h in t h e r a n g e


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Comparison of effects of extrusion a~d pelleting on trout feed 83

T A B L E 5I n f l u e n c e O f E x t r u s i o n a n d P e l l e t P r o c e s s i n g o n : 4 a- ni no A c i d C o n t e n t a n d o n

D i g e s t i b i l i t yAmino acid Extntded diet Pelleted diet

Content in diet Digestibility Content in diet Digestibility(%2 (%) (~2 (TqAsp 3.19 81.6 3-26 82.8Thr 1-45 83.7 1-35 82.5Ser 1-48 85.4 1-47 85-9Glu 4.52 86.4 4.55 87.7Pro 2.06 86.3 2.18 88-1Gly 2-37 85.7 2.24 83-0Ala 2-21 87-4 2-29 87.6Cys 0-33 86.6 0.36 81.5Val 1.54 85.6 1.56 87.5Met 1.00 95-8 1-30 92.6tie 1.05 83-6 1-04 85.1Leu 2.70 87.9 2-57 88.9Tyr 0-94 91-4 0.98 87-6Phe 1.38 86.3 1.39 88.0Lys 2-54 89.7 2-71 89-4His 1.07 88.3 1.11 89.0Arg 2.03 88.6 2-03 87-8Sum of amino acids 31-86 86.7 32-39 87-0Crude protein 35.3 83.9 35.0 83-8

Cause of variance DF MQ FDigestibility of amino acids 16 16.74Extrusion/pelleting 1 0.83Residue 16 2.36

7.1"**

***p


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84 B. Vens-Cappellof analytical error the amino acid compositions for the two experi-mental diets were the same. Two-way analysis of variance indicatedsignificant differences (p < 0-001) for the mean digestion coefficientsof individual amino acids, but no difference could be detected betweenthe two modes of processing.

DISCUSSIONIt has been clearly demonst rat ed that there is an improvement indigestibility of energy when a feed with high carbohydrate content isprocessed by extrusion. It is necessary to consider which factor may beresponsible for this effect. The extrusion process is not better thanpelleting for the digestibility of protein (Table 3). The contribution offat to total digestible energy in the experimental diets is low whereasthe digestibility of fat in general is high (Windell e t a l . , 1974; Austrenge t a l . , 1980); the extruded diet may thus improve the digestibility ofenergy by partial hydrolysis of carbohydrate. This conclusion is inagreement with earlier observations (Inaba e t a l . , 1963; Cho and Slinger,1979). Smith (1971) (administering a diet of 50% starch content)observed that starch digestibility was increased from 24 to 51-5% bycooking. Singh and Nose (1967) demonst rated that the digestibility ofstarch depends on its concentration in the diet. The results of Bergotand Br6que (1983), cited in the introduction, and those results pre-sented in this paper demonst rate that increasing the starch intakeresults in a depression in its digestibility, and this effect is all the moreaggravating if the digestibility of (native) starch is already poor.Spannhof and Plantikow (1983) have recently succeeded in elucidatingthis ph enomenon on physiological and biochemical bases. They havedemonstrated that crude starch reduces amylase activity and acceleratesthe passage of intestinal juice, thus reducing the availability for digestionand absorption.

The formulation of least cost commercial feed mixtures requires anexact knowledge of the nutritive value of the ingredients of these feedmixtures. Proximate analysis, digestion coefficients, metabolizableenergy and other information about individual feedstuffs are compiledin food value tables (National Research Council, 1973). The digestibleenergy content of a feed mixture, for instance, can be calculated byadding the contributions to the digestible energy of the individual


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Comparison of effects of extrusion and pelleting on trout feed 85feedstuffs composing the mixture. As discussed above, starch digesti-bility, however, depends on a number of parameters, such as the originof starch, its content in feed, feed intake and feed processing. That iswhy at present it is difficult to predict exactly the digestible ener~mjcontent of a teed mixture composed of feedstuffs with high starchcontent using feed value tables. The energy digestion coefficients forstarch-containing feedstuffs are only valid for practical feed formula-tion if they are determined under experimental conditions which arecomparable to those to be expected when the very feedstuffs are fedas ingredients of commercial feeds, i.e. the starch content of an experi-mental diet may not exceed that of a prospective commercial feed andintake of the experimental diet should be of the order to be expectedunder practical conditions.On account of the dependence of energy digestibility on feed intake,the effects of extrusion and pelleting on the digestibility of energy canonly be compared on the basis of equal feed intakes. Using the grossenergy conte nt and the coefficients of energy digestibility at a constantfeeding level of 1-5% of body weight daily (Table 3) it can be calculatedthat the gain in digestible energy due to extrusion is 2360 kJ (560 kcal)per kg feed. In order to supply the pelleted feed with the same amountof additional digestible energy, for instance, about 6% marine fish oilwould have to be added, assuming 38 kJ (9 kcal) digestible energy per g.An additional cost o f 9 Deutschmarks per 100 kg feed would result,assuming a price of 150 Deutschmarks per 100 kg fish oil. The highercost o f extrusion processing, about 5-7 Deutschmarks per 100 kg(Mehler, personal communication), is thus compensated by the highervalue of the ex truded product.

Extrusion and pelleting did not influence the digestibility of proteinand amino acids differently. This is an unexpected result since duringextrusion some of the factors which are known to enhance Maillard-typereactions were apparently cooperating: humidity, heat and the presenceof reducing carbohydrates (Herrmann, 1966). Lysine, arginine and tyro-sine, in particular, are reactive to glucose (Mazurke, according toHerrmann, 1966). Therefore a depression in the digestibility of theseamino acids could have been expected. The result of the digestion trial(b) gave no indication that heat damage to protein caused by extrusionprocessing exceeded that caused by pelleting. The fact that there aresignificant differences between digestion coefficients for individualamino acids is discussed in detail elsewhere (Vens-Cappell, 1983).


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86 B . V e n s - C a p p e l lT h e s u p e r i o r c o n v e r s i o n o f t h e e x t r u d e d a s c o m p a r e d w i t h th e

p e l l e t e d f e e d i s e v i d e n t l y d u e t o i ts h i g h e r c o n t e n t o f d i g e st ib l e e n e rg y .T i e w s e t a l . ( 1 9 7 2 ) r e p o r t e d c o m p a r a b l e r e s u l ts a f t e r f e e d i n g a d i e tw i t h n a ti ve a n d c o o k e d c o r n s t a rc h . B y c o n t r a s t L u q u e t a n d B e r g o t( 1 9 7 6 ) d id n o t f in d a n i m p r o v e m e n t in f e e d c o n v e r s i o n b u t t h e yo b s e r v e d a h i g h e r g r o w t h r a te a n d h i g h e r e n e r g y c o n t e n t in b o d yc o m p o s i t i o n . H i l to n e t a l . ( 1 98 1 ) c o m p a r e d t h e p h y s i o l o g i c a l p r o p e r t i e so f s t e a m p e l l e t e d a n d e x t r u d e d d i e t s c o n t a i n i n g 3 3 % s t a r c h . T h e r e s u l t sw e r e c o m p a r a b l e w i t h t h o s e p r e s e n t e d h e r e : f e e d c o n v e r s i o n w a s b e t t e r( 0 -9 ) w h e n t h e e x t r u d e d f e e d w a s f e d , t h e p e l l e t e d f e e d h a v i n g a v a l u eo f 1 -2, b u t b y c o n t r a s t t r o u t r e a r e d o n e x t r u d e d p e l l e ts s h o w e d sig ni-f i c a n t l y l o w e r w e i g h t g a in d u e t o a p r o l o n g e d g a s t ri c e m p t y i n g t i m e a n da re d u c e d d a i ly f e e d c o n s u m p t i o n .

T h e p r o t e i n s p ar in g a c t i o n o f e n e r g y b e c o m e s a p p a r e n t w h e n t h ep r o t e i n e f f i c i e n c y r a ti o s o f t h e e x p e r i m e n t a l d i e t s ( T a b l e 4 ) ar e c o m -p a r e d . T h e P E R f o r t h e e x t r u d e d f e e d w a s a b o u t 2 5% h i g h e r t h a n t h a to f t h e p e l l e t e d a n d c o m m e r c i a l d ie t s. W i th r e s p e c t to t h e g e n e r a l s h o r t-a g e a n d h i g h c o s t o f p r o t e i n - r i c h f e e d s t u f f s i t c a n b e e x p e c t e d t h a td ig e st ib le c a r b o h y d r a t e w ill b e c o m e m o r e i m p o r t a n t f o r t r o u t n u t r i t io nin f u t u r e . O n t h e o t h e r h a n d , i t is k n o w n t h a t t h e e x ce s s iv e u s e o fc a r b o h y d r a t e s i n t r o u t n u t r i t io n c a u se s m e t a b o l i c p r o b l e m s r e su l ti n g ing l y c a e m i e ( B e r g o t , 1 9 7 9 b ) a n d f a t a n d g l y c o g e n d e p o s i t i o n in l iv e r( A b e l e t a l . , 1979 ; H i l l e e t a l . , 1 9 8 0) . I t is n o t k n o w n t o w h a t e x t e n ts u c h n e g a t i v e p h y s i o l o g i c a l e f f e c t s o f c a r b o h y d r a t e o n t r o u t c a n b et o l e r a t e d u n d e r p r a c t ic a l r e a r in g c o n d i t i o n s . I t m u s t b e a s s u m e d t h a tf is h w i t h s y m p t o m s o f li v er d e g e n e r a t i o n w i ll r e a c t m o r e s e n s it iv e l y t os tr e s s, w h i c h t o a c e r t a i n e x t e n t is n o r m a l in i n t e n s i v e f i sh c u l t u r e . I tw a s o b s e r v e d , h o w e v e r , t h a t a f t e r t h e t e r m i n a t i o n o f t h e f e e d i n g e x p e ri -m e n t ( a) l as ti n g 5 6 d a y s l iv e rs r e g e n e r a t e d w i t h i n 10 d a y s a f t e r c h a n g i n gt h e d i e t .

W i t h r e s p e c t t o t h e p h y s i o l o g i c a l c o m p l i c a t i o n s r e s u l t i n g f r o m t h ee x ce s si ve i n t a k e o f c a r b o h y d r a t e b y t r o u t t h e r e s e e m t o b e s o m e l im i ta -t io n s t o f u r t h e r d e v e l o p m e n t o f f lo a t in g e x t r u d e d f ee d s. A s m e n t i o n e di n t h e i n t r o d u c t i o n , f l o a t a b i li t y o f p e l le t s is a d e c is iv e a r g u m e n t t oj u s t i f y t h e h i g h e r c o s t o f e x t r u s i o n . I f f l o a t a b i l i ty o f p e l le t s is n o td e s ir e d p e r h a p s i t w o u l d b e c h e a p e r t o a d d e x t r u d e d c o r n m e a l t o af e e d m i x t u r e a n d t h e n p e l l e t i t. F r o m a p h y s i o l o g i c a l p o i n t o f v i e w itw o u l d b e d e s ir a b le t o l i m i t t h e c o n t e n t o f d i g es t ib l e c a r b o h y d r a t e t ole ss t h a n 2 0% , b u t t h is w o u l d n o t b e c o n s i s t e n t w i t h t h e a im to g e t


17/19

Comparison of effects of extrusion and pelleting on trout feed 87f l o a t a b l e a n d w a t e r - s t a b l e p e l le t s . P e r h a p s t h e a d d i t i o n o f s p e c i f icb i n d i n g a g e n t s a n d o t h e r s u b s t a n c e s f a c i l i t a t i n g t h e e x p a n s i o n t o af l o a t a b l e p e l l e t c o u l d h e l p to c o m p e n s a t e f o r t h e h ig h e r c a r b o h y d r a t ec o n t e n t r e q u i r e d o t h e r w i s e .

A C K N O W L E D G E M E N T ST h e a u t h o r w i s h e s t o e x p r e s s h i s g r a t i t u d e t o P ro f . D r H . -J . H o r s t m a n n ,I n s t i t u t f f ir P h y s i o l o g i s c h e C h e m i e d e r U n i v e rs i t/ i t E r l a n g e n - N f i rn b e r g ,f o r p e r f o r m i n g t h e a m i n o a c i d a n a l y s e s ; H e r r M e h l e r, M e l a - S i lv e r -C u pa n d H e r r M f i ll er , l n t e r q u e l l f o r s u p p l y i n g t h e p e l l e t e d a n d e x t r u d e dd i et s ; D r R e i c h l e , F a c h b e r a t u n g f ii r F i s c h e r e i d e s B e z i rk s O b e r p f a l z f o rm a t e r i a l a n d f i n a n c i a l s u p p o r t ; a n d P r o f. D r R o s e n t h a l , B i o l o g i s c h eA n s t a l t H e l g o l a n d , H a m b u r g f o r r e v ie w i n g t h e m a n u s c r i p t .

R E F E R E N C E S

Abel, H., Pieper, A. & Pfeffer, E. (1979). Untersuchungen an wachsenden Regen-bogenforeUen (Salmo gairdneri R.) 0bet die intermedi/ire Anpassung an Proteinoder Kohlenhydrate als EnergietrSger im Futter . Z. Tierphys. Tierern. Futter-mittelkde., 4 1 , 3 2 5 - 3 4 .

Austreng, E., Skrede, A. & Eldegard, A. (19 80 ). Digestibility o f fat and fat ty acidsin ra inbow trout and mink. Aquaculture, 19, 93-5 .Bergot, F . (197 9a ). Probl~m es particuli~res po s~ s par l 'utilisation des glucides chezla truite arc-en-ciel. Annales de la Nutrition et de l'Alimentation, 3 3 , 2 4 7 - 5 7 .Bergot, F . (197 9b) . Effec ts of d ie tary carbohydrates and of the ir m ode o f dis tr ibu-tion on glycaemia in rainbow trout (Salmo gairdneri Richardson). Comp. Bio-chem. Physiol., 64A, 543-7 .

Bergot, F. & B r~qu e, J. (19 83). Digestibility o f starch b y rainbow tro ut: effe cts ofthe physical state and o f the intake level. Aquaculture, 34, 203-12 .Butz, 1. & Vens-Cappell, B. (198 2). Org anic load from metabolic prod ucts of rain-bow t rou t f ed wi th dry food . EIFAC Technical Paper 41, 73- 82 .Castell, J. D. & Tiews, K. (eds) (1980). Rep ort o f the EIFAC, IUNS and IC ESworking gro up on standardization o f m etho do log y in f is h nutrition research(21-23 M arch 1979). EIFAC Technical Paper 36.Cho, C. Y. & Slinger, S. J. (1979). Apparent digestibility measurement in feed-

stuffs for ra inbow trout . Finfish Nutrition and Fishfeed Technology: Proceedingsof a World Symposium Sponsored by EIFAC (FAO), ICES, IUNS, Hamburg,


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88 B. l/ens-Cappell20-23 June 1978, Vol . I I . eds J . E. Halver and K. Tiews, Heenemann Verlags-geseUschaft, Berlin.

Her rm ann, J . (1966) . Ha l tba rm achun g , Vera rbe it en un d Zub ere i t en unse rerNahrungs - und Fut t e rmi t t e l . Vergleichende Erniihrungslehre des Menschen undseinerHaustiere, ed. A. Hock, Gustav Fischer Verlag, S tut tgar t . pp. 97-160.

Hi l le , S . , Deufel , J . , Kausch, H. & Pla tz , F . (1980) . Ents tehung e ines Fet t leber-syndroms be i Regenbogenfore l l en (Salmo gairdneri) in Abh ~ingigkei t vomKohlenhydra t - und P ro te ingeha l t des Fu t t e r s , sowie Uber f t i t t e rung . Arch.Hydrobiol., Suppl . 59 (12) , 1-16.H ilton , J . W ., Ch o, C. Y. & Slinger, S. J . (1 98 1). Eff ect o f ex trus ion processingand s t eam pe l l e t ing d ie t s on pe l l e t durab i l i ty , pe l l e t wa te r absorp t ion , and thephys io log ica l re sponse of ra inbow t rou t (Salmo gairdneri R.). Aquaculture, 2 5 ,1 8 5 - 9 4 .Inaba, D. , Og ino, C. , Ta kam atsu, C. , Ved a, T. & Ku rokaw a, K. (1963) . Diges tibi li tyof d ie tary c om po ne nts in f i shes. I I . Diges t ibi l ity o f die tar y prote in an d s tarch inr a in b o w t r o u t . Bull. Jap. Soc. Sci Fish., 2 9 , 2 4 2 - 4 .

Josh ida , M. (1960) . Rapid co lor ime t r i c de te rm ina t ion of chrom ic ox ide wi thd iphenylca rbac ide . Bull. Nat. Inst. Agricult. Sciences Japan, 1 9 , 1 2 7 - 3 2 .

Ki tamikado, M. and Tachino, S . (1960) . S tudies on the diges t ive enzymes of ra in-bow t ro u t . 1 . Carbohydrases . Bull. Jap. Soc. Sci. Fish., 26, 679-84 .

Luquet , P . & Bergot , F . (1976) . Evaluat ion de divers t ra i tements technologiquesdes cereales. VII. U ti l isat ion de ma is press~, floc on n~ , expans~ et ex trud ~ dartsl 'a l im enta t ion de la t rui te arc-en-ciel . Ann. Zootechn., 25, 63-9 .Na t iona l Resea rch Counc i l (1973) . Nu t r i en t requ i rement s o f t rou t , s a lmon and cat -fish. In: Nutrient Requirements of Domestic Animals, N a t i o n a l A c a d e m y o fSciences, Washington DC.

Nau ma nn, K . & Bass le r , R . (1976) . Handbuch der landwirtschaftlichen Versuchs-und Untersuchungsmethodik (Methodenbuch ). Die chemische Untersuchung yonFuttermitteln, Verlag J . Ne um ann-N eudam m, Ber lin .

Pea rson , E . S . & Har t l ey , H . O . (eds ) (1966) . Biometrica Tables for Statisticians,Vol . I , Cam bridge.Pe t ty , H . & R app , W. (1970 /71) . Zur P roblemat ik de r Ch rom 0xidbe s t imm ung inVerdauungsversuchen . Z. Tierern. u. Futtermittelkd., 27, 18 I-9.

Pfeffer , E. & Pot tha s t , V. (197 7) . Un tersuchu ngen t iber den Ansatz yon EnergiePro te in und minera l i schen Mengen e lementen bei wachsenden Regenbogenfore l l en .Erni~hrungsphysiologische Untersuchungen an Karpfen und Forellen. Fortschrittein der Tierphysiologie, Tiererniihrung und Futterrnittelkunde, Vol. 8. eds Ch.Meske and E. Pfeffer , Paul Parey, Ham burg, B erl in , pp. 32 -57 .

Roth, S . & Becket , F . (1956) . Kalorimetrische Methoden. Verfahrens-undMef~-kunde der Natt~rwissenschaften, Vol. 12, F. Vieweg und Sohn, Braunschweig.

Sachs , L. ( t974) . Angewandte Statistik. 4. neubearbeitete und erwei~erte Au~age.Springer-Verlag, Berlin.


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Comparison o f e f fec ts o f ex trusion and pellet ing on trout feed 89Singh, R. P . & N ose. T. (19 67) . Diges t ibi l i ty o f carb ohy drates in youn g ra inbow

t r o u t . Bull. Fresh w. Fish. Res. Lab. To ky o, 17, 21-5.Slinger, S. J . , Razzaque, A. & Cho, C. Y. (19791). Effect of feed processing andleaching on the losses of cer ta in vi tamins in f i sh die ts . Finfish Nutri t ion andFishfeed Technology. Proceedings o f a World Sym pos ium Sponso red and &~p-por ted by E IFA C (FAO) , ICES, IUNS, Hamburg , 20-2 3 June 1978, Vol. II, edsJ. E. H alver an d K. Tiews, H een em an n VerlagsgeseUschaft , Berl in.

Sm ith, R. R. (1971) . A m eth od for measuring diges t ibi li ty and m etabol izable energyo f fish feeds. Progressive F ish-Culturist, 3 3 , 1 3 2 - 5 .

Spannho f , L . & P lan t ikow , H . (1983) . S tud ies on ca rb ohyd ra te d iges tion in ra inbowt rout . Aquacul ture , 3 0 , 9 5 - 1 0 8 .

Tiews, K. , Grop p, J . , Ko ops , H . & Tiews, K. (1972 ) . 0be r die Ges ta l tung yo nMischfut terra t ionen f~r Fore t len in der Netzk~if ighal tung. Z. Tierphys. Tierern.Fut te rmi t te lkd . , 2 9 , 2 6 7 - 7 5 .

Tiews, K. , Koops , H. , Gropp, J . & Tiews, J . ( t973) . Uber die K6rperzusammen-setz un g netzk,~figgehaltener ForeU en (Salmo gairdneri) in Abh/ingigkeit yonF i i t te rung und W achs tum. Arch. Fischereiwissenschaft, 24, 261-9 .

Vens-Cappell , B. (19 80) Versuche zur Q ual i t / it skontrol le yon F orel len fut ter .Fischer u. Teichw., 3 1 , 3 9 - 4 4 .

Vens-Cappell , B. (1983 ) . Ex perim ente l le Erpro bun g eines Kon zepts der l inearenOpt imie rung yon Trockenmischfu t t e r fa r d i e Regenbogenfore l l e (Salmo gairdoneri Richa rdson) au f der Bas is der verdau l ichen N fihrs toffe . Thesis, Univers i ty ofHamburg.Weber, E. (1972). Grund rif~ de r biologischen Statistik. 7. A uf l., Gustav Fischer,Verlag, Stuttgart .

W indell , J . Y., Ar m stron g, R. & Clinebell, J . R. (197 4). Su bs ti tut ion o f brewerssingle cell protein into pelleted fish feed. Feeds tu f f s , 46, 22-3 .

vens cappell 1984 aquacultural engineering

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