-

University of Nigeria Virtual Library

Serial No

Author 1 OBIZOBA, Ikemefuna Christopher

Author 2 ADKINS, James .S. Author 3 EDWARDS, Cecile .H.

Title Biochemical Evaluation of Wheat-Soy-Beef Mixtures Fed Weanling Rats.

Keywords

Description

Biochemical Evaluation of Wheat-Soy-Beef Mixtures Fed Weanling Rats.

Category

Agriculture

Publisher Nutrition Reports International

Publication Date June, 1977

Signature

NUTRITION REPORTS INTERNATIONAL

BlOCHPiICGL EVALUATI.ON OF WHEAT-SOY-BEEF

MIXTURES FED WEANLING RATS'''

by

Ikemefuna Christopher Obizoba, Cec i l e H. Edwards

and

James S. Adkins School of Human Ecology

Howard Univers i ty Waehington, D.C. 20059

ABSTRACT

Weanling male rats (55-602) were fed e i g h t isonitrcgenouo mixed p r o t e i n d i e t s i n two sepa ra t e experiments. The diet^ conrsjncd whole wheat f l o u r (Wj, soy p r o t e i n concent ra te (SC), i s o l a t e d soy p r o t e i n ( I S ) , and ground beef (GB) i n var:.ous blends, and provided 13.4% p r o t e i n f o r 26 and 28 daye 0 5 t he s tudy per iods . Addition of SC o r SC:GB t o WF r e s u l t e d i n 1owe.r blood urea n i t rogen (BUN) l e v e l s with t h e BUN of t h e WF:SC:GB d i e t being almost a s low a s t h a t f o r the c a s e i n d i e t . BUN l e v e l s were s i g n i f i c a n t l y h igher (PLO:05) i n r a t s fed t h e WF o r WF:IS d i e t than those of con t ro l . SC o r GB as a supple- ment t o W F caused equal i nc r ea se s i n plasma albumin; however, t o t a l plasma p r o t e i n va lues f o r r a t s fed t he WF:SC d i e t were s i g n i f i c a n t l y g r e a t e r than t hose of t h e o t h e r experimental groups. When a po r t i on o f t he SC o r a l l of i t was replaced wi th an equal amount of GB, l e v e l s o f plasma p r o t e i n were decreased, probably because both SC and GB a r e l i m i t i n g i n methionine. SC was supe r io r t o IS as shown by i nc rea se s i n plasma albumin. GB o r a combination of GB with SC produced t he g r e a t e s t i n c r e a s e i n l i v e r weight and l i v e r n i t rogen . However, GB showed s u p e r i o r i t y t o SC a s a supplement t o WF a s shown by t he in- c r e a s e i n q u a n t i t i e s of l i v e r n i t r ogen which occurred when GB was i nges t ed .

'submitted t o the School of Human Ecology, Howard Univers i ty , Washington, D. C., i n p a r t i a l f u l f i l l m e n t of the requirements f o r t he Ph.D. degree i n Nu t r i t i on . (I.C.0).

' ~ e q u e s t s f o r r e p r i n t s should be addressed to: Ikemefuna Christopher Obizoha, Associate Professor of Nu t r i t i on , Vlr- g i n i a S t a t e College, P. 0 . Box 21, Pe tersburg , V i rg in i a 238G3.

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NUTRITION REPORTS INTERNATIONAL

Plasma p r o t e i n of r a t s f e d c a s e i n v e r s u s ground b e r f were s i g n i f i c a n t l y d i f f e r e n t from one another (P L 0.05); however, plasma albumin and p r o t e i n concent ra t ione of r a t s f e d WF d i e t s supplemented by SC o r GB were s i g n i f i c a n t l y h igher i n experiment 1; i n experiment 2 , b o t h SC and a combination of SC w i t h GB produced s i g n i f i c a n t in - c r e a s e s i n plarrma p r o t e i n s . I n experiment 1 plasma p r o t e i n s were n o t improved by a d d i t i o n of I S a l o n e t o t h e WF d i e t , though t h e feed ing of a combination of I S wi th GB r e s u l t e d i n plasma valuesl which were comparable t o t h o s e of t h e c o n t r o l .

INTRODUCTION

Many i n v e s t i g a t o r s have used plasma free amino a c i d l e v e l 8 a s a n index o f d i e t a r y p r o t e i n q u a l i t y . However, o n l y a few i n v e s t i g a t o r o have u t i l i z e d measurements of blood urea n i t r o g e n (BUN) as a means of e v a l u a t i n g p r o t e i n q u a l i t y . This does not i n d i c a t e t h a t t h e l a t t e r method is l e s s u s e f u l f o r t h e purpose. In t h i s paper , t h e use of plasma p r o t e i n s , l i v e r n i t rogen , and BUN l e v e l s a s i n d i c e s of d i e t a r y p r o t e i n q u a l i t y i s d i scussed . Eggun (1) i n experiments w i t h growkng r a t s and p i g s found a very h igh n e g a t i v e c o r r e l a t i o n between t h e b i o l o g i c a l v a l u e of t h e f e e d and t h e BW l e v e l . He observed t h a t t h e BUN l e v e l increased wi th t h e p r o t e i n c o n t e n t of t h e d i e t . I n h i s ex- periments t h e BUN l e v e l increased by 2.4 u n i t s each t ime t h e r a t s were suppl ied w i t h ano ther 10 mg N/day, and h e concluded t h a t BUN de- pended on bo th t h e q u a l i t y and t h e q u a n t i t y of t h e p r o t e i n suppl ied i n t h e d i e t . However, B r m (2) r epor ted BUN t o be l e s s p r e c i s e then t h e u r i n a r y urea e x c r e t i o n as a n i n d i c a t o r of p r o t e i n q u a l i t y .

Eggun (1) suggested t h a t by s t a n d a r d i z i n g t h e cachnique it i s p o s s i b l e t o e l i m i n a t e t h e e f f e c t s o f both p r o t e i n con ten t and tima a f t e r feed ings . Thus, t h e p r o t e i n q u a l i t y should be t h e d e c i s i v e fac- t o r i n f l u e n c i n g BUN l e v e l . ,

It has been shown (3, 4 ) t h a t p r o t e i n o r amino acid deficiency decreaees t h e c i r c u l a t i n g plasma p r o t e i n e , and t h a t d i f f e r e n t p r o t e i n fractions do n o t p a r t i c i p a t e e q u a l l y i n ldss of t o t a l plasma p r o t e i n : albumin d e c r e a s e s much f a s t e r than g lobul in , probably a s a s i g n of e a r l y l i v e r damage o r r a p i d decreases o f l i v e r p r o t e i n .

There were f o u r s p e c i f i c o b j e c t i v e s For t h i s ntudy: (1) t o provide d a t a on some blood c o n s t i t u e n t s of t h e weanling r a t s f e d wheat - soy - beef mixtures; (2) t o determine t h e changes i n concen- t r a t i o n a o f t h e s e c o n s t i t u e n t s i n weanling r a t e fed a whole wheat d i e t o r t h i s d i e t supplemented w i t h o t h e r p r o t e i n s ; (3) t o compare t h e supplementary e f f e c t a of soy p r o t e i n concent ra te and ground beef on whole wheat f e d weanling r a t s , and ( 4 ) t o observe t h e e f f e c t s of t h e s e p r o t e i n s o u r c e s on l i v e r weight , l i v e r n i t rogen , and f a t . The results o f t h e comparisons could b e used t o determine whether o r no t t h e mixture which proved s u p e r i o r t o o t h e r s might be i n v e s t i g a t e d f u r t h e r b e f o r e i t l a considered f o r u s e as a p r o t e i n supplement o r a s a s o l e source o f p r o t e i n i n t h e d i e t s of weaned i n f a n t s and pre- school c h i l d r e n .

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MATERIALS AND METHODS

One hundred and fourteen male weanling ~ o l t z m a d r a t s were used t o conduct two eepara te experiments. The experimental design, sex, age, and body weight of t he animals, and s t a t i a t i c a l analyses of t h e da t a were reported previously (5). Liver n i t rogen was determined by the AOAC methods (6). Tota l l i v e r l i p i d 6 were determined by the method of Folch et a l . (7). The composition of d i e t a i n Experiment 2 was shown elsewhere (5). In d i e t 1, whole wheat f l ou r (WF) provided 100% of the d i e t a ry prote in ; I n d i e t 2 , ground beef (CB) provided 100% of the d ie tary prote in ; a WF and GB (70:30) combination was provided i n d i e t 3; a mixture of WF and soy p ro te in concentrate (SC) 70:30 was provided i n d i e t 4; and WF, SC, and GB 70:15:15 were pro- vided i n d i e t 5 , a s sources of d i e t a ry prote in , a l l fed a t t he l e v e l of 13.4 percent . Diet 6 waa the prote in- f ree d i e t .

A t t he end of the experiments heparinized syringea were used to draw blood samples by h a r t puncture from each r a t f o r plasma p ro te in analyeas.

Plasma albumin and prote in and blood urea nitrogen were de t e r - mined us ing an Ames blood analyzer4 according t o the procedures out- l i ned by the manufacturer f o r determining these blood cons t i t uen t s . Plasma p ro te ins of r a t s fed the prote in- f ree d i e t were not estimated because i t was not poss ib le t o ob ta in enough blood from these animale a t s a c r i f i c e .

RESULTS AND DISCUSSION

Experiment 1. Table 1 containa summary r e su l t a f o r blood urea ' ni t rogen and plaama protein8 of r a t s i n Experiment 1.

Blood Urea Nitrogen. Blood urea n i t rogen (BUN) l e v e l s of r a t s i n a l l group8 varied. However, t h e BUN l e v e l s of r a t s fed d i e t s 3 to 6 d id not d i f f e r from one another (P > 0.05) nor were there any d i f - ferences a t 5% l e v e l between those fed d f e t s 1 t o 3. The BUK l e v e l s of r a t a fed the con t ro l d i e t were lower than t h a t of rats fed d i e t a 1 and 2 ( P C 0.05). Diet 1 increased t h e BUN l e v e l of r a t s compared to those of r a t s fed d i e t s 4, 5, and 6. The high s ign i f i can t d i f ferences be- tween BUN values of r a t s fed d i e t s 2 and 4 of Experiment 1 may have

many metabolic implications. The increase i n BUN values of these anl- mals appears t o suggest t h a t d i e t 2 d id not supply adequate amino ac ids f o r prote in synthes is ; a s a r e s u l t , the animals may have been catabo-

1 l i z i n g t h e i r t i s s u e p ro te in reserves t o meet t h e i r p ro t e in require- mente. This increase i n BUN r e f l e c t s high plaama l e v e l s of p ro te in 1 . end products (urea and ammonia) which a r e high when animals (mammalm)

'~a1t-n Co., Animal Breeders, 421 Holtzman Road, Madison, Wisconsin 53713.

bitme. Co., Mllea Diviaiun, Miles Laboratories. Inc . . Elkhart, Indiana 46514.

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TABLE I: E f f e c t of Fltlole Wheat FLOUT, I a o l a t c d Soy P r o t e i n , Soy P r o t e i n Concent ra te , Ground Beef. and Casain on Plasma P r o t e i n Levels and Blood Urea Nitrogen oE Weanling Rate [Experiment 1 )

1

D i e t Source BUN Plasma P r o t e i n s 1) of P r o t e i n T o t a l Albumin

6 CAS : 100 15.323.7 4.6:. 4a 3 . 3 2 . 6" b

' ~ a c h v a l u e r e p r e s e n t s t h e mean +SD f o r 6 r a t s per t reatment f o r t h e 26-day per iod . Means w i t h d i f f e r e n t s u p e r s c r i p t l e t t e r s i n t h e same column d i f f e r s i g n i f i c a n t l y (P C 0.05) from each o t h e r .

a r e e x c r e t i n g amino a c i d s from low q u a l i t y . p r o t e i n o r amino a e i d a pro- duced a s a r e s u l t of t i s s u e p r o t e i n catabol ism. The-high BUN v a l u e may a l s o imply t h a t t h e d i e t d i d n o t have adequate c a l o r i e s , a s a r e s u l t . t h e r a t s may have been c a t a b o l i z i n g t h e i r d i e t a r y amino a c i d s t o produce carbohydra te i n t e r m e d i a t e s which w i l l e v e n t u a l l y s e r v e a s s o u r c e s of energy. The h i g h BUN l e v e l s f o r r a t s f e d d i e t 1 c a n a l s o b e explained by t h e above hypothes i s .

Diets 4 and 5 seemed t o c o n t a i n high quality p r o t e i n whkch sup- p l i e d adequate amino a c i d s f o r p r o t e i n s y n t h e s i s . The adequate supply of t h e s e amino a c i d s f o r anabol ic purposes r a t h e r than f o r c a t a b o l i c purposes l e d t o lower BUN l e v e l s of t h e s e rate, which were s lmFlar t o t h o s e of t h e c o n t r o l groups. This o b s e r v a t i o n f u r t h e r suppor t s t h e ev idence t h a t p r o t e i n supplementat ion improved t h e n u t r i t i o n a l q u a l i t y ,of whole wheat f l o u r .

Plasma P r o t e i n and Albumin. The plasma protein l e v e l s o f rats r e c e i v i n g d i e t s 2 t o 6 were d i f f e r e n t ; however, t h e d i f f e r e n c e s were n o t s i g n i f i c a n t (P 7 0 . 0 5 ) . T o t a l plasma p r o t e i n of r a t s fed d i e t s 2 t o 5 and t h e c o n t r o l (6) d i d no t d i f f e r s i g n i f i c a n t l y (P 7 0.05).

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This obeerva t ion seemed t o i n d i c a t e t h a t a blend of WF and I S o r GB o r SC o r combination o f theae suppl ied amounts of amino a c i d s which were u t i l i z e d s i m i l a r t o t h o s e of c a s e i n f o r plasma p r o t e i n s y n t h e s i s . The WF:100, WF:IS 70:30, and t h e WF:SC:GB 70:15:15 d i e t s induced lower l e v e l s of plaema p r o t e i n e ( p r o t e i n and albumin) compared t o t h o s e of t h e ~ 0 d t r 0 l f e d case in . T h i s r e d u c t i o n ( p a r t i c u l a r l y of t o t a l a lbu- min) s u g g e s t s t h a t t h e d i e t s auppl ied i n s t i f f i c i e n t amino a c i d s t o t h e animals which l e d t o a r a p i d decrease of l i v e r p r o t e i n . The r a p i d d e c r e a s e of l i v e r p r o t e i n may have a f f e c t e d albumin s y n t h e s i s a s t h e l i v e r i a t h e s i t e f o r i t a s y n t h e s i s , and t h e l i v e r depends a o l e l y on adequate d i e t a r y p r o t e i n a s a p recursor of albumin and o t h e r plasma p r o t e i n e .

It has been shown i n previous publ ished papers (4) t h a t pro- t e i n and amino a c i d d e f i c i e n c y decreases t h e c i r c u l a t i n g plasma pro- t e i n s , and t h a t d i f f e r e n t p r o t e i n f r a c t i o n s do no t p a r t i c i p a t e e q u a l l y i n l o s s o f t o t a l plasma pro te in : t h e albumin decreases much f a s t e r than t h e g l o b u l i n , probably a s a s i g n of e a r l y l i v e r damage. Thus, t h e d e c r e a s e i n plasma p r o t e i n l e v e l s of t h e s e r a t s may be due t o poor q u a l i t y p r o t e i n i n g e s t e d o r e a r l y l i v e r damage o r a combination of both f a c t o r s . The s imultaneous i n g e s t i o n of two o r more s o u r c e s of d i e t a r y p r o t e i n , r e s u l t i n g i n a b e t t e r p r o t e i n q u a l i t y than any pf t h e s o u r c e s i n d i v i d u a l l y , is r e f e r r e d t o a s t h e mutual supplemen- t a t i o n e f f e c t . This i e u s u a l l y achieved by t h e mixing of p r o t e i n reeourcea having d i f f e r e n t f i r s t l i m i t i n g amino ac ids . I n t h i s s tudy t h e t o t a l plasma albumin o f ra t s fed d i e t 5 was low, though no t lower t h a n that o f r a t s f e d d i e t 4 . T h i s appears t o sugges t l a c k of mutual supplementat ion e f f e c t by SC and GB t o WF because t h e s e pro- t e i n s a r e bo th l i m i t i n g i n methionine ( M a t t i l (8). Kies and Fox (9 and LO).

Experiment 2. Preuented i n Table 11 a r e t h e mean v a l u e s f o r f r e s h l i v e r t re igh ts , l i v e r n i t r o g e n and f a t , and plasma p r o t e i n and albumin i n Experiment 2. S ince t h e r e were same s i c k animals and ua many as t h r e e i n one group, o n l y 9 of t h e 1 2 were used f o r a l l groups.

Plasma P r o t e i n and-Albumin. T o t a l plasma p r o t e i n o f r a t s re- c e i v i n g the+GB:100 d i e t was h igher than t h a t of r a t s f e d any o f t h e o t h e r d i e t s . There was no d i f f e r e n c e i n plasma p r o t e i n c o n c e n t r a t i o n s of r a t s f e d t h e WF:GB 70:30 d i e t and those fed t h e WF:SC:GB 70:15:15 d i e t ; however, bo th had s i g n i f i c a n t l y lower plasma p r o t e i n than t h o s e f e d t h e m:SC d i e t . Plasma albumin o f r a t e fed t h e GB:100 d i e t was h i g h e r than t h a t o f r a t s fed any of t h e o t h e r d i e t s . There was no d i f f e r e n c e i n plasma albumin between r a t s r e c e i v i n g t h e W:GB and t h e W:SC d i e t s , a l though , they had h igher albumin than those rats f e d t h e KP:SC:GB d i e t , a t r e n d observed i n Experiment 1. Rats re - c e i v i n g t h e WF:100 d i e t had t h e lowest plasma albumin.

Fresh Liver WeiShcs. There were s i g n i f i c a n t d i f f e r e n c e s i n t h e f r e s h l i v e r weight8 of r a t s r e c e i v i n g t h e GB:100 d i e t compared t o t h o s e r e c e i v i n g o t h e r d i e t s . However, t h e r e was no d i f f e r e n c e i n t h e l i v e r weigh ts of t h o s e f e d t h e W:GB d i e t and those fed t h e WF:SC:GB d i e t .

JUNE 1977 VOL. 15 NO. 6

TABLE 11: Lfver Weights, Liver Mtrogen and Fat, and Plasma Proteins of Weanling Rats Fed Whole Wheat Flour Alone o r with Soy Protein Con~en t ra te~~Ground Beef

Alone o r v l t h Whole Wheat Flour (Experiment 2)

Source of Fresh Liver (wet1 Plasma Protein Protein Liver (13.4%) Weight Uitrogen Fat Total Albrnain

g g/ l fver g f l t v e r g/100ml g/100ml

-4

< 0 h e h value represents t h e u n r5o of 9 rat. pe r treatment t o r the 4 week period. r L

Meleana i n the same colmrm vith d i f fe ren t superscr ip t l e t t e r s d i f f e r s ignif icant ly VI (P < 0.05) f r o m each other. Z -0 br

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Liver Nitrogen and Fat. Total l i v e r nitrogen (N) of r a t e fed tho GB:100 d i e t was higher than those of r a t s fed other d i e t e . The concentratione of l i v e r N of r a t e receiving the WF:GB and tho WF:SC:GB d i e t s were not d i f f e r e n t from one another ( P 7 0.05). Animal6 fed t h e WF:SC d i e t had lower l i v e r N compared t o those fed the WF:GB and the WP:SC:GB d i e t s . In addit ion, the l i v e r N of r a t s fed the WP:100 d i e t waa s ign i f i can t ly lower than t h a t of r a t a fed other d i e t s . There was no di f ference i n l i v e r f a t between r a t s fed any of t h e d i e t e except f o r thoee fed the W:SC:GB d i e t , which wae s ign i f i can t ly higher.

Addition of SC o r GB t o WF s ign i f i can t ly increaeed plasma pro- t e i n s i n both experiments. The repor ts of Klosterman and coworkers (11) Whiting and coworkera (12), and Atinmo and coworkers (13), indica t h a t t he l e v e l s of t o t a l plaena prote in can be a l t e r e d by the lev% and qua l i ty of prote in i n t h e d i e t , and t h a t i t i a epecif icall- plasma albumin l e v e l which im more eeribuely impaired. The increased leve l s of plaema prote ine obeerved when SC o r GB were provided ae rupplenmnts t o t h e WF d i e t i n t h i s study ind ica te a bene f i c i a l e f f e c t of SC and GB ae eupplementa t o WF.

Though t h e l i v e r weight and l i v e r nitrogen of rate fed t h e W : S C d i e t were e ign i f i can t ly lower than thoee of r a t s fed the W:GB d i e t , t h e e ign i f i can t ly higher value f o r t o t a l plasma p ro te in of r a t s fed the WP:SC blend i n comparison with those fed t h e W:GB blend i n t h e etudy argues i n favor of SC a e a supplement t o WF. However, t h e p r a c t i c a l s igni f icance of these d i f ferences depends on the s i t u a t i o n i n which t h e product i s used. The economics of i t s use and i t 6 avai l - a b i l i t y ehould be explored i n developing nations.

The author (1.0) wlshee t o expreaa his dmep gra t i tude to D r . Lucile Mameon, Professor, School of Human Ecology, for her valuable diecuseione and advlce i n this etudy; and thanka go a l so t o Mra. M. Y. Jenkins and Mra. G. V. Mitchell , Nutr i t ional Science8 Branch, U. S. Foad and Drug Adminietration, Waahington, D. C. f o r t h e i r technical a s s i s t ance i n chemical and biological analyeis of t e a t materiale and t h e i r ass is tance i n e a c r i f i c i n g of the t e s t anirnale.

LITERATURE CITED

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2. Brom, J. A. and Cline, T. 8. Urea Excretion i n the Pig: An Indicator o f k o t e i n Quality and Amino Acid Requirements. J. Nutr. 104, 542 (1974).

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Rothachi ld, M. A., Murray, 0. and Sidney, S. S. Plasma Protefn Metabolism, Regulat ion of Synthes i s , D i s t r i b u t i o n , and Degradation, ed. by Rothechi ld and Thomas, W . ; publ ished by Academic Press , New York and London, 1970, p . 199.

Albaneee. A. A. and Orto, L. A. The Role o f P r o t e i n Deficiency i n M a l n u t r i t i o n . I n Modern N u t r i t i o n i n Health and Disease (R, S. Goodhart and M. E . S h i l e , eds . ) , Lea and Fabiger, Ph i lade lph ia , 1973, p. 80.

Obizoba, I. C, , Adkins, J. S. and Edwards, C. H. B i o l o g i c a l Eva lua t ion o f t h e P r o t e i n Q u a l i t y of Wheat-Soy-Beef W x t u r e a i n Weanling Rste. Nutr. Reports I n t . , ( ).

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Accepted for publication: March 2 4 , 1977.

JUNE 1977 VOL. 15 NO, 6