USE OF THE BALANCE TECHNIQUE FOR ESTIMATING PROTEIN REiUIRHviENT FOR
NITROGEN BALANCE AND ./EIGHT MAINTENANCE
IN THE LABORATORY RAT

Anna Louise K e lle y

AN ABSTRACT
Submitted, t o th e School o f G raduate S tu d i e s o f M ichigan S t a t e
C o lle g e o f A g r i c u l t u r e and A pplied S c ie n c e i n p a r t i a l
f u l f i l l m e n t o f th e re q u ire m e n t f o r th e d e g re e
of
DOCTOR OF PHILOSOPHY

D epartm ent o f Foods end N u t r i t i o n
Y ear

Approved

1952

T H E S IS

Anna L ouise Kel

THESIS ABSTRACT

Weight change, c a l o r i c i n t a k e and n i t r o g e n m etab olism f o r p r e ­
d i c t i n g p r o t e i n minima f o r l^O gram a lb in o r a t s were o b ta in e d from
t h r e e g ro u p s o f 2j r a t s f e d 0, 2 and 1| p e r c e n t egg d i e t s i n a c r o s s ­
o v e r ty p e f e e d in g p a t t e r n .

V a r i a t i o n s i n animal r e s p o n s e s r a i s e d a

q u e s t i o n r e g a r d in g th e j u s t i f i c a t i o n o f such p r e d i c t i o n s .

T herefore,

d a t a o b ta in e d were s u b je c te d t o a com prehensive s t a t i s t i c a l a n a l y s i s
to d e te r m in e which e x p e r im e n ta l f a c t o r s had a s i g n i f i c a n t in f l u e n c e
i n c o n t r o l l i n g animal re s p o n s e s t o th e d i e t s fed*
An a n a l y s i s o f v a r ia n c e e v a l u a t i n g th e e f f e c t s o f r a t s , fe e d in g
sequence and d i e t s on w eig h t change, c a l o r i c i n t a k e , n i t r o g e n i n ta k e
and n i t r o g e n r e t e n t i o n o f th e r a t s i n d i c a t e d t h a t d i e t was th e only
f a c t o r which had a s i g n i f i c a n t i n f l u e n c e on anim al re s p o n s e s end
d i e t e f f e c t s were h ig h ly s i g n i f i c a n t ( P .^ 0 . 0 1 ) .
H ighly s i g n i f i c a n t co2*relations were found between w eight change
and n i t r o g e n i n t a k e , w eight change and n i t r o g e n r e t e n t i o n , and w eig h t
change and c a l o r i c i n t a k e ; and between n i t r o g e n r e t e n t i o n and n i t r o g e n
i n t a k e and n i t r o g e n r e t e n t i o n and c a l o r i c i n t a k e .

When m u l t i p l e r e ­

g r e s s i o n s were u sed to study i n c i v i d u a l e f f e c t s o f n i t r o g e n i n t a k e ,
n i t r o g e n r e t e n t i o n and c a l o r i c in ta k e on w eig h t change, n i t r o g e n r e ­
t e n t i o n was found t o be th e f a c t o r most c l o s e l y a s s o c i a t e d w ith th e
w eig h t changes o bserved i n th e e x p e r im e n ta l anim als*

The m u l t i p l e

r e g r e s s i o n in v o lv in g n i t r o g e n r e t e n t i o n v e rs u s n i t r o g e n in t a k e end

Anna L ouise K e lle y
-2 -

c a l o r i c i n t a k e i n d i c a t e d t h a t n i t r o g e n r e t e n t i o n was d ependent on
n itro g e n in ta k e .

C a l o r ic i n t a k e s o f th e s e a n im a ls d id not a p p ea r

t o be a l i m i t i n g f a c t o r i n e i t h e r th e w e ig h t changes o r n i t r o g e n
r e t e n t i o n s o b se rv e d i n t h i s s tu d y .
Yiftien t h r e e g ro up s o f 2; r a t s were f e d , i n d i f f e r e n t seq u en ce,
d i e t s c o n t a i n i n g 0, 2 and 4 p e r c e n t d r i e d whole egg, t h e mean
u r i n a r y n i t r o g e n o f each g roup d e c re a s e d d u rin g th e t h r e e s u c c e s s iv e
f e e d i n g p e r i o d s r e g a r d l e s s o f fe e d in g sequ en ce.

T h is p a t t e r n i s

s i m i l a r t o t h a t o b s e rv e d by o t h e r i n v e s t i g a t o r s w ith r a t s on con­
t i n u o u s l o w - n it r o g e n fe e d in g and on d i e t s c o n ta i n in g 0 and 4 p e r c e n t
whole d r i e d egg f e d i n d i f f e r e n t seq uence.
S ix a d d i t i o n a l g ro u p s o f anim als were fe d d i e t s c o n t a i n i n g 0 , 4
and 10 p e r c e n t d r i e d whole egg, i n d i f f e r e n t se q u e n c e .

A sim ila r

p a t t e r n o f u r i n a r y n i t r o g e n e x c r e t i o n was o b serv ed i n f o u r o f th e s e
g ro u p s ; one g roup o f r a t s i n t h i s s e r i e s gave a p a t t e r n o f n i t r o g e n
e x c r e t i o n w hich was e x a c t l y o p p o s ite t o t h a t d e s c r ib e d ; one group had
an i n c o n s i s t e n t p a t t e r n .

The lo w - n it r o g e n d i e t r e s u l t e d i n th e g r e a t ­

e s t u r i n a r y n i t r o g e n e x c r e t i o n o n ly when i t was f e d f i r s t i n a d i e t
se rie s.

These f i n d i n g s do n o t j u s t i f y th e use o f a lo w - n it r o g e n d i e t

t o d e te r m in e endogenous n i t r o g e n m e ta b o lism o r to d e m o n stra te n i t r o g e n
s p a r in g a c t i o n o f d i e t a r y p r o t e i n .
L in e a r r e g r e s s i o n s showing r e l a t i o n s h i p s betw een w eight change
and n i t r o g e n i n t a k e and n i t r o g e n r e t e n t i o n and betw een n i t r o g e n r e ­
t e n t i o n and n i t r o g e n i n t a k e a r e r e p r o d u c i b l e u n d e r s i m i l a r e x p e r im e n ta l
c o n d itio n s.

These r e g r e s s i o n s , t h e r e f o r e , sh o u ld f u r n i s h a v a l i d

e s t i m a t e o f minimum n i t r o g e n r e q u ir e m e n ts o f r a t s f o r m a in te n an c e o f

iiuna .Louise J ie iie y
- 3-

body w eig ht and n i t r o g e n e q u i l i b r i u m .

R esponses o f r e .ts t o d i e t s

c o n t a i n i n g 0, 4 and 10 p e r c e n t d r i e d v/hole egg i n d i c a t e d t h a t th e
r e l a t i o n s h i p betw een w e ig h t change and n i t r o g e n i n t a k e and w eight
cnange and n i t r o g e n b a la n c e becomes c u r v i l i n e a r i n th e a r e a o f w e ig h t
m a in te n a n c e .

A l i n e a r r e l a t i o n s h i p between n i t r o g e n r e t e n t i o n and

n i t r o g e n i n t a k e a p p e a rs t o e x te n d w e ll i n t o th e p o s i t i v e n i t r o g e n
b a la n c e a r e a f o r th e s e r a t s .

T h is i s re g a rd e d as an i n d i c a t i o n t h a t

below th e p o i n t o f w e ig h t m a in te n a n c e , w e ig h t change i s dependent on
t h e a b i l i t y o f the anim al t o r e t a i n n i t r o g e n w h ile above t h i s p o i n t
w e ig h t change may become more c l o s e l y r e l a t e d t o some o th e r f a c t o r .
For th e a n im a ls observed i n th e e x p e rim e n t, i t was n oted t h a t th e
l i n e a r r e g r e s s i o n c o e f f i c i e n t o f n i t r o g e n i n t a k e was g r e a t e r below
th e p o i n t o f w eight m a in te n a n c e th a n above w h ile th e l i n e a r r e g r e s s i o n
c o e f f i c i e n t o f c a l o r i c in ta k e i s g r e a t e r above th e p o in t o f w eigh t
m a in te n a n c e .

T h is i s i n t e r p r e t e d es i n d i c a t i n g t h a t above th e p o i n t

o f w eight m a in te n a n c e w eig ht change i n a n im a ls may become more d e ­
p en den t on c a l o r i c in ta k e and l e s s dependent on n i t r o g e n i n t a k e .
D i e t s c o n t a i n i n g 0 to 4 p e r c e n t d r i e d whole egg and 0 t o 20
p e r c e n t M i c h e l i t e p e a bean p r e p a r a t i o n were f e d to lj;0 gram r a t s .
The a v e r a g e d a i l y re q u ire m e n t f o r m a in ta in in g body w eig ht i n t h e s e
a n im a ls was found t o be 45*4 m illig r a m s o f egg n i t r o g e n ; nd 112.1
m illi g r a m s bean n i t r o g e n .

The av erag e d a i l y re q u ire m e n t f o r m a i n t a i n ­

in g n i t r o g e n e q u i l i b r i u m i n th e 150 gram r a t was found t o be 37*3
m i l l i g r a m s egg n i t r o g e n and 8 3 .1 m illig r a m s bean n i t r o g e n .

Animals on

t h i s s tu d y were i n p o s i t i v e n i t r o g e n b a la n c e when th ey were m a i n t a i n ­
in g body w e ig h t.

USE OF THE BALANCE TECHNIQUE FOR ESTIMATING PROTEIN REQUIREMENT FOR
NITROGEN BALANCE AND //EIGHT MAINTENANCE
IN THE LABORATORY RAT

By

Anna Louise K e lle y

A THESIS
Subm itted t o th e School o f Graduate S tu d ie s o f M ichigan S ta te
C o lleg e o f A g r icu ltu r e and Applied S c ie n c e in p a r t ia l
f u lf illm e n t o f th e requirem ent fo r th e degree
of
DOCTOR OF PHILOSOPHY

Department o f Foods and N u tr itio n
Year

1932

ProQuest Number: 10008348

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T'C / 2 , 3

K 3<
7

AGKNOHJiDGE/iMr

The a u th o r w ishes t o e x p r e s s h e r s i n c e r e a p p r e c i a t i o n
t o Dr* M argaret A. Ohlson f o r h e r g u idance d u rin g th e course
o f t h i s s tu d y , t o o t h e r members o f th e Foods and N u t r i t i o n
Department f o r t h e i r a d v ic e and c o o p e r a tio n , and t o D r. W illiam
D. B aten f o r h i s d i r e c t i o n o f th e s t a t i s t i c a l a n a ly s e s r e p o r t e d
i n t h i s work.

TABLE OF CONTENTS
Page
ACKNOWLEDGBvlENTS.......................................................................................................
STATEMENT AND JUSTIFICATION OF THE PROBLEM.............................................
EXPERIMENTAL PROCEDURE
DISCUSSION OF RESULTS ...........................................................................

1
'

. . . .

D is c u s s io n o f r e s u l t s from d e s ig n one............................................... -

6
9
9

V a r i a t i o n s o b serv ed i n r e s p o n s e s of r a t s ......................

10

E v a lu a tio n o f e f f e c t s o f e x p e rim e n ta l p ro c e d u re on r a t
r e s p o n s e s by an a n a l y s i s o f v a r ia n c e
....................................

16

P r e d i c t i o n o f w eight changes and n i t r o g e n r e t e n t i o n o f
r a t s u s in g l i n e a r and m u ltip l e r e g r e s s i o n s ...........................

17

E f f e c t o f e x p e rim e n ta l v a r i a b l e s on r e s p o n s e s of r a t s
a s d eterm in ed by an a n a l y s i s o f c o v a ria n c e
.......................

22

D i f f e r e n c e s i n r a t re s p o n s e s to d i e t s measured by t
.....................................................................................
te sts. . . . . .

23

S ig n ific an c e of in d iv id u a l v a r ia b le s in m u ltip le
r e g r e s s i o n s as measured by c o r r e l a t i o n c o e f f i c i e n t s .

. .

24

Summary.................................................................................................. .... .

23

D is c u s s i o n o f f a c t o r s r e l a t e d to the problem o f i n t e r p r e t i n g
n i t r o g e n m etabo lism d a t a .............................................................
26
S i g n i f i c a n c e o f n i t r o g e n e x c r e t i o n i n the e v a l u a t i o n o f
n i t r o g e n m e ta b o lism .
.......................................................................

27

R e p r o d u c i b i l i t y o f r e g r e s s i o n l i n e s based on r a t re s p o n s e s
t o 0 t o 4 P e r cen t egg d i e t s .........................................................
3°
Use o f r e g r e s s i o n l i n e s o b ta in e d from n i t r o g e n m etab olism
d a t a in th e p re d o m in a te ly n e g a tiv e n i t r o g e n b a la n c e a r e a
f o r e e t i m t t i n g p r o t e i n minima f o r th e a l b i n o r e t . . . .

3i

N itro g e n b a la n c e and w eight change i n a r e a s o f n e g a tiv e
and p o s i t i v e n i t r o g e n b a l a n c e ............................... ......................*

32

Page
The e f f e c t o f added f a t on th e r e s p o n s e s o f r a t s
t o d i e t s c o n t a i n i n g 0 t o 10 p e r c e n t whole d r i e d egg. .

35

Summary........................................................................................................ 3?
Comparison o f m ainten an ce re q u ire m e n ts o f a lb in o r a t s on
d i e t s c o n ta i n in g whole d r i e d eggs and M Lchelite pea beans
a s s o u r c e s o f d i e t a r y n i t r o g e n ..........................................................

3^

E s tim a tio n o f minimum bean n i t r o g e n re q u ire m e n ts . . . .

38

M aintenance re q u ir e m e n ts o f d i e t a r y n i t r o g e n s o u rc e s

. .

39

.

41

Summary................................................................................................. •

GENERAL SUMMARY ANL CONCLUSIONS................................................................ 42
LIST OF REFERENCES................................................................................................45
TABLES..........................................................................................................................................

1.

C om position of e x p e r im e n ta l d i e t s ...........................................49

2a.

R e s u lts from d e s ig n one c a l c u l a t e d t o u n i t s p e r
i n i t i a l w eig h t (IV/).............................................................................. 50

2b .

R e s u l t s from d e sig n two c a l c u l a t e d t o u n i t s p e r
i n i t i a l w eig h t (IV/)......................................................................... 52

2c.

R e s u lts from d e s ig n t h r e e c a l c u l a t e d t o u n i t s p e r
i n i t i a l w eight ( I f / ) ......................................................................... 5 4

2d .

R e s u lts from d e s ig n f o u r c a l c u l a t e d t o u n i t s p e r
i n i t i a l w eig h t ( I / / ) ......................................................................... 5 6

2e.

R e s u l t s from d i e t s I and J i n d e sig n f i v e c a l c u l a t e d
t o u n i t s p e r i n i t i a l w eight ( I * ? ) .......................................... 5 ^

3.

Range and mean v a lu e s from double c r o s s - o v e r d e s ig n
one c a l c u l a t e d t o u n i t s p e r gram i n i t i a l w e ig h t. * * .

59

E f f e c t o f p e r i o d o f f e e d in g on group re s p o n se o f
an im a ls i n d e s ig n o n e ................................................ * * . . .

60

4*

5*

Mean u r i n a r y and t o t a l n i t r o g e n e x c r e t i o n o f an im a ls
i n r e l a t i o n t o p e r i o d s , d i e t s and anim al group
r e s p o n s e s ................................................................................................ 61

fifige
6.

E f f e c t o f d i e t sequence on n i t r o g e n e x c r e t i o n
p a t t e r n ............................................................................................................ o2

7 » D esign used f o r s t a t i s t i c a l a n a l y s i s o f d a t a .........................63
8.

Sums o f s q u a r e s and sums o f p ro d u c ts used i n an
a n a l y s i s o f c o v a ria n c e o f d i e t e f f e c t s ..................................... 6Z|

9 * E q u a tio n s f o r p r e d i c t i n g w e ig h t changes and n i t r o g e n
r e t e n t i o n i n anim als r e c e i v i n g t h r e e l e v e l s of egg
n i t r o g e n .................................................................................................
10.
11.

12.

66

Values o f t f o r o b serv ed and a d ju s t e d w e ig h t change
means i n 12 r a t s on t h r e e l e v e l s o f n i t r o g e n i n t a k e . .

67

M i l t i p l e and p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s from
e r r o r sums o f s q u a r e s o f an a n a l y s i s o f v a r ia n c e b a se d
on d a t a from r a t s r e c e i v i n g g ra d e d i n t a k e s o f egg
n itro g en .
................................................................................

68

The u t i l i z a t i o n o f th e n i t r o g e n o f whole egg by th e
young r a t ........................................................................................................69

13* Mean n i t r o g e n e x c r e t i o n and n i t r o g e n b a lan c e o f s i x
g ro u p s o f r a t s fe d g ra d e d amounts o f d r i e d whole egg .

70

IZj..

R e g r e s s io n s c a l c u l a t e d from d a t a i n d e s ig n s two end
t h r e e ................................................................................................................ 71

13.

R e g re s s io n s c a l c u l a t e d f o r r a t re s p o n se to bean d i e t s ,

72

FIGURES............................................................................................................................
la .

R e l a tio n o f n i t r o g e n i n t a k e t o w eight change i n
i n d i v i d u a l r a t s fe d 0, 2 and 4 p e r c e n t egg d i e t s i n
d i f f e r e n t seq u e n c e ................................................................................... 73

Ib»

R e l a t i o n o f c a l o r i c i n t a k e t o w eight change i n
i n d i v i d u a l r a t s f e d 0 f 2 and 4 p e r c e n t egg d i e t s in
d i f f e r e n t s e q u e n c e ................................................................................... 74

Ic.

R e l a t i o n of n i t r o g e n b a la n c e t o w e ig h t change i n
i n d i v i d u a l r a t s f e d 0, 2 and 4 Pe r c e n t egg d i e t s i n
d i f f e r e n t seq u e n c e ............................................................................... 75

I la .

R e l a t i o n o f w eight change t o n i t r o g e n i n t a k e f o r r a t s
fe d d i e t s c o n t a i n i n g 0 , 2 and 4 p e r c e n t egg d i e t s
d u rin g 3 seven day p e r i o d s .................................................................. 76

Page
lib .

R e l a t i o n o f w eight change t o c a l o r i c i n t a k e f o r
r a t s f e d d i e t s c o n t a i n i n g 0 , 2 and 4 p e r c e n t
egg d i e t s d u rin g 3 seven day p e r i o d s ...................................

77

lie .

R e l a t i o n o f w eight change t o n i t r o g e n r e t e n t i o n f o r
r a t s f e d d i e t s c o n t a i n i n g 0 , ^ and 4 p e r c e n t egg d i e t s
d u rin g 3 seven day p e r i o d s .
....................................
78

lid .

R elatio n of n itro g e n r e te n tio n to n itro g e n in ta k e fo r
r a t s f e d d i e t s c o n ta i n in g 0 , 2 and 4 P®r c e n t egg d i e t s
d u rin g 3 seven day p e r i o d s ......................
79

lie .

R e l a t i o n o f n i t r o g e n r e t e n t i o n to c a l o r i c i n ta k e f o r
r a t s fe d d i e t s c o n ta i n in g 0 , 2 and 4 p e r cen t egg d i e t s
...................... •
80
d u rin g 3 seven day p e r i o d s .

Ilia .

Illb .

IIIc.

IV a .

E f f e c t o f v a r y in g th e c a l o r i c v a lu e o f d i e t s on w eigh t
change v e r s u s n itr o g e n in t a k e cu rv e s f o r r a t s fe d
g ra d e d l e v e l s o f egg n i t r o g e n .................................................

81

E f f e c t of v a ry in g th e c a l o r i c v a lu e of d i e t s on w eight
change v e r s u s n i t r o g e n r e t e n t i o n curves f o r r a t s
f e d g ra d e d l e v e l s of egg n i t r o g e n .........................................

82

E f f e c t o f v a ry in g th e c a l o r i c v a lu e of d i e t s on
n i t r o g e n r e t e n t i o n v e rs u s n i t r o g e n i n ta k e c u rv e s f o r
r a t s fe d g ra d e d l e v e l s of egg n i t r o g e n ...............................

83

Comparison o f w eigh t change v e rs u s n i t r o g e n in t a k e
c u rv e s f o r two g ro u p s o f r a t s f e d d i e t s c o n ta i n in g
0 t o 4 p e r c e n t d r i e d e g g ..............................................................

84

IV b .

Comparison o f w e ig h t change v e r s u s n itr o g e n r e t e n t i o n
c u rv e s f o r two groups o f r a t s fed d i e t s c o n ta i n in g
0 t o 4 p e r cen t d r i e d e gg ...................... ........................................ 83

IV c .

Comparison o f n i t r o g e n r e t e n t i o n v e r s u s n i t r o g e n in t a k e
c u rv e s f o r two g rou p s o f r a t s fe d d i e t s c o n ta in in g 0
t o 4 p e r cen t d r i e d e g g ........................................................................ 86

V a.

Vb*

S c a t t e r diagram showing re s p o n s e s o f i n d i v i d u a l r a t s
t o d i e t s c o n t a i n i n g 0 t o 20 p e r c e n t pea b e a n s . . . .

87

S c a t t e r diagram showing re s p o n s e s o f i n d i v i d u a l r a t s
t o d i e t s c o n t a i n i n g 0 t o 20 p e r c e n t p ea b e a n s . . . .

88

Page
Vc

S c a t t e r diagram showing re s p o n s e s o f i n d i v i d u a l
r a t s t o d i e t s c o n t a i n i n g 0 t o 20 p e r c e n t pea b e a n s . •

89

V ia .

R e l a t i o n o f w eig ht change t o n i t r o g e n in t a k e i n
a l b i n o r a t s f e d d i e t s c o n ta i n in g 0 t o 20 p e r c e n t
p e a b e a n s . ................................................................................................... 90

V lb .

R e l a t i o n o f w e ig h t change t o n i t r o g e n r e t e n t i o n in
a l b i n o r a t s f e d d i e t s c o n ta i n in g 0 t o 20 p e r c e n t
p ea b e a n s .................................................................................. ...

91

R e l a t i o n o f n i t r o g e n r e t e n t i o n t o n i t r o g e n i n ta k e i n
a l b i n o r a t s fe d d i e t s c o n ta i n in g 0 t o 20 p e r cent pea
b e a n s ..........................................................................................................

92

V ic .

V ile .

Comparison o f w eig ht change v e r s u s n i t r o g e n i n t a k e
c u rv e s f o r r a t s r e c e i v i n g 0 to 3«74 mg* hean n i t r o g e n
and 0 t o 3*93 “ g* eE£ n i t r o g e n p e r gram i n i t i a l w e ig h t
p e r w e e k ........................................................................................................93

V llb .

Comparison o f w eight change v e r s u s n i t r o g e n r e t e n t i o n
c u rv e s f o r r a t s r e c e i v i n g 0 t o 5*74 mg« hean n i t r o g e n
and 0 t o 3*93
e && n i t r o g e n p e r gram i n i t i a l w eight
p e r week
...............................................................................

V ile .

94

Comparison o f n i t r o g e n r e t e n t i o n v e r s u s n i t r o g e n i n t a k e
c u rv e s f o r r a t s r e c e i v i n g 0 t o 3*74 JBg* hean n i t r o g e n
and 0 t o 3 . 9 3 mg. egg n i t r o g e n p e r gram i n i t i a l w eight
p e r w e e k ....................................................................................................... 93

STATEMENT MID JUSTIFICATION OF ThE

PROBLEM

The u se o f n itro g e n b ala n ce experim ents f o r stud ying p r o te in
m etabolism d a tes back to I 893 when, according to Mmro (1 9 3 1 ),
B ou ssin gau lt d e scr ib e d th e f i r s t n itro g e n balance experiment in a
French s c i e n t i f i c journal*

I n v e s tig a to r s o f the l a t t e r h a lf o f th e

n in etee n th century used t h i s techniq ue m ainly a s a to o l fo r stu d y in g
p r o te in requirem ents and tr y in g to e s t a b lis h a minimum p r o te in r e q u ir e ­
ment fo r man.

Rubner (1897) advanced the h y p o th e sis th a t p r o te in s from

v a r io u s food sou rces were not a l l o f the same v a lu e in n u t r it io n and
th a t th er e was not a s in g le " p rotein minimum" f o r humans but as many
p r o te in minima as th ere are p r o te in s .

The ex p la n a tio n fo r the e x is t e n c e

o f th e se v a r io u s p r o te in minima l i e s in the f a c t th a t n a tu r a lly occu rrin g
p r o te in s d i f f e r in t h e ir amino a c id com position and so d i f f e r in t h e ir
a b i l i t y t o supply amino a c id zequirem ents o f o th er s p e c ie s and in the
f a c t th a t p r o te in requirem ents are in flu en ced by n o n -p ro tein c a lo r ie s
o f th e d ie t (M inro, 1931) 011(1 o th e r fa c to r s (C a th ea rt, 1921, Ifeln ick
and C o w g ill, 1937)*

Subsequently t h i s d iffe r e n c e in n u t r it iv e v a lu e o f

p r o te in s was measured by s e v e r a l " b io lo g ic a l value" methods, the
b io lo g ic a l valu e o f a g iv e n p r o te in being g e n e r a lly d efin ed as the
fr a c t io n o f absorbed food n itr o g e n which i s r e ta in e d in th e body o f an
an im al.

For a com prehensive review on the su b jec t o f b io lo g ic a l v a lu e

- 2 -

o f food p r o t e i n s and m ethods o f e s t i m a t i n g b i o l o g i c a l v a l u e s , th e
r e a d e r i s r e f e r r e d t o th e f o ll o w i n g :

M i t c h e l l and H am ilton (1 92 9),

B o a s -F ix se n ( 1 9 3 4 )» M i t c h e l l ( 1 9 4 4 ) . C a h i l l ( 19 4 5 ) 011(1 -Block and
M i t c h e l l (1 94 6 )-

The work r e p o r t e d h e re d e a ls w ith th e e v a l u a t i o n

o f d i e t a r y p r o t e i n u s in g m aintenan ce o f n i t r o g e n b a la n c e and body
w e ig h t a s c r i t e r i a o f b i o l o g i c a l v a l u e .
Thomas ( 1 9 0 9 ) p ro p o se d a method f o r e s t i m a t i n g th e b i o l o g i c a l
v a lu e o f v a r i o u s p r o t e i n s f o r humans which made use o f t h e n i tr o g e n
b a la n c e te c h n iq u e .

T h is method has been developed f o r use w ith th e

la b o r a t o r y r a t by M i t c h e l l and cow orkers (I9 2 4 , 1 9 4 4 ) who b a se t h e i r
concept

o f b i o l o g i c a l v a lu e on the assu m ption t h a t the n i t r o g e n e x ­

c r e t i o n o f an animal on a p r o t e i n - f r e e r a t i o n , or th e endogenous n i t r o ­
gen e x c r e t i o n , i s c o n s ta n t f o r a g iv e n a n im a l, and so can be used f o r
d e te r m in in g th e a c t u a l amount o f n i t r o g e n a bso rb ed from a r a t i o n to
which p r o t e i n from a foo d so u rce has been added.
The i d e a o f an e x i s t e n c e o f a c o n s ta n t endogenous n i t r o g e n e x ­
c r e t i o n i s based p r i m a r i l y on th e e a r l y th e o r y o f F o l i n ( 1 9 0 5 ) which
d i s t i n g u i s h e s between two k in d s o f p r o t e i n c a ta b o lis m , one o f which " i s
e x tre m e ly v a r i a b l e i n q u a n t i t y , th e o t h e r te n d s to re m a in c o n s t a n t . "
The v a r i a b l e c a ta b o lis m o f F o l i n was c o n sid e re d to be o f d i e t a r y o r i g i n
and th e c o n s t a n t , o f t i s s u e o r i g i n r e p r e s e n t i n g "an e s s e n t i a l p e r t o f
th e a c t i v i t y which d i s t i n g u i s h e s l i v i n g c e l l s from dead o n e s."
The e x i s t e n c e o f com plete independence o f endogenous and exogenous
t y p e s o f n i t r o g e n m e ta b o lism has been c h a lle n g e d by s e v e r a l i n v e s t i g a t o r s .
Schoenheim er and a s s o c i a t e s (1939) u s in g amino a c id s w ith i s o t o p i c n i t r o ­
gen have shown a r a p i d and e x t e n s i v e in te r c h a n g e of n i t r o g e n between d i e t ­
a r y amino a c id s and t i s s u e p r o t e i n s .

From t h i s ana s i m i l a r s t u d i e s ,

Schoenheim er ( 1 9 4 2 ) p r e s e n te d h i s concept o f a dynamic s t a t e o f bouy

- 3 -

c o n s t i t u e n t s , w hich, a c c o rd in g t o th e a u t h o r , “can s c a r c e l y be r e c o n c i l e d
w ith th e th e o ry o f in d e p e n d e n t endogenous and exogenous ty p e s o f m e ta b o lism ."
The e x i s t e n c e o f a c e r t a i n f l u i d i t y o f food and t i s s u e p r o t e i n s i s
a l s o im p lie d by Madden and Whipple ( 1940)

t h e i r rev iew on s o u rc e , p r o ­

d u c tio n and u t i l i z a t i o n o f plasm a p r o t e i n s .
Willman and cow orkers (1945) found t h a t when th e a lb in o r a t i s fe d
a r a t i o n low i n n itr o g e n o u s c o n s t i t u e n t s b u t o th e rw is e a d e q u a te , th e
n i t r o g e n m e ta b o lism , a f t e r an i n i t i a l r e d u c t i o n , p ro c e e d s a t a fai&y
co n sta n t r a t e .

However, when whole egg, e q u i v a l e n t t o 3 .5 p e r c e n t o f

p r o t e i n supplem ented th e r a t i o n i n a second m etab olism p e r i o d , th e
q u a n t i t y o f n itr o g e n e l i m i n a t e d i n th e u r i n e was about o n e - t h i r d l e s s
th a n -chat o f th e p r e v io u s n itr o g e n - l o w p e r io d .
o f c r e a t i n i n e t o be s i m i l a r l y a l t e r e d .

They found th e e x c r e t i o n

These a u th o r s f e e l t h a t , "the

d e p r e s s i o n o f th e s o - c a l l e d endogenous m etab olism by th e sim ple a d d i t i o n
o f foo d p r o t e i n c a s t s doubt on th e v a l i d i t y o f th e d i s t i n c t i o n made by
F o l i n betw een endogenous and exogenous m e ta b o lism , and g i v e s vfeight
from a n o th e r e x p e r im e n ta l approach t o r e c e n t c o n c e p ts o f th e f l u i d i t y
o f body p r o c e s s e s and o f th e e x i s t e n c e of a dynamic r e l a t i o n between
food p r o t e i n s and t i s s u e p r o t e i n s . "
M i t c h e l l ( 19.5 0 ) , however, m a in ta in s t h a t th e "independence o f
endogenous and th e exogenous m etab olism o f n i t r o g e n was co n firm ed
e x p e rim e n ta lly ."
The i n c r e a s i n g evidence t h a t body c o n s t i t u e n t s a re i n a c o n s ta n t
s t a t e o f f l u x coupled w ith th e f a c t thatrrany w orkers have e x p e rie n c e d
d i f f i c u l t y i n o b t a i n i n g c o n s ta n t endogenous v a l u e s f o r e x p e r im e n ta l
a n im a ls has l e d t o a d i f f e r e n t approach to t h e problem o f a s s e s s i n g
p r o t e i n r e q u ir e m e n ts o f a n im a ls by th e b a la n c e te c h n iq u e .

-4 -

R e c e n tly M elnick and Cowgill ( 1937) d e s c r ib e d a method f o r
e s t i m a t i n g t h e " p r o t e i n minimum f o r n i t r o g e n e q u i l i b r i u m i n d o g s."
The method used by th e s e i n v e s t i g a t o r s employs a d i r e c t b a la n c e s h e e t
t e c h n iq u e which makes no c o r r e c t i o n f o r endogenous n i t r o g e n e x c r e t i o n
and which i n v o l v e s th e u se of a n im als i n n e g a ti v e n itr o g e n b a la n c e a t
s e v e r a l l e v e l s o f n i t r o g e n i n t a k e ,j i t h a d eq uate c a l o r i c i n t a k e .

Under

th e s e c o n d i t i o n s t h e a u th o r s found a l i n e a r r e l a t i o n s h i p between n i t r o ­
gen b a la n c e and th e p e r c e n t p r o t e i n c a l o r i e s i n th e d i e t .

In t h i s

method minimum p r o t e i n re q u ire m e n t f o r n i t r o g e n e q u i l i b r i u m i n th e anim al
i s e s ti m a te d from th e z e ro n i t r o g e n b a lan c e i n t e r c e p t and b i o l o g i c a l
v a lu e s a r e c a l c u l a t e d a s s i g n i n g la c ta lb u m in a va lu e o f 100 p e r c e n t ,
A L lison e t a l . (1945» 194&) u sed t h i s method i n s t u d i e s on dogs to
" e s t a b l i s h more c l e a r l y o ver a w id e r range o f v a lu e s t h e r e l a t i o n b e ­
tween ab so rb ed food n i t r o g e n , n i t r o g e n b a la n c e , and th e b i o l o g i c a l v a lu e
of p ro te in s."

B r i c k e r , M i t c h e l l and Kinsman ( 194 5 ) a n d B egsted and c o ­

w orkers (1946) have a d ap te d t h i s method t o th e stu d y o f n i t r o g e n r e q u i r e ­
m ents o f a d u l t human s u b j e c t s and B r ic k e r and M itc h e ll ( 1 9 4 7 ) have u s e d a
m o d i f i c a t i o n o f t h i s method f o r e s ti m a ti n g p r o t e i n re q u ire m e n ts of a d u lt r a t s .
Osborne and Mendel ( 1915* 1919) d e v ise d a method f o r a s s e s s i n g th e
v a lu e of fo o d p r o t e i n by a l t e r i n g p r o t e i n i n t a k e of a n im als u n t i l body
w eight rem ained c o n s ta n t f o r s e v e r a l weeks.

These a u th o r s r e p o r t e d wide

v a r i a t i o n i n r e s p o n s e s o f i n d i v i d u a l anim als and concluded t h a t sm all
d i f f e r e n c e s between p r o t e i n s were not d i s t i n g u i s h e d by t h i s method.
G o e tts c h ( 1951) r e p o r t e d work i n which b o th n i t r o g e n b a la n c e and
w eig h t m aintenance .vere used a s i n d i c e s o f minimum p r o t e i n m ain ten ance
needs.

T his work i n d i c a t e d t h a t th e minimum n i t r o g e n re q u ire m e n t f o r

w eigh t m aintenance i s s l i g h t l y h ig h er than th a t fo r maintenance o f
n itr o g e n e q u ilib r iu m .
I t i s the purpose o f the work rep orted h e r e in to e v a lu a te o b j e c t iv e ly
th e a p p lic a tio n o f th e se b io lo g ic a l v a lu e tech n iq u es to the problem o f
e stim a tin g minimum n itr o g e n balan ce and w eight m aintenance requirem ents
fo r the young a lb in o r a t .

EXPERIMENTAL PROCEDURE

Sprague Bawley a l b i n o r a t s w eighing a p p ro x im a te ly 150 grams
were used, as e x p e r im e n ta l a n im a ls.

A b a s a l d i e t (T ab le 1 ) supplem ented

w ith g ra d e d amounts o f n i t r o g e n and f a t was used th ro u g h o u t th e
e x p e r im e n t.

Sources o f d i e t a r y n i t r o g e n were a com m ercially d r i e d whole

egg p ro d u c t w hich had been f a t e x t r a c t e d i n th e l a b o r a t o r y and a
M i c h i l e t e pea bean su p p lem en t.

T h is was p re p a re d a s fo llow s* d r i e d

b eans were soaked o v e r n i g h t , b o i l e d slow ly f o r f i v e b o u rs e , pushed
th ro u g h a c o a r s e s i e v e , r e d r i e d a t room te m p e r a tu r e , and ground t o a
c o a r s e powder i n a commercial c o f f e e g r i n d e r .
s o u rc e o f added f a t .

Lard was u sed as a

The supplem ents were added to e x p e r im e n ta l

d i e t s i n amounts i n d i c a t e d i n T able 1 .

D ie ts B, C, E, D, and F were

supplem ented w i t h from 2 t o 10 p e r cent d r ie d whole egg, d i e t s D and
F v/ith an a d d i t i o n a l 8 p e r c e n t f a t , and d i e t s G, H, I , and J w ith
from 12 t o 20 p e r c e n t o f th e bean p r e p a r a t i o n .

D ie ta r y supplem ents

r e p la c e d e q u a l w e ig h ts o f c o r n s t a r c h i n th e b a s a l d i e t .

New d i e t s

were compounded f o r e ac h 11 day p e r i o d end s to r e d i n th e r e f r i g e r a t o r .
The co m p o sitio n o f th e s e e x p e r im e n ta l d i e t s i s s i m i l a r to th o s e commonly
used i n b i o l o g i c a l v a lu e d e te r m in a tio n e x p e rim e n ts.
Animals were housed i n i n d i v i d u a l cages and o f f e r e d 12 t o 13
grains o f food p e r day.

Food was weighed d a i l y and mixed w ith d i s t i l l e d

w a te r to a t h i c k p a s t e t o p re v e n t s c a t t e r i n g .

Waste food was c o l l e c t e d

-7 -

d r ie d a t room tem perature and w eighed in order to o b ta in food in ta k e .
The fe e d in g p a tte rn used in t h i s experim ent was a double c r o s s -o v e r
d e sig n in which 3 groups o f 4 anim als each ( t o t a l o f 12 anim als)
r e c e iv e d the same 3 l i e t s in d if f e r e n t sequence.

T his fe e d in g p a tte rn

i s p resen ted in Table 7 fo r the f i r s t 12 anim als (D esign 1 , d i e t s A,
B, C) and was r e p lic a te d f o r d ie t s A, C and D in D esign 2 (an im als
13 t o 2 4 ). fo r d ie t s A, C and F in D esign 3 (anim als 23 to 3 6 ) , and fo r
d i e t s G, H and I in D esign 4 (a n im tls 37 to 47)*

R e su lts from d ie t

I and J (an im als 48 t o 71) were taken from a s im ila r fe e d in g experim ent*
Table 7 a ls o d e s c r ib e s the p a tte rn fo r s t a t i s t i c a l e v a lu a tio n o f the
e f f e c t s o f in d iv id u a l r a t s , sequence o f fe e d in g d ie t s (I* I I , I I I ) ,
groups o f anim als (a , b , c end d ) , end d ie t s f e d .
E leven day fe e d in g p erio d s c o n s is t in g o f a 4 day adjustm ent and a
7 day b alan ce oeriod were used throughout the experim ent.

At the

b eginn ing o f each balance p erio d anim als were weighed and th e ir cages
were p la ced over la r g e pyrex d is h e s lin e d w ith f i l t e r paper which had
been tr e a te d w ith d ilu t e h y d ro ch lo ric a cid fo r c o lle c t i n g u rin e sam ples.
U rine, f e c e s and s c a tte r e d food were c o lle c t e d every 24-48 hours during
balance p e r io d s .

Hair and s c a tte r e d food were brushed from u rin e and

f e c a l sam ples w ith a f in e ca m el-h a ir brush.

Separate com p osites o f

u rin e and f e c e s fo r each balance p erio d were sto r e d in 20 per cen t
(by w eigh t) h y d ro ch lo ric a c id .

At the end o f th e seven day c o l l e c t i o n ,

anim als were w eighed and p la ced on the next d ie t in th e fe e d in g s e r i e s .
The d iffe r e n c e between the w eig h ts taken at the b egin n in g and a t the
end o f a b alan ce p erio d i s th e w eight change fo r th at p e r io d .

-8 -

C aloric v a lu e s and n itro g e n co n ten t were determ ined fo r each
l o t o f d ie t s prepared (Table 1 ) .

A cid d ig e s t s were made o f the

seven day com p osites o f u rin e and f e c a l c o lle c t i o n s according to th e
procedure o f S tearn s (1929)•

S u ita b le a liq u o ts o f th ese were used fo r

determ inin g n itro g e n e x c r e tio n .

N itrogen con ten t o f fo o d , urine and

f e c e s was determ ined by th e Gunning-Arnold m o d ific a tio n o f the K jeld ah l
procedure (A s so c ia tio n o f O f f ic i a l A g ricu ltu re Chem ists, 1940)*

Cal o r i c

con ten t o f food sam ples was determ ined by d ir e c t combustion in the
liner son bomb*

DISCUSSION OF RESULTS

Data on n i t r o g e n b a la n c e and w eight change f o r i n d i v i d u a l r a t s
a re p r e s e n t e d i n th e f o ll o w i n g t a b l e s * 2a, 2b, 2 c , 2d, and 2e«
These d a t a have been red u ced t o u n i t s p e r gram i n i t i a l w eig h t i n o r d e r
t o e l i m i n a t e d i f f e r e n c e s i n w eight as a s t a t i s t i c a l v a r i a b l e .

Group

means a re a l s o shown i n T a b le s 2a t o 2 e .
In th e d i s c u s s i o n which f o l l o w s , r e s u l t s o f t h i s stu d y a r e
c o n s id e r e d i n t h r e e u n its *
(1 )

The d i s c u s s i o n o f a s t a t i s t i c a l tr e a tm e n t o f d e s ig n

one i s p r e s e n t e d .

The d i e t s o f f e r e d a n im a ls i n t h i s d e sig n

g iv e n i t r o g e n b a la n c e c a rv e s s i m i l a r t o th o se r e p o r t e d i n
t h e Jifelnick-C ow gill ( 1937) stm s i m i l a r b i o l o g i c a l v a lu e
method s t u d i e s ;

t h a t i s , c u rv e s based p r i m a r i l y on d a t a from

a n im a ls i n n e g a tiv e n i t r o g e n b a la n c e .
(2 )

The d i s c u s s i o n i n t h i s c a s e i s concerned w ith f a c t o r s

r e l a t e d t o th e problem o f i n t e r p r e t i n g n i t r o g e n m e ta b o lism
d a ta .

D rie d whole egg was u sed a s a sou rce o f n i t r o g e n f o r

t h e r e s u l t s d i s c u s s e d i n u n i t s ( l ) and ( 2 ) .
(3 )

T h is d i s c u s s i o n c o n s i d e r s th e r e s u l t s from a s e r i e s of

d i e t s c o n t a i n i n g M L chilete pea beans as a s o u rc e o f n i t r o g e n .
(1)

Di s c u s s i o n o f r e s u l t s from d e s ig n one
The t h r e e d i e t s used i n d e s ig n one w ere:

D ie t A, a b a s a l o r lcw -

n i t r o g e n d i e t t o w hich no p r o t e i n supplem ent had been added;

D ie t B,

a d i e t c o n t a i n i n g an amount o f egg p r o t e i n i n s u f f i c i e n t t o m a in ta in

10-

n i t r o g e n e q u i l i b r i u m i n th e a n im a ls ; and d i e t C, a d i e t c o n ta i n in g
enough egg n i t r o g e n t o su p p o rt n i t r o g e n e q u i l i b r i u m i n some o f th e
e x p e r im e n ta l a n im a ls as d e te rm in e d by B r ic k e r and M itc h e ll ( 1947)*
These d i e t s were fe d i n d i f f e r e n t sequence t o t h r e e groups o f f o u r
r a t s e ach t o o b t a i n d a ta f o r p r e d i c t i n g t h e i r minimum p r o t e i n r e q u i r e ­
m e n ts .

V a r i a t i o n s were ob serv ed i n anim al re s p o n s e s which r a i s e d a

q u e s t i o n r e g a r d i n g th e j u s t i f i c a t i o n o f such p r e d i c t i o n s .

T h erefore,

a com prehensive s t a t i s t i c a l a n a l y s i s o f d a t a was c a r r i e d o u t i n an
a tte m p t t o d e te rm in e what f a c t o r s had s i g n i f i c a n t i n f l u e n c e i n
c o n t r o l l i n g anim al re s p o n s e s t o th e d i e t s f e d .
a.

V a r i a t i o n s o b se rv e d i n r e s p o n s e s o f i n d i v i d u a l r a t s and

g ro u p s o f r a t s .

E x a m in a tio n o f d a t a from d e sig n one (T able 2a ) shows

d i f f e r e n c e s i n i n d i v i d u a l r e s p o n s e s t o th e d i e t s f e d .

.Although th e

mean i n i t i a l w eig h t o f each group o f a n im als a t th e b e g in n in g o f th e
e x p erim en t was a p p ro x im a te ly ljjO gram s, t h i s w eight was not m a in ta in e d
d u rin g th e f i r s t f o u r - d a y a d ju stm en t p e r io d f o r any group o f anim als*
A f a i l u r e t o m a in ta in body w e ig h t on d i e t A ( t h e lo w -n itro g e n d i e t )
and d i e t B ( t h e b a s a l d i e t w ith two grams o f s t a r c h r e p l a c e d by d r i e d
egg) d u rin g th e t h r e e b a la n c e p e r i o d s i s c l e a r l y shown.

T h is l o s s

o f body w e ig h t, how ever, cannot be a t t r i b u t e d t o f a i l u r e to consume
s u f f i c i e n t c a l o r i e s f o r w eigh t m aintenan ce s in c e th e c a l o r i c in t a k e
p e r gram i n i t i a l w eight was a s h ig h f o r some a nim els on d i e t s A and
B t h a t were l o s i n g w eight a s f o r th o s e anim als on d i e t G ( th e 4 p e r
c e n t egg d i e t ) which were g a in in g w e ig h t.

N itro g e n i n t a k e s o f

i n d i v i d u a l a n im a ls on d i e t A showed a v a r i a t i o n o f from 0 .2 0 t o 0 .4 4

-1 1 -

m illi g r a m s p e r gram i n i t i a l w eig h t p e r week.

On d i e t B n i t r o g e n i n -

S

t a k e v a r i e d from 0.81 t o 1 .^ 6 m illi g r a m s , and on d i e t C from 1 .6 1
t o 3*15 m i l l i g r a m s p e r gram i n i t i a l w eig ht p e r week.

N itro g e n

r e t e n t i o n s o f t h e s e a n im als a p p e a rs to be a s s o c i a t e d w ith w eight
changes i n t h a t r a t s w ith n e g a tiv e n i t r o g e n b a la n c e were l o s i n g
w eight and t h o s e w ith p o s i t i v e n i t r o g e n b a la n c e were m a in ta in in g
w eig ht o r g a i n i n g .
The ra n g e s and means o f r e s u l t s (Table 3 ) i n d i c a t e re sp o n se
d i f f e r e n c e s f o r th e t h r e e g ro u p s o f anim als o b s e rv e d .

The p e r i o d o f

f e e d in g any one d i e t a p p e a rs m arkedly t o i n f l u e n c e r e s u l t s o b ta in e d .
Animals r e c e i v i n g d i e t A (low n i t r o g e n ) d u rin g p e r io d I l o s t an a v erag e
o f 0 .1 1 2 grams p e r gram i n i t i a l w eig ht d u rin g th e seven day b a la n c e
p e r i o d ; a n im a ls which r e c e iv e d t h i s d i e t i n p e r i o d I I l o s t an av erag e
o f 0 .0 9 1 grams p e r gram i n i t i a l w eight and th o se on t h i s same d i e t in
p e r i o d I I I l o s t o n ly O.O67 grams p e r gram i n i t i a l w e ig h t.

Thus, d u rin g

s u c c e s s iv e b a la n c e p e r i o d s , t h e r e a p p e a rs t o be a decreasing, r a t e of
l o s s i n th e two g ro up s o f an im als o f f e r e d d i e t A a f t e r d i e t s C and B
re sp e c tiv e ly .

N itro g e n l o s s e s on d i e t A fo llo w e d th e same p a t t e r n ;

f o r p e r io d s I , I I and I I I th e n i t r o g e n l o s s e s were 2 . 0 4 , 1 .2 8 and I . I 3
m i l l i g r a m s pergrain i n i t i a l w eigh t r e s p e c t i v e l y .

Food in ta k e a s i n ­

d i c a t e d by c a l o r i c consum ption a l s o showed a s i m i l a r d e c r e a s e ; t h a t
I
i s , f o r p e r i o d s I , I I and I I I , 1 -3 1 *
ancl 1 .0 6 c a l o r i e s p e r gram
i n i t i a l w e ig h t were consumed, r e s p e c t i v e l y .
While th e o v e r a l l a v erag e w eig h t d e c r e a s e f o r a n im a ls on th e
d i e t t o which 2 p e r c e n t whole d e f a t t e d d r ie d egg was added ( d i e t B)
was 0.030 grams p e r gram i n i t i a l w eight a s compared t o 0.090 gram l o s s on

-1 2 -

th e l o w - n it r o g e n d i e t ( d i e t A), and w h ile th e average n i t r o g e n l o s s
was 0 .0 5 8 m illi g r a m s f o r d i e t B c o n t r a s t e d t o 0.1 4 3 f o r d i e t A, xhe
g e n e r a l p a t t e r n o f re s p o n se f o r a n im a ls on d i e t B was s i m i l a r t o t h a t
d e s c r ib e d f o r d i e t A.

The a n im a ls which r e c e i v e d d i e t B d u rin g

p e r i o d I l o s t an av erag e o f O.O64 grams p e r gram i n i t i a l w e ig h t; i n
p e r i o d s I I and I I I th e a v erag e l o s s e s d e c re a s e d t o O.Olo and 0.011
grams p e r gram i n i t i a l w e ig h t r e s p e c t i v e l y .

Average n i t r o g e n l o s s e s

o f a n im a ls on d i e t B d u r in g the t h r e e b a la n c e p e r i o d s were 0 . 115»
0*038 and 0 .0 1 c m illi g r a m s p e r gram i n i t i a l w e ig h t.

C a lo ric consum ption

on t h i s d i e t was about th e same d u rin g p e r i o d s I and I I ( 1 .5 8 c a l o r i e s
i n I and I .5 8 c a l o r i e s i n I I ) b u t d e c re a s e d t c 1 .2 7 c a l o r i e s p e r gram
i n i t i a l w e ig h t i n p e r i o d I I I .
Thus, th e change i n re s p o n se observed i n anim als on d i e t s A and
B was a d e c r e a s e i n w e ig h t l o s s , n i t r o g e n l o s s end c a l o r i c consumption
d u rin g th e t h r e e s u c c e s s i v e b a la n c e p e r i o d s .
A c o n s i s t e n t change i n anim al re s p o n se s d u rin g s u c c e s s iv e f e e d ­
in g p e r i o d s was n o t o b serv ed when an im als were fe d a d i e t supplem ented
w ith 4 p e r c e n t d r i e d egg ( d i e t C).

Most anim als g a in e d w eight and were

i n p o s i t i v e n i t r o g e n b a la n c e on t h i s d i e t .

For p e r i o d s I , I I and I I I

w eig h t changes were 0.041* 0.011 and 0.028 grams; n i t r o g e n r e t e n t i o n s 1*30,
O.33 and 0 .7 2 m illi g r a m s ; and energy i n t a k e s 2 . 2 2 , I . 7 0 and 1.49
c a l o r i c s consumed p e r gram i n i t i a l w eig h t r e s p e c t i v e l y .

The p a t t e r n s

o f w e ig h t change and n i t r o g e n r e t e n t i o n f o r d i e t C a re s i m i l a r i n t h a t
th e l a r g e s t w eig h t g a in and g r e a t e s t n itr o g e n r e t e n t i o n on t h i s d i e t
o c c u r r e d i n p e r io d I , th e s m a l l e s t w eig ht g a i n and l e a s t n i t r o g e n
r e t e n t i o n o c c u r re d i n p e r i o d I I , and th e r e s u l t s f o r p e r i o d I I I f o r

13 -

b o th th e s e v a r i a b l e s were i n t e m e d i a t e between tn o s e o f p e r i o d s I and
II.

The e f f e c t s on w eight ch an ge, c a l o r i e s e a t e n , n i t r o g e n in ta k e

and n i t r o g e n b a la n c e produced by th e sequence o f fe e d in g th e t h r e e
d i e t s a re summarized (T able 4 )*
R o s e n th a l and A l l i s o n ( 19.51) have shown t h a t th r e e dogs w ith
d i f f e r e n t p r o t e i n s t o r e s ( f u l l , i n t e r m e d i a t e and d e p l e t e d ) showed
m arked ly d i f f e r e n t n i t r o g e n r e t e n t i o n s on a d i e t f u r n i s h i n g 3 .8 2
grains o f c a s e i n n i t r o g e n and 478 c a l o r i e s p e r day p e r sq u are m e te r o f
body s u r f a c e .

The dog w ith f u l l n i t r o g e n s t o r e s was i n n e g a ti v e n i t r o ­

gen b a la n c e i n th e p re s e n c e o f th e amount o f n i t r o g e n fe d d u rin g the
e x p e r im e n t.

The dog w ith in t e r m e d i a t e s t o r e s showed i n i t i a l n itr o g e n

e q u i l i b r i u m when f e d t h i s d i e t ; th e d e p le t e d dog was i n p o s i t i v e
n i t r o g e n b a la n c e a t th e b e g in n in g o f th e e x p e rim e n t.

The r e s u l t s

o b ta in e d w ith t h e r a t s i n th e s tu d y r e p o r t e d h e r e i n may be s i m i l a r as
i n d i c a t e d below .
The p r o t e i n s t o r e s of th e s e r a t s were a p p a r e n tly und erg oin g
d e p l e t i o n whenever d i e t s A ( t h e b a s a l d i e t ) o r B ( th e 2 p e r c e n t egg
d i e t ) were f e d a s e v id en c e d by n e g a tiv e n i t r o g e n b a la n c e s f o r t h e s e
two d i e t s ; t h e r e f o r e , i t a p p e a rs p o s s i b l e t h a t d i f f e r e n c e s i n r e s p o n s e s
o f a n im a ls f e d th e same d i e t d u r in g d i f f e r e n t f e e d in g p e r io d s m ight
be due i n p a r t , t o d i f f e r e n c e s i n p r o t e i n s t o r e s o f th e a n im a ls .

The

d e c r e a s e i n th e av erag e w eight l o s s f o r anim als on d i e t s A and B d u r­
in g t h e t h r e e s u c c e s s i v e f e e d in g p e r i o d s a lso may be re g a rd e d a s an
i n d i c a t i o n t h a t th e p r o t e i n s t o r e s o f th e s e a nim als d i f f e r e d end th e s e
d i f f e r e n c e s a r e r e f l e c t e d i n t h e i r re s p o n s e t o th e e x p e r im e n ta l d i e t s .

-1 4 -

Changes i n u r i n a r y and t o t a l n i t r o g e n e x c r e t i o n o f th e anim als
d u r in g th e t h r e e m e ta b o lism p e r io d s

a re shown (T a b le 3 )»

Means f o r

p e r i o d s , d i e t s and g ro u p s o f an im a ls a r e i n d i c a t e d f o r e ac h group o f
f o u r a n im a ls and f o r e l l tw elv e a n im a ls .

The average u r i n a r y n i t r o g e n

f o r th e 12 an im a ls used i n t h i s s tu d y was 1 .3 3 m illi g r a m s p e r gram
i n i t i a l w e ig h t p e r week on d i e t A ( t h e lo w - n itr o g e n d i e t ) , 1 .1 7 m i l l i ­
grams p e r gram i n i t i a l w eight p e r week on d i e t B (th e 2 p e r c e n t egg
d i e t ) , and 1 .0 8 m illig r a m s p e r gram i n i t i a l w eight p e r week on d i e t
C ( t h e 4 P e r c e n t egg d i e t ) ,

however, average t o t a l n i t r o g e n e x c r e t i o n s

d id n o t vary m a rk e d ly , b e in g l » 7 7 t 1 *7° and 1-73 m illig r a m s p e r gram
i n i t i a l w eig h t f o r d i e t s A, B and 0 r e s p e c t i v e l y .

E f f e c t o f d i e t on

u r i n a r y and t o t a l n i t r o g e n e x c r e t i o n were i n c o n s i s t e n t f o r the 3 g ro u p s
o f a n im a ls o b s e rv e d .

One group o f anim als ( 1- 4 ) showed th e l a r g e s t

u r i n a r y and t o t a l n i t r o g e n e x c r e t i o n s on d i e t A , i n t e r m e d i a t e e x c r e t i o n s
on d i e t B and th e s m a l l e s t l o s s on d i e t C.

N itro g e n excretz'ons f o r

an im a ls 5 - 8 were g r e a t e s t f o r d i e t B, i n t e r m e d i a t e f o r d i e t C and s m a ll­
e s t f o r d i e t A, end f o r r a t s y - 1 2 th e l a r g e s t , i n t e r m e d i a t e end s m a l le s t
n i t r o g e n e x c r e t i o n s o c c u rre d on d i e t s C, A end B r e s p e c t i v e l y .
The u r i n a r y n i t r o g e n e x c r e t i o n o f anim als on d i e t A was 1 . 93* 1*16
and O.98 m il l i g r a m s p e r gram i n i t i a l weight d u r in g p e r io d s I, I I and

III r e s p e c t i v e l y .

Comparable p e rio d l o s s e s f o r an im als on d i e t s B and

C were o b ta in e d .

These were 1 . 6 6, 1 .0 5 and 0 .7 8 m illi g r a m s f o r d i e t B

and f o r d i e t C, 1 . 2 0 , 1 .21 and 0 .8 4 m illig ra m s p e r gram i n i t i a l w eight
i n p e r i o d s I, II and I I I r e s p e c t i v e l y .

S im ilar p a tte r n s o f t o t a l n i t r o ­

gen e x c r e t i o n were o b serv ed f o r t h e t h r e e d i e t s .

-1 5 -

The e f f e c t o f p e r i o d s on mean u r i n a r y and t o t a l n i t r o g e n e x c r e t i o n
o f t h e t h r e e g ro u p s o f an im a ls o b serv ed i s s i m i l a r to th e e f f e c t o f d i e t
r e s p o n s e s d u r in g s u c c e s s iv e p e r io d s ; namely, n itr o g e n e x c r e t i o n f o r any
one group o f a n im a ls d e c re a se d w ith s u c c e s s iv e fe e d in g p e r i o d s r e g a r d l e s s
o f d i e t fe d (T ab le 6 ) .

The s i g n i f i c a n c e o f t h i s d e c re a s e i n u r i n a r y

n i t r o g e n e x c r e t i o n w i l l be d i s c u s s e d i n P a r t Two.
A s e r i e s o f diagram s ( F ig u r e s l a t o I c ) have been p re p a re d t o

show t h e r e l a t i o n o f w e ig h t change (y ) t o n i t r o g e n e a t e n ( x ) , c a l o r i e s
e a t e n ( z ) and n i t r o g e n b a la n c e (w ).

The diagrams showing th e r e l a t i o n

o f n i t r o g e n b a la n c e (w) t o n i t r o g e n e a te n ( x ) and c a l o r i e s e a te n ( z )
show s i m i l a r v a r i a t i o n s so a re not re p ro d u c e d h e r e .

P o i n t s on th e

d iag ram s o b ta in e d from i n d i v i d u a l r a t s a re co n n ected t o i n d i c a t e
i n d i v i d u a l d i f f e r e n c e s o f an im als which r e c e iv e d th e t h r e e d i e t s i n th e
order in d ic a te d .

E xam ination o f t h i s s e r i e s o f diagram s c o n firm s th e

o b s e r v a t i o n t h a t th e p a t t e r n o f re sp o n se f o r i n d i v i d u a l r a t s a p p e a rs
t o be i n f l u e n c e d by th e o r d e r o r sequence o f f e e d in g th e t h r e e d i e t s .
S pot diagram s o f w e ig h t change ( y ) v e r s u s n i t r o g e n i n t a k e ( x ) ,
c a l o r i c i n t a k e ( z ) and n i t r o g e n b s la n c e (..)'» and n i t r o g e n b a la n c e (w)
v e r s u s n i t r o g e n in ta k e (x ) - n d c a l o r i c in ta k e ( z ) were p r e p a r e d , ( F ig ­
u re

Ila to

lie ).

R e g r e s s io n l i n e s f o r th e s e p o i n t s were computed u s ­

in g th e fo rm u la f o r a s t r a i g h t l i n e and w i l l be d is c u s s e d l a t e r .

In

th e s e d ia g ra m s, p o i n t s r e p r e s e n t i n g d a ta o b ta in e d i n th e t h r e e d i f f e r e n t
p e rio d s are in d ic a te d .

Exam ination o f th e s e p o i n t s s u b s t a n t i a t e s th e

o b s e r v a t i o n t h a t th e e f f e c t o f p e r io d s m ight be a d e te rm in in g f a c t o r
i n p r e d i c t i n g minimum n i t r o g e n and c a l o r i c in t a k e re q u ir e m e n ts f o r
w eig h t m a in te n a n c e .

There i s a marked tendency f o r p o i n t s o b ta in e d

-1 6 -

from p e r i o d I I t o f a l l between t h o s e from p e r io d s I and I I I i n th e
r e g r e s s i o n o f w e ig h t change on n i t r o g e n in ta k e (y = a + bx) and c a l o r i c
i n t a k e (y = a + bz)*

The same p a t t e r n f o r p e r io d s i s e v id e n t f o r th e

p r e d i c t i o n o f n i t r o g e n r e t e n t i o n u s in g n i t r o g e n in t a k e (w = a + bx) and
c a l o r i c i n t a k e (w = a + b z ) a s in d e p en d e n t v a r i a b l e s .

P o i n t s on th e

r e g r e s s i o n o f Y/eight change and n i t r o g e n r e t e n t i o n (y = a + bw), however,
a p p e a r t o be much l e s s a f f e c t e d by p e r i o d s o f f e e d in g .
b.

E v a lu a tio n o f e f f e c t s of e x p e r im e n ta l p ro c e d u re on r a t re s p o n s e s

by an a n a l y s i s o f v a r i a n c e .

E x p e rim en ta l v a r i a t i o n s such as th o s e

d e s c r ib e d l e d t o th e use o f s t a t i s t i c a l a n a l y s i s f o r f u r t h e r i n t e r p r e t a t i o n
o f d a t a from d e s ig n one.
The f i r s t q u e s t i o n c o n s id e r e d i n t h i s i n t e r p r e t a t i o n was th e
s i g n i f i c a n c e o f th e e f f e c t o f i n d i v i d u a l a n im a ls ( r a t s ) , f e e d in g p e r io d s
( p e r i o d s ) and d i e t s on th e r e s p o n s e s o f an im als o b s e r v e d .

For t h i s

e v a l u a t i o n d a t a were grouped i n f o u r L a tin s q u a r e s a s i n d i c a t e d i n Table
7 and s u b j e c t e d t o an a n a l y s i s o f v a r i a n c e .

Goulden (1952 ) and Snedecor

( 1946) and Cochran e t a l . ( 194^ ) were used as r e f e r e n c e s f o r th e
s t a t i s t i c a l a n a l y s i s o f th e s e d a t a .
R e s u l t s o f th e a n a l y s i s o f v a r ia n c e a re shown i n Table 8 .

Mean

s q u a r e s and F v a l u e s were c a l c u l a t e d f o r a l l sums o f s q u a r e s i n t h i s
t a b l e and th o se t h a t were found t o d i f f e r s i g n i f i c a n t l y from th e e r r o r
sums o f s q u a r e s were s t a r r e d .

I n t h i s a n a l y s i s of v e r ia n c e o n ly d i e t

e f f e c t s were found t o be s i g n i f i c a n t l y d i f f e r e d from th e e r r o r sums
o f s q u a r e s and a l l t h e s e d i f f e r e n c e s were h ig h ly s i g n i f i c a n t ( P < 0 . 01) .
D ie t t h e r e f o r e , was the o n ly e x p e r im e n ta l v a r i a b l e t h a t was found to

-1 7 -

have a s i g n i f i c a n t e f f e c t on n i t r o g e n i n t a k e , n i t r o g e n b a la n c e , c a l o r i c
i n t a k e and w e ig h t change o f th e s e r a t s .
c«

P r e d i c t i o n o f w e ig h t changes and n i t r o g e n r e t e n t i o n o f r a t s

u s i n g l i n e a r and m u l t i p l e r e g r e s s i o n s .

I n o r d e r t o s tu d y th e i n t e r ­

r e l a t i o n s o f e x p e r im e n ta l v a r i a b l e s , r e g r e s s i o n c o e f f i c i e n t s , c o r r e l a t i o n
c o e f f i c i e n t s and s ta n d a r d e r r o r s o f e s t i m a t e s o f s e v e r a l l i n e a r and
m u l t i p l e r e g r e s s i o n s i n v o lv in g w e ig h t change, n i t r o g e n i n t a k e , c a l o r i c
i n t a k e and n i t r o g e n r e t e n t i o n were c a l c u l a t e d (T ab le 9 )»

Ib e c o r r e l a t i o n

c o e f f i c i e n t s f o r t h e s e r e g r e s s i o n s were a l l s t a t i s t i c a l l y s i g n i f i c a n t
( P < 0 . 0 1 ) a t th e one p e r c e n t l e v e l .

The r e g r e s s i o n c o e f f i c i e n t s

i n d i c a t e th e s lo p e o f th e r e g r e s s i o n l i n e i n l i n e a r r e g r e s s i o n s .

The

r e g r e s s i o n c o e f f i c i e n t s i n th e e q u a tio n s f o r th e r e g r e s s i o n s c o n t a i n ­
in g two in d e p e n d e n t v a r i a b l e s r e p r e s e n t c h a r a c t e r i s t i c s o f th e p l a n e .
The s ta n d a r d e r r o r o f e s t i m a t e s g iv e an i n d i c a t i o n o f th e c lo s e n e s s
o f f i t o f p o i n t s on th e r e g r e s s i o n .
The p r e d i c t i o n s f o r w eight change a re o f i n t e r e s t i n view o f th e
f a c t t h a t w h ile th e r e l a t i o n s h i p s o f w eight change t o n i t r o g e n i n t a k e
have b een c o n s id e re d (Osborne and Mendel, 1919)* t h i s r e l a t i o n s h i p ,
a s f a r a s th e a u th o r h a s been a b le t o a s c e r t a i n , has n o t been compared
w ith t h e r e l a t i o n w hich e x i s t s betw een n i t r o g e n r e t e n t i o n and w eigh t
change f o r l i n e a r r e g r e s s i o n s as p r e s e n te d i n t h i s p a p e r .

F or th e

e q u a t i o n s f o r t h e l i n e a r r e g r e s s i o n s i n which w eight change (y ) i s
p r e d i c t e d (T ab le 9 , E q u a tio n s 1 , 2 , 3 ) , n i t r o g e n r e t e n t i o n (w) l e a d s t o
a low er s t a n d a r d e r r o r o f e s t i m a t e f o r p r e d i c t i n g w eig h t change th a n
e i t h e r n itr o g e n in ta k e (x ) o r c a lo r ic in ta k e ( z ) .

To c l a r i f y t h i s s t a t e ­

m e n t, th e s t a n d a r d e r r o r o f e s t i m a t e o f w eight change (y ) i s 0.0 1 6 grams

-1 8 -

p e r gram i n i t i a l weight when n i t r o g e n r e t e n t i o n i s used as th e i n ­
dependent v e r i a b l e f o r p r e d i c t i n g w eight change, 0.029 gram p e r gram
i n i t i a l w e ig h t when n i t r o g e n i n t a k e i s used as th e in d e p en d e n t v a r i a b l e
and O.O^l gram p e r gram i n i t i a l w eig ht when c a l o r i c i n ta k e (z ) i s used
a s th e in d e p en d e n t v e r i a b l e .

Weight change i n th e a re a o f p re d o m in a te ly

n e g a ti v e n i t r o g e n b a la n c e th u s a p p e a rs t o depend more on the v a r i a t i o n
i n th e a b i l i t y o f i n d i v i d u a l r a t s to r e t a i n n i t r o g e n than on e i t h e r
th e n i t r o g e n i n t a k e o r c a l o r i c i n t a k e .

Weight change p r e d i c t i o n s such

a s t h e s e d e s c r ib e d above might be c r i t i c i z e d on th e b a s i s t h a t th e y
r e p r e s e n t w e ig h t changes o c c u r r in g d u rin g a s h o r t p e r io d o f tim e .

The

rang e o f w e ig h t change, however, was la r g e enough (from -21 to +9 grams
per

b a la n c e p e r i o d ) to make such p r e d i c t i o n s seem j u s t i f i e d .

An

i n d i c a t i o n o f th e f i t of p o i n t s on th e se r e g r e s s i o n l i n e s i s g iv e in
F ig u re I l a t o l i e where r e g r e s s i o n l i n e s and s ta n d a r d e r r o r c f e s t i m a t e s
a r e i n d i c a t e d u s in g th e seme s c a l e f o r w eight change i n a l l r e g r e s s i o n s .
S in ce th e l i n e a r r e g r e s s i o n s o f th e dependent v a r i a b l e w eig h t change
( y ) on th e in d e p e n d e n t v a r i a b l e s a l l i n d i c a t e h ig h ly s i g n i f i c a n t
c o r r e l a t i o n c o e f f i c i e n t s , th e s e v a r i a b l e s were combined i n s e v e r a l
m u l t i p l e r e g r e s s i o n s (T able 9 ) f o r a d i f f e r e n t approach t o th e q u e s ti o n
of w hich in d e p en d e n t v a r i a b l e had th e g r e e t e s t i n f l u e n c e on w eight changes
o b serv ed i n t h e s e a n im a ls .

In th e m u l t i p l e r e g r e s s i o n s i n which n itro g e B

r e t e n t i o n a p p e a rs a s an in d e p en d e n t v a r i a b l e f o r p r e d i c t i n g w eight
change (T able 9 , E q u a tio n s 4 . 6 , 7 )* th e s ta n d a r d e r r o r s of e s t i m a t e f o r
w e ig h t change (0 .0 1 5 ) a re s m a lle r th a n t h a t f o r th e m u l t i p l e r e g r e s s i o n
(T ab le 9 , E q u a tio n 3 ) , i n which n i t r o g e n r e t e n t i o n does not ap p ea r as
an in d e p e n d e n t v a r i a b l e .

T h is f u r t h e r i n d i c a t e s a c l o s e r r e l a t i o n s h i p

betw een w e ig h t change and o t h e r v a r i a b l e s where w eight change i s r e l a t e d
t o n i t r o g e n r e t e n t i o n th a n where w eight change i s r e l a t e d to n i t r o g e n
in t a k e a n d / o r c a l o r i c i n t a k e s .
P a r t i a l re g re ssio n c o e f fic ie n ts in a m u ltip le re g re ssio n re p re se n t
i n f l u e n c e s on th e dependent v e r i a b l e which a re n o t a f f e c t e d by o t h e r
p a r t i a l r e g r e s s i o n c o e f f i c i e n t s i n th e same e q u a ti o n .

In th e m u l t i p l e

r e g r e s s i o n f o r p r e d i c t i n g w eight change u s in g n i t r o g e n r e t e n t i o n and
n i t r o g e n i n t a k e a s in d e p e n d e n t v a r i a b l e s (T a b le 9 * E q u a tio n 4 )» th e
p a r t i a l r e g r e s s i o n c o e f f i c i e n t f o r n i t r o g e n r e t e n t i o n (0 .0 4 0 9 ) i s about
t e n tim e s a s l a r g e a s t h a t f o r n i t r o g e n e a te n (0 .0 0 4 2 ) a s compared t o
l i n e a r r e g r e s s i o n c o e f f i c i e n t s o f 0 . 0382w (E q u a tio n 2 ) and 0 . 049^x
(E q u a tio n 1 ) f o r th e s e v a r i a b l e s *

For th e r e g r e s s i o n i n which n i t r o g e n

r e t e n t i o n i s u sed w ith c a l o r i c i n t a k e f o r p r e d i c t i n g w eight change (Table
9 , E q u a tio n 6 ) , th e p a r t i a l r e g r e s s i o n c o e f f i c i e n t f o r n i t r o g e n r e t e n t i o n
(0.0500w) i s s l i g h t l y l e s s th a n th e l i n e a r r e g r e s s i o n c o e f f i c i e n t o f
O.Q528w (E q u a tio n 2 ) .

On th e o t h e r hand, th e p a r t i a l r e g r e s s i o n

c o e f f i c i e n t o f c a lo r ic in ta k e i n t h i s m u ltip le re g re ss io n (0 .0 1 l6 z )
i s s e v e r a l tim e s l e s s th a n th e l i n e a r r e g r e s s i o n c o e f f i c i e n t o f c a l o r i c
in ta k e ( 0 . 0979z , E q u a tio n 3 ) .

In th e s e two e q u a ti o n s th e p a r t i a l

r e g r e s s i o n c o e f f i c i e n t s o f n i t r o g e n i n ta k e and c a l o r i c i n t a k e a r e
s m a l le r n u m e r ic a l ly th a n t h e i r l i n e a r r e g r e s s i o n c o e f f i c i e n t s .

The

p a r t i a l r e g r e s s i o n c o e f f i c i e n t o f n i t r o g e n r e t e n t i o n re m a in s about
th e same i n b o th t h e l i n e a r and th e s e two m u l t i p l e r e g r e s s i o n s f o r
p r e d i c t i n g w eig h t chang e.
The l i n e a r r e g r e s s i o n c o e f f i c i e n t of c a l o r i c i n t a k e ( 0 . 0979z )
i n th e e q u a t i o n f o r p r e d i c t i n g w eig ht change (Table 9 » E q u a tio n 3 )

■20-

i s l a r g e r th a n th e p a r t i a l r e g r e s s i o n c o e f f i c i e n t o f c a l o r i c in t a k e
( - 0 .0 3 1 9 2 ) i a e q u a t i o n 3 (T able 9 )«

This r e d u c t i o n o f th e r e g r e s s i o n

c o e f f i c i e n t o f c a l o r i c i n t a k e i n a l l th re e r e g r e s s i o n s i n which i t
a p p e a rs f o r p r e d i c t i n g w e ig h t change i s i n t e r p r e t e d as an i n d i c a t i o n
t h a t c a l o r i e s a lo n e had a m inor r o l e i n th e p a t t e r n o f w eig h t change
o f t h e a n im a ls i n t h i s s tu d y .

T h e r e f o r e , w h ile c a l o r i e i n t a k e i s

s i g n i f i c a n t l y c o r r e l a t e d w ith w eight change, i t does n o t a p p ea r t o be
a s im p o r ta n t a f a c t o r a s e i t h e r n i t r o g e n i n t a k e o r n i t r o g e n r e t e n t i o n
i n th e w e ig h t change p i c t u r e .

The c o n sta n c y o f th e r e g r e s s i o n c o ­

e f f i c i e n t s o f n i t r o g e n r e t e n t i o n i n p r e d i c t i n g w eight change em phasizes
th e c l o s e r e l a t i o n t h a t e x i s t s betw een th e s e two v a r i a b l e s .
The p a r t i a l r e g r e s s i o n c o e f f i c i e n t o f n i t r o g e n i n t a k e i n e q u a tio n
3 (T ab le 9 ) where t h i s v a r i a b l e and c a l o r i c i n t a k e a r e used f o r p r e ­
d i c t i n g w e ig h t change i s l a r g e r th a n th e l i n e a r r e g r e s s i o n c o e f f i c i e n t
o f 0 . 049Sx f o r n i t r o g e n i n t a k e (T able 9 » E q u atio n 1 ) .

J u s t what e f f e c t

c a l o r i c i n t a k e h a s on t h i s v a lu e i s not a p p a re n t a t th e p r e s e n t tim e .
The combined e f f e c t s o f n i t r o g e n i n t a k e , c a l o r i c i n t a k e and n i t r o g e n
r e t e n t i o n a r e shown i n th e e q u a ti o n 7 (T ab le 9 )*

From t h i s e q u a ti o n ,

one m igh t draw a f i n a l c o n c lu s io n t h a t n i t r o g e n r e t e n t i o n i s th e f a c t o r
r e s p o n s i b l e f o r th e w eight changes observed i n t h i s e x p e r im e n t.

It is

n o ta b le t h a t th e p a r t i a l r e g r e s s i o n o f n i t r o g e n r e t e n t i o n i n t h i s
e q u a ti o n ( 0 . 0328w) i s th e same a s t h a t f o r th e l i n e a r r e g r e s s i o n co­
e f f i c i e n t o f n i t r o g e n r e t e n t i o n i n e q u a tio n 2 (T able 9 )»

T h is o b s e r v a t i o n

m ight l e a d t o th e c o n c lu s io n t h a t th e e f f e c t s o f n i t r o g e n i n t a k e c a n c e l
th e e f f e c t s o f c a l o r i c i n ta k e i n t h i s f i n a l p r e d i c t i o n .

-2 1 -

While n i t r o g e n r e t e n t i o n has been used a s an in d e p en d e n t v a r i a b l e
i n r e g a r d t o w e ig h t change, i t i n t u r n depends on n i t r o g e n in t a k e and
p e rh a p s t o some e x t e n t , on c a l o r i c in ta k e o f the e x p erim en tal a n im a ls
(M inro, 193^)*

The l i n e a r and m u l t i p l e r e g r e s s i o n s used t o p r e d i c t

n i t r o g e n r e t e n t i o n (T able 9 * E q u a tio n s 8 , 9* 10) i n d i c a t e t h a t n i t r o g e n
r e t e n t i o n i s more c l o s e l y r e l a t e d t o n i t r o g e n in t a k e th a n t o c a l o r i c
i n t a k e , s in c e the p a r t i a l r e g r e s s i o n c o e f f i c i e n t o f n i t r o g e n in ta k e i n
th e m u l t i p l e r e g r e s s i o n i n th e l a s t e q u a tio n i s g r e a t e r th a n t h a t f o r
th e l i n e a r r e g r e s s i o n , whereas t h a t o f th e c a l o r i c in ta k e i s s m a l l e r
th a n th e l i n e a r r e g r e s s i o n c o e f f i c i e n t .

This r e l a t i o n s h i p i s i n d i c a t e d

i n F i g u r e s l i e and l i d , where i t i s shown t h a t a lth o u g h n i t r o g e n r e t e n t i o n
i n c r e a s e s w i t h in c re asin g ; n i t r o g e n and c a l o r i c i n t a k e s , th e f i t o f the
p o i n t s on th e r e g r e s s i o n o f n i t r o g e n r e t e n t i o n on c a l o r i c in ta k e where
th e s ta n d a r d e r r o r o f e s ti m a te e q u a ls 0*793 m illig r a m s p e r gram i n i t i a l
w eig ht i s not as good a s th e f i t o f p o i n t s about th e l i n e a r r e g r e s s i o n
o f n i t r o g e n r e t e n t i o n on n i t r o g e n in ta k e where th e s ta n d a rd e r r o r o f
e s ti m a te i s 0.4 3 9 m illi g r a m s p e r gram i n i t i a l w e ig h t.

The f i t o f p o i n t s

on t h e r e g r e s s i o n o f n i t r o g e n r e t e n t i o n on n i t r o g e n i n t a k e ( s ta n d a r d
e r r o r o f e s t i m a t e e q u a ls 0.493 m illi g r a m s ) i s n o t g r e a t l y improved when
n i t r o g e n i n t a k e end c a l o r i c in ta k e a re used t o g e t h e r f o r p r e d i c t i n g
n i t r o g e n r e t e n t i o n i n th e m u l t i p l e r e g r e s s i o n w s 1.3932x - I.3 3 0 3 2 - 0.2214
( s t a n d a r d e r r o r o f e s t i m a t e e q u a ls 0 . 43^ m illig ra m s p e r gram i n i t i a l
w e ig h t).

P a r t i a l r e g r e s s i o n c o e f f i c i e n t of c a l o r i c i n t a k e a re

n e g a t i v e i n b o th th e e q u a ti o n ib r p r e d i c t i n g w eight change and th e e q u a tio n
f o r p r e d i c t i n g n i t r o g e n r e t e n t i o n u sin g th e com b in ation o f n i t r o g e n

,22-

i n t a k e and c a l o r i c i n t a k e a s in d e p e n d e n t v a r i a b l e s .

F o r t h i s re a s o n

th e s e d a t a do n o t d e m o n s tra te a s p a r in g a c t i o n o f c a l o r i e s on n i t r o g e n
i n th e m e t a b o l i c exchanges o f th e s e a n im a ls.
d*

E f f e c t o f e x p e r im e n ta l v a r i a b l e s on re s p o n s e s of r a t s a s

d e te rm in e d by an a n a l y s i s o f c o v a r ia n c e .

Since th e e f f e c t o f d i e t

was t h e only e x p e r im e n t a l v a r i a b l e found t o cause a s i g n i f i c a n t
d i f f e r e n c e i n the an im al re s p o n s e s which were tx-eated s t a t i s t i c a l l y
i n t h i s e x p e rim e n t, th e sum o f s q u a r e s o f d i e t and e r r o r were used
i n an a n a l y s i s o f c o v a ria n c e o f w eight change ( y ) , n i t r o g e n i n t a k e
( x ) , c a l o r i c i n t a k e ( z ) and n i t r o g e n r e t e n t i o n (w ).

T h is a n a l y s i s

sh o u ld g iv e an i n d i c a t i o n o f how c l o s e l y th e d a ta o b ta in e d i n t h i s
ex p e rim e n t would f i t th e r e g r e s s i o n s i n d i c a t e d i n T able 9

they

n o t been i n f l u e n c e d by th e e x p e r im e n ta l v a r i a b l e s which were removed
i n th e a n a l y s i s o f v a r ie n c e (T ab le 8 ) .

The F v a l u e s o b ta in e d from

th e s e a n a l y s e s o f c o v a r ie n c e a r e t a b u l a t e d i n Table 9 »

I t i s n o te d

t h a t whenever n i t r o g e n r e t e n t i o n a p p e a rs a s an in d e p en d e n t v a r i a b l e
i n an e q u a t i o n p r e d i c t i n g w eight change, the F v a lu e showing th e
e f f e c t o f d i e t s on mean w eight change a re e i t h e r not s i g n i f i c a n t o r
o n ly so ( P < 0 . 0j j ) .

When n i t r o g e n in t a k e o r c a l o r i c in ta k e however,

were c o n s id e r e d e i t h e r s e p a r a t e l y o r t o g e t h e r a s in d ep en d en t v a r i a b l e s
c o n t r o l l i n g w e ig h t ch an g e , i t was found t h a t mean w eig ht changes o f the
r a t s when fe d th e v a r i o u s d i e t s were s i g n i f i c a n t l y d i f f e r e n t from each
o t h e r ( P < 0 . 01 ) .
No s i g n i f i c a n t d i f f e r e n c e s betw een mean n i t r o g e n r e t e n t i o n o f
a n im a ls were found a t v a r io u s l e v e l s o f n i t r o g e n i n t a k e o r c a l o r i c
in ta k e .

No s i g n i f i c a n t d i f f e r e n c e s were found between mean n i t r o g e n

r e t e n t i o n s f o r th e t h r e e d i e t s when n i t r o g e n i n ta k e and c a l o r i c i n ta k e
were u sed t o g e t h e r f o r p r e d i c t i n g n i t r o g e n r e t e n t i o n .
e.

D i f f e r e n c e s i n r a t r e s p o n s e s t o d i e t s m easured by t t e s t s .

I t i s p o s s i b l e t o d e term in e s t a t i s t i c a l l y which d i e t s had s i g n i f i c a n t l y
d i f f e r e n t e f f e c t s on a d j u s t e d w eight changes and n i t r o g e n r e t e n t i o n .
T h is i s done by a d j u s t i n g a c t u a l means o f th e dependent v a r i a b l e t o
th e same

tr e a tm e n t v a lu e o r t c th e v alu e o f th e g e n e r a l tr e a tm e n t

mean end

s u b j e c t i n g th e s e a d j u s t e d means t o s ta n d a r d t t e s t s .

Ob­

s e r v e d and a d ju s t e d means and t v a lu e s o f d i f f e r e n c e s between the
a d j u s t e d means a re shown i n T able 1 0 -

For th e r e g r e s s i o n o f w eight

change v e r s u s n i t r o g e n in ta k e (T ab le 10, E q u a tio n 1 ) , the a d ju s t e d
means o f w eigh t change (y ) f o r d i e t s A ( l o w - n i t r o g e n ) and B (2 p e r c e n t
®gg) do n o t d i f f e r s i g n i f i c a n t l y from each o t h e r j on xhe o t h e r hand,
th e a d j u s t e d mean f o r d i e t C (ij. p e r c e n t egg) d i f f e r s s i g n i f i c a n t l y
from th e

a d j u s t e d means o f b o th d i e t s A and B ( P 2. 0 . 0.5 ) .

means o f

t h e s e t h r e e d i e t s a r e i n d i c a t e d by th e t n r e e c i r c l e d d o ts

on th e l i n e a r r e g r e s s i o n i n F ig u re l i e .

The a c t u a l

I f a l i n e were drawn th ro u g h

th e s e a c t u a l means a s l i g h t c u r v i l i n e a r r e l a t i o n s h i p between th e s e two
v a r i a b l e s m igh t be i n d i c a t e d .
Wien mean w e ig h t changes a r e a d ju s t e d to th e same c a l o r i c in t a k e
f o r d i e t s A, B and C in th e r e g r e s s i o n o f w eig ht change (y ) on c e l o r i c
i n t a k e ( z ) (T able 1 0 , E q u a tio n 2 ) , th e t h r e e a d j u s t e d means o f w eight
change d i f f e r s i g n i f i c a n t l y (P <-0 . 0 1 ) .

T his i s re g a rd e d as f u r t h e r

i n d i c a t i o n t h a t c a l o r i c i n t a k e s i n th e se a n im a ls were not c l o s e l y
r e l a t e d t o w eig h t ch an g es.

-2 4 -

The a d j u s t e d means o f w eigh t change f o r d i e t s A t B and C i n
e q u a ti o n 3 (T able 10) a r e p r e s e n t e d .

However, one of th e in d ep en d en t

v a r i a b l e s i n t h i s e q u a t i o n , n i t r o g e n r e t e n t i o n , i s dependent on the
o t h e r in d e p e n d e n t v a r i a b l e , n i t r o g e n i n t a k e ; f o r t h i s r e a s o n , p ro b a b ly
no s i g n i f i c a n c e sho uld be a tt a c h e d to d i f f e r e n c e s i n d i c a t e d by th e t
te sts.

The F v a lu e f o r e q u a tio n 4 (Table 10) was s l i g h t l y above th e

fiv e p er cent le v e l .

When t h i s i s th e c a s e , the a p p l i c a t i o n o f th e t

t e s t may n o t i n d i c a t e s i g n i f i c a n t d i f f e r e n c e s .

This a p p e a rs to be th e

c ase f o r t h i s r e g r e s s i o n .
f*

S ig n ific an c e o f in d iv id u a l v a r ia b le s in m u ltip le re g re ssio n s

a s m easured by c o r r e l a t i o n c o e f f i c i e n t s .

As a fin a l

s t e p i n th e

a n a l y s i s o f c o v a r ia n c e , m u l t i p l e and p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s
were c a l c u l a t e d f o r th e v a r i o u s r e g r e s s i o n s u s in g the e r r o r sum o f
s q u a r e s (T ab le 1 1 ) .

When b a se d on the e r r o r sum o f s q u a r e s , c o r r e c t i o n

c o e f f i c i e n t s can be re g a rd e d a s r e p r e s e n t i n g e f f e c t s w hich a r e not
i n f l u e n c e d by th e o t h e r e x p e r im e n ta l v a r i a b l e s i n th e s tu d y .

The

m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t s c a l c u l a t e d i n t h i s stu dy were a l l
s ig n ific a n t (P ^ O .O l).

T h e se , however, show n o th in g c o n c e rn in g e f f e c t s

o f i n d i v i d u a l in d e p e n d e n t v a r i a b l e s on th e dependent v e r i a b l e i n the
r e g r e s s i o n when c e r t a i n v a r i a b l e s were h e ld c o n s t a n t .

In d iv id u al

e f f e c t s when o t h e r v a r i a b l e s a r e h e ld c o n s ta n t e re i n d i c a t e d by the
p a r tia l c o rre la tio n c o e ffic ie n ts .

For example, i n the m u l t i p l e

r e g r e s s i o n y * a -v bx -v- cw, th e p a r t i a l c o r r e l a t i o n c o e f f i c i e n t o f yx
w ith th e e f f e c t o f w h e ld c o n s ta n t o r e lim in a te d i s h i g h l y s i g n i f i c a n t

-2 5 -

(ry x .w = 0 • 7 3 * * ) w h ile t h e c o r r e l a t i o n c o e f f i c i e n t o f yw when x i s

h e l d c o n s t a n t i s not s i g n i f i c a n t ( r ^ ^ = - 0 . 0 8 ) .

T h is cou ld be

i n t e r p r e t e d t o i n d i c a t e t h a t i f e f f e c t s o f o t h e r e x p e r im e n ta l v a r i a b l e s
were removed from t h i s r e g r e s s i o n , w eight changes would be more c l o s e l y
r e l a t e d t o n i t r o g e n i n t a k e th a n t o n i t r o g e n r e t e n t i o n , a s i n d i c a t e d by
p r e v io u s s t a t i s t i c a l e s t i m a t e s .

A s a lr e a d y p o in te d o u t,

t h i s may n o t

be a t r u i s m s i n c e one o f th e in d e p en d e n t v a r i a b l e s i n t h i s e q u a ti o n
( n i t r o g e n r e t e n t i o n o r w) i s dependent on th e o th e r in d e p e n d e n t v a r i a b l e
(n itro g en in ta k e o r x ) .

The same re a so n in g c o u ld apply t o th e p a r t i a l

c o r r e l a t i o n c o e f f i c i e n t s f o r t h e r e g r e s s i o n y = a + bx -v c z + d w

where

th e p a r t i a l r e g r e s s i o n o f w eight change on n i t r o g e n in ta k e w ith c a l o r i c
i n t a k e and n i t r o g e n b a la n c e h e ld c o n s ta n t ( r y X„2W) i s s i g n i f i c a n t a t the
f i v e p e r c e n t l e v e l w h ile t h a t o f w eight change on n i t r o g e n r e t e n t i o n w ith
n i t r o g e n and c a l o r i c i n t a k e s h e ld c o n s te n t (r.._
v „ ) i s not s i g n i f i c a n t .
y w• ac
The two m u l t i p l e r e g r e s s i o n s i n which ind e p en d e n t v a r i a b l e s a re n o t d e ­
p e n d en t on e ac h o t h e r (y => a

bx + cz

and

y = a -v bw -v c z ) g iv e a

chance p r e d i c t i o n t h a t w eight change would be s i g n i f i c a n t l y c o r r e l a t e d
w ith n i t r o g e n i n t a k e , n i t r o g e n b a la n c e and c a l o r i c i n t a k e i f e f f e c t s o f
o t h e r e x p e r im e n ta l v a r i a b l e s were e lim in a te d from th e e x p e rim e n t.
For t h e r e g r e s s i o n w = a -t bx -v c z , the c o r r e l a t i o n c o e f f i c i e n t b e ­
tween n i t r o g e n r e t e n t i o n and n i t r o g e n in ta k e w ith c a l o r i c i n t a k e h e ld
c o n s t a n t ( r wX. z ) i s s i g n i f i c a n t ( P < 0 . 0 1 ) w h ile t h a t betw een n i t r o g e n r e ­
t e n t i o n and c a l o r i c i n t a k e
i s not s ig n if ic a n t.

w ith n i t r o g e n in t a k e h e la c o n s te n t ( r wz. x )

T h is g iv e s f u r t h e r emphasis to th e dependency i n t h i s

ex p erim en t o f n i t r o g e n r e t e n t i o n on n i t r o g e n i n t a k e r a t h e r th a n on c a l o r i c
in ta k e .
g.

Summary.

The fo r e g o in g d i s c u s s i o n i s concerned w ith an e v a l u a t i o n

-

26 “

o f n i t r o g e n m e ta b o lism , c a l o r i c i n t a k e and w eight change d a t a o b ta in e d
from t h r e e g ro u p s o f a l b i n o r a t s f e d t h r e e d i e t s c o n ta i n in g 0, 2 and
4 p e r c e n t whole d r i e d e g g , th e d i e t s b e in g o f f e r e d i n d i f f e r e n t
sequence.

U rin a ry and t o t a l n i t r o g e n e x c r e t i o n o f th e a n im a ls de­

c r e a s e d d u rin g t h r e e s u c c e s s iv e b a la n c e p e r i o d s .

T h is d e c r e a s e i n

n i t r o g e n e x c r e t i o n o c c u r r e d r e g a r d l e s s o f d i e t seq u en ce.

An a n a l y s i s

o f v a r ia n c e d e s ig n e d t o e v a lu a te th e e f f e c t s o f i n d i v i d u a l r a t s ,
f e e d i n g sequence u sed and d i e t f e d on n i t r o g e n i n t a k e , n i t r o g e n b a l a n c e ,
c a l o r i e i n t a k e and w eig h t change i n d i c a t e d t h a t d i e t was th e only one
o f t h e t h r e e f a c t o r s w hich had a s t a t i s t i c a l l y s i g n i f i c a n t e f f e c t .
H ighly s i g n i f i c a n t c o r r e l a t i o n s were found between w eig ht change and
n i t r o g e n i n t a k e , w eigh t change and n i t r o g e n r e t e n t i o n , and w eight
change and c a l o r i c i n t a k e ; and between n i t r o g e n r e t e n t i o n and n i t r o g e n
i n t a k e and n i t r o g e n r e t e n t i o n and c a l o r i c i n t a k e .

When m u l t i p l e

r e g r e s s i o n s were u sed t o stud y i n d i v i d u a l e f f e c t s o f n i t r o g e n i n t a k e ,
n i t r o g e n r e t e n t i o n and c a l o r i c i n t a k e on w eight change, n i t r o g e n r e t e n t i o n
was fo u n d t o be th e f a c t o r most c l o s e l y a s s o c i a t e d w ith th e w eight
changes o b serv ed i n the e x p e rim e n ta l a n im a ls .

The m u l t i p l e r e g r e s s i o n

i n v o l v i n g n i t r o g e n r e t e n t i o n v e r s u s n i t r o g e n i n t a k e and c a l o r i c i n t a k e
i n d i c a t e d t h a t n i t r o g e n r e t e n t i o n was dependent on n i t r o g e n i n t a k e .
C a l o r i c i n t a k e s o f th e s e a n im als d id n o t appear to be a l i m i t i n g f a c t o r
i n e i t h e r th e w e ig h t ehanges o r n i t r o g e n r e t e n t i o n s o b serv ed i n t h i s
s tu d y .
( 2 ) . D is c u s s io n o f f a c t o r s r e l a t e d t o the problem o f i n t e r p r e t i n g
n i t r o g e n m e ta b o lism d a t a .
With a group o f tw e lv e 150 gram a l b i n o r a t s fed d i e t s c o n ta i n in g
g ra d e d amounts o f egg n i t r o g e n , th e r e l a t i o n s h i p between w eigh t change

-2 7 -

and n i t r o g e n i n ta k e a p p e a re d t o be s l i g h t l y c u r v i l i n e a r i n t h e a r e a
of p r e d o m in a te ly n e g a t i v e n i t r o g e n b a la n c e .

The r e l a t i o n s h i p s between

w e ig h t change and n i t r o g e n r e t e n t ' o n and between n i t r o g e n r e t e n t i o n and
n i t r o g e n i n t a k e were b o th found t o be r e c t i l i n e a r i n t h i s a r e a .
The r e g r e s s i o n s o b ta in e d i n t h i s study a re o f i n t e r e s t i n t h a t
th e y m ight f u r n i s h a v a l i d b a s i s f o r e s t i m a t i n g minimum p r o t e i n r e ­
q u ire m e n ts f o r m ain ten an ce o f n itr o g e n e q u i l i b r i u m and body weight
in r a ts of th is siz e .

The fo llo w in g d i s c u s s i o n i s concerned w ith

s e v e r a l f a c t o r s in v o lv e d i n th e a p p l i c a t i o n o f t h i s method t o th e
problem o f e s t i m a t i n g p r o t e i n minima.
a.

S i g n i f i c a n c e o f n i t r o g e n e x c r e t i o n i n th e e v a l u a t i o n o f

n i t r o g e n m e ta b o lism .

Much s i g n i f i c a n c e has been a tt a c h e d to u r in a r y

n i t r o g e n o f e x p e r im e n ta l r a t s .

In t h i s d is c u s s io n a com parison w i l l

be made betw een n i t r o g e n e x c r e t i o n s o b ta in e d i n th e s e e x p e rim e n ts and
th o se from s e v e r a l o t h e r e x p e r im e n ts .

B r ic k e r end M itc h e ll

a d a p te d th e M elnick and Cowgill ( 1937) method o f a s s ig n in g b i o l o g i c a l
v a l u e s t o p r o t e i n s when e s t i m a t i n g t h e p r o t e i n r e q u ire m e n ts of a d u l t
r a t s ; however, they base t h e i r i n t e r p r e t a t i o n o f the method on th e concept
o f a c o n s t a n t endogenous n i t r o g e n e x c r e t i o n .
P a r t one o f t h i s t h e s i s p r e s e n te d r e s u l t s o f an e x p erim en t i n
which t h r e e g ro up s o f r a t s were fe d e lo w -n itro g e n d i e t and two d i e t s
c o n t a i n i n g added egg n i t r o g e n .

U rin a ry and t o t a l n i t r o g e n e x c r e t i o n

o f a n im a ls i n t h i s s tu d y d e c re a s e d as the experim ent p r o g r e s s e d
i r r e s p e c t i v e o f the sequence i n which th e d i e t s were fe d (T ab le 6 ) .

-2 8 -

B r i c k e r and M i t c h e l l (1947) have r e p o r t e d work on young r a t s u s in g
d i e t s s i m i l a r t o th o s e u sed i n t h i s stu d y ; d a t a from t h e i r p a p e r
have been re p ro d u c e d i n T able 12.

The c h i e f d i f f e r e n c e s i n th e two

s t u d i e s a p p e a r t o be th e ag es o f the r a t s observed and th e l e n g t h o f
fe e d in g p e rio d s .

B r i c k e r ' s an im a ls were observed o v e r t h r e e s u c c e s s ­

i v e 7 day f e e d i n g p e r i o d s (21 days t o t a l ) , w hereas the anim als i n
t h i s s tu d y were fe d each d i e t s u c c e s s iv e ly f o r e le v e n days (33 days
to ta l).

When t a b u l a t e d i n the o r d e r f e d , b o th s e t s o f d a t a show a

c o n s t a n t s h i f t from h ig h t o medium to low u r i n a r y n i t r o g e n e x c r e t i o n .
While th e a u th o r s o f th e p a p e r c i t e d acknowledge t h i s s h i f t i n n i t r o g e n
e x c r e t i o n , th e y m a in ta in t h a t th e i n d i v i d u a l d i f f e r e n c e s i n th e two
g rou ps o f r a t s between th e o b serv ed v a lu e f o r th e second p e r i o d and
th e mean f o r p e r i o d s 1 and 3 were n o t s t a t i s t i c a l l y d i s t i n c t .
B urroughs e t a l . ( 1940)* p r e s e n t e d d a ta from a group o f r a t s fe d
a l o w - n i t r o g e n d i e t f o r a 20 day p e r i o d .

These d a ta i n d i c a t e d t h a t

f o llo w in g a p r e l i m i n a r y 3 day a d ju stm e n t p e r i o d , r a t s showed s u c c e s s iv e
d e c r e a s e s i n u r i n a r y n i t r o g e n e x c r e t i o n d u rin g th e n e x t t h r e e con­
s e c u t i v e 3 o r 3 day p e r i o d s .

These a u th o r s conclude t h a t t h i s im p lie s

t h a t endogenous m eta b o lism p u rs u e s a c o n s ta n t o r a r e c t i l i n e a r l y
changing c o u rse th ro u g h o u t th e e x p e rim e n ta l p e r i o d s .
Swanson e t a l . ( 1944) end Brush e t a l . ( 1947) used a s i m i l a r
te c h n iq u e t o s tu d y th e s p a r in g a c t i o n o f egg and amino a c id n i t r o g e n
on body n i t r o g e n .

These a u t h o r s n o te d a marked r e d u c tio n i n th e

q u a n t i t y o f n i t r o g e n e x c r e t e d i n th e u r in e f o llo w in g th e i n t r o d u c t i o n
o f whole egg o r amino a c i d n i tr o g e n i n t o th e d i e t and re g a rd e d t h i s

■29-

as c l e a r l y showing t h a t eggs and a m ix tu re o f th e t e n e s s e n t i a l amino
a c i d s have th e coionion p r o p e r t y of d e p r e s s in g the n itr o g e n o u s e x c r e t i o n
c h a r a c t e r i s t i c o f a p ro te in -f re e p e rio d .
Table 13 shows th e u r in a r y and t o t a l n itr o g e n e x c r e t i o n s c f s i x
g ro u p s o f r a t s o b serv ed d u rin g 3 s u c c e s s iv e n i t r o g e n b a la n c e p e r i o d s
in th is la b o ra to ry .

Each group o f a n im als r e c e iv e d a lo w - n itr o g e n

d i e t ( d i e t A) d u rin g one o f the th r e e p e r i o d s and d i e t s c o n ta i n in g 4
and 10 p e r c e n t d r i e d egg which gave e s s e n t i a l l y p o s i t i v e n itr o g e n
b a l a n c e s i n th e o t h e r two p e r io d s ( d i e t s C, D, E and F)«

For th e s e

r a t s th e lo w - n it r o g e n d i e t r e s u l t e d i n the g r e a t e s t n i t r o g e n e x c r e t i o n
f o r th e d i e t s e r i e s only when i t was fe d f i r s t ( r a t s I 3 - I 6 and 2 3 -2 8 ).
The c o n tin u o u s ly d e c r e a s i n g u r i n a r y n i t r o g e n e x c r e t i o n s o f fo u r groups
o f r a t s (17*204 21-23* 23 -2 8 , 2 9-3 2) i s s i m i l a r t o t h a t r e p o r t e d by
B r ic k e r and M itc h e ll ( 1947) end i n th e f i r s t p a r t o f t h i s s tu d y f o r
t

r a t s r e c e i v i n g 0 t o 1; p e r c e n t egg d i e t s and by Burroughs e t a l . ( 194° )
f o r r a t s on c o n tin u o u s lo w -n itro g e n f e e d in g .

This i s i n d i r e c t c o n t r a s t

t o th e s ta t e m e n t o f B r i c k e r and M itc h e ll ( 1947) who n o te d t h a t the
u r i n a r y n i t r o g e n o b ta in e d w ith a lo w - n it r o g e n d i e t was i n no case
d e p re s s e d by egg p r o t e i n .
One group o f r a t s i n t h i s experim ent (33 ~3 b) showed a p a t t e r n of

urinary n i t r o g e n e x c r e t i o n w hich was e x a c t l y o p p o s ite to

t n e d e c re a s in g

one end a n o th e r group ( 1 3 - l b ) had an i n c o n s i s t e n t p a t t e r n o f n i t r o g e n
e x cretio n .

Three groups o f r e t s re c e iv e d as th e f i r s t d i e t o f a s e r i e s ,

e i t h e r a lo w -n itro g e n d i e t (1 3 -1 6 ), a L p e r cen t egg d i e t (1 7 -2 0 ) o r a
10 p e r c e n t egg d i e t ( 21- 2 4 ) .

R e g a rd le s s o f th e d i e t fed f i r s t ,

w heth er i t c o n ta in e d 0, 4 o r 10 p e r cen t egg, a l l groups had th e same

av erag e u r i n a r y n i t r o g e n e x c r e t i o n (1 .4 9 m illi g r a m s ) p e r gram i n i t i a l
w e ig h t.

The 4 p e r c e n t egg d i e t s (C and F) w h eth er they fo llo w e d th e

0 o r th e 10 p e r c e n t egg, r e s u l t e d in v i r t u a l l y th e sase e x c r e t i o n
v a lu e.

S i m i l a r l y , th e 10 p e r c e n t egg, w hether i t fo llo w e d th e 0 or

t h e 4 p e r c e n t egg d i e t s , a ls o gave p r a c t i c a l l y c o n s ta n t v a l u e s .
These o b s e r v a t i o n s , t h e r e f o r e , le a d one t o q u e s ti o n th e v a l i d i t y o f
th e u s e o f u r i n a r y n i t r o g e n e x c r e t i o n s f o r e x p r e s s in g endogenous n i t r o g e n
o r f o r d e m o n s tra tin g th e s p a r in g a c t i o n o f d i e t a r y n i t r o g e n on body
p ro te in .

C o n se q u e n tly , no assu m p tio n s a r e made r e g a r d i n g th e endogenous

n i t r o g e n e x c r e t i o n s o f r a t s u sed i n th e s e e x p e rim e n ts.
b»

R e p r o d u c i b i l i t y o f r e g r e s s i o n l i n e s based on r a t re s p o n s e s t o

0 to 4- P e r c e n t egg d i e t s .

R e g re s s io n l i n e s d is c u s s e d i n the f i r s t

p a r t of t h i s t h e s i s were based on two d i e t s ( d i e t s A and B) b o th o f
w hich r e s u l t e d i n l o s s o f w eig h t and l o s s o f body n i t r o g e n and one d i e t
( d i e t C) which allo w ed r a t s t o g a in w e ig h t 3nd produced p o s i t i v e n i t r o g e n
b a lan c e s.

R ats used i n t h i s experim ent t h e r e f o r e showed a n e t weight

l o s s and n e g a ti v e n i t r o g e n b a la n c e f o r th e 33

o b serv atio n p e rio d .

F or t h i s r e a s o n , t h e q u e s t i o n a ro s e as t o w hether th e r e g r e s s i o n s ob­
t a i n e d from t h i s group o f r a t s r e p r e s e n t e d re s p o n s e s which were i n f l u e n c e d
by th e f e e d in g p a t t e r n used o r w h e th er they were a r e s u l t o f d i e t s
fe d p e r s e .

T h e r e f o r e , a second group o f 12 r a t s were fe d t h r e e d i e t s

i n a f e e d i n g d e s ig n p a r a l l e l t o th e one used f o r the f i r s t experim ent
d iscu ssed .

The o nly change made i n th e p roced ure f o r t h i s experim ent

(T a b le s 2b and 2c ) was t h a t d i e t D (10 p e r cen t egg) r e p la c e d d i e t B
(2 p e r c e n t egg) i n th e d i e t s e r i e s .

T h is s u b s t i t u t i o n r e s u l t e d i n

o v e r a l l w e ig h t g a in s and n i t r o g e n r e t e n t i o n s f o r th e 33

o b s e r v a tio n

-3 1 -

p e rio d .

F ig u r e s XVa t o IVc shows th e com parison o f th e r e g r e s s i o n s

c a l c u l a t e d from a l l t h r e e d i e t s i n th e f i r s t e x perim ent w ith th o s e
f o r d i e t s A and C i n th e second f e e d in g s e r i e s (T able 1 4 )•

The

s i m i l a r i t y o f t h e s e r e g r e s s i o n s i s s t r i k i n g and le a d s t o th e c o n c l u s i o n
t h a t t h e anim al re s p o n s e s t o d i e t s A ( lo w - n itr o g e n ) and C (4 p e r c e n t
e g g) were n o t a l t e r e d by r e p l a c i n g d i e t B (2 p e r c e n t egg) w ith d i e t D
(10 p e r c e n t eg g ) i n th e f e e d in g s e r i e s .

T h e r e f o r e , th e r e g r e s s i o n s

o b ta in e d a p p e a r t o depend on r a t re s p o n s e s to i n d i v i d u a l d i e t s fe d and
so s h o u ld be r e p r o d u c i b l e u n d e r s i m i l a r e x p e rim e n ta l c o n d i t i o n s .
c.

Use o f r e g r e s s i o n l i n e s o b ta in e d from n i t r o g e n m etab olism

d a t a i n th e p re d o m in a te ly n e g a ti v e n i t r o g e n b a la n c e a r e a f o r e s t i m a t i n g
p r o t e i n minima f o r th e a l b i n o r a t .

Since the p r e d i c t i n g e q u a ti o n s

d e s c r ib e d i n th e f i r s t p a r t o f t h i s study a re r e p r o d u c i b l e , th e y should
f u r n i s h a v a l i d i n d i c a t i o n o f th e minimum n itr o g e n re q u ire m e n ts f o r
m ain ten an ce o f body w e ig h t and n i t r o g e n e q u i l i b r i u m of anim als in
th e s e e x p e r im e n ts .

The z e ro i n t e r c e p t f o r w eigh t m aintenance and

n i t r o g e n b a la n c e can be used t o e s tim a te the av erag e minimum r e q u i r e ­
ments o f th e an im a ls s t u d i e d .

The c a l c u l a t e d minimum re q u ire m e n t o f

egg n i t r o g e n f o r m a i n t a i n i n g n i t r o g e n e q u i l i b r i u m i s 1*77 m i l l i g r a m s
p e r gram i n i t i a l w eight p e r week f o r th e r e g r e s s i o n l i n e ABC and 1.71
m illi g r a m s f o r th e r e g r e s s i o n l i n e o f d i e t s A and C w ith a mean o f 1-74
m illig ra m s.

I f th is - mean i s u sed t o e s tim a te th e n i t r o g e n re q u ire m e n t

f o r m a in te n a n c e o f n i t r o g e n e q u ilib r iu m , we a r r i v e a t a v a lu e o f 261
m i l l i g r a m s o f egg n i t r o g e n a week, o r 37*3 m illig ra m s p e r day f o r
m a i n t a i n i n g n i t r o g e n e q u i l i b r i u m i n a 150 gram l a b o r a t o r y r a t
( 1 .7 4 x 1 3 0 /7 = 3 7 . 3 ) .

The amount o f egg n i t r o g e n n e c e s s a ry f o r

-3 2 -

m a i n t a i n i n g body w e ig h t i n th e s e a n im a ls i s s l i g h t l y h ig h e r .

Rrom

th e two d e s ig n s u s e d , t h i s re q u ire m e n t i s e i t h e r 1*91 o r 2 .3 3 (a v e ra g e
2*12) m i l l i g r a m s n i t r o g e n p e r gram s t a r t i n g w eight p e r week.

To a llo w

f o r w e ig h t m a in te n a n c e , a I50 gram anim al would need 3 ^® m illig r a m s
egg n i t r o g e n p e r week o r 45*4 m illi g r a m s p e r day*

Since an im als

a p p e a re d t o be i n s l i g h t p o s i t i v e n i t r o g e n b a la n c e when m a in ta in in g
body w e ig h t, th e e q u a ti o n s f o r w eight change v e r s u s n i t r o g e n b a la n c e
were s o lv e d f o r y = 0 and n i t r o g e n b a la n c e was found t o e q u a l 0 . 11*4
o r 0 .1 6 3 m illi g r a m s n i t r o g e n p e r gram i n i t i a l w e ig h t, th e av erag e b e in g
0 .1 3 4 m i l l i g r a m s .

T h is i n d i c a t e s t h a t a 150 gram r a t would need about

3*2 m illi g r a m s o f egg n i t r o g e n p e r day over and above h i s re q u ire m e n t
f o r n i t r o g e n e q u i l i b r i u m i n o r d e r to m a in ta in body, w eight on th e d i e t s
fed .
B r i c k e r and M i t c h e l l ( 1947) r e p o r t e d 3 .6 0 p e r c e n t added egg
p r o t e i n a s th e minimum d i e t a r y p r o t e i n f o r m aintenan ce o f n i t r o g e n
e q u i l i b r i u m i n th e a d u l t r a t .

They found t h a t a d i e t c o n ta i n in g 3*28

p e r c e n t egg p r o t e i n f a i l e d t o m a in ta in n i t r o g e n e q u i l i b r i u m i n a l l
an im a ls o b s e r v e d .

I n th e work r e p o r t e d h e r e , a t o t a l of 36 young

male r a t s r e c e i v e d a d i e t c o n ta i n in g app ro x im a te ly 3 .2 6 (N x 6 .2 5 )
per cent p ro te in .

AL1 e x c e p t one o f th e 36 a n im a ls o b se rv e d i n t h i s

l a b o r a t o r y were i n p o s i t i v e n i t r o g e n b alan ce a t t h i s l e v e l o f p r o t e i n
in ta k e •
d.

N itr o g e n b a la n c e and w eight change i n a r e a s o f n e g a ti v e and

p o s itiv e n itro g e n b a lan c e .

N itro g e n b a la n c e and w eight change d e s c r ib e d

f o r r a t s r e c e i v i n g d i e t s c o n ta i n in g 4 Pe r cent

from 0 t o 4

p e r c e n t egg n i t r o g e n a p p e a r to be l i n e a r o r a p p ro x im a te ly l i n e a r

-3 3 -

th ro u g h o u t th e rang e o f n i t r o g e n in t a k e s o b se rv e d .

In o r d e r t o o b ta in

an e s t i m a t e o f how f a r t h i s l i n e a r r e l a t i o n s h i p might e x te n d i n t o th e
r e g i o n o f p o s i t i v e n i t r o g e n b a la n c e , tw elve r a t s were fe d a d i e t con­
t a i n i n g 10 p e r c e n t d r i e d whole egg.

F ig u r e s I l i a t o I I I c show c a l ­

c u l a t e d r e g r e s s i o n c u rv e s (Table 14) based on re s p o n se s o f r a t s fe d
d i e t s c o n t a i n i n g 4 p e r c e n t l a r d and 0 t o 10 p e r c e n t whole d r ie d egg.
The d a t a f o r th e s e r e g r e s s i o n s a r e t a b u l a t e d i n T a b le s 2b and 2c .
I n th e p r e v io u s d i s c u s s i o n , i t was p o in te d out t h a t th e curve
showing th e r e l a t i o n s h i p between w eight change and n itr o g e n i n t a k e
appeared to become c u r v i l i n e a r somewhere in th e r e g io n o f w eight
m a in te n a n c e .

The curve showing t h i s r e l a t i o n s h i p f o r d i e t s c o n t a i n ­

in g 0 t o 10 p e r c e n t egg (ACS) i n d i c a t e s t h a t a d e f i n i t e c u r v i l i n e a r
r e l a t i o n s h i p does e x i s t between t h e s e two v a r i a b l e s .

However, the

e x a c t shape o f t h i s c u rv e cannot be shown from a v a i l a b l e d a te .
The r e l a t i o n s h i p between w eight change and n i tr o g e n r e t e n t i o n
a l s o becomes c u r v i l i n e a r i n th e a r e a o f w eight m a in te n an c e ; however,
th e s e d a t a t o o , a re i n s u f f i c i e n t t o show the e x a c t n a tu r e o f t h e curve
in th is area.

Since th e curve o b ta in e d f o r w eight change v e r s u s

n i t r o g e n r e t e n t i o n f o r d i e t s ABC i n p a r t one o f t h i s t h e s i s shows a
r e c t i l i n e a r r e l a t i o n s h i p between th e s e two v a r i a b l e s up to th e h ig h ­
e s t l e v e l o f n i t r o g e n fe d (4 p e r c e n t egg), t h i s r e g r e s s i o n must b e ­
come c u r v i l i n e a r some\vhere i n th e a re a o f p o s i t i v e n i t r o g e n b a la n c e .
The f a c t t h a t a l i n e a r r e l a t i o n s h i p does e x i s t beyond th e p o in t of
w e ig h t m a in te n a n c e , m ight be i n t e r p r e t e d as i n d i c a t i n g t h a t the n i t r o ­
gen r e t a i n e d up t o some point- i n t h i s area r e p r e s e n t s an amount of
n i t r o g e n e s s e n t i a l f o r m ain te n an c e o f s t a t u s quo o f the animal un der

“34“

th e p r e v a i l i n g e x p e r im e n ta l c o n d itio n s *

The n i t r o g e n r e t a i n e d above

th e amount i n d i c a t e d by th e change o f d i r e c t i o n of th e curve might
th e n be a v a i l a b l e f o r body p r o c e s s e s o t h e r th a n s u r v i v a l ••
M sln ic k and Cowgill ( 1937) found t h a t f o r a d u l t uogs a l i n e a r
r e l a t i o n s h i p betw een n i t r o g e n in ta k e and n i t r o g e n r e t e n t i o n e x i s t s
i n th e r e g i o n o f n e g a ti v e n i t r o g e n b a la n c e .

P a r t One o f t h i s t h e s i s

i n d i c a t e s t h a t t h i s r e l a t i o n s h i p f o r immature w h ite r a t s e x te n d s
i n t o th e r e g i o n o f p o s i t i v e n i t r o g e n b a la n c e .

Tne curve showing th e

r e l a t i o n s h i p betw een n i t r o g e n i n t a k e and n i t r o g e n balance f o r d i e t s
c o n t a i n i n g 0 t o 10 p e r c e n t whole d r i e d egg (F ig u re I I I c ) con firm s
t h i s f i n d i n g and s u g g e s ts f u r t h e r t h a t a r e c t i l i n e a r r e l a t i o n s h i p
betw een n i t r o g e n i n t a k e and n itr o g e n b a la n c e e x i s t s w e ll i n t o th e
p o s i t i v e n i t r o g e n b a la n c e a r e a f o r th e s e r a t s .
The f a c t t h a t th e c u rv e s o f w eig h t change f o r th e s e a n im a ls a r e
c u r v i l i n e a r i n th e a r e a o f w eight m ain ten ance w h ile th e r e l a t i o n s h i p
betw een n i t r o g e n i n t a k e and n i t r o g e n r e t e n t i o n a p p e a rs to be l i n e a r
beyond t h i s r e g i o n m ight i n d i c a t e an in c r e a s e i n th e m e ta b o lic n i ­
tr o g e n r e q u ire m e n t o f th e anim al due t o w eight i n c r e a s e s .

It is

n o te d (T ab le 1 4 ) th a t i n e q u a ti o n s for- p re a c t i n g w eight change (y )
th e r e g r e s s i o n c o e f f i c i e n t s f o r n i tr o g e n in t a k e ( x ) and n i t r o g e n
r e t e n t i o n (w) a r e l a r g e r below th e a r e a of w e ig h t m ain ten ance th a n
above t h i s a r e a w h ile th e r e g r e s s i o n c o e f f i c i e n t o f c a l o r i c i n t a k e
( z ) i s l a r g e r i n th e a re a above w eight m ain te n an c e .

This change i n

m ag nitud e o f t h e s e r e g r e s s i o n c o e f f i c i e n t s might imply t h a t below o r
n e a r th e p o i n t o f w eig h t m a in te n a n c e , w eight changes a re l a r g e l y
d ep en d en t on t h e a b i l i t y o f t h e anim al to r e t a i n n i t r o g e n w h ile above

t h i s p o i n t , w e ig h t changes become more c l o s e l y a s s o c i a t e d w ith c a l o r i c
in ta k e .

I f t h i s i s t r u e , a t some p o in t i n the re g io n o f p o s i t i v e

n i t r o g e n b a l a n c e , w e ig h t change would be found t o b e a r l i t t l e r e l a t i o n ­
s h ip t o n i t r o g e n in t a k e o f th e an im a l.
e.

The e f f e c t o f added f a t on the re s p o n s e s o f r a t s t o d i e t s

c o n t a i n i n g 0 t o 10 p e r c e n t whole d r ie d e g g .

In lo w - n itr o g e n fe e d in g

e x p e r im e n ts w ith a d u l t r a t s , S tevenso n e t a l . (1 9 4 6 ), Wiliman e t a l .

(1947) stid Swanson (1951) found t h a t b o th f a t and c a rb o h y d ra te have a
s p a r in g a c t i o n on body p r o t e i n and Hoover and Swanson ( 1950)• r e p o r t e d
s i m i l a r r e s u l t s from f o r c e d fe e d in g e x p e r im e n ts .

T r e i c h l e r and M i t c h e l l

( 1941) ahd Vars and Gurd ( 1947) found t h a t m oderate r e s t r i c t i o n o f
c a l o r i c i n t a k e s o f r a t s do n o t seem t o a f f e c t n i t r o g e n o u t p u t .

Minro

(1951) c i t e s u n p u b lis h e d d a t a from fe e d in g e x p erim en ts w ith r a t s on
c o n s t a n t p r o t e i n i n t a k e s and v a r y in g c a l o r i c i n t a k e s which i n d i c a t e d
a dynamic r e l a t i o n s h i p between energy in ta k e and n i t r o g e n b a la n c e .

In

the f i r s t p a r t o f t h i s e x p e rim e n t, e s p a r in g a c t i o n o f c a l o r i e s on
body n i t r o g e n was n o t i n d i c a t e d when c a l o r i c v a l u e s o f d i e t s were
e s s e n t i a l l y eq u al.

The e f f e c t o f i n c r e a s i n g th e c a l o r i c v a lu e o f

d i e t s c o n t a i n i n g v a r io u s amounts o f egg n i t r o g e n i s c o n s id e re d i n
t h is d iscu ssio n .
The e f f e c t o f f e e d in g d i e t s c o n ta in in g 0 t o 10 p e r c e n t egg
which were n o t i s o c a l o r i c i s i l l u s t r a t e d by a com parison o f re s p o n s e s
o f a n im a ls to d i e t s G and E (4 P©r c en t l a r d ) w ith d a ta from anim als on
d i e t s D and F (12 p e r c e n t l a r d ) .
g iv e n i n T a b le s 2b and 2 c .

D ata f o r th e s e com parisons a re

These e x p e rim e n ts were c a r r i e d out s i ­

m u lta n e o u s ly and d i e t A was r e p e a t e d f o r t h i s g roup o f r a t s .

The

c a l o r i c v a l u e s o f d i e t s A, 0 , E, E and F were 4 . 10, 4 . 1 4 , 4 .7 4 ,
4 '3 0 and 4*^3 c a l o r i e s p e r gram r e s p e c t i v e l y .

The c a l c u l a t e d

r e g r e s s i o n s (T able 15) o f w eight change v e rs u s n i t r o g e n i n t a k e ,
w e ig h t change v e r s u s n i t r o g e n b a la n c e and n i t r o g e n b a la n c e v e r s u s
n i t r o g e n i n t a k e f o r th e two l e v e l s o f c a l o r i e s a re shown f o r compar­
i s o n i n F ig u r e I l i a t o I I I c .

A lthough th e same lo w - n itr o g e n d i e t was

fe d th e s e a n im a ls , one group o f tw elv e r a t s l o s t more w eight th a n the
o t h e r group on t h i s d i e t .

For t h i s re a so n th e o r i g i n s o f th e two l i n e s

showing r e l a t i o n s h i p s o f w eight changes do not c o i n c i d e .

The f i g u r e

showing r e l a t i o n s h i p between w eig h t change and n i t r o g e n in ta k e
i n d i c a t e s t h a t t h e a n im a ls on th e h ig h e r c a l o r i c d i e t s g a in e d l e s s
w e ig h t on s i m i l a r n i t r o g e n i n t a k e s th an did an im a ls on the low c a l o r i e
d ie ts.

The added c a l o r i e s , th e n , do not a p p e a r t o improve th e r a t e

o f th e w e ig h t change o f th e s e r a t s s in c e f o r a g iv e n n i t r o g e n i n t a k e ,
c a l o r i c i n t a k e s o f an im a ls on th e h ig h e r c a l o r i e d i e t s were g r e a t e r
th a n th o s e o f a n im a ls on th e low c a l o r i e d i e t s .

On th e o t h e r hand,

when th e c u rv e s f o r n i t r o g e n r e t e n t i o n v e r s u s n i t r o g e n i n ta k e were
compared, i t was found t h a t r a t s on th e h ig h c a l o r i e d i e t s r e t a i n e d
more n i t r o g e n on a s i m i l a r n i t r o g e n in ta k e th a n d id r a t s on th e low
c alo rie d ie ts .

T h is i s i n agreem ent w ith th e f i n d i n g s t h a t n o n - p r o t e i n

c a l o r i e s have a s p a r i n g a c t i o n on n i t r o g e n in m e ta b o lic p r o c e s s e s .

The

c u rv e s (F ig u re I l l b ) showing th e r e l a t i o n s h i p between w eight change
and n i t r o g e n r e t e n t i o n i n d i c a t e s t h a t a n im als on the h ig h e r c a l o r i e
d i e t s were i n g r e a t e r p o s i t i v e n i t r o g e n b a lan c e a t a g iv e n p o in t
th e n were an im a ls on th e low er c a l o r i e d i e t s .

Thus, th e added c a l o r i e s

a p p ea re d t o l e a d t o g r e a t e r n i t r o g e n r e t e n t i o n i n th e s e a n im a ls w ith o u t
i n c r e a s i n g th e w e ig h t.

-3 7 -

The p u rp o se o f t h i s s tu d y i s t o e s t a b l i s h c u rv e s f o r e s ti m a ti n g
p r o t e i n minima f o r r a t s w eighing ap p ro x im a te ly 150 grams.

The above

o b s e r v a t i o n s show t h a t a v a r i a t i o n i n th e e x p e rim e n ta l d i e t o t h e r
th a n th e v a r i a t i o n o f p r o t e i n c o n te n t a f f e c t s th e re s p o n se o f r a t s
t o t h e e x p e r im e n ta l d i e t s .

T h is em phasizes th e im po rtan ce o f main­

t a i n i n g i d e n t i c a l e x p e r im e n ta l c o n d i t i o n s i f r e s u l t s from v a r io u s
b i o l o g i c a l v a lu e s t u d i e s a r e t o be compared.
f.

Summary*

Four g ro u p s o f r a t s fe d d i e t s c o n ta i n in g 0, 4 an^

10 p e r c e n t d r i e d egg i n d i f f e r e n t sequence showed a c o n s ta n t d e c re a s e
i n u r i n a r y n i t r o g e n e x c r e t i o n r e g a r d l e s s o f sequence o f f e e d in g .

The

lo w - n i t r o g e n d i e t r e s u l t e d i n g r e a t e s t n i t r o g e n e x c r e t i o n f o r a group
o f r a t s o n ly where i t was f e d f i r s t i n a d i e t s e r i e s .

These f i n d i n g s

l e a d one t o q u e s t i o n th e v a l i d i t y o f th e use of u r i n a r y n i t r o g e n
e x c r e t i o n f o r e s t i m a t i n g endogenous n i t r o g e n o r f o r d e m o n stra tin g
s p a r in g a c t i o n o f d i e t a r y n i t r o g e n on body p r o t e i n .
R e c t i l i n e a r r e g r e s s i o n s f o r e s t i m a t i n g minimum n i t r o g e n r e q u i r e ­
ments o f l^O gram r a t s were shown t o be r e p r o d u c ib le i n p a r a l l e l ex­
p e r im e n ts , b u t a p p e a r t o be in f l u e n c e d by i n c r e a s i n g th e c a l o r i c
v a lu e o f e x p e r im e n ta l d i e t s .
The r e l a t i o n s h i p s between w e ig h t change and n itr o g e n i n t a k e
and betw een w e ig h t change and n i t r o g e n r e t e n t i o n appear to become
c u r v i l i n e a r i n t h e r e g io n o f w eig h t m a in te n an c e .

A re c tilin e a r

r e l a t i o n s h i p betw een n i t r o g e n r e t e n t i o n and n i t r o g e n in ta k e a p p e a r s
t o e x ten d w e ll i n t o th e a r e a o f p o s i t i v e n i t r o g e n b a la n c e .
The a v e ra g e d a i l y minimum n i t r o g e n r e q u i r e n e n t s o f 130 gram
r a t s when whole d r i e d egg was u sed a s a sou rce o f n i t r o g e n were found

-3 8 -

t o be 4 5 #4 m il l i g r a m s f o r w eight m ain ten ance and 37*3 m illig r a m s f o r
m a in te n an c e o f n i t r o g e n e q u i l i b r i u m .
( 3 ) Comparison of. m a in ten ance re q u ire m e n ts o f a lb in o r a t s on d i e t s
c o n ta i n in g whole d r i e d eggs and M L chelite pea beans a s s o u rc e s o f
d ie ta ry n itro g e n .
A method f o r e s t i m a t i n g minimum n itr o g e n re q u ire m e n ts f o r m ain­

t a i n i n g w e ig h t and n i t r o g e n e q u ilib r iu m i n th e la b o r a t o r y r a t u s in g
egg a s a s o u rc e o f n i t r o g e n h as been p r e s e n t e d and has been found t o
g iv e com parable r e s u l t s u n d e r s i m i l a r e x p e rim e n ta l c o n d i t i o n s .

The

f o l l o w i n g d i s c u s s i o n i s concerned w ith th e a p p l i c a t i o n of t h i s
method t o th e d e t e r m i n a t i o n o f tn e minimum n i t r o g e n re q u ire m e n ts
o f r a t s u s in g th e M L ch elite pea bean as a source o f n i t r o g e n and t o
com paring th e m a in te n an c e re q u ire m e n ts f o r th e s e two s o u rc e s o f
n itro g e n .
a.

E s tim a tio n o f minimum bean n itr o g e n r e q u ir e m e n ts .

S e v e ra l

r e g r e s s i o n c u rv e s u sed f o r e s t i m a t i n g th e minimum re q u ire m e n t o f
Lean n i t r o g e n fox1 m a in ta in in g n itr o g e n e q u i l i b r i u m and w eight a re
shown i n F ig u r e V a t o Vc.

C om position o f d i e t s used f o r t h e s e cu rves

a re g iv e n i n T able 1 and t a b u l a t e d d a t a f o r th e s e c u rv e s a r e shown
i n T able 2a , 2d and 2e .

The bean d i e t s used (A ,G ,H ,I and J ) a r e i s o ­

c a l o r i c d i e t s c o n ta i n in g from 0 t o 20 p e r c e n t d r i e d M Lchelite pea
beans.
When r a t s were f e d i n c r e a s i n g amounts of d i e t a r y bean n i t r o g e n ,
an i n c o n s i s t e n t p a t t e r n o f resp on se was o b ta in e d ; r e s p o n s e s d id not
alw ays improve on h i g h e r n i t r o g e n i n t a k e s .

Mean re s p o n s e s o f gro up s

o f a n im als f e d t h e s e d i e t s were - 0 . 009. - 0 .0 2 0 , - 0 . 034* -0 .0 2 0 and
-0 .0 1 0 grams w e ig h t change p e r gram i n i t i a l w eig h t p e r week f o r d i e t s

-3 9 -

c o n t a i n i n g 1 2 , 15, 1 8 , 20 and 20 p e r cen t o f th e bean p r e p a r a t i o n
re sp e c tiv e ly .

In th e same o r d e r mean n itr o g e n i n t a k e s were 2 . 0 4 ,

3 *°8 , 3*38, 3*91 sftd _5• OS m i lli g r a m s p e r gram i n i t i a l w eig h t and
n i t r o g e n b a l a n c e s were - 0 . 7 5 , - 0 . 2 8 , - 0 . 1 6 , 0.96 and 0 . 3 I m illi g r a m s
p e r gram i n i t i a l w e ig h t pei' week.

These d i e t s were fe d as p a r t o f

s e v e r a l e x p e r im e n ts and r e s u l t s were combined i n an e f f o r t t o e s ­
t i m a t e th e amount o f bean n i t r o g e n r e q u ir e d t o m a in ta in n i t r o g e n
e q u i l i b r i u m and body w eight i n th e w h ite r a t .

The re a so n f o r combin­

in g t h i s s e r i e s o f d i e t s becomes obvious when one examines t h e s e r i e s
o f r e g r e s s i o n s o b ta in e d when th e s e v e r a l p o s s i b l e co m b inatio ns of
th e s e d i e t s a r e u sed f o r p r e d i c t i n g p r o t e i n minima (Table 15 )•

When

d i e t c o m b in a tio n s A l l , AILJ, and AGBJ were u sed f o r p r e d i c t i n g w eight
change and n i t r o g e n r e t e n t i o n , t h e r e was a marked s i m i l a r i t y between
th e t h r e e r e g r e s s i o n s c a l c u l a t e d ; however, when th e GHI d i e t combina­
t i o n was u s e d f o r th e s e p r e d i c t i o n s , th e c a l c u l a t e d r e g r e s s i o n s were
n o t a l l co m parab le.

F ig u r e s Va t o Vc i n d i c a t e th e s c a t t e r o f p o i n t s

about t h e s e r e g r e s s i o n s .

The com b inatio n o f e l l d i e t s (AGHIIJ) gave

r e g r e s s i o n e q u a t i o n s t h a t were s i m i l a r to th o s e g iv e n by th e d i e t
c o m b in a tio n s A IJ , A1 I J and AGHJ; ana when th e mean re s p o n s e s f o r each
d i e t were i n d i c a t e d on th e s e r e g r e s s i o n s f o r combined d i e t s , a l l p o i n t s
f e l l v e ry n e a r th e r e g r e s s i o n l i n e s (F ig u re s V ia t o V ic ) .

These combined

d i e t r e s p o n s e s were used t o e s ti m a te the minimum bean n i t r o g e n r e q u i r e ­
m en ts o f t h e r a t s i n t h i s e x p e rim e n t.
b.

M aintenance re q u ire m e n ts o f d i e t a r y n itr o g e n s o u r c e s .

u r e s V i l a t o V I I c r e g r e s s i o n s o b ta in e d from r a t s r e c e i v i n g d i e t s con­
t a i n i n g 4 p e r c e n t l a r d and graded amount o f egg and bean n i t r o g e n .

In F ig ­

- 40 -

a r e com pared-

The h ig h e s t l e v e l o f n itr o g e n in ta k e on th e egg d i e t s

was 3*93 M illig ra m s p e r gram i n i t i a l w eight end th e h ig h e s t n itr o g e n
i n t a k e on th e bean d i e t s was 3*74 m illig ra m s .

W hile th e ran g e o f

n itr o g e n in ta k e s f o r th e s e two d i e t s i s s i m i l a r , th e r e i s a d e f i n i t e
b re a k i n th e r e g r e s s io n s o f w eig h t change on n itr o g e n in ta k e and w eig h t
change on n itr o g e n b a la n c e f o r th e egg d i e t s , w hereas th e s e same r e ­
g r e s s io n s f o r th e bean d i e t s a p p ea r t o be l i n e a r th ro u g h o u t t h i s i n ­
ta k e ra n g e .

T here i s a l e s s pronounced b re a k in th e r e g r e s s io n f o r

p r e d i c t i n g n itr o g e n r e t e n t i o n from in ta k e s o f egg n itr o g e n and t h i s
r e g r e s s io n a ls o a p p e a rs to be l i n e a r f o r th e bean d i e t s .

N itro g e n

in ta k e s r e q u ir e d f o r m a in ta in in g body w eight and n itr o g e n b a la n c e
d i f f e r w id e ly f o r th e s e two n itr o g e n so u rc e s (1 .8 8 mg. egg and 3*30
mg. b ean n itr o g e n f o r w e ig h t m ain ten an ce; 1 .7 1 mg. egg end 3*^8 mg.
bean n itr o g e n p e r gram i n i t i a l w eight p e r week f o r m ain ten an ce o f
n itr o g e n b a la n c e .)

In a d d itio n , a t th e p o in t o f w eight m ain ten an ce

th e p o s i t i v e n itr o g e n b a la n c e in an im als r e c e iv in g th e egg n itr o g e n (0 .1 6 3
m illig r a m s ) i s s m a lle r th an th e p o s i t i v e n itr o g e n b a la n c e o f an im als on
th e bean d i e t s (0 .6 7 3 m illig r a m s ) .

For th e 130 gram r a t , th e av erag e

d a ily re q u ire m e n t o f bean n itr o g e n a p p ea rs to be 63*1 m illig ra m s f o r
m ain ten an ce o f n itr o g e n b a la n c e and 112.1 m illig ra m s f o r w eig h t m a in te n an c e .
G o e tts c h ( 1931) r e p o r te d a re q u ire m e n t o f 39 m illig ra m s n itr o g e n
p e r dey p e r 100 gram s f o r m ain ten an ce o f body w eig h t o ver a 28 day
p e rio d i n 50 t o 160 gram r e t s on a r ic e - b e e n - c a s e in d i e t .

In t h i s

s tu d y , d a i l y re q u ire m e n ts f o r m ain ten an ce o f w eight in 130 gram r e t s
w ere found to be 30 m illig ra m s egg n itr o g e n and 7 6 m illig ra m s been
n i t r o g e n , p e r 100 gram s.

Animals in b o th th e s e s tu d ie s were in p o s i t i v e

n itr o g e n b a la n c e when th e y were m a in ta in in g body w e ig h t.

-4 1 -

c«

Summery.

S ix d i e t s c o n ta in in g 0 to 20 p e r c en t M ic h ile te

p ea bean p r e p a r a t io n w ere u sed f o r e s tim a tin g d a ily minimum n itr o g e n
re q u ire m e n ts o f 150 gram r a t s .

These an im als were found t o r e q u ir e

an a v e ra g e d a ily in ta k e o f 112.1 m illig ra m s o f b ean n itr o g e n f o r
w eig h t m a in te n an c e and 83.1 m illig ra m s f o r m ain ten an ce o f n itr o g e n
e q u ilib r iu m .

GENiP.AL SUMv^HY A1\D CCWCLUSIONS

W eight ch an g e, c a l o r i c in ta k e end n itr o g e n m etab o lism f o r p r e ­
d i c t i n g p r o t e i n minima f o r 1_50 gram a lb in o r a t s w ere o b ta in e d from
t h r e e g ro u p s o f 4 r a t s fe d 0 , 2 and ^ p e r c e n t egg d i e t s i n a c r o s s ­
o v e r ty p e fe e d in g p a t t e r n .

V a r ia tio n s i n anim al re sp o n se s r a i s e d a

q u e s tio n re g a rd in g th e j u s t i f i c a t i o n o f such p r e d i c tio n s .

T h e re fo re ,

d a ta o b ta in e d were s u b je c te d to a com prehensive s t a t i s t i c a l a n a ly s is
to d e term in e w hich e x p e rim e n ta l f a c t o r s had a s i g n i f i c a n t in f lu e n c e
i n c o n t r o l l i n g anim al re s p o n s e s to th e d i e t s fe d .
An a n a l y s i s o f v a ria n c e e v a lu a tin g th e e f f e c t s o f r a t s , fe e d in g
sequence and d i e t s on w eig h t change, c a l o r i c in ta k e , n itr o g e n in ta k e
and n itr o g e n r e t e n t i o n o f th e r a t s in d ic a te d th a t d i e t was th e only
f a c t o r w hich had a s i g n i f i c a n t in f lu e n c e on anim al re s p o n s e s and
d i e t e f f e c t s were h ig h ly s i g n i f i c a n t ( P < Q .0 l ) .
H ig h ly s i g n i f i c a n t c o r r e l a t i o n s w ere found betw een w eig h t change
and n itr o g e n i n t a k e , w eig h t change end n itr o g e n r e t e n t i o n , and w eig h t
change and c a l o r i c in ta k e ; and betw een n itr o g e n r e t e n ti o n and n itr o g e n
in ta k e and n itr o g e n r e t e n t i o n and c a l o r i c in ta k e .

iYnen m u ltip le r e ­

g r e s s io n s w ere u sed to stu d y in d iv id u a l e f f e c t s o f n itr o g e n i n t a k e ,
n itr o g e n r e t e n t i o n ana c a l o r i c in ta k e on w eight change, n itr o g e n r e ­
t e n t i o n was found to be th e f a c to r most c lo s e ly a s s o c ia te d w ith th e
w eig h t changes o b se rv e d i n th e e x p e rim e n ta l a n im a ls.

Ih e m u ltip le

r e g r e s s io n in v o lv in g n itr o g e n r e t e n t i o n v e rs u s n itr o g e n in ta x e and

-4 3 -

c a l o r i c in ta k e in d i c a t e d t h a t n itr o g e n r e t e n t i o n was dependent on
n itr o g e n i n t a k e .

C a lo ric i n ta k e s o f th e s e a n im a ls d id not a p p e a r

to be a l i m i t i n g f a c t o r in e i t h e r th e w eig h t changes or n itr o g e n
r e t e n t i o n s o b se rv e d i n t h i s study*
When th r e e g ro u p s o f 4 r a t s were f e d , in d i f f e r e n t seq u en ce,
d i e t s c o n ta in in g 0 , 2 and 4 p e r c e n t d r ie d whole egg, th e mean
u r in a r y n itr o g e n o f each group d e c re a se d d u rin g th e th r e e s u c c e s s iv e
fe e d in g p e r io d s r e g a r d le s s o f fe e d in g seq u e n c e.

T h is p a t t e r n i s

s i m i l a r to t h a t o b serv ed by o th e r i n v e s t i g a t o r s w ith r a t s on con­
tin u o u s lo w -n itro g e n fe e d in g end on d i e t s c o n ta in in g 0 and 4 p e r c e n t
whole d r ie d egg fe d i n d i f f e r e n t seq u en ce.
S ix a d d i t j o n e l g ro u p s o f an im als were fe d d i e t s c o n ta in in g 0, 4
and 10 p e r c e n t d r ie d w hole egg, i n d i f f e r e n t sequence.

A s i m il a r

p a t t e r n o f u r in a r y n itr o g e n e x c r e tio n was o b serv ed in fo u r o f th e se
g ro u p s; one group o f r a t s i n t h i s s e r i e s gave a p a t t e r n o f n itr o g e n
e x c r e tio n w hich was e x a c tly o p p o s ite to t h a t d e s c rib e d ; one group had
an i n c o n s i s t e n t p a t t e r n -

The lo w -n itro g e n d i e t r e s u l t e d in th e g r e a t ­

e s t u r in a r y n itr o g e n e x c r e tio n o n ly when i t was fe d f i r s t in a d i e t
s e rie s .

These f in d in g s do n o t j u s t i f y th e u s e o f a lo w -n itro g e n d ie t

to d e te rm in e endogenous n itr o g e n m etab o lism o r to d e m o n strate n itr o g e n
s p a r in g a c tio n o f d i e t a r y p r o te in .
L in e a r r e g r e s s io n s showing r e l a t i o n s h i p s betw een w eight change
and n itr o g e n in ta k e and n itr o g e n r e t e n t i o n and betw een n itr o g e n r e ­
t e n t i o n and n itr o g e n in ta k e a re re p ro d u c ib le u n d e r s im ila r e x p e rim e n ta l
c o n d itio n s .

These r e g r e s s io n s , t h e r e f o r e , should f u r n is h a v a lid

e s tim a te o f minimum n itr o g e n re q u ire m e n ts of r a t s f o r m ain ten an ce o f

-4 4 -

body w eig h t and n itr o g e n e q u ilib riu m .

R esponses o f r a t s to d i e t s

c o n ta in in g , 0 , 4 and 10 p e r c e n t d rie d whole egg in d ic a te d th a t th e
r e l a t i o n s h i p betw een w eight change and n itr o g e n in ta k e and w eig h t
change and n itr o g e n b a la n c e becomes c u r v i l i n e a r in the a re a o f we^ht
m a in te n a n c e .

A l i n e a r r e l a t i o n s h i p betw een n itr o g e n r e t e n t i o n and

n itr o g e n in ta k e a p p e a rs to e x te n a w ell in to th e p o s i t i v e n itr o g e n
b a la n c e a re a f o r th e s e r a t s .

T h is i s re g a rd e d as an i n d i c a t i o n t h a t

below th e p o in t o f w eight m a in te n an c e , w eig h t change i s dependent on
th e a b i l i t y o f th e anim al t o r e t a i n n itr o g e n w h ile above t h i s p o in t
w eig h t change may become more c lo s e ly r e l a t e d to some o th e r f a c t o r .
F o r th e a n im a ls o b serv ed i n th e ex p erim en t, i t was no ted t h a t th e
l i n e a r r e g r e s s io n c o e f f i c i e n t o f n itr o g e n in ta k e was g r e a t e r below
th e p o in t o f w eight m ain ten an ce th a n above w hile th e l i n e a r r e g r e s s io n
c o e f f i c i e n t of c a l o r i c in ta k e i s g r e a t e r above th e p o in t o f w eig h t
m a in te n a n c e .

T h is i s i n t e r p r e t e d a s in d ic a t ng t h a t above th e p o in t

o f w e ig h t m a in te n an c e w eig h t change i n an im als may become more de­
p e n d en t on c a l o r i c in ta k e and l e s s dependent on n itr o g e n in ta k e .
D ie ts c o n ta in in g 0 to 4 p e r c e n t d r ie d whole egg and 0 to 20
p e r c e n t M ic n e lite pea bean p r e p a r a tio n were fe d to 1^0 gram r a t s .
The a v e ra g e d a i l y re q u ire m e n t f o r m a in ta in in g body w eight i n th e s e
a n im a ls was fo u n d to be 45*4 m illig ra m s o f egg n itr o g e n and 112.1
m illig ra m s bean n itro g e n *

The a v erag e d a ily re q u ire m e n t f o r m a in ta in ­

in g n itr o g e n e q u ilib r iu m i n th e lyO gram r a t v.as found to be 37*3
m illig ra m s egg n itr o g e n and 6 3 .1 m illig ra m s bean n i tr o g e n .

Animals on

t h i s stu d y were i n p o s i t i v e n itr o g e n b a la n c e -when they w ere m a in ta in ­
in g body w e ig h t.

LIST OF REFERENCES

A l lis o n , J . B. and J . A* A nderson 1945 The r e l a t i o n betw een ab so rb ed
n i t r o g e n , n itr o g e n b a la n c e and b io l o g i c a l v a lu e o f p r o t e i n s in
a d u lt d o g s. J . N u t r . , v o l. 29, p p . 4 1 3 -4 2 0 .
A llis o n , J , B ., J . A. A nderson and R. D. S e e le y 194& The d e te rm i­
n a tio n o f th e n itr o g e n b a la n c e in d ex i n noim al and h y p o p ro tein em ic
d o g s. Ann. N. Y. Acad. S c i . , v o l. 47, p p . 243- 271.
A s s o c ia tio n o f O f f i c i a l A g r ic u ltu r a l C hem ists I940 O f f i c i a l and
t e n t a t i v e m ethods o f a n a ly s is . 3 t h e d . 757 pp.
B lock, R. J . and H. H.- M itc h e ll. 194& The c o r r e l a t i o n o f th e amino
a c id c o m p o sitio n o f p r o te i n s w ith t h e i r n u t r i t i v e v a lu e .
N u tr itio n A b str. and Rev. v o l . 1 6 , pp. 24 9 - 2 7 8 .
B o a s-F ix sen , M.A. 1934 The b io lo g ic a l value o f p r o te in in n u t r it io n .
N u tr itio n A b str. and Rev. v o l. 4 . PP* 447- 459*
B r ic k e r , M. L ., H. H. M itc h e ll and G. M# Kinsman 1945 The p r o t e in
re q u ire m e n ts o f a d u lt human s u b je c ts i n term s o f th e p r o t e i n
c o n ta in e d i n i n d i v i d u a l fo o d s and c o m b in a tio n s. J . N u tr. v o l. 3 0 ,
p p . 6 29-683.
v /B ric k e r, M. L. and H. H. M itc h e ll 1947 The p r o te in re q u ire m e n ts o f
th e a d u lt r a t i n term s o f th e p r o te i n c o n ta in e d i n eg g , m ilk
and soy f l o u r . J . N u tr. v o l . 3 4 » PP* 491”5 ° 6 *
B ru sh , M ., W. W illm an and P . P . Swanson 1947 Amino a c id s i n n itr o g e n
m e ta b o lism w ith p a r t i c u l a r re f e r e n c e to th e r o le o f m e th io n in e .
J . N u tr. v o l . 33» PP* 389-410*
B u rro u g h s, E . W., B u rro u g h s, H. S. and H. H. M itc h e ll 1940 The
in d ep en d en ce o f th e endogenous and exogenous m etab o lism o f
n itr o g e n . J . N u tr. v o l . 1 9 * PP* 271-283*
C a h ill, W. M. 1945 Methods fo r th e determ ination o f the n u t r it iv e
v a lu e o f p r o t e in s . J* Amer. D ie t. Assn. v o l. 21, pp. 433- 435*
C ath cart, E. P. 1921 The p h y sio lo g y o f p r o te in m etabolism .
Longmans Green and C o., v i i i , 17& PP*

Io n d o n ,

Cochran, W. G ., K. M. A utrey and C. Y. Cannon 1941 A double change­
o v e r d e s ig n f o r d a ir y c a t t l e fe e d in g e x p e rim e n ts. D a iry S c i.
v o l . 24, p p . 937- 9 5 1 *

F o lin , 0. I 9 0 5 A th eory o f p r o te in m etabolism .
v o l . 1 3 , pp. 1 1 7 - 1 3 8 .

Amer. J

P h y s io l.,

i/G o e ttsc h , M. 1951 Minimum p r o te in requirem ent o f the a d u lt r a t fo r
28-day p e r io d s o f m aintenance o f body w eig h t. J . N u tr itio n ,
v o l . 4 5 , pp. 6 0 9 - 6 2 0 .
Goulden, C. H. Methods o f S t a t i s t i c a l A n a ly sis 1952
John W iley and Sons, I n c ., 2 nd ed . 4 67 pp.

New York,

H egsted, D. M ., A. G. Tsongan, D. B. Abbott and F. J . S ta re 1946
P r o te in requirem ents o f a d u lts . J . Lab. C lin . Med., v o l . 3 1 ,
pp. 2 6 1 - 2 8 4 .
^H oover, C. and P . Swanson 1950
Fed. P r o c .,v o l . 9» P« 3 6 2 .
Madden, S. C .f and G. W. Whipple
p rod u ction and u t i l i z a t i o n .

Role o f f a t in p r o te in m etabolism .

1940 Plasma p r o te in s j t h e ir sou rce,
P h y sio l. R ev ., v o l. 2 0 . pp. 194-217.

I fe ln ic k , D. and G. R. C ow gill 1937 The p r o te in minima fo r n itro g en
e q u ilib r iu m w ith d if f e r e n t p r o te in s . J. N u tritio n , v o l. 1 3 , pp. 4 °l-4 2 4 *
-/M itc h e ll, H. H. 1924 A method fo r determ ining the b io lo g ic a l v a lu e o f
p r o te in . J . B io l. Chem., v o l. 5 8 * PP« 873-903.
M itc h e ll, H- H. and T. S . Hamilton 1929 The B iochem istry o f the
Amino A cid s, A .C .S. Monograph no. 48, Reinhold P u b lish in g C orp.,
New york, p . 5G3*
M itc h e ll, H. H. 1944 D eterm ination o f the n u t r it iv e valu e o f the
p r o te in s o f food p rod u cts. Ind. Eng. Chem., Anal. E d., v o l. 16,
pp. 6 9 6 - 7 OO.
M itc h e ll, H. H. 1950 Some s p e c ie s and age d iffe r e n c e s in amino a cid
req u irem en ts. P r o te in and Amino Acid Requirem ents. Academic
P r e s s , I n c ., A. A. A lbanese, E d ito r, p .2 2 .
^Munro, H* N. 1951 Carbohydrate ad f a t as fa c t o r s in p r o te in
u t i l i z a t i o n and m etabolism . P h y s io l. R ev., v o l. 3^» PP* 449Osborne, T. B. and L. B. Mendel 1915 The comparative n u t r it iv e valu e
o f c e r ta in p r o te in s in growth and the problem o f the p r o te in
minimum. J* B io l. Chem., v o l. 2 0 , pp. 35^-390.
Osborne, T. B. and L. B. Mendel 1919 The n u t r it iv e v a lu e o f the
wheat k e rn el and i t s m illin g p ro d u cts. J. B io l. Chem., v o l. 3 7 1
PP* 5 5 7 - ^ 0 1 .

-4 7 -

R o s e n th a l, H. L . and. J* B. A llis o n 1931
in ta k e on n itr o g e n b a lan c e i n dogs.
p p . 423- 431R ubner, M. V.
L e ip z ig .

1897

Some e f f e c t s o f c a l o r i c
J . N u t r i t i o n , v o l. 4 4 .

L eyden’s "Handbuch d e r E rn sh u n g s th e ra p ie "

S choenheim er, R ., S. R a tn e r and D. R itte n b e rg 1939 S tu d ie s i n p r o ­
t e i n m e ta b o lism . X The m e ta b o lic a c t i v i t y o f body p r o t e in s
i n v e s t i g a t e d w ith l ( - ) - l e u c i n e c o n ta in in g two is o t o p e s . J .
B i o l . Chem., v o l . I3 0 , p p . 703-732.
S choenheim er, R. 1942 The Dynamic S ta te o f Body C o n s titu e n ts
C am bridge, M a s s a c h u s e tts , Howard U n iv e rs ity P r e s s , 78 pp.
S n e d e c o r, G. B. 194& S t a t i s t i c a l M ethods A pplied to E xperim ents
i n A g r ic u ltu r e and B io lo g y , Ames, Iowa, The Iowa S t a t e C o lleg e
P r e s s , 4t h e d . , 473 PPS te a r n s , G. 1929 A r a p id m ethod f o r th e p r e p a r a tio n o f f e c a l d i g e s t s
s u i t a b l e f o r use i n n itr o g e n and m in e ra l a n a ly s i s . J . Lab.
C lin . M ed., v o l . 1 4 * PP« 934- 937S te v e n so n , G ., P . P . Swanson, W. W illman and M. B rush 1946 N itro g e n
m e ta b o lism a s in flu e n c e d by l e v e l o f c a lo r ic in ta k e , c h a r a c te r
o f d i e t , end n u t r i t i o n a l s t a t e o f a n im a l. Fed. P r o c ., v o l. 3 »
p . 240.
Swanson, P . P . , G. F, S te w a rt, W. W illm an, M. M a rsh a ll, E. Brown and
M. Hauck 1944 Egg p r o te in in th e r e g u la t io n o f n itr o g e n m etab­
o lis m . N a tio n a l C o o p e ra tiv e P r o je c t - C o n se rv a tio n o f N u tr i t iv e
Va lu e o f Foods, P ro g re s s N0t e s no. 1 , 4 PP*
Swanson, P- P . 1931 In flu en ce o f n on -p ro tein c a lo r ie s on p r o te in
m etab olism . Fed. P r o c ., v o l. 1 0 , pp. 661- 669*
Thomas, K. 1909 Uber de b io lo g is c h e W e rtig k e it d e r S ti c k s ta f f s u b s t a n z e n
i n v e rs c h ie d e n e n N a h ru n g sm itte ln . B e itra g e g u r Frage Nache dem
p h y s io lo g is h e n S tic k sta ff-m in im u m . A rch iv es f u r P h y s io lo g ie , pp 219-302
T r e i c h l e r , R. and H. H. M itc h e ll 1941 The in flu e n c e o f p la n e o f
n u t r i t i o n and e n v iro n m e n ta l te m p e ra tu re on th e r e l a t i o n s h i p
betw een b a s a l m etab o lism and endogenous n itr o g e n m etabolism
s u b s e q u e n tly d e te rm in e d . J* N u t r i t i o n , v o l. 22, p p . 333- 3 4 3 V o rs, H. M. and F. N. Gurd 1947 P o le o f d ie ta r y p r o t e i n in
e x p e rim e n ta l l i v e r re g e n e ra tio n * A n itr o g e n b a la n c e s tu d y .
Amer. J . P h y s i o l ., v o l. 1 3 1 * PP- 391- 398-

-4 8 -

W esson, L . G. 1932 & m o d if ic a tio n o f th e Osborne-Lfendel s a l t
m ix tu r e c o n ta in in g o n ly in o rg a n ic c o n s t i t u e n t s . S c ie n c e ,
v o l . 7 3 , p p . 339- 340.
W illm an, W ., P . P . Swanson, G. F. S te w a rt, G. T . S tev en so n and
1!> B rush 1943 B io lo g ic a l e f f ic ie n c y o f egg p r o t e i n s .
F e d . P r o c ., v o l . 4 » P» 1&4 «

-4 9 -

t a b le 1

COMPOSITION OF EXPERIMENTAL DIETS
B a s a l D ie t (A)
gm.%

D ie t

Supplem ent
la rd
gm.%

S u c ro se

bean
gm.%

N itro g e n ^
C ontent
mg./gm .

C aloric-^
C ontent
C a lo rie s/g m

0 .9 0

4 .1 0

10

Agar a g a r

2

A

Wesson salts"*’

4

B

2

3 .I 6

4 .0 7

L ard

4

C

4

3 .1 8

4 .1 4

Cod l i v e r o i l

3

D

10

10.91

4 .7 4

V itam in o i l ^

3

E

10

1 0 .9 8

4 .3 0

V itam in s t a r c h 5

1

T

4

4 .8 3

4 .6 3

73

G

13

6.6 7

4 .0 3

H

18

7 .9 2

4 .0 4

I

20

9.13

4 .0 0

J

12

9.92

4 .0 0

Corn s t a r c h

1.
2.
3.
4.

8

8

Wesson (1932)
K je ld a h l n itr o g e n
D ir e c t ca lo rim etry in th e Emerson bomb
Corn o i l fu rn ish in g I .2 3 mg. alpha to co p h ero l ana 0 .1 3
me-napthaquinone per 100 gm. d i e t .
3 * Corn s t a r c h f u r n is h in g 2 .8 mg. calciu m p a n to th e n a te , 1 .0
mg* n i a c i n , 0*3 mg. r i b o f l a v i n , 0*4 mg. th ia m in , 0*3 mg*
p e r id o x in e , 2 0 .0 mg. p-am ino b en zo ic a c id , 2 0 .0 mg.
i n o s i t o l , 2 0 .0 mg. a s c o rb ic a c id , 30.O mg. c h o lin e p e r
100 gm. d i e t .

- 50 -

TABLE 2a

RESULTS PROM DESIGN ONE CALCULATED TO UNITS
PER INITIAL WEIGHT (IW)

B alance
P eriod

I

Rat
No.

Weight
Change

N itrogen
C a lo ries
N itrogen
Eaten
Consumed
Balanced
(x )
(y)
(w)
(z)
gm./em. 1W mg. /gm. 1W C a lo ries/sm . 1 W mg./gm. IW
Diet A

I n itia l
Weight
gm.

1
2
3
4 .

127
128
144
147

-0 .1 0 2
-0 .0 8 6
-0 .1 1 8
- 0.143

O.32
O.44
O.33
0 .3 4

1 .1 8
1.61
1 .2 0
1 .2 4

-2 .1 5
- 1 .7 7
-1 .8 6
-2 .3 7

III

3
6
7
8

117
119
123
134

-0 .0 6 8
-0 .0 8 4
-0 .0 6 5
-0 .0 5 2

0 .2 0
0 .3 0
0.2 4
0.21

0 .8 8
I .3 3
1 .0 7
0 .9 4

-1 .0 2
-1 .4 6
- 0.95
-1 .0 9

II

9
10
11
12

131
137
133
149

-0 .0 7 6
-0 .1 1 7
-0 .0 6 5
-O .087

O.32
0 .2 0
0 .25
0 .2 7

1 .4 7
0.92
1 .1 4
I.2 5

- I .3 6
- I .6 9
-1.11
-O .96

'

M |

134

|

-0 .0 9 0

|

0 .2 9

|

1-18

|

- 1 .4 8

D ie t B

II

1
2
3
4

115
117
129
127

- 0 .0 1 7
-0 .0 0 8
-0 .0 2 3
-0 .0 1 6

1 .0 6
1.07
1 .18
I .4 6

1.40
1 .4 0
1.59
1.92

-0 .3 8
- 0 .3 0
-0 .3 3
- 0 .4 2

I

8
6
7
8

128
136
139
142

- 0.039
-0 .0 8 8
-0 .0 8 6
-0 .0 4 2

I .2 3
1.29
1 .3 0
I .3 2

1.50
1-37
1-37
I .6 0

-1 .2 0
- 1 .3 6
-1 .1 2
-O .84

III

9
10
11
12

123
122
141
135

0.000
-0 .0 1 6
-0 .0 3 6
0.007

1 .08
0.92
0.81
O.98

1 .4 6
1 .2 4
1.09
1 .2 9

0 .0 4
-0 .2 7
-0 .2 8
- 0.18

129

-0 .0 3 0

1 .1 4

1 .4 7

-O .56

M |

-3 1 -

TABLE 2a (Continued)

Balance
P eriod

Weight
Nitrogen
C a lo ries
N itrogen
Change
Eaten
Consumed
Balanced
(
z
)
(w)
(y )
(x )
am./ggii IW .ia&t/sa« IW C alories/sm .. IW. ■fflfif./ga« IW
D iet C

Bat
No.

I n itia l
Weight

III

1
2
3
4

115
118
12?
127

0.000
0.042
0.0 1 6
0.033

1.61
1 .9 8
1.88
2.49

1 .2 0
1.48
1.41
1 .8 6

0.31
0 .7 0
0 .7 6
0.93

II

c
6
7
6

122
129
129
133

0.016
-0 .0 1 6
0.000
0.043

2.28
2 .3 4
2 .0 8
2 . 1|8

1 .73
1 .8 0
1 .6 0
1 .9 0

0 .3 0
-0 .1 6
0 .4 4
o .7 4

I

9
10
11
12

139
144
134
139

0.007
0.049
0.038
0.030

2 .8 2
2 .9 7
3 .0 4
3*15

2 .0 9
2 .2 0
2 .2 6
2 .3 3

0 .9 2
1 .0 6
1 .0 3
1 .1 1

M

133

0.028

2.43

1 .8 2

0 .7 0

“5 2 -

TABLE 2b

RESULTS FROM DESIGN TWO CALCULATED TO UNITS
PER INITIAL 'WEIGHT ( I f )
B alance
P e rio d

R at
No.

Weight
Change

In itia l
Weight

(y)

gm.

g m ./rn . IW

N itro g e n
E aten

(x)
jm s . / W

.

C a lo rie s
N itro g e n
Consumed
B alance
(z )
(w)
IW C a lo rie s /c m . IW m u . / e m . IW

D ie t A
I

13
14
15
16

126
132
143
137

-O .064
-O .098
-O .I3 3
- 0.095

0.38
0 .3 6
0.30
0 .3 8

1 .8 4
I.7 0
1.49
I.8 5

- 1 .4 1
- I .8 3
- I .7 8
- I .7 6

III

17
18
19
20

I83
190
187
153

-0 .0 9 3
-0 .0 7 4
- 0.075
-0w052

0.21
O.33
0.29
0.26

0 .9 1
1.42
1 .2 3
1 .10

-1 .1 6
-1 .1 0
-1 .0 5
-0 .9 5

II

21
22
23
24

174
173
1?0
166

-0 .0 8 6
-0 .0 9 2
-0 .0 6 5
-0 .0 8 4

0 .2 0
0.20
0.21
0.21

1.23
1.25
1.32
1.30

-1 .5 6
-1 .4 8
-1 .4 9
-1 .4 1

161

-0 .0 8 4

0 .2 8

1 .3 9

-1 .4 1

,

M

D ie t C
II

13
14
15
16

120
124
132
129

0.025
0.02 4
0.008
-0 .0 0 8

1 .9 5
2 .0 6
1 .7 2
1.64

1 .7 2
I .8 3
1 .5 2
1 .4 4

0 .5 1
0 .3 8
0 .4 0
0 .2 2

I

17
18
19
20

145
155
156
124

0.021
0.0 0 6
0.000
-0 .0 3 2

2 .52
2.77
2 • 66
1.87

2 .0 4
2 .2 4
2 .1 5
1.52

0 .5 5
0 .7 5
0 .6 6
-0 .7 2

III

21
22
23
24

*
166
167
137

*
0.0 4 2
0.032
0 .0 5 7

*
2.02
1 .9 0
2.41

*
1.72
1 .6 1
2.05

*
0 .6 1
0 .4 4
1 .1 3

0.025

2 .1 4

1 .8 1

0 .4 6

M
*

|

144

1

C a l c u la tio n s l o s t

-

53 -

TABLE 2b (C o n tin u ed )

B alance
P e rio d

R at
No.

In itia l
W eight
«a.

Weight
Change

N itro g e n
C a lo rie s
E aten
Consumed
(x )
(z )
(y)
p m ./m . IW m p./em . IW C alo ri es/em . IW

N itro g e n
B alance
(w)

D ie t D
III

13
14
13
16

147
137
162
133

0.122
0.121
0.036
0.133

3 .6 4
3 -1 9
3 -4 2
3 .9 0

2 .4 1
2.22
2 .3 1
2 .3 2

3 .6 1
3 .1 9
3 .4 6
3 .6 9

ii

17
18
19
20

176
182
180
133

0.119
0.093
0.106
0.078

3 .0 8
4 .9 2
4 .9 1
4*37

2 .2 6
2.19
2 .19
2 .0 4

3 .1 4
3 .8 2
3 .0 3
2 .3 7

I

21
22
23
24

171
162
162
131

0.064
0.092
0.103
0.093

3 .3 6
3 .3 8
3 .6 2
3*93

2 .31
2 .4 0
2 .4 2
2 .3 6

3 .1 0
3 .2 3
3 .6 3
3*43

M

I63

0.099

3 -3 4

2 .3 2

3 .3 1

TABUS 2 c
RESULTS jRQM DESIGN THREE CALCULATED TO UNITS
PER INITIAL WEIGHT (IW)

Balance
P eriod

Rat
No.

I n itia l
Weight
gm.

Weight
Change
(y )
m ./so n . IW

N itrogen
Eaten
(x )
IW

C a lo ries
N itrogen
Consumed
Balance
(w)
(2 )
C alories/cm . IW me:. Aon. IW

D iet A

I

23
26
27
28

141
123
123
146

-0 .0 6 4
-0 .0 6 4
-0 .0 8 9
-0 .1 2 3

0.42
0.4 1
0.34
0 .2 6

2 .0 3
2 .0 0
I .6 7
1.27

- I .3 9
-1 .7 8
—1 .8 3
-1 .7 8

III

29
30
31
32

173
194
176
199

-0 .0 6 9
-0 .0 3 7
-0 .0 3 7
-0 .0 4 0

0.32
0.28
0.33
0 .3 6

1 .3 7
1.23
1. •2
1.33

-0 .9 0
-1 .0 1
-1 .1 3
-0 .8 4

II

33
34
33
36

143
133
144
133

-0 .0 7 7
-0 .0 7 3
-0 .0 7 6
-0 .0 3 9

0 .1 8
0 .1 4
0 .2 1
0.22

1.13
0 .8 8
1.29
1*33

-1 .3 1
- 1 .1 8
- I .3 1
- 1-34

M

133

-0 .0 7 1

0 .2 9

1.4 4

-1 .3 3

D iet E

11

23
26
27
28

163
148
149
136

0 .1 0 9
0.128
0.1 3 4
0.109

3 -3 3
^.83
3 .9 1
3*33

2 .2 0
2 .4 1
2 .4 4
2 .2 8

3 .2 7
3 .6 0
3 .6 3
3 -3 4

I

29
30
31
32

131
173
160
173

0.112
0.0 9 2
0.094
0.073

6.13
3 .3 8
3 .6 7
3 .2 7

2 .3 6
2 .0 7
2 .1 8
2 .0 3

3 .3 7
3 .1 9
3 .3 2
3 .2 3

III

33
34
33
36

160
131
163
136

0.1 4 4
0.132
0.121
0.102

3 .8 1
3 .6 6
3*77

2 .1 8
2 .3 2
2 .1 3
2 .1 9

3-33
4 .0 4
3* 66
3 .0 2

M

139

0.11 3

3 .7 0

2 .2 3

3 .3 2

o .lO

-5 5 -

table

B alan ce
P e rio d

R at
No.

In itia l
Weight

am.

2c (C ontinued)

W eight
N itro g e n
C a lo rie s
Change
Eaten
E aten
(z )
(y )
(x )
am . /am. IW ma:./<aii. IW C a lo rie s/e m . IW

N itro g e n
B alance
(w)
IW

D ie t F
III

1.94
2 .2 7
2.12

1.92
1.80
2.11
1.81

0.82
O.63
0.37
O.76

0.011
0.023

2.22
2 .0 0

2 .2 0
1.98

0.43
0.40

0.022
0.0 1 0

2.05

2.03

0 .3 4

2 .0 2

2 .0 0

0.33

130
140
149

0.007
0.007

2 .2 4

2.14
2.28

0.020

2 .3 1

36

155

- 0.071

2.41
2.13

0.62
O.36
O.67

2.06

O.46

M

170

0.012

2.16

2.03

O.38

188
163
107
174

0.027
O.03I
O.O36
0.023

31
32

175
197
183
195

33
34
35

25

26
27
28
II

29

30

I

2.06

2.38

-5 6 -

TABLE 2d
RESULTS FROM RESIGN FOUR CALCULATED T'O UNITS
PER INITIAL WEIGHT (Iff)

B alance
P eriod

Rat
No.

I n itia l
Weight
«»>•

Weight
Change

N itrogen
Eaten

C a lo ries
Eaten
(y)
(z )
U)
«a./en> IW irn, J e m , LW _C alories/gm . IW

N itrogen
Balance
(w)

D ie t G
I

37
38
39
40

123
126
132
103

0.008
-O.O63
-0 .0 8 6
- 0.048

3 .8 2
3 -3 ^
2 .4 8
4 .4 6

1 .88
1 .65
1.22
2 .2 0

-0 .0 5
-O .38
- I .6 0
-0 .2 0

III

41
42
43
44

113
ill
128
149

- 0.018
-O.O36
0.0 0 0
-0 .0 3 4

2 .6 7
1 .9 9
3 .2 0
2 .7 4

1 .3 4
1.00
1.61
I .3 8

0.03
- 0 .3 7
0 .2 0
-0 .1 6

II

43
46
47

117
121
143

-0 .0 2 6
-0 .0 3 0
-0 .0 2 8

3 .3 2
2 .3 2
3-34

1 .7 8
I .3 0
1 .7 9

0 .0 7
- 0 .2 9
-0 .1 4

M

126

-0 .0 2 6

3 .0 6

I .3 6

-0 .2 8

D ie t H

II

37
38
39
•40

124
112
133
108

-0 .0 2 4
-0 .0 1 8
- 0.043
- 0.009

3 .8 3
4 .3 3
2 .0 3
4 .91

1 .6 8
1 .9 0
1.23
2 .1 3

- 0 .4 7
0 .7 4
-0 .8 1
0 .9 8

I

41
42
43
44

119
120
140
163

- 0.0 3 9
-0 .0 6 7
- 0.0 3 7
-O.067

3*33
3-37
4-03
3 .7 0

1.42
1 .4 3
1 .71
1 .6 0

- 0 .6 8
-1 .1 3
-0 .2 3
-0 .6 4

III

43
46
47

116
116
143

0.009
- 0.009
- 0.034

3-46
3*6 4
2 .8 7

1 .3 3
1 .2 8

0 .3 7
0.02
-0 .1 1

M

127

- 0.034

3 .3 8

I .3 6

-0 .1 6

1 .1 8

-57-

t a b l e 2 d (C o n tin u ed )

B alance
P e rio d

R at
No.

In itia l
Weight

Km.

W eight
Change

N itro g e n
E aten

C a lo rie s
E a te n

N itro g e n
B alance

(y)

(x)

(z)

(w)

sm ./cm . IW me. / em. IW C a lo rie s/e m . IW iek./kto. IW
D ie t I

III

37
38
39
40

123
111
12?
107

-0 .0 1 6
0.000
-0 .0 1 6
-0 .0 2 8

3-49
2.93
2 .8 8
3 .0 8

I.5 2
1 .2 8
1 .2 6
1-35

0 .5 1
-0 .1 3
-0 .2 2
0.05

II

41
42
43
44

112
117
131
134

-0 .0 0 9
-0 .0 5 1
-0 .0 2 3
-0 .0 1 9

5 -3 5
3 .9 6
4 .1 7
4 .0 1

2 .1 3
1-57
1 .0 6
1*59

1 .3 6
0 .1 0
0 .4 1
0 .1 3

I

45
46
47

122
130
160

0.0 0 0
-0 .0 5 4
-0 .0 7 5

5 -5 2
3 .6 9
3-99

2 .1 2
1 .4 2
1 .5 3

0 .4 8
-0 .8 9
-0 .7 3

M

127

-0 .0 2 6

3 .9 1

1 .3 6

0 .9 6

-5 8 -

TABLE 2e
RESULTS FROM DIETS I AND J IN DESIGN FIVE CALCULATED
TO UNITS PER INITIAL WEEGUT (IW)

B alance
Period

Rat
No.

I n itia l
Weight
cm.

Weight
N itrogen
N itrogen
C a lo ries
Change
Eaten
Balance
Eaten
(w)
(y )
(x )
(z )
cm./cm. BIT me./cm. IW C a lo ries/em . IW m e./cm . IW
D ie t I

I

48
49
50
51

175
166
I65
156

-0 .0 8 0
-0.0 7 2
-0 .0 6 7
0.026

4*8o
5 .0 6
4 .6 4
5 -7 4

1.8 9
1-99
1.82
2 .5 1

- 0 .5 1
0 .23
-0 .0 4
0 .5 1

III

52
53
54
55

171
157
151
150

0.023
0 .0 0 6
0.040
0.0 0 7

4 .8 2
4 .8 8
4 .9 0
5 -3 5

1 .9 4
1 .9 6
1 .9 7
2 .15

0 .5 0
0 .3 0
0 .4 6
0 .5 0

II

56
57
56
59

154
161
157
133

0.006
0.024
-0 .0 1 3
-0 .0 2 3

4 .7 7
5*49
4 .7 7
5 .0 6

2 .5 5
2.1 9
I .9 0
2.02

0 .5 4
1 .0 8
0 .6 6
0 .3 6

M

158

-0 .0 1 0

5 .0 2

2 .0 7

0 .3 8

II

60
61
62
63

140
158
140
155

- 0 .0 7 I
-0 .1 0 8
-0 .0 3 6
-0 .1 0 3

1.56
2.0 8
2.13
1.63

0.9 8
I.3 0
1.34
I .0 3

1 1 1 1
0. .0 . 0. i- 1
Ln ^
O

D ie t J

I

64
65
66
67

127
138
144
146

-O.O03
-0.O05
-0 .0 6 9
-0 .0 8 9

2 .7 3
2 .6 6
2 .8 4
I .8 5

I .6 4
I .6 0
1 .7 0
1.11

-I .3 6
- 1 .2 6
-O .83
- 1 .7 0

III

68
69
70
71

loO
I07
I69
159

-0 .0 6 2
-0 .0 4 2
- 0.047
-0 .0 6 9

1-53
1-94
1 .8 4
1.69

0 .9 1
1.1 5
I .0 9
1.01

-0 .3 2
- 0 .3 4
- 0 .2 6
-0 .3 0

M

130

-0 .0 6 9

2 .0 4

1.24

- 0 .7 5

-59-

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- 61-

TABLE 5

MEAN URINARY AND 'TOTAL NITROGEN EXCRETION 01 ANIMALS IN RELATION

TO PERIODS, DIETS AND ANIMAL C-ROUP RESPONSES

U rin a ry N itro g e n E x c re tio n 1'

T o ta l N itro g e n E x c re tio n ^ -

E f f e c t o f P e rio d

D ie t
P e r. I
A
B
C
M

1 .9 3
1 .6 6
1 .2 0
1 .6 o

P e r. I I
1 .1 6
1 .0 6
1 .2 1
1 .1 4

P e r. I l l

P e r. I

O.98
O.78
0 .8 4
O.87

2 .4 0
2 .4 4
I .9 6
2 .2 7

P e r. I I

P e r. I l l

1-33
1 .55
1 .9 6
1 .6 8

1 .3 7
1.12
1 .2 7
1.25

E f f e c t o f D ie t

Grout)

1 - 4
5 -8
9-12
M

D ie t A

D ie t B

D ie t C

D ie t A

D ie t B

D ie t C

1 .9 3
0 .9 8
1 .1 6
1-33

1.06
1 .6 6
0 .76
1 .1 7

O.84
1.21
1 .20
1 .0 8

2.ZjO
1 .3 7
1-33
1*77

1 .5 3
2 .4 4
1 .1 2
1 .7 0

1 .2 7
I .9 6
I .9 6
1 .7 3

E f f e c t o f Group

P rtt nrt

I
II
III
M

R a ts
1 -4

R a ts
9-8

R ats
9-12

R ats
1 ~4.—

R ats
9—
8

R a ts
9-12

1*93
1 .0 b
0 .8 4
1 .2 8

1 .6 6
1.21
0 ,9 8
1 .2 8

1 .2 0
1 .1 6
O.78
1.05

2 .4 0
1*33
1 .2 7
1 .7 4

2 .4 4
I .9 6
1-37
I .9 2

I .9 6
1-53
1 .1 2
1-33

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TABLE 7

DESIGN USED FOR STATISTICAL
ANALYSIS OF DATA
B alance
P e r io d s

S quares

D ie t A1
no.

I

II

III

a
b
c
d

1
2
3

a
b
c
d
a
b
c
d

D ie t B1
Animals
no.

D ie t C1
no.

3
6
7
8

9
10
11
12

9
10
11
12

1
2
3

3
6
7
8

_/c.

9
10
11
12

b

6
7
8

b

1
2
3
h

D iSt v a r i a b l e s o b se rv e d j
y =
x »
w =
z =

gm. w eight change/gm . i n i t i a l w eig h t
mg* n itr o g e n eate n /g m . i n i t i a l w eight
mg* n itr o g e n balanced/gm . i n i t i a l w eig h t
c a l o r i e s consumed/gm. i n i t i a l w eight

-6 4 -

TABLE 8

SUMS OF SQUARES AND SUMS OF PRODUCTS USED IN AN ANALYSIS
OF' COVARIANCE OF DIET EFFECTS

S ource o f

Sum o f S q u ares (SS) o f y , x , z , and w*
DF

V a r ia tio n

T o ta l

SS X

SS z

SS V

SS Y

35

31.0162

4.8723

35.2881

O.I06945

R ate

8

0.4313

0.3690

2.2547

O.OO6137

P e rio d s

8

1.3098

1.2666

1.1258

0.006288

S q u a re s

3

0.2077

0.1471

O.33I8

O.OOI647

D ie ts

2

27.8931**

S q u a re s X D ie ts

6

0.2124

E rro r

8

0.7620

2.4485**

28. 7640**

0.082266**

0.1754

0.1794

0.003487

0.4657

I.6324

0.007120

TABLE 8 (Continued)

S ource o f
DP
V a r ia tio n

Sum o f P ro d u c ts (SP) o f y , x t z , and w*
SP XZ

SP xar

SP XX

SP zw

SP ZY

SP YW

T o ta l

35

10.7614

28.6822

1-5455

8.4142

0-4771

1.8621

R ats

8

0 . 3H 9

0.4983

0.0121

0.3133

0.0040

0.1 0 1 7

P e rio d s

8

1.3100

-1 .3 0 0 6

-0 .0 7 3 1

-1 .1 8 4 4

-0 .0 3 9 8

0.0998

S q u a re s

3

0.1719

0.1243

0.0132

0.0680

0.0123

0.0122

D ie ts

2

8.2330

28.3132

1.5021

6.3895

0.4480

1.3302

S q u a re s X D ie ts

6

0.1738

0.6434

0.0223

0.0946

0.0182

0.0204

E r ro r

8

0.3378

1.0996

0.0689

0.7333

0.0330

0.0978

*

y
x
2
w

-

gjn^ w eight change/gm- i n i t i a l w eight
mg. n itr o g e n eaten /g ra. i n i t i a l w eight
c a l o r i e s e ate n /g m . i n i t i a l w eight
mg. n itr o g e n re ta in e d /g m . i n i t i a l w eight

s t a t i s t i c a l l y s i g n i f i c a n t a t th e one p e r c e n t le v e l

-6 6 -

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-6 8 -

TABLE 11

MULTIPLE idMD PARTIAL CORRELATION COEFFICIENTS FROM
ERROR SUMS OF SQUARES OF AN ANALYSIS OF VARIANCE
BASED ON DATA FROM RATS RECEIVING- GRADED
INTAKES OF EGG NITROGEN

M u ltip le R eg ressio n ^

DF

M u ltip le
C o r r e la tio n
R

P a r t i a l C o r r e la tio n
R eg ressio n

C o r r e la tio n
C o e f f ic ie n t

y = a -v bx -v cw

2-34

0 . 94**

yx*w
yw*x

O.73**
- 0 .0 8

y s a-v bx-v cz

2-34

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y x .z
yz*x

O.65**
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y s a + bw + cz

2-34

O.97**

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yz*w

0 . 3 4 **
0.88**

y s a + b x + c z + dw

2-33

yx*zw
yw*zx

O.43**
0 .0 4

w = a -v bx + cz

2 -3 4

wx*z
w z.x

0.80**
- 0 .2 7

Q.94**

1 V a r ia b le s i n m u ltip le r e g r e s s io n :
y - w eig h t change
x - n itr o g e n in ta k e
z - c a l o r i c in ta k e
w - n itr o g e n r e t e n t i o n

-6 9 -

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cO

• Qj
00 Cd
35 ©
6^ O
4 - rH
V -/

Q

ll

weight change/gm. i n i t i a l w eight
nitrogen e ate n /g n i9 i n i t i a l w eight
nitrogen re ta in ed /g m . i n i t i a l w eig h t

V i

o 4 3 cp pi-

CM (T v IX ^ O N

II II *
>>

X

Et

-7 2 -

table

15

REGRESSIONS CALCULATED FOR RAT RESPONSE TO LEAN DIETS

D ie ts In
R e g re ssio n ^

S tan d ard
E rro r of
E stim a te

No.
R a ts

R eg ressio n ^

A,I,J

35

y
O.OI39X - 0.3860
y * 0 . 0372w - 0.0334
w • 0.4033* - 1.3383

0 .024
0.019
O.463

0 .7 2
0 .8 4
0 .8 1

A .I .I .J

47

y » 0 . 0178x - 0.0984
y » 0 . 0403vr - 0.0303
w » 0 . 4017X - 1.3338

0.027
0.024
O.464

0 .7 8
0 .8 3
0 .8 3

G,H,I

33

y - 0.0072x - 0.0363
y « 0.0321w - 0.0267
w - 0.4036X - 1*3493

0.023
0 .017
O.319

0 .2 2
O.76
O.33

A,G,H, J

46

y - 0 . 0249X - 0.1108
y - 0 . 0400X - 0.0284
w - 0 . 3812X - 1.3277

0.013
0.023
O.318

0 .9 2
0 .7 9
0 .7 1

A ,G ,H ,1 , 1 , J

69

y - 0.0181* - 0.0939
y » O.O4O3W - 0.0273
w - O.399OX - 1.3473

0.028
0.024
0.480

0*73
0.81
0 ,8 0

^ P e rc e n t bean supplem ent in d i e t s t
A
0 ( v a lu e s on r e g r e s s io n from d e sig n one)
G
1.5
H
18
I
20
J
12
^ y * gm. w eig h t change/gm - i n i t i a l w eight
x * mg. n itr o g e n eaten /g m . i n i t i a l w eight
w » mg. n itr o g e n re ta in e d /g m . i n i t i a l w eight

C o r r e la tio n
C o e f f ic ie n t

F igure l a

« R e la tio n o f n itr o g e n in ta k e t o w e ig h t change i n i n ­

d iv id u a l r a t s fe d 0 , 2 and 4 p e r c e n t egg d i e t s i n d i f f e r e n t s e q u e n c e .
The to p diagram shows r e sp o n se s o f r a t s r e c e iv in g th e th r e e d i e t s in
th e ord er l i s t e d a b o v e.

The c e n t e r diagram shows r e s p o n s e s o f a n im a ls

f o r w hich th e d i e t sequence was 2 , 4 and 0 p er c e n t egg d ie t } and th e
lo w e s t diagram r e p r e s e n ts a 4* 0 &ad 2 p e r cen t eg g d i e t se q u e n c e .

In ­

d iv id u a l r a t r e s p o n s e s to the 0 , 2 and 4 p er cen t e g g d i e t s a re in d ic a t e d
by c r o s s e s , d o ts and sq u a r e s r e s p e c t i v e l y .

-

73-

.05

*

-05

- gm. wei ght

change

/ g m. i ni tial we i g h t

-.10

/
/

-.15
.0 5

/
_l

L
.

-I

I

L

J

------1
-------L
1

0

-.05
-----------------------------

-.10

-.05

-15

i

-»

I

L

-I

1----- '----- *-

i

i

i

i

I
2
.
3
x- mg. nitrogen eate n / g m . initial w e i g h t

F ig u re I b - R e la tio n o f c a lo r i c in t a k e t o w eig h t change i n i n ­
d iv id u a l r a t s fe d 0 , 2 and 4

c e n t egg d i e t s i n d i f f e r e n t se q u e n c e .

The top diagram shows r e s p o n se s o f r a t s r e c e iv in g th e th r e e d i e t s in
th e ord er l i s t e d ab ove.

The c e n te r diagram shows r e s p o n se s o f an im als

f o r w hich th e d i e t sequence was 2 , 4 acid- 0 p er c e n t e g g d ie t ; and th e
lo w e st diagram r e p r e s e n ts a 4* 0 and 2 p e r c e n t egg d i e t sequence*

In ­

d iv id u a l r a t r e s p o n se s t o the 0 , 2 and 4 p e r c en t egg d i e t s a re in d ic a t e d
by c r o s s e s , d o t s and sq u a res r e s p e c t i v e l y .

-7 4 -

.05

-.05

change

-.15
.05

-.05

- g m . weight

/ gm. initial weight

-.10

-.10

. 05

-.05

-.10

-.15
z - c a l o r i e s con su m ed / g m . initial weight

F ig u re I c - R e la tio n o f n itr o g e n b a la n c e to w eig h t change i n i n ­
d iv id u a l r a t s fe d 0 , 2 and 4 per c e n t eg g d i e t s i n d i f f e r e n t s e q u e n c e .
The top diagram shows r e s p o n se s o f r a t s r e c e iv in g th e th r e e d i e t s i n
the ord er l i s t e d above.

The c e n te r diagram shows r e s p o n s e s o f an im als

f o r w hich th e d i e t sequence was 2 , 4

0 p er c e n t egg d ie t ;

and th e

lo w e s t diagram r e p r e s e n ts a 4» 0 and 2 p er c e n t eg g d ie t s e q u e n c e .

In ­

d iv id u a l r a t r e sp o n se s t o the 0 , 2 and 4 p er cen t e g g d i e t s are in d ic a t e d
by c r o sse s* d o ts and sq u a r e s, r e s p e c t i v e l y .

-7 5 -

.05

0

05

-.10

-.15 ^ i
05

i—i—I— i— ■— i i j

i

i_ i

i

l_ i

■ ■ ■

J

I

I

_
_I—
I_
_1 I I I
I_

L

■ ■ ■ ■ Lju.

0

.05

-.10

-15 I i ■ I i ■ i i ■ ■ . <

t I ■ ■ i ■ i—l—I—I—I—1—1—I—I—I 1 1—I—L

05

0

.05

-.10

-.15
w - m g . nitrogen b a l a n c e / g m . initial weight

.

I

■

F igu re I I a «* R e la tio n o f w eig h t change t o n it r o g e n in ta k e f o r r a t s
f e d d i e t s c o n ta in in g

0 , 2 and 4 p er c en t e g g d i e t s d u rin g 3 s e v e n day

p e r io d s .

I I and I I I are in d ic a t e d by c r o s s e s , d o ts and c i r c l e s

P e r io d s I ,

r e s p e c tiv e ly .

C ir c le d d o ts r e p r e s e n t d ie t means f o r th e 12 r a ts *

c o r r e la t io n c o e f f i c i e n t
0 . 8 4 ; th e c a lc u la t e d

The

betw een w eight change and n it r o g e n in ta k e i s

r e g r e s s io n i s y s 0 .0 4 9 8 x - 0 .0 9 5 2 ± 0 .0 2 9 gm*

-mg. nitrogen

eaten

/gm.

initial

weight

-7 6 -

XX

•\o ® x

ID

ig&ia/w |Di|mi 1 1 1 6 / a6uDijo jq&ja/w‘uj6 - A

F ig u r e H b «» R e l a t i o n o f w e ig h t change t o c a l o r i c i n t a k e f o r r a t s
f e d d i e t s c o n ta i n in g 0 , 2 and 4 p e r c e n t eg g d i e t s d u rin g 3 s e v e n day
p e rio d s .

P e r io d s I , I I and I I I a r e i n d i c a t e d by c r o s s e s , d o ts and c i r c l e s

re s p e c tiv e ly .

C ir c le d d o ts r e p r e s e n t d i e t m eans f o r th e 12 r a t s .

Tie

c o r r e l a t i o n c o e f f i c i e n t b etw een w e ig h t change and c a l o r i c in t a k e i s 0 . 6 6 j
th e c a l c u l a t e d r e g r e s s i o n i s y ■ 0 .0 9 7 9 z ~ 0 .1 7 7 4

± 0 .0 4 gm*

-7 7 -

XX

-calories

in

consumed

CVI

/ g m . initial weight

lD

ir>
O

o
O

mO
QI

7

jq6i9/v\ |DU|ui uu 6/ 9 6 udijo w6i9M iu6-A

Figure H e - R e la tio n o f w eig h t change t o n itr o g e n r e t e n t io n fo r
r a t s fe d d i e t s c o n ta in in g 0 , 2 and 4 p er c e n t egg d i e t s d u rin g 3 sev e n
day p erio d s*

P e r io d s I , I I and I I I a r e in d ic a te d by c r o s s e s , d o ts and

c i r c l e s r e s p e c t iv e ly *
r a ts.

C ir c le d d o ts r e p r e s e n t d ie t means f o r th e 12

The c o r r e la t io n c o e f f i c i e n t betw een w eig h t change and n itr o g e n

r e t e n t io n i s O.9 6 ; th e c a lc u la te d r e g r e s s io n i s y * 0 .0 5 2 8 w - 0 .0 0 7 6
- 0 .0 1 6 gm.

-7 8 -

- m g . n i t r o ge n

r e t a i ned

•o

/ g m . initial w e i g h t

OJ

;lj5!0/v\ iDijjUi-uu 6 / 0 6 u d mo | i | 6 i 9 M w & - A

E lg u r a I I d - R e la tio n o f n itr o g e n r e t e n t io n t o n itr o g e n in ta k e
fo r r a t a fe d d i e t s c o n ta in in g 0 , 2 and 4 p er c e n t egg d i e t s d u rin g 3
sev e n day p e r io d s .

P e r io d s I , I I and I I I are in d ic a te d by c r o s s e s ,

d o ts and c i r c l e s r e s p e c t i v e l y .
th e 12 r a t s .

C ir c le d d o ts r e p r e s e n t d i e t means fo r

The c o r r e la t io n c o e f f i c i e n t betw een n it r o g e n r e t e n t io n

and n itr o g e n in ta k e i s 0 *8 9 ; th e c a lc u la t e d r e g r e s s io n i s w s 0 . 9 2 4 $ x
“ 1*6356

i °*49

nitrogen

eaten

/ g m . initial w e i g h t

-7 9 -

-mg.

• •

o

CM

I
4q 6 | 9 /w 1D14. iui *0 1 6 / p a u i D j a j u a 6 o j | i u ’B u j - m

O

F ig u r e I I e - R e l a tio n o f n i t r o g e n r e t e n t i o n t o c a l o r i c i n t a k e
f o r r a t s fe d d i e t s c o n ta i n in g 0 , 2 and 4 p e r c e n t eg g d i e t s d u rin g 3
se v e n day p e r i o d s .

P e r io d s I f I I and I I I a r e i n d i c a t e d by c r o s s e s ,

d o ts and c i r c l e s r e s p e c t i v e l y .
th e 12 r a t s .

C ir c le d d o ts r e p r e s e n t d i e t m eans f o r

The c o r r e l a t i o n c o e f f i c i e n t b e tw e e n n i t r o g e n r e t e n t i o n

and c a l o r i c in ta k e i s 0 .6 2 ; th e c a l c u l a t e d r e g r e s s i o n i s w » I .7 2 6 9 z
« 3 .0 2 6 3

± 0 .7 6 mg.

-calories

consumed

/ g m . initial w e ig h t

- 80-

o

I

CJ

I
414619 M | 0 { i | u i l u 5 / p a u j D i a j u a & o j j i t r & w - M

O

F ig u r e I I I a ** E f f e c t o f v a r y in g th e c a l o r i c v a lu e o f d i e t s on
w e ig h t change v e r s u s n i t r o g e n i n t a k e c u rv e s f o r r a t s f e d g ra d e d l e v e l s
o f egg n itr o g e n .

S o li d l i n e and p o i n t s i n d i c a t e re s p o n s e s t o low

e a l o r i e d i e t s ; b ro k e n l i n e s and c i r c l e s show e f f e c t o f i n c r e a s i n g
d ie ta ry f a t .

Lower p o r t i o n s o f two l i n e s a r e b a s e d on 0 an d 4 P®**

c e n t e g g d i e t s ; p o r t i o n s o f l i n e s above i n f l e c t i o n b a s e d on 4 and
10 p e r c e n t egg d i e t s .

-mg.

n i t r ogen

ro

e at e n

/gm .

m

initial w e i g h t

-8 1 -

•••

in

if)
j i j Di dM (D141 u) * i u 5 / a 6 u D q o m f t j a M - u i f i - A

f i g u r e H I b - E f f e c t o f v a r y in g th e c a l o r i c v a lu e o f d i e t s o n
w e ig h t change v e r s u s n i t r o g e n r e t e n t i o n c u rv e s f o r r a t s f e d g ra d e d
le v e ls o f egg n itr o g e n .

S o l i d l i n e an d p o i n t s i n d i c a t e r e s p o n s e s t o

low c a l o r i e d i e t s ; b ro k e n l i n e s and c i r c l e s show e f f e c t o f i n c r e a s i n g
d ie ta ry f a t .

Lower p o r t i o n s o f two l i n e s a r e b a s e d on 0 an d 4 p e r

c e n t egg d i e t s ; p o r t i o n s o f l i n e s above i n f l e c t i o n b a s e d on 4 an d 10
p e r c e n t egg d ie ts #

-mg.nitrogen

r e t a i n e d / g m . initial weight

- 82 -

OJ

m t\9N i

|o 14.!UI 'UU6 / 96UDL|0 4 M6 I3 M Uj6 -A

F igu re I I I c - E f f e c t o f v a r y in g th e c a lo r i c v a lu e o f d i e t s on
n itr o g e n r e t e n t io n v e r s u s n it r o g e n in ta k e c u r v e s fo r r a t s fe d graded
l e v e l s o f eg g n it r o g e n .

S o lid l i n e and p o in t s in d ic a t e r e s p o n s e s t o

low c a lo r i e d ie t s ; broken l i n e s and c i r c l e s show e f f e c t o f in c r e a s in g
d ie ta r y f a t .

Lower p o r tio n s o f two l i n e s a r e b a sed on 0 and 4 p er

c e n t egg d i e t s ; p o r tio n s o f l i n e s above i n f l e c t i o n b ased on 4 and 10
per c e n t egg d ie t s *

CVJ

•V

• ••

O
|
; q 6 i 9 M iDijiui 0 1 6 / p e u i D j a j u 96 o j j i u ’5 u j - m
vj-

rO

<Ni

CVJ

-mg. nitrogen

rO

eaten / gm. initial weight

-8 3 .

F igu re XV a » Comparison o f w eigh t change v e r s u s n it r o g e n in ta k e
c u r v e s fo r two groups o f r a t s fe d d i e t s c o n ta in in g 0 t o 4 P er cen t
d r ie d e g g .

Broken l i n e b ased on 0 , 2 and 4 per c e n t egg d i e t s ;

l i n e and p o in t s on 0 and 4 P er c en t eg g d i e t s .

s o lid

C r o sse s, d o ts and

c i r c l e s in d ic a t e p e r io d s I , I I and I I I r e s p e c t i v e l y .

The c o r r e la t io n

c o e f f i c i e n t betw een w eig h t change and n itr o g e n in ta k e fo r th e 0 , 2
and 4 P©t* cen t egg d i e t s i s 0 .8 3 ; th e c a lc u la t e d r e g r e s s io n i s :
y « 0 .0 4 9 8 x - 0 .0 9 3 2

1 0 .0 2 9 gnu

For th e 0 and 4 P©r cen t eg g d i e t s , th e c o r r e la t io n c o e f f i c i e n t f o r
th e two v a r ia b le s i s 0*90; th e c a lc u la t e d r e g r e s s io n i s
y ■ 0 .0 3 0 8 x - 0 .0 9 3 3

1 0 .0 2 4 gm.

/ g m . initial weight

TO

-m g. nitrogen

eaten

O

in

in

;g5i9M idijiim uj6/ a&uDtp jgSjaM *uj6-A

F ig u re IV b - Comparison o f w eig h t change v e r s u s n itr o g e n
c u rv es f o r two groups o f r a t s fe d d i e t s c o n ta in in g 0 , t o 4
egg.

r e t e n t io n

P er c e n t d r ie d

Broken l i n e b a sed on 0 , 2 and 4 p e r c en t egg d i e t s ; s o l i d l i n e and

p o in t s on 0 and 4 p e r c e n t e g g d i e t s .
p e r io d s I* I I and I I I r e s p e c t i v e l y .

C r o ss e s , d o ts and c i r c l e s in d ic a t e
The c o r r e la t io n c o e f f i c i e n t betw een

w eigh t change and n it r o g e n r e t e n t io n fo r th e 0 , 2 and 4 Pe r c e n t egg
d i e t s i s 0*96; th e c a lc u la t e d r e g r e s s io n is *
y m 0 .0 3 2 8 w - 0 .0 0 7 6

1 0 .0 1 6 gm.

For th e 0 and 4 Per c e n t eg g d i e t s th e c o r r e la t io n c o e f f i c i e n t fo r th e
two v a r ia b le s i s 0 .0 9 6 ; th e c a lc u la t e d r e g r e s s io n is *
y m 0.0527 w •» 0 .0 0 8 6

1 0 .0 1 5 gm..

-mg. nitrogen

retained

/g m . initial w e i g h t

-8 5 -

ir>
i
4lj6l9/w

|D |IU j'U J5 /a& U D L |0

4Lj6l9/V\

uj6

-A

F igu re IV c - Comparison o f n itr o g e n r e t e n t io n v e r s u s n itr o g e n
in t a k e cu rv es f o r two groups o f r a t s fe d d i e t s c o n ta in in g 0 t o 4
p er cen t d r ie d e g g .

Broken l i n e based on 0 , 2 and 4 p er c en t eg g

d i e t s ; s o l i d l i n e and p o in t s on 0 and 4 P er c en t egg d i e t s .
d o ts and c i r c l e s in d ic a t e p e r io d s I , I I and I I I r e s p e c t i v e l y .

C r o sse s,
The

c o r r e la t io n c o e f f ic ie n t betw een n itr o g e n r e t e n t io n and n it r o g e n in ta k e
f o r th e 0 , 2 and 4 p er cen t e g g d i e t s i s 0 .8 7 ; th e c a lc u la t e d r e ­
g r e s s io n i s ;
w - O.9248 x - I .0 3 5 6

1 0 .4 9 3 mg.

For th e 0 and 4 p e r c e n t egg d i e t s th e c o r r e la t io n c o e f f i c i e n t f o r
th e two v a r ia b le s i s 0.94} 'the c a lc u la t e d r e g r e s s io n is *
w - 0 .9 6 9 3 x - 1«6593

IO .3 4 8 nig*

-mg. nitrogen eaten /gm. initial weight

-8 6 -

O

T

~

Jl|6l9M |D|4jUj UJ&/ P9UID48J U960JJ}U &
UJ - M

F igure V a - S c a t t e r diagram showing r e s p o n se s o f in d iv id u a l r a t s
t o d i e t s c o n ta in in g 0 t o 20 p e r cen t p ea beans*

R e g r e ss io n fo r y ■ a

bx

are in d ic a t e d by s o l i d l i n e f o r 0 , 1 2 , 15 and 18 p er c e n t bean d ie t s * by
broken l i n e f o r 0 , 12 , 20 and 20 p e r cen t bean d ie t s * by l i n e broken w ith
s i n g l e d o ts f o r 0 , 12 and 20 p er cen t bean d ie t s ; and by l i n e broken w ith
two d o ts f o r 1 5 , 18 and 20 p er cen t bean d i e t s .

I n d iv id u a l r a t r e s p o n se s

to 0 , 1 2 , 15* 18 end 20 p er c en t bean d i e t s are in d ic a t e d by c i r c l e s , d o t s ,
t r i a n g l e s , s o l i d sq u ares and open sq u a res r e s p e c t i v e l y .

-

87-

in -c
o>

o>
TJ

o»
OJ .tr
O'

in

ji| 6 iaM |oii!U| *Lu6 / a 6 uouo j i| 6 j8 M m 6 -A

F ig u r e V b «■ S c a t t e r d ia g ra m show ing r e s p o n s e s o f i n d i v i d u a l r a t s
t o d i e t s c o n ta i n in g 0 t o 20 p e r c e n t p e a b e a n s .

R e g r e s s io n f o r y g a

bw

a r e i n d i c a t e d by s o l i d l i n e f o r 0 , 1 2 , 13 and 18 p e r c e n t b e a n d i e t s ; by
b ro k e n l i n e f o r 0 , 1 2 , 20 and 20 p e r c e n t b e a n d i e t s ; b y l i n e b ro k e n w it h
s i n g l e d o ts f o r 0 , 12 and 20 p e r c e n t b ean d i e t s ;
two d o ts f o r 13, 18 and 20 p e r c e n t b e a n d i e t s .

and by l i n e b ro k e n w ith
In d iv id u a l r a t re sp o n se s

t o 0 , 1 2 , 13, 18 and 20 p e r c e n t b e a n d i e t s a r e i n d i c a t e d by c i r c l e s , d o t s ,
t r i a n g l e s , s o l i d s q u a r e s and open s q u a r e s r e s p e c t i v e l y .

retained / gm. initial weight

-8 8 -

- m g . nitrogen

■o

«o

rO

4ij6i9M |D)4jUj

u u 6 / 9 6 u D i p m6i9«\ *UJ5-A

F ig u r e V c - S c a t t e r diagram show ing r e sp o n se s o f in d iv id u a l r a t s
to d i e t s c o n ta in in g 0 t o 20 p er c e n t pea b e a n s.

R e g r e ssio n f o r v e a

bx

a re in d ic a t e d by s o l i d l i n e f o r 0 , 1 2 , 15 and 18 p e r c e n t bean d i e t s ; by
broken l i n e f o r 0 , 1 2 , 20 and 20 p e r c e n t bean d i e t s ; by l i n e broken
w ith s in g le d o ts fo r 0 , 12 and 20 p er c en t bean d i e t s ; and by l i n e broken
w ith two d o ts f o r 13 * 18 and 20 p e r c e n t bean d i e t s .

I n d iv id u a l r a t

r e s p o n s e s to 0 , 1 2 , 1 5 . 18 and 20 p e r cen t bean d i e t s a r e in d ic a t e d by
c i r c l e s , d o t s , t r i a n g l e s , s o l i d squares end open sq u a res r e s p e c t i v e l y .

-8 9 -

m
4L |6i9w

|D i|iui

iju 6 /p a u jD ^ a j

u a 6 o - u m

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eaten

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-mg. nitrogen

/gm. initial weight

in

F igu re VI a - R e la tio n o f w eig h t change t o n itr o g e n in ta k e in
a lb in o r a t s fe d d i e t s c o n ta in in g 0 t o 20 p e r cent pea b e a n s .

Each

p o in t shown r e p r e s e n ts th e mean r esp o n se o f 11 o r 12 a n im a ls.

The

c o r r e la t io n c o e f f i c i e n t betw een th e two v a r ia b le s i s 0*73i "the
c a lc u la t e d r e g r e s s io n i s
y s 0.0181 x - 0 .0 9 5 9

1 0 .0 2 8 gra

F igu re VI b - R e la tio n o f w eig h t change t o n itr o g e n r e t e n t io n in
a lb in o r a t s fe d d ie t s c o n ta in in g 0 to 20 p er cent p ea b e a n s .

Each

p o in t shown r e p r e s e n ts th e mean r esp o n se o f 11 or 12 a n im a ls.

The

c o r r e la t io n c o e f f i c i e n t betw een th e two v a r ia b le s i s 0 .8 1 ; th e
c a lc u la t e d r e g r e s s io n i s
y e 0.0405 w - 0.0275

1 0 .0 2 4 gm.

- m g . nitrogen

re t a i ned

/ g m . initial

weight

-9 1 -

| L| Bj 0 M | 0 | 4IUI U l 6 / 9 &llDl |0 j q 6 »9 M I U 6 - A

F igure VI e - R e la tio n o f n itr o g e n r e t e n t io n t o n it r o g e n in ta k e
in a lb in o r a t s fe d d i e t s c o n ta in in g 0 t o 20 p e r c e n t pea b e a n s.
p o in t shown r e p r e s e n t s the mean r e sp o n se o f 11 or 12 anim als*
c o r r e la t io n c o e f f i c i e n t betw een th e two v a r ia b le s i s 0*80j th e
c a lc u la t e d r e g r e s s io n i s
w ■ 0*3990 x - 1*3473 ± 0*480 mg.

Each
The

o

r
m B i a w |Djjiuj u i B / pauiD^aj ua6oJ*»u B uli9

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F igu re V II a - Comparison o f w eig h t change v e r s u s n it r o g e n in ta k e
c u r v e s f o r r a t s r e c e iv in g 0 t o 5 *7 k

bean n it r o g e n and 0 t o 5 * 9 3 113&•

eg g n itr o g e n p er gram i n i t i a l w eig h t p e r week*

S o lid l i n e o b ta in e d from

r a t r e s p o n se s to egg d i e t s , broken l i n e o b ta in e d from r a t r e s p o n se s t o
bean d ie t s *

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o

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F ig u re V II b - C om parison o f w e ig h t change v e r s u s n i t r o g e n
r e t e n t i o n c u r v e s f o r r a t s r e c e i v i n g 0 t o 3 * 7 4 rag* b e a n n i t r o g e n
and 0 t o 3*93 “ g* e gg n it r o g e n p e r gram i n i t i a l w e ig h t p e r w eek.
S o l i d l i n e o b ta in e d fro m r a t r e s p o n s e s to eg g d i e t s , b ro k e n l i n e
o b ta in e d from r a t r e s p o n s e s t o b e a n d i e t s .

-mg. nitrogen

balance

rO

/ g m . initial w e i g h t

-94-

in

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o

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4 g6 j9 M | D ! | i u r u j 5 / 9 6 u D q o

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Or
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F ig u r e V I I c - C om p arison o f n i t r o g e n r e t e n t i o n v e r s u s n i t r o g e n
i n t a k e c u r v e s f o r r a t s r e c e i v i n g 0 t o 5 * 7 4 rag. b e a n n i t r o g e n and 0 t o

3*93 rag* e g g n i t r o g e n p e r gram i n i t i a l w e i g h t p e r w e e k .

S o lid lin e

o b t a i n e d from r a t r e s p o n s e s t o e g g d i e t s , b r o k e n l i n e o b t a i n e d fro m
r a t r e sp o n se s to bean d ie ts *

95-

- mg. nitrogen

eaten

/g m .in itial weight

-

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OJ

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