Forage intake of Hereford and 75% Simmental-25% Hereford cows grazing Montana foothill
rangeland
by Scott Lloyd Kronberg
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Range Science
Montana State University
© Copyright by Scott Lloyd Kronberg (1983)
Abstract:
Forage intake was estimated for Hereford and 75% Simmental-25% Hereford cows grazing in north
central Montana during the summer. The cows ranged freely over a 8lha (200ac) pasture of foothill
rangeland. Intake was estimated for 4 dry cows of each breed type in 1981 and 6 dry and 6 lactating
cows of each breed type in 1982. The fecal output of dry cows was measured with total fecal
collections and estimated with the chromic oxide dilution technique. Only the chromic oxide technique
was used for lactating cows. Three to 4 esophageal fistulated cows of each breed type were used for
collection of dietary material suitable for typical in vitro digestibility laboratory analysis. The average
body weight of the dry Hereford cows was 440kg in 1981 and 553kg in 1982. The average body weight
of the dry crossbred cows was 607kg in 1981 and 638kg in 1982. The average body weights of
lactating Hereford and crossbred cows were 460 and 572kg, respectively. Forage intake estimates were
expressed as a percent of body weight/day (OMB). Estimates of forage intake for the larger crossbred
cows were compared to estimates obtained for the smaller Hereford cows. Intake estimates reported
here were determined using the chromic oxide derived fecal output estimates. Estimates of dry
Hereford intake were 1.1 and 1.3 for 1981 and 1982, respectively. The intake of dry crossbreds was
estimated at 0.9 and 1.3 for 1981 ana 1982, respectively. Intake of dry Hereford and crossbred cows
was not different (P>.10), but the lactating crossbred cows consume more (P<.10) forage (2.1) than the
lactating Hereford cows (1.9). With metabolizable energy of the range forage estimated at 1.8 Mcal/kg
(0MB), ME consumption was estimated at 15.6 and 21.6 Mcal/day for the lactating Hereford and
crossbred cows, respectively. FORAGE INTAKE OF HEREFORD AND
75% SIMMENTAL-25% HEREFORD COWS
GRAZING MONTANA FOOTHILL RANGELAND
by
S c o t t Lloyd Kronberg
A th e s is subm itted in p a r ti a l f u lf illm e n t
of the re quirem ents fo r the degree
of
M aster of S cience
in
Range S c i e n c e
MONTANA STATE UNIVERSITY
B oz em an , M o n t a n a
D e c e m b e r 1 983
MAIN l ib .
N 37$
11
K 92P
COD. «
APPROVAL
o f a t h e s i s s u b m i t t e d by
S c o t t Lloyd K ronberg
T h i s t h e s i s h a s b e e n r e a d by e a c h m e m b e r o f t h e t h e s i s c o m m i t t e e
a n d h a s b e e n f o u n d t o be s a t i s f a c t o r y r e g a r d i n g c o n t e n t , E n g l i s h
u s a g e , f o r m a t , c i t a t i o n s , b i b l i o g r a p h i c s t y l e , and c o n s i s t e n c y , and i s
ready fo r subm ission to the C ollege of G raduate S tu d ie s .
tihkz
Date
________________
1
_______________
C hairperson,
Approval f o r
th e Major D epartm ent
Head,
Date
Approved f o r
Major D e p a rtm e n t
the C ollege of G raduate S tu d ie s
.s iy
/2 ' 7 of
D ate
G r a d u a te Committee
G r a d u a t e Dean
ill
STATEMENT OF PERMISSION TO COPY
In
p resen tin g
req u irem en ts
for
th is
th esis
in
fu lfillm en t
of
th e
a m a s t e r ' s d e g r e e a t M ontana S t a t e U n i v e r s i t y ,
a g r e e t h a t t h e L i b r a r y s h a l l make i t
r u le s of the L ibrary.
w ithout s p e c ia l
p a rtia l
available
I
to b o rro w ers under the
B r ie f q u o ta tio n s from t h i s t h e s i s a r e a llo w a b le
perm ission,
provided t h a t a c c u r a te acknowledgem ent of
s o u r c e i s made.
Perm ission
for
extensive
quotation
from
t h e s i s may be g r a n t e d by my m a j o r p r o f e s s o r ,
or re p ro d u c tio n
or in h is absence,
D i r e c t o r o f L i b r a r i e s when, i n t h e o p i n i o n o f e i t h e r ,
of the m a te ria l i s
for
m aterial
th esis
in
th is
scholarly
for
w i t h o u t my w r i t t e n p e r m i s s i o n .
S ignature
D ate
\
purposes.
fin an cial
of
by t h e
th e proposed use
Any c o p y i n g o r u s e o f
gain
sh all
this
not
be
the
allow ed
iv
Acknowledgements
T h e r e w e r e m any p e o p l e who w e r e i n v o l v e d i n t h i s p r o j e c t a n d I
feel
t h a t i n many w a y s i t
was a team e f f o r t .
S t e f f a n and Mark T u r n e r f o r
I t h a n k my f r i e n d s Chuck
th e ir h elp w ith
the seem in g ly e n d le s s
h o u rs of c a tc h i n g cows and c l e a n i n g f e c a l bags.
Eldon A yers f o r
criticism
th e sam e r e a s o n s .
and i n s t r u c t i o n .
I also
th an k
C o llen e
Lahaye.
W e in z etl,
Their s u p p o rt i s
I
thank
th a n k him f o r h i s a d v i c e ,
I l e a r n e d much f r o m E l d o n .
F o r t h e i r i n s t r u c t i o n and a s s i s t a n c e
I
I t h a n k my f r i e n d
G ay le
sincerely
Jeanne B lee f o r
w ith
W a tts,
my l a b o r a t o r y
Nancy
R oth
analysis
ana
C h ris
appreciated.
typing
portio n s
o f my t h e s i s
ana f o r
t e a c h i n g me how t o u s e t h e w o r d p r o c e s s i n g s y s t e m .
I
thank
Dr.
Don
K ress,
Dan
Doornbos
p r o v i d i n g t h e cows an d f a c i l i t i e s f o r
thank C h a r lo tte
and W e b s te r
and
Don
the field w o rk fo r
A nderson
t h i s study.
for
I
T h ac k ery fo r t h e i r generous h o s p i t a l i t y
a n d s u p p o r t d u r i n g t h e two s um me rs o f f i e l d w o r k .
I a l s o t h a n k my g r a d u a t e c o m m i t t e e , D r s . M a u r i c e H u l l , C l a y t o n
Marlow an d B r i a n S i n d e l a r f o r
F in ally ,
I w ould l i k e
t h e i r p a t i e n c e and s u p p o r t .
t o t h a n k my f r i e n d a n a a d v i s o r D r . K r i s
H a v s t a d f o r h i s p a t i e n c e and g u i d a n c e an d f o r t h e c o u n t l e s s h o u r s t h a t
he worked w i t h
I ’l l
shared in
never
me i n
th e Bearpaws.
forget
th e Bearpaws.
the
com radery
th a t K ris,
E ldon,
Mark a n a I
V
TABLE OF CONTENTS
L I S T OF TABLES .............................................................................................. ........................
P age
vi
ABSTRACT................................... .................................................................................. ............... v i i
I
LITERATURE REVIEW . . . . . . ........ ................................ .... ....................................
U
I n t r o d u c t i o n .................................... ............
R e g u la tio n of F orage In ta k e •
F a c to rs A ff e c tin g Forage In ta k e .
G e n e r a l T r e n d s ................................................................................................... ....
DESCRIPTION OF STUDY SITE ......................................... " .. .............................................
METHODOLOGY
.............. ............................................. ...................................................
U l -Er
INTRODUCTION ..................................................... ...................... ....................................... ..
14
16
20
20
E x p e r i m e n t a l D e s i g n ............................... ......................................................... ....
I n t a k e ...........................................................................
20
■ F e c a l O u t p u t ....................... .................................... ........................................ ..
2022.
D ie t D i g e s t i b i l i t y ........................................... .... . .................. ........................
S t a t i s t i c a l A n a l y s i s ........................................................ .. .............................. . 22
RESULTS .............................................
C o m p a r i s o n o f F e c a l O u t p u t E s t i m a t e s ..................................... . . ; . .
F o r a g e D i g e s t i b i l i t y .................. ..................................... ..................................
F o r a g e I n t a k e o f Dry C o w s .................. ........................................................ '.
F o r a g e I n t a k e o f L a c t a t i n g Cows ............................ ...................................
C o m p a r i s o n o f F o r a g e I n t a k e o f Dry a n d L a c t a t i n g Cows . . . .
F a c t o r s E x p l a i n i n g V a r i a t i o n I n I n t a k e E s t i m a t e s .....................
DISCUSSION ................................................
F e c a l O u t p u t E s t i m a t i n g T e c h n i q u e ......................................... ................
F e c a l O u t p u t E s t i m a t e s .................................................................... .................
F o r a g e I n t a k e ........................................................ ........................
F a c t o r s E x p l a i n i n g V a r i a t i o n I n I n t a k e ..............................................
E n e r g y I n t a k e ............................................................................................... ..
23
23
24
25
27
28
28
30
30
31
32
34
34
SUMMARY........ .......................................... x. ......................................................................... ....
38
LITERATURE CITED ........................................................... ................................................. ..
41
APPENDICES ..................... .................................... ..............................................................
50
Appendix
Appendix
A ............. ................... .................................................................................
B ...........................................
51
53
vi
L I S T OF TABLES
Table
1
2
3
4
5
Page
D a i l y f e c a l . o u t p u t o f d r y cows a s e s t i m a t e d u s i n g t h e
t o t a l c o l l e c t i o n a n d c h r o m i c o x i d e t e c h n i q u e s * .....................
23
F o r a g e d i g e s t i b i l i t y o f d i e t s s e l e c t e d by e s o p h a g e a l
f i s t u l a t e d cows ....................................................................................................
D a i l y f o r a g e i n t a k e o f d r y cows u s i n g f e c a l o r g a n i c
m a tte r o u tp u t e s tim a te s determ ined w ith the t o t a l
c o l l e c t i o n and chrom ic o x id e d i l u t i o n t e c h n i q u e s
24
26
D a ily f e c a l o u t p u t and f o r a g e i n t a k e o f l a c t a t i n g
H e r e f o r d a n d c r o s s b r e d cows ..........................................................
D a i l y f o r a g e i n t a k e o f d r y a n d l a c t a t i n g cows u s i n g
f e c a l o rg a n ic m a tte r o u tp u t e s tim a te s determ ined w ith
t h e c h r o m i c o x i d e d i l u t i o n t e c h n i q u e ............. .. . . . . ..................
27
28
A ppendix T a b l e s
6
7
L a c t a t i o n s t a t u s , m i l k p r o d u c t i o n , b od y w e i g h t a n d
f o r a g e i n t a k e i n f o r m a t i o n f o r f r e e - r o a m i n g cows
c o m p i l e d f r o m t h e l i t e r a t u r e ................................................................ *
53
Prom inent p l a n t s p e c ie s o c c u r r in g i n th e study p a s tu r e
w i t h e s t i m a t e s o f t h e i r canopy c o v e r a g e and i m p o r t a n c e
in the community .......................... .......................................................
54
vii
ABSTRACT
F o r a g e i n t a k e w a s e s t i m a t e d f o r H e r e f o r d a n d 75J5 S i m m e n t a l - 2 5 %
H e r e f o r d cows g r a z i n g i n n o r t h c e n t r a l Montana d u r i n g t h e summer.
The
c o w s r a n g e d f r e e l y o v e r a 8 1h a ( 2 0 0 a c ) p a s t u r e o f f o o t h i l l r a n g e l a n d .
I n t a k e w a s e s t i m a t e d f o r 4 d r y c o w s o f e a c h b r e e d t y p e i n 19 8 1 a n d 6
d r y a n d 6 l a c t a t i n g c o w s o f e a c h b r e e d t y p e i n 1982.
The f e c a l o u t p u t
o f d ry cows was m e asu red w i t h t o t a l f e c a l c o l l e c t i o n s and e s t i m a t e d
w ith the chrom ic oxide d i l u ti o n tech n iq u e .
Only t h e c h r o m i c o x i d e
te c h n i q u e was u se d f o r l a c t a t i n g cows.
Three to 4 e s o p h a g e a l
f i s t u l a t e d cows o f each b re e d ty p e w ere used f o r c o l l e c t i o n o f d i e t a r y
m aterial su ita b le for ty p ical
v itro d ig e s tib ility lab o rato ry
analysis.
The a v e r a g e b o d y w e i g h t o f t h e d r y H e r e f o r d c o w s w a s 4 4 0 k g
i n 1 9 81 a n d 5 5 3 k g i n 1 9 8 2 .
Th e a v e r a g e b o d y w e i g h t o f t h e d r y
c r o s s b r e d c o w s w a s 6 0 7 k g i n 1981 a n d 638 k g i n 1982.
The a v e r a g e b od y
w e i g h t s o f l a c t a t i n g H e r e f o r d a n d c r o s s b r e d c o w s w e r e 460 a n d 5 7 2 k g ,
respectively.
Forage in t a k e e s t i m a t e s w ere ex p ressed as a p e rc e n t of
b o d y w e i g h t / d a y (0MB).
E s tim a te s of fo ra g e in ta k e f o r the l a r g e r
c r o s s b r e d cows w ere com pared to e s t i m a t e s o b ta in e d f o r th e s m a l l e r
H e r e f o r d cows. I n t a k e e s t i m a t e s r e p o r t e d h e r e w e re d e t e r m i n e d u s i n g
the chrom ic oxide d e riv e d f e c a l o u tp u t e s tim a te s .
E s tim a te s of dry
H e r e f o r d i n t a k e w e r e 1.1 a n d 1.3 f o r 1981 a n d 1982, r e s p e c t i v e l y .
The
i n t a k e o f d r y c r o s s b r e d s w a s e s t i m a t e d a t 0.9 a n d 1.3 f o r 1981 a n a
1982, r e s p e c t i v e l y .
I n t a k e o f d r y H e r e f o r d and c r o s s b r e d cows was n o t
d i f f e r e n t ( P X 10 ) , b u t t h e l a c t a t i n g c r o s s b r e d c o w s c o n s u m e m o r e
(P<.10) f o r a g e (2 .1 ) t h a n t h e l a c t a t i n g H e r e f o r d cow s (1 .9 ).
W ith
m e t a b o l i z a b l e e n e r g y o f t h e r a n g e f o r a g e e s t i m a t e d a t 1. 8 M c a l / k g
(0MB), ME c o n s u m p t i o n w a s e s t i m a t e d a t 15.6 a n d 21. 6 M c a l / d a y f o r t h e
l a c t a t i n g H e r e f o r d and c r o s s b r e d cows, r e s p e c t i v e l y .
I
INTRODUCTION
T h e re a r e 262 m i l l i o n h e c t a r e s o f r a n g e l a n d i n t h e w e s t e r n and
G reat
P lain s
states.
l i v e s t o c k (USDA,
num erous ways,
and
one
of
Of
19 7 4 ) .
th ese,
app ro x im ately
89% a r e
grazed
by
These a n i m a l s i n t e r a c t i n r a n g e e c o s y s te m s i n
but t h e i r in ta k e of v e g e ta tio n i s a prim ary i n t e r a c t io n
great
im portance
to
range
m anagers.
Range
m anagers
i n t e r e s t e d in p ro d u c in g l i v e s t o c k and m a i n t a i n i n g v ig o r o u s fo r a g e
p r o d u c t i o n m u s t know how much f o r a g e t h e i r l i v e s t o c k e a t a n a how much
forage
th eir
range
cap acity of th e ir
produces
land.
in
order
to
d eterm in e
carrying
T h e q u a n t i t y o f v e g e t a t i o n c o n s u m e d by a n
h e r b i v o r e d e p e n d s on t h e
n u tritio n al
the q u a n tity
of forage a v a ila b le to i t
and q u a l i t y
the
requirem ents
n u t r i t i o n a l r e q u i r e m e n t s a r e d e t e r m i n e d by i t s
of
that
(Bines,
anim al
and
1971) .
Its
m etabolic ra te ,
grow th
and r e p r o d u c t i v e s t a t u s and i t s e n e rg y e x p e n d i t u r e s r e l a t i v e to th e
environm ent i t
m in erals
e x ists in
(i.e.
a n d w a t e r ) (Cook,
t h e r m o r e g u l a t i o n and t r a v e l
fo r forage,
197 0) .
F o r a g e i n t a k e e s t i m a t e s h a v e b e e n ma de f o r many d o m e s t i c a n d w i l d
r u m i n a n t s w i t h v a r y i n g n u t r i t i o n a l r e q u i r e m e n t s , b u t o n ly a few o f
these
estim ates
have
b e e n made f o r
g r a z i n g U.S. r a n g e l a n d s 19 8 0 ) .
There
rangelands.
d ifferen ces
are
in
cows v ary
body s i z e ,
e n v i r o n m e n ts and
the l a c t a t i n g
many d i f f e r e n t
These
beh av io r
one of
age,
in
breed
t h e m o s t common r u m i n a n t s
b e e f cow (Van Dyne e t
al.,
ty p e s of cows g ra z in g
U.S.
n u tritio n a l
re q u irem en ts
r e p r o d u c t i v e ana l a c t a t i o n
(Cook,
1970).
L ittle
research
due
to
statu s,
has
been
conducted which p ro v id e s a b a s i s to compare th e fo r a g e consum ption o f
2
laeta tin g
cows w ith
d ifferen t
n u tritio n a l
p ro v id e s i n s i g h t i n t o which d i f f e r e n c e s ,
types,
rap id ly
in creasin g
beef production
(F errell
becom ing i n c r e a s i n g l y
cow h e r d s .
produce
w ith
producers
are
intro d u ce
traits
and B r i t i s h
h eav ier
to
in to
the
th eir
calves.
1983).
The f i r s t
p ro fits
of
ca ttle
the
in
beef
producers are
the p ro d u c tiv e e f f ic ie n c y of
w eaning
larg er
cow
w eights.
European
herd
To
w hich
im pression is
for livestock
before
this
straig h tb red
w ill
producers,
th is,
of
to
some
ca ttle
re su lt
in
to
the
progeny o f European
th e ir calv es are
H ereford
th at
striv in g
do
breeds
or
Angus co w s
tnese la rg e r calv es
but several
c o n c l u s i o n c a n be a c c u r a t e l y
f a c t o r s m u s t be
ma de .
Production
to th e pounds o f c a l f p ro d u c e d i n a co w 's l i f e t i m e ,
calv es
afte r
w eaning and c a r c a s s v a lu e
calves are a l l im p o rtan t f a c to r s for consideration.
of
p ro fits
b reed s a re used in a com m ercial herd,
facto rs related
grow th
1 98 2) ,
When t h e c r o s s b r e d
t y p i c a l l y l a r g e r than c a lv e s o f
considered
reduced
and J e n k i n s ,
concerned w ith
tu rn in g
production of h ea v ie r
increase
and
At t h e sam e t i m e many c a t t l e m e n a r e
calv es
(S teffan,
costs
a n d w i t h t h e cow h e r d c o n s u m i n g a b o u t 60 % o f f e e d r e q u i r e d
production,
th eir
amo ng c o w s o f d i f f e r e n t b r e e d
a r e most a c c o u n ta b le f o r d i f f e r e n c e s i n fo ra g e in ta k e .
W ith
for
r e q u i r e m e n t s and w hich
of
the fin is h e d
M aintenance c o s ts
cow m u s t t h e n b e w e i g h e d a g a i n s t h e r p r o d u c t i v e a b i l i t y
determ ine her productive e ffic ie n c y .
include h e a lth care,
L ivestock f a c i l i t y
The m a i n t e n a n c e c o s t o f
livestock f a c i l i t i e s
cost
are
reasonably
to
t h e cow
and t h e f o r a g e s h e consum es.
uniform
for
cows o f
different
3
breed
ty p es,
asse sse d to
breed
but
the
costs
for
h ealth
care
m ust
be
type.
N orthern
A g ricu ltu ral
p ro d u ctiv ities
of
a n im a l s c i e n t i s t s a s s o c i a t e d w i t h M ontana's
R esearch
H ereford
and
C enter
have
pro d u ctiv ities
in
of
d ifferen t
feed lo t
in v estig ated
and
forage
breed
calf
intake
compare th e p ro d u c ti v e
types
carcass
of
estim ating fecal
of
of
cows,
value.
cow s.
the r a t e
T heir
the
output
chrom ic
could
the
T heir
com pare th e
of gain of
research
has
not
so th e y c o u ld n o t
e f f i c i e n c i e s a m o ng c o w s o f d i f f e r e n t
o u tp u t of dry H ereford
A ccuracy
com paring
they.can
th e g r a z i n g cow s,
T h is s tu d y had tw o o b j e c t i v e s .
measure fe c a l
been
S im m ental-H ereford
r e s e a r c h i s g a t h e r i n g i n f o r m a t i o n w ith w hich
cows.
forage
d e t e r m i n e t h e m a i n t e n a n c e c o s t s f o r a cow o f a p a r t i c u l a r
For th e p a s t 6 y e a rs,
calv es
and
breeding.
The f i r s t w a s t o e s t i m a t e a n d
a n d 75% S i m m e n t a l - 25% H e r e f o r d
oxide
in d icato r
t h e n be a s s e s s e d .
technique
for
The s e c o n d o b j e c t i v e
was to e s t i m a t e th e f o r a g e i n t a k e o f d ry and l a c t a t i n g H e re fo r d ana
75% S i m m e n t a l - 25% H e r e f o r d c o w s .
With t h i s i n f o r m a t i o n ,
com parisons
o f i n t a k e c o u l d be ma de amon g t h e t w o b r e e d s o f c o w s a n a a m o ng d r y a n a
l a c t a t i n g cow s.
T his in f o r m a t i o n co u ld a ls o
be c o m b i n e d w i t h cow
pro d u ctio n re c o rd s to e s tim a te p ro d u ctiv e e f f i c i e n c i e s of the Hereford
a n d 75% S i m m e n t a l - 2 5 % H e r e f o r d c o w s .
LITERATURE REVIEW
JiLtr_o_d_uotion
i
Of t h e v a r i o u s
n u trie n ts required
w a te r-le s s portion of forage (energy
v itam in s,
and
m in erals),
n u trie n ts required in
n u rsing
calv es,
reproduction.
E stim ates
the
by c a t t l e
supplying
energy
energy
com pounds,
supplying
th e l a r g e s t amounts
req u ire
and a v a i l a b l e i n
for
(Knox,
proteins,
compounds a r e
1967)«
m aintenance,
the
Mature
tne
cows,
lactatio n
ana
Im m atu re cows r e q u i r e a d d i t i o n a l en e rg y f o r g ro w th .
of
daily
m etab o lic
energy
needs
for
m aintenance
and
i
l a c t a t i o n v a ry from
and
quantity
of
cows r e q u i r e
and
m ilk p ro d u ctio n
additional
p o ssib ly
197%).
15 .9 t o 2 7 .5 M ea l d e p e n d i n g on t h e c o w ’s w e i g h t
for
H avstad
the
energy
extra
(NRC,
for
grazing,
work o f
(1981) o b s e r v e d
1 97 6) .
Free-roam ing la c ta tin g
travel,
handling
a 45$ i n c r e a s e
bulky
in
therm oregulation
forage
energy
(O suji,
expenditures
o f f r e e - r o a m i n g h e i f e r s compared to t h a t o f t h e i r housed c o u n t e r p a r t s .
He a t t r i b u t e d
trav el.
Young (1 9 7 0 ) a n d W a l l a c e (1 9 5 6 ) f o u n d f r e e - r o a m i n g e n e r g y
expenditures,
for
50$ o f t h i s a d d i t i o n a l e n e r g y c o s t t o g r a z i n g a n d 20$ t o
for
m aintenance.
f r e e ^ r o a m i n g cows,
needs p re v io u sly
cattle,
to
b e 60
a n d 50$ a b o v e e n e r g y
A s s u m i n g a 50$ i n c r e a s e
in
energy
expenditures
expenditures
for
and u s i n g th e e s t i m a t e s f o r d a i l y m e t a b o l i c energ y
m entioned,
m e t a b o l i c energy re q u ire m e n ts fo r f r e e -
r o a m i n g l a c t a t i n g c ow s may be a s h i g h a s 2 3 . 9 t o 4 1 . 3 M c a l / d a y .
There i s
m atch
th eir
(McClymont,
considerable
energy
1967;
evidence t h a t an im a ls g e n e r a lly a tte m p t to
in tak e
B laxter,
w ith
1962; B i n e s ,
th eir
1971;
energy
ex p e n d itu res
B a i l e and F o r b e s ,
19711),
5
With t h e m e t a b l i c e n e r g y c o n t e n t o f w e s t e r n f o o t h i l l g r a s s e s a v e r a g i n g
2.2M cal/kg
on a n
o rg an ic
m atter
basis
(OMB) (NCR,
1976),
a free-
r o a m i n g l a c t a t i n g c o w w o u l d h a v e t o c o n s u m e a b o u t 10.9 t o 1 8 . 8 k g o f
f o r a g e / d a y , depending of h er p a r t i c u l a r re q u ir e m e n ts ,
to m eet h er
e n e r g y needs.
R e g u l a t i o n &£ f . o r a g e I n t a k e
The f a c t
density
one
or
th a t rum inants
stop e a tin g
more
m etab o lic
before f i l l i n g
p h y siological
in ta k e (Bines,
1971).
control:
lik ely
Forbes
su b m itted
th at
to high c a l o r i c
th e ir reticu lo -ru m en suggests
processes
chem o static,
ex ist
which
regulate
therm ostatic
to p h y s ic a l c o n tr o l
(1979) p ro p o s e d
resp o n sib le
o f m edium
th eir
that
food
M e i j s (1981) s u g g e s t e d 3 t y p e s o f m e c h a n is m s o f
several fa c to rs re la te d
in tak e.
fed a d ie t
for
research
intake
w hich
ana
ana
t h a t may r e g u l a t e f o o d
th a t a com bination
reg u latio n .
clearly
lip o sta tic
Va n
of fa c to rs
Soest
d em o n strates
a
are
(1982)
sin g le
mechanism r e s p o n s i b l e f o r i n t a k e r e g u l a t i o n does not e x i s t .
F o r r u m i n a n t s on h i g h l y d i g e s t i b l e d i e t s w i t h o u t h e a t , c o l d o r
n u tritio n
stress,
phagic
behavior
is
believed
to
be
co ntrolled
p r i m a r i l y by l e v e l s o f a v a i l a b l e e n e r g y s u b s t r a t e s ( v o l a t i l e f a t t y
a c i d s ) i n th e body ( B a i l e and F o r b e s ,
1974; M e ijs ,
1981).
B a ile and
Mayer (1968) and B in e s (1971) s u g g e s t e d t h a t r e c e p t o r s s e n s i t i v e to
v o l a t i l e f a t t y a c i d s may o c c u r on t h e l u m e n s i d e o f t h e r u m e n w a l l a n d
in
the v e in s
d rain in g
the
rum en.
Forbes
re c e p to rs s e n s i t i v e to the v o l a t i l e f a t t y
the
liv er.
believed
N eural
or
horm onal
to i n t e g r a t e in
sig n als
(1979) p r o p o s e d
that
the
a c i d p r o p i o n a t e may o c c u r i n
from
these
receptors
th e h y p o th a la m u s w here a s a t i e t y
are
co n tro l
6
center
is
believed
to e x is t
proposes th a t in ta k e i s
(Van S o e s t , 19 82 ).
in itiate d
e n e r g y a v a i l a b l e i n t h e body,
energy
av ailab le
This c h e m o s t a t i c model
when e n e r g y r e q u i r e m e n t s e x c e e d
minus a lo w e r th r e s h o l d ,
exceeds energy re q u ire m e n ts
(Anil
a n d s t o p s wh e n
and F o rb es,
1977).
B a lc h and C a m p lin g (1962) and M ontgom ery and B au m g ard t (1965) h ave
proposed
that
intake.
there
T his
may
theory
se n sitiv e centers in
197 2 ;
M eijs,
therm ostatic
is
based
on
m echanisms
the
controlling
ex isten ce
of
t h e h y p o t h a l a m u s w h i c h may r e s p o n d
body t e m p e r a t u r e due
(Jones,
be
to h e a t
1981).
produced d u rin g
food
tem p eratu re
to changes i n
n u t r i e n t m etabolism
E xperim ents designed
to
test
this
theory
h a v e g e n e r a l l y b e e n u n a b l e t o show t h a t t n e r m o s t a t i c r e g u l a t i o n o f
in tak e
o p erates
C am pling,
1962;
tem p eratu re
1977,
as
under norm al
J ones,
1972).
does appear
cited
p h y sio lo g ical
to
by M e i j s ,
H owever,
affect
1981).
conditions
changes
food in ta k e
in
and
environm ental
(Jones,
B a i l e and F o rb e s
(B alch
1972;
Rohr,
( 19711) a n d B i n e s
(1971) d e t e r m in e d t h a t fo o d i n t a k e of r u m i n a n t s i n c r e a s e d i n a c o ld
e n v i r o n m e n t a n d d e c r e a s e d i n a warm o r h o t e n v i r o n m e n t .
Sm ith
(1976)
found
th at
under
extreem ly
cold
M alechek and
conditions,
ca ttle
reduced g ra z in g tim e.
F in ally ,
lip o sta tic
suggested
ru m in an t food in ta k e
m echanism s
that
anim als
(B alch
striv e
and
to
may be p a r t i a l l y
C am pling,
m aintain
a
co ntrolled
1962).
M eijs
p articu lar
by
(1981)
condition
by
e a t i n g wh e n t h e y a r e t o o t h i n a n d t r y i n g t o b u i l d - u p s o m e f a t r e s e r v e s
when
p o ssib le.
fa tty
acid s
Journet
may d i r e c t l y
hypothalam us.
B aum gardt
a n d Remond ( 1 9 7 6 ) h a v e p r o p o s e d
affect
the
(1970) h a s
in tak e
control
proposed
th at
th at fre e
cen ter
the s iz e
in
the
of the
7
adipose
cells
(1970)
may p r o v i d e
and B a ile
horm onal
co n tro l
hypothalam us.
theories
and
Forbes
to
th e h y o th alam u s w h ile Baumgardt
(1974)
lin k in g
No c l e a r
(M eijs,
signals
suggested
ce n te rs
evidence has
1 98 1 ).
Bines
et
of
th at
fat
may
accu m u latio n
been found f o r
al
there
to
any one o f
(1969) d e m o n s t r a t e d
be
a
tne
these
th a t intake
o f c o n c e n t r a t e s i s re d u c e d i n f a t r u m i n a n t s b e f o r e th e rumen i s f i l l e d
to c a p a c ity .
p artially
the
gut
T his s u g g e s ts t h a t a l i p o s t a t i c
account fo r
reduce
the
reg u latio n
a b ility
of
of
intake.
these
digesta
that
In
ad d itio n
intake,
rum en
th e s e organs can hold
there
is
capacity
C am pling,
additions
to
the
can
affect
1962; B a i l e and F o r b e s ,
of food i n t o
that
intake
expand
1970;
lim itations
in
w ith in
the
q u an tity
of
Forbes,
thought
rum inants
around
1970).
to
reg u late
of re tic u lo (B alch
and
1974). C am p lin g (1970) fo u n d t h a t
the re tic u lo -ru m e n ,
an im m e d ia te d e c re a s e i n
to
processes
evidence
food
accum ulations
to l i m i t the
(Campling,
m etabolic
considerable
Fat
organs
abdom inal c a v ity and th u s a c t i n d i r e c t l y
c o n t r o l m ay a t l e a s t
through
a fistula,
e a t i n g w h ile rem oval of food from
c a u s e d t h e a n i m a l t o e a t much l o n g e r t h a n n o r m a l .
caused
th e rumen
Grovum ( 1 9 7 9 ) f o u n d
t h a t when t h e r e t i c u l u m s o f sh e e p w e re d i s t e n d e d w i t h w a t e r - f i l l e d
ballo o n s
t h e i r food in ta k e
removed,
th e anim al
was d e p r e s s e d .
resumed fe e d in g .
Conrad e t a l .
t h e f o o d i n t a k e o f l a c t a t i n g d a i r y c o w s . The
of
When t h e b a l l o o n s w e r e
(1964) d e t e r m i n e d
dry m a t t e r d i g e s t i b i l i t y
the r a t i o n s ranged
b e t w e e n 52 a n d 80% a n d t h e cow w e i g h t s v a r i e d
b e t w e e n 283 a n d 6 6 1 k g .
They c o n c l u d e d t h a t p h y s i c a l a n d p h y s i o l o g i c a l
facto rs
re g u la tin g
d ig estib ility
food in ta k e
of the d ie t.
change in im portance w ith in c re a sin g
W ith low
d ig estib ilities,
body w e ig h t
8
(reflec tin g
reticu lo -ru m en
d ig e stib ility
of
d ig estib ilities,
d iet
am ong
cow s
capacity
appeared
low
o f 55%),
a positive
forage
two f a c t o r s .
intake
be
was
in tak e.
reg u la ted
N utt e t
p astu re
relatio n sh ip
o f d i g e s t a and
al.
by
At
(1980)
(average
existed
o f 60 %),
high
m etabolism ,
found
dry
that
m atter
betw een rumen
For cows g ra z in g hig h q u a l i t y
(average dry m a tte r d i g e s t i b i l i t y
th at
passage ra te
re g u la te
to
q u ality
and f o r a g e i n t a k e .
between th e s e
to
d ig estib ility .
g razin g
d ig estib ility
appear
intake
p r o d u c tio n and d i e t
cap acity ),
pasture
th e y fo u n d no r e l a t i o n s h i p
From t h e i r r e s u l t s t h e y a l s o h y p o t h e s i z e d
reg u la ted
by
d ifferen t
facto rs
cows
g r a z i n g h ig h and low q u a l i t y
pasture.
strong p o sitiv e a sso c ia tio n
betw een th e a p p a re n t d i g e s t i b i l i t y
ro u g h a g e s and
t h e a m o u n t c o n s u m e d by s h e e p .
d e m o n s t r a t e d t h a t movement o f d i g e s t a
lim ited
by p a s s a g e
o rific e into
B laxter e t al.
for
(1961) showed a
F urther research has
through the a lim e n ta ry
canal i s
o f d i g e s t a . p a r t i c l e s through th e r e ti c u lo - r u m e n
t h e omas um ( B a l c h a n d C a m p l i n g ,
1962) .
P a r t i c l e s m u s t be
of a s m a ll s i z e to p a s s o u t o f th e rum en (B alch ana C am pling,
P a r t i c l e s a r e r e d u c e d i n s i z e p r i m a r i l y by c h e w i n g ,
and r u m i n a t i o n ,
of
d ig estiv e
actio n
1962).
during m a stic a tio n
of m ic ro b ia l fe rm e n ta tio n in the
r e t i c u l o - r u m e n and m u s c u la r a c t i o n o f th e g u t (B alch and C am pling,
I 962).
The r a t e a t w h i c h m i c r o b i a l f e r m e n t a t i o n o c c u r s d e p e n d s on
w hat ty p e and number o f m ic ro o rg a n is m s e x i s t in th e r e t i c u l o - r u m e n
(Van S o e s t , . I 9 8 2 ) .
to
the
chem ical
The n u m b e r a n d t y p e o f r u m e n m i c r o b e s i s r e l a t e d
content
of
the in g e s ta
(B ines,
1971).
D iets w ith
a d e q u a te p r o t e i n l e v e l s u s u a l l y have h ig h e r b a c t e r i a l num bers th an
t h o s e w i t h d i e t s low i n
protein
(Church,
1 97 6) .
D iets th a t are ric h e r
9
in re a d ily
content)
et
support g re a te r
al.,
19 6 6 ) .
b acterial
fed
f e r m e n t a b l e n u t r i e n t s ( h i g h e r d i g e s t i b i l i t y and p r o t e i n
Thorley e t a l.
species
different
in
Church,
numbers o f m ic ro b e s
cows
and P i e t r a s z e k
1976) f o u n d s u b s t a n t i a l
and M aluszynska
differences
in
cultures
(1970,
isolated
often
o f low
Dyne e t a l . ,
to
medium d i g e s t i b i l i t y
1 98 0 ).
lacta tin g
d ig estib ility
Conrad e t a l .
cows
d ig estib ility .
and
fed
d iets
He c o n c l u d e d
could in c r e a s e
vary in g
that
in tak es
lim ited
by
not
"critical
used
alone
as
energy
be t a k e n i n t o
and p r o t e i n
50
intake
physical
the
content
through
rate
80% d r y
m atter
o f 67% o r
greater
to
to
intake
meet
th eir
energy
t h a n 67 % d r y m a t t e r d i g e s t i b i l i t y
capacity
out
th at
crite ria
p o in t" f o r c o n tro l of in ta k e .
of ingesta,
also
be
Range f o r a g e
the feed
cows f e d r a t i o n s
Montgomery an d B a u m g a rd t (1965) p o i n t e d
should
The
1979; K o t h m a n n , 1 980; Van
from
or d ec rea se
th eir
protein
(1964) s t u d i e d
n eeds w h i l e cows fe d r a t i o n s o f l e s s
had
bacterial
of the r e tic u lo - r u m e n to p ro c e ss lo w er q u a l i t y fo ra g e has
much o f t h e y e a r ( K a r t c h n e r and C a m p b e l l ,
of
were
as c ite d
o r meadow h a y .
i m p o r t a n t i m p l i c a t i o n s on f o r a g e i n t a k e o f r a n g e c a t t l e .
is
Giesecke
d ifferen ces in
whe n i s o l a t e d
c o m p o s i t i o n s o f s h e e p when f e d e i t h e r a l f a l f a
lim itations
1965;
(1968) fo u n d s u b s t a n t i a l
c o m p o s itio n from
ratio n s
(W arner,
on
to
d iet
w hich
process
food.
d ig estib ility
to
base
F a c to rs such as p h y sical
concentrations
and p a s s a g e r a t e s
the
form
must
account.
f a c t o r s A f f e c t i n g Forage In ta k e
In M eijs's
in tak e
(1981) t h o r o u g h r e v i e w o f t h e f a c t o r s a i f e e t i n g f o r a g e
of g razin g an im als,
divided in
3 groups:
factors
he s u g g e s te d
related
that
directly
these fa c to rs
to
the anim al,
c a n be
factors
10
related
d irec tly
to t h e f o r a g e r e s o u r c e and f a c t o r s r e l a t e d
management of th e a n im a l and f o r a g e r e s o u r c e .
to tn e
M eijs acknowledged t h a t
these fa c to rs are i n te r r e la te d .
The p r i m a r y
pregnancy s t a t u s ,
facto rs
re la ted
to
the
anim al
l a c t a t i o n s t a t u s and c o n d i t i o n
are:
(M eijs,
a n im a ls r e q u i r e a d d i t i o n a l n u t r i e n t s f o r grow th.
compounds a r e th e n u t r i e n t s r e q u i r e d
in
age,
w eight,
1981) .
Young
Energy su p p ly in g
g re a te st ad d itio n al
am ounts
f o l l o w e d by p r o t e i n s a n d v a r i o u s m i n e r a l s q n d v i t a m i n s ( M a y n a r d e t
a l.,
1 97 9 ) .
0.33 k g / d a y ,
energy to
A 2-year
old
w ould r e q u i r e
satisfy
h e ife r,w ith
a
app ro x im ately
h e r energy re q u ire m e n ts
d aily
g row th
3,%50 K c a l
for
grow th
ra te
of
of m etabolic
(Hav st a d ,
1982 ).
To m e e t t h i s m e t a b o l i c e n e r g y n e e d , s h e w o u l d h a v e t o c o n s u m e a b o u t
1.6 k g o f f o r a g e i n a d d i t i o n t o t h e f o r a g e s h e c o n s u m e d t o m e e t h e r
o th e r energy needs.
H eavier a n im a ls
g enerally
t h a n l i g h t e r a n i m a l s (Van S o e s t ,
cited
by B i n e s ,
1982) .
w e i g h t o f d a i r y cows.
t h a t rum inant g a s t r o i n t e s t i n a l
to body s i z e .
H y p p o l a a n d Ha su ne r i ( 1970,
as
1976) f o u n d a c o r r e l a t i o n o f 0. 7 9 b e t w e e n r o u g h a g e d r y
m a t t e r i n t a k e and th e l i v e
suggested
consum e g re a te r q u a n t i t ie s of forage
T herefore,
capacity
Van S o e s t ( 1 9 8 2 )
is
d irectly
related
a l a r g e r a n im a l would h a v e th e a b i l i t y
to
consume g r e a t e r q u a n t i t i e s of fo ra g e b e fo re re a c h in g i t s r e t i c u l o rumen c a p a c i t y ,
intake.
when f o r a g e q u a l i t y
Conrad e t
al.
is
(1964) fo u n d t h a t
the
prim ary
factor
regulating
th e i n t a k e o f l a c t a t i n g cows
v a r i e d i n d i r e c t p r o p o r t i o n to body w e i g h t when t h e d i e t d ry m a t t e r
d ig estib ility
w a s b e l o w 66 %.
11
Changes
pregnant
in
forage
rum inants
intake
have
(C am pling,
been
1966;
clearly
Forbes
docum ented
1970;
B ines
for
1971).
P e n z h o rn and M e i n t z e s (1972) and B in e s (1976) o b s e r v e d i n c r e a s e s i n
food i n t a k e
of
th is
of
pregnant n o n -la c ta tin g
in crease
to
pregnancy
and
heifers.
part
They a t t r i b u t e d
to
grow th.
M eijs
part
(1981)
s u g g e s t e d t h a t t h e a f f e c t o f e a r l y and m i d - p r e g n a n c y on t h e f o r a g e
intake
o f cows i n n o t w e l l u n d e rs to o d .
C am pling (1966),
(1966) and C u rre n e t a l . (1967) h av e d e m o n s tr a te d
Johnson e t a i.
t h a t cows in t h e i r
l a s t 6 w e e k s o f p r e g n a n c y r e d u c e t h e i r r o u g h a g e i n t a k e b y 12 t o 15 * .
T his i s
generally
believed
t o be a s s o c i a t e d
w ith
the re d u c tio n in
rum en c a p a c i t y due to f e t a l g ro w th ( M e ijs ,
1981), b u t F o rb e s (1970)
suggested
p artly
th at
the
changes r e l a t e d
to
Increased
reduced
consum ption
(1 9 6 1 ) show
lacta tin g
of
food
by
a 25 a n d 32% i n c r e a s e
cows o v e r
tw in s , w hile Jones e t a l.
m atter
provided
for
lacta tin g
intake.
This
lactatin g
in
org an ic
cows (L eav er e t
suggested
that
th at
of
al.,
of
cows
m atter
th eir
not understood.
is
w ell
intake
of
over th a t of
n o n -lactatin g
( 1 9 6 5 ) n o t e d a 35% i n c r e a s e i n
increase
the alim en tary
1969;
in
tract
intake
t h i s hypertrophy a r i s e s
but
is
which o c c u rs
Sm ith and B a ld w in ,
changes a s s o c ia te d w ith the beginning of l a c t a ti o n ,
is
horm onal
The r e c o r d s o f E l l i o t e t
sig n ifican t
by t h e h y p e r t r o p h y
( 1970)
to
F i e l d ( 1 9 6 6 ) o b s e r v e d a 25% i n c r e a s e i n d r y
of la c ta tin g
o rg an ic
C am pling
due
A f r i k a n d e r and M ashona cow s, r e s p e c t i v e l y ,
m atter in tak e
in
be
1963; C am p lin g 1966).
t h e i r dry c o u n te r p a r ts .
id en tical
may
pregnancy.
docum ented (H u tto n ,
al.
intake
from
1 97 H).
endocrine
t h e mechanism
12
Social
(Arnold,
b e h a v i o r o f r u m i n a n t s may a l s o
1970 ;
Jam ieson,
1975,
as c ite d
a f fe c t th e ir forage in tak e
by M e i j s ,
1981).
Tribe
(1950)
o b s e r v e d t h a t whe n a g r o u p o f s h e e p w e r e s u p p l e m e n t e d w i t h g r a i n ,
supplem ented
sheep
unsupplem ented
conducted
sheep
sim ilar
unsupplem ented
grazed
then
lo n g er
when
experim ents
sheep
tended
they
w ith
when
they
w ere
alone.
sheep,
to. d e c re a s e
w ere
but
grazing
w ith
H older
found
and
the
the
(1962)
that
intake
the
to match
t h a t of the supplem ented sheep.
The
forage
in tak e
of
rum inants
is
also
a sso c ia te d d i r e c t ly w ith the f o r a g e r e s o u r c e .
(1967) and R o d r i q u e z
and Hodgson (1974)
f a c t o r s most im p o rta n t i n
forage d ig e s t i b il i t y ,
related
to fo ra g e
found
that
cell
in
forage
(Van S o e s t ,
were
been d is c u s s e d
Forage d i g e t i b i l i t y
content
intake
The r e l a t i o n s h i p
and i n t a k e h a s a l r e a d y
w all
facto rs
tne forage r e la te d
f o r a g e m ass and f o r a g e h e i g h t .
th i s rev iew .
by
A rnold and D u d z in s k i
explaining v a ria tio n
betw een fo ra g e d i g e s t i b i l i t y
some e x t e n t i n
affected
to
appears d ire c tly
1965).
Va n S o e s t
(1965) r e p o r t e d t h a t when c e l l - w a l l c o n t e n t i s h i g h and t h e p r o p o r t i o n
of c e ll- w a ll
c o n stitu e n ts increase,
(1975) a t t r i b u t e d
differences, in
voluntary in tak e d eclines.
fo ra g e in ta k e between fo ra g e s p e c ie s
to d i f f e r e n c e s in p ro p o r tio n of c e l l - w a l l c o n te n ts .
(1963)
found
resu lted in
of
the
in tak e
red u ctio n
forage
d ig estib ility
of grazing d airy
o ccu rrin g
at
the
C orbett e t al.
from
80 t o 6 8%
cows w i t h more
lo w er
lev els
of
Other ex p e rim en ts designed to look a t th e r e l a t i o n s h i p
changing
conclusive
a change in
a 5% r e d u c t i o n i n i n t a k e
d ig estib ility .
betw een
th at
Baker
(M eijs,
forage
1 98 1 ).
d ig estib ility
S tu d ies
on
and
intake
the r e la tio n s h ip
have
of
been l e s s
changes
in
13
forage
mass,
due
by c h a n g e s i n
to
m aturity,
forage
and f o r a g e i n t a k e
d ig estib ility
or
av ailab le
are often
forage
confounded
(M eijs,
1981).
S t o b b s ( 1 9 7 3 a ) s u g g e s t e d t h a t b i t e s i z e m a y b e a l i m i t i n g f a c t o r on
i n t a k e a t low l e v e l s
of fo r a g e m ass.
Hodgson (1968) v a r i e d f o r a g e
m ass w ith v a ry in g l e v e l s o f n itr o g e n f e r t i l i z a t i o n
w hile d i g e s t i b i l i t y
in tak e,
of
the
diet
79 % o f v a r i a t i o n i n f o r a g e
explained
fo ra g e m ass did not s i g n i f i c a n t l y a f f e c t in ta k e .
W h i t t a k e r (1970) fo u n d a c l o s e a s s o c i a t i o n
intake
of
grazing
dem onstrated
sheep
th a t forage
and
tille r
density i s
affectin g b ite size in tropical
show
ana found t h a t
a re latio n sh ip
d istrib u tio n
of
of forage
S tobbs
( 1973 b )
forage fa cto r
but n e ith e r of these stu d ie s
forage
in tak e
and
sp atial
the fo rag e resource.
Another f o r a g e
content.
to tal
w hile
most im p o rta n t
pastures,
betw een
betw een r a t e
len g th ,
the
A lden and
related
factor
that
may a f f e c t
intake is
m ineral
K i r c h g e s s n e r a n d R o t h ( 1 9 7 2 a s c i t e d by M e i j s , 1 9 8 1 ) f o u n d
t h a t f o r a g e p h o s p h o r u s c o n t e n t h ad a s i g n i f i c a n t p o s i t i v e e f f e c t on
in ta k e of grazing c a ttle ,
E rnst
(1978 a s
cited
by M e i j s ,
forage intake.
depend
on
in d ividual
There
management
the
cited
by M e i j s ,
1 9 8 1 ) a n d F i n g e r a n d W e r k (1973 a s
1981) fo u n d a p o s i t i v e
The a f f e c t o f m i n e r a l
p articu lar
a f f e c t of sodium
c o n t e n t on
c o n t e n t o f f o r a g e o n i n t a k e may
req u irem en ts
and
d eficien cies
of
an
or group o f anim als.
are
that
a
number
consumed
of
can in flu e n c e
a v a ila b le to a g razing
forage
b u t sodium c a lc iu m and m agnesium d id n o t.
by
facto rs
re la ted
forage intake.
to
anim al
The q u a n t i t y
ana fo ra g e
of forage
anim al can o b v io u sly in f lu e n c e th e q u a n t i t y of
the
an im al,
but
the
level
at
w hich
forage
14
av ailab ility
becomes a c o n t r o l l i n g
on t h e q u a n t i t y
reported
and q u a l i t y
of
factor
the
on i n t a k e
forage.
a p p e a r s to depend
H avstad
et
al.
(1983)
th a t in ta k e v a lu e s fo r c a t t l e g ra zin g a d im in ish in g supply of.
c re ste d w heatgrass ( d i g e s t i b i li t y
o f 33 t o 43%) w e r e n o t s i g n i f i c a n t l y
d i f f e r e n t w h e n f o r a g e a v a i l a b i l i t y d e c r e a s e d f r o m 920 t o 14 0 k g / h a .
This
study
indicates
lim its in tak e,
may n o t
alter
that
under
conditions
where
daily
intake.
d ig estib ility
O ther
facto rs
fertiliza tio n ,
intake.
forage
quality
th e q u a n t i t y of fo ra g e a v a i l a b l e to a g ra z in g an im al
Handl
and
R ittenhouse
(1972)
reported
a
d r o p p e d b e l o w 176 k g / h a
d e c l i n e i n i n t a k e when f o r a g e a v a i l a b i l i t y
(forage
low
66 %).
of
such
as
d ietary
su p p lem en tatio n ,
n itrogen
se a so n o f use and g r a z in g s y ste m s can a f f e c t fo r a g e
Adequate re v ie w
l i t e r a t u r e review ,
of
these f a c to r s i s
therefore,
beyond t h e
scope of t h i s
they a r e n o t in c lu d e d .
-Oiaaeral Jrmds
Cordova e t a l .
( 1 9 7 8 ) r e v i e w e d t h e l i t e r a t u r e on f o r a g e i n t a k e o f
grazing liv e sto c k .
They r e p o r t e d t h a t m o s t e s t i m a t e s o f i n t a k e f o r
s h e e p and
cattle,
grazing
o f body w e i g h t / d a y .
lite ratu re
w e s t e r n U.S.
ranges,
lie
betw een
I a n d 2.8%
Van Dyne e t a l . ( 1 9 8 0 ) e x t e n s i v e l y r e v i e w e d t h e
on f o r a g e i n t a k e
of la rg e range herb iv o res.
They r e p o r t e d
c a t t l e i n t a k e e s t i m a t e s f r o m 51 d i f f e r e n t s t u d i e s w h i c h u s e d a v a r i e t y
of te c h n iq u e s to e s tim a te fo rag e in ta k e .
e x p r e s s e d a s a % o f body w e i g h t / d a y ,
Forage in t a k e e s tim a te s ,
r a n g e d f r o m a lo w o f 0.96 f o r
c a ttle
g r a z i n g n o r t h e r n d e s e r t s h r u b i n w i n t e r t o a h i g h o f 3.2 f o r
calves
grazing
season.
From
ryegrass
the
and
estim ates
w hite
clover
expressed
pasture
during
on an o r g a n i c
the
grow ing
m atter
b asis
.
15
(OMB),
they r e p o r te d
grazing,
basis
respectively.
(DMB),
grazing.
because of
19 78 ).
From t h e e s t i m a t e s
expressed
on a d ry m a t t e r
they re p o rte d
a v e r a g e s o f 2.1 f o r b o t h s p r i n g a n d s u m m e r
Forage in ta k e i s
o f t e n e x p r e s s e d on a n o r g a n i c m a t t e r b a s i s
the high ash c o n te n t of range forage
E stim ates of forage
estim ates
a v e r a g e s o f 2.U a n d 2. 1 f o r s p r i n g a n d s u m m e r
for
intake
steers
or
for
range
h eifers
cows a r e
(Van D yne,
(C ordova e t a l .
much l e s s
1980;
1 97 8) .
common t h a n
C ordova e t
al.,
T a b l e 6 i n Appendix B p r e s e n t s some e s t i m a t e s o f f o r a g e i n t a k e
f o r f r e e - r o a m i n g cows c o m p iled from th e l i t e r a t u r e .
16
DESCRIPTION OF STUDY SITE
The s t u d y p a s t u r e w a s l o c a t e d a t
I P i g - I B 2JIm ( 2IOOO- 2J2JOOft.) o n t h e
n o r t h w e s t e r n s l o p e s o f t h e Bearpaw m o u n t a i n s i n n o r t h c e n t r a l Montana.
The p a s t u r e w a s a p p r o x i m a t e l y
terrain
was
rugged
pred o m in an tly
upland
A verage an n u al
19 76).
w ith
slo p es
w ith
a
by r o u g h f e s c u e
id ah o en sis
spicatum
[ P u rsh ] S cribn.
th at
habitat
to
sm all
25%.
s i z e and i t s
The
scattered
p astu re
low land
was
areas.
2JST-SOBmm ( 1 8 - 2 0 i n c h e s ) (USDA-SCS,
is
(F estuca
E lm er)
the
p o t e n t i a l l y one o f
M ontana.
( 20 0 a c r e s ) i n
(USDA-SCS,
197 6) c l a s s i f i e d
the
range s i t e w ith p o t e n tia l clim ax v e g e ta tio n p rim a rily
(F estuca
in
up
C onservation S erv ice
area as a s i l t y
su g g ested
few
p re cip ita tio n
The S o i l
dom inated
Si h e c t a r e s
and
scab rella
bluebunch
& Sm ith).
rough
T o rr.),
w heatgrass
M ueggler
fescue-Idaho
Idaho fe s c u e
and
fescue
the m ost p ro d u c tiv e upland fo ra g e
(A groovron
S tew art
h ab itat
types for
(1980)
type
is
ca ttle
They f o u n d t h a t a r e l a t i v e l y u n d i s t u r b e d a r e a o f t h i s
type produces a t l e a s t
v e g e t a t i o n which i s
1,120 k g / h a (1000 I b s / a c r e ) o f a i r - d r y
m ostly p a la ta b le g ra sse s.
T ypically,
the biom ass
o f t h e s e a r e a s i s 30-85% r o u g h f e s c u e w i t h 70-80% o f t h e t o t a l
biom ass
com posed
be v e r y
of
gram inoids.
Rough
fescue
is
considered
p a l a t a b l e to c a t t l e and d e c lin e s under heavy g ra z in g
S tew art,
I 980).
suggested
that
this
of
h abitat
th is
[Lam.]
(M ueggler and
B o t h M u e g g l e r a n d S t e w a r t ( 1 9 8 0 ) a n d t h e SCS ( 1 9 7 6 )
Idaho fe sc u e
type.
h ab itat
Beauv.),
to
Other
type
are:
threadleaf
usually
species
which
p ra irie
sedge
increases
under heavy
increase
ju n eg rass
under
N utt.),
in
heavy g r a z i n g
(K o elaria
(Carex f i l i f o l i a
grazing
ovram idata
prairiesm oke
17
Pui 1s h ) j d f l n t h o n i o . (D^nfctionjLa s p p e)^ K s n t u c k y b l u e g n a s s
(HUrJAJR
( 2 & a .BTAtfiflaLa L . ) ,
lup in e
shrubby
(ktiLPlnjiS s p p . ) » a r r o w l e a f
[P urs h ] N utt.),
pussytoes
JfljJJ-jgjjgljjaffl L.)
Sandberg
annuals
cin q u efo il
The m a j o r i t y
of
bluegrass
the
spp.),
w estern
(Poa s a n d b e r g i i
1980) a n d (USDA,
study
fru tico sa
L.),
b a l s a m r o o t (B alsam orhiza s a g i t t a t a
(I n t e j n n a r i a
(M ueggler and S t e w a r t ,
(P o te n tilla
yarrow
(A chillea
Vasey) and v a r i o u s
1976 ).
p a s t u r e was g r a s s l a n d ,
but a sm all
p o r t i o n o f t h e p a s t u r e h ad a p o n d e r o s a p i n e ( P in u s p o n d e r o s a Laws)
o v ersto ry .
The
ponderosa
pine
was
not
considered
in
sp ecies
c o m p o s i t i o n e s t i m a t e s b e c a u s e i t was n o t c o n s i d e r e d a p o t e n t i a l f o r a g e
sp ecies fo r c a ttle .
S p e c i e s c o m p o s i t i o n w as b a s e d on ca n o p y c o v e r .
R o u g h f e s c u e a n d I d a h o f e s c u e c o m p o s e d a n a v e r a g e o f I 5% a n d I OjE o f
the upland v e g e ta tio n ,
respectively.
w h e a t g r a s s (A s x p m r s n d a s y a t a o h y u m
( S t i s a SJSfflSla T r l n . & R u p r . ) ,
a v e r a g e o f 2,
8,
5 and I
Bluebunch w h e a t g r a s s ,
(Hook.) S c r i b n . ) ,
thickspike
n eed lean d th read
and t h r e a d l e a f sed g e a c c o u n t e d f o r an
of the u p land v e g e ta tio n ,
resp ectiv ely .
T o g e t h e r t h e s e g r a m i n o i d s p e c i e s c o m p o s e d an a v e r a g e o f 54% o f t h e
upland
veg etatio n .
The f o r b
p h l o x CEfoLgX IafifidiJL R i c h . ) ,
v eg e ta tio n ,
resp ectiv ely .
accounted fo r
the rem aining
sp ecies
71% o f
the
low land
M iscellaneous
grass
and
a n d Hood’s
5 a n d 5% o f t h e
forb
sp ecies
11% o f t h e v e g e t a t i o n .
the low land v e g e ta tio n .
v eg e ta tio n
was
W estern w h e a tg ra s s (A aropyron s m i t h i i
n eed leg rass
prairiesm oke
c o m p o s e d a n a v e r a g e o f 16,
Kentucky b l u e g r a s s d o m in ated
of
lupine,
GgfoLBS J J L r J L d t a a . T r i n . ) ,
composed
R ydb.),
and
of
th is
An a v e r a g e
sp ecies.
Idaho fe s c u e ,
n eed leleaf
sedge
green
(C arex
e l e o c h a r i s ( B a i l e y ) H u l t e n ) , a c c o u n t e d f o r a n a v e r a g e o f 3» I , I a n d
18
1%
or
the
low land
v eg etativ e
( j&mJ Bha rl Aar fj Pa a c ^ d a i t a l i s
Porter),
accounted
for
w hile lup in e,
sticky
p rairiesm o k e
and
co m p o sitio n .
Hook .) ,
and
prairie
a m ea n o f 7 a n d 3% o f
geranium
h airy
W estern
rose
(Rosa
arkansana
the low land com position
C Ge r an i um v i s c o s i s s i m u m
g o ld en aster
snow berry
(H etero th eca
Fisch.
v illo sa
& Mey.)
(Pursh)
S h i n n e r s ) ma de u p 5 , 4 , 2 a n d 1% o f l o w l a n d v e g e t a t i v e c o m p o s i t i o n .
list
of
plant
A p p e n d i x A.
species
Table 7
occurring in
the
study
pasture i s
A
presented in
i n A p p e n d ix B p r e s e n t s i n f o r m a t i o n on c a n o p y
c o v e r and c o m p o s i t io n o f p ro m in e n t s p e c i e s i n t h e p a s t u r e .
U s i n g t h e SCS p r o c e d u r e f o r r a n g e c o n d i t i o n r a t i n g a n d b i o m a s s
data collected
from r e p r e s e n t a t i v e
a r e a s were r a t e d
i n e x e ll e n t range co n d itio n .
produced a s i g n i f i c a n t
range
co n d itio n
preponderance of
a re a s of the study p a s tu re ,
qu an tity
was
rated
the invader
of forage
poor
for
upland
Although lo w la n d a r e a s
re la tiv e
these
to
areas
th eir
due
size,
to
th e
s p e c i e s Kentucky b l u e g r a s s .
S o i l s o f t h e s t u d y p a s t u r e a r e m o d e r a t e l y d eep H a p l o b o r o l l s on
s l o p e s and lo w la n d s and s h a llo w
( M ontagne e t a l . ,
(C aprio,
1965).
1982);
L i t h i c H a p l o b o r o l l s on r i d g e
A verage f r o s t f r e e
A verage d a te o f l a s t
season i s
spring freeze i s
nin ety
tops
days
June fo u rth
w h ile th e av e ra g e d a te of f i r s t f r e e z e i s Septem ber second (C aprio,
I 9 6 5 ) . T h e t y p i c a l g r a z i n g s e a s o n i n t h e a r e a b e g i n s i n May a n d e n d s
i n N ovem ber t o D e cem b er d e p e n d i n g on f o r a g e a v a i l a b i l i t y
and snow
depth.
Several
plants
poisonous to c a t t l e occurred i n th e study p astu re .
Two-grooved m i lk v e t c h
(A s j f c r ag u l us b i s u l c a t u s
(Hook. )) o c c u r r e d i n
s t u d y p a s t u r e , b u t d i d n o t a p p e a r to be g r a z e d .
the
C hokecherry (Prunus
19
yiX&Utifrna W
a lso occurred in fre q u e n tly ,
very sm all q u a n titie s i f
they
b u t t h e cows o n ly a t e i t i n
ate i t a t a ll.
Green p o n d e ro sa p in e
n e e d l e s w e re a v a i l a b l e b u t t h e cow s d i d n o t a p p e a r t o be c o n s u m in g
them.
No c o w s w e r e o b s e r v e d s u f f e r i n g f r o m p o i s o n i n g d u r i n g t h e
summers o f t h e stu d y .
two
20
METHODOLOGY
E x p erim e n ta l Design
,
The e x p e r i m e n t h a d a r a n d o m i z e d
co m p lete block design.
Forage
i n t a k e e s t i m a t e s w e r e d e t e r m i n e d on r a n d o m l y s e l e c t e d H e r e f o r d a n d 75$
S i m m e n t a l - 2 5 % H e r e f o r d c o w s a n d b l o c k e d by t h e m o n t h s o f f e c a l o u t p u t
and f o r a g e . d i g e s t i b i l i t y
estim ation.
Intake
F o r a g e i n t a k e was e s t i m a t e d u s i n g t h e e q u a t i o n :
Total f e c a l o rg a n ic m a tte r o u tp u t
---------------------------------------------------------------------I- d ie ta r y organic m atter d i g e s t i b i l i t y
Organic m a tte r in t a k e =
O rganic
m atter
intake
was e x p r e s s e d
.
a s a $ o f body w e ig h t.
Body
w e i g h t s w e re d e t e r m in e d p r i o r to e a c h c o l l e c t i o n f o l l o w i n g a H lhr
o v e r n i g h t s h r i n k p e r i o d w h e re a l l cow s w e r e k e p t o f f f e e d and w a t e r so
as to sta n d a rd iz e th e ir
p r e -w e ig h in g f e e d and w a te r i n t a k e l e v e l s .
F e c a l Output
Total fe c a l organic m a tte r
c o l l e c t i o n s and th e
1980).
T otal
periods
once
as
chrom ic
fecal
by
oxide
co llec tio n s
p e r month.
d escrib ed
o u tp u t was e s t i m a t e d w i t h t o t a l f e c a l
Fecal
K artch n er
C o l l e c t i o n s w e re made i n J u l y
t h r o u g h S e p t e m b e r o f 1982.
d ilu tio n
b ag s and f e c e s - u r i n e
R itten h o u se
(1979)
through S etptem ber of
collection
tw ice
daily
at
et
al.,
w ere
flaps
used.
19 8 1 and J u n e
Four cows o f each b re e d ty p e w ere used i n
1982.
19 81 a n d s i x c o w s o f e a c h b r e e d t y p e w e r e u s e d i n
gathered
(Raleigh
w e r e m a d e o n d r y c o w s f o r 96 h o u r
collection
and
technique
ap p ro x im ately
bags w ere th en removed,
12 h o u r
w eighed,
Cows w e r e
in terv a ls.
em ptied
into
Fecal
containers,
21
cleaned,
cow.
relin ed
w ith
plastic
liners,
r e w e i g h e d and r e a t t a c h e d t o t h e
C o n te n ts o f ea ch c o n t a i n e r was t h e n th r o u g h ly m ixed and sam pled.
The s a m p l e s w e r e p r o m p t l y f r o z e n .
analyzed
for
At a ^ l a t t e r d a t e t h e s e s a m p l e s w e r e
dry m a t t e r and o rg a n ic
m atter
follow ing
AOAC ( 1 9 7 0 )
procedures.
B eg in n in g s i x days p r i o r to th e t o t a l f e c a l c o l l e c t i o n p e r io d ,
e a c h cow w a s d o s e d d a i l y ,
chrom ic oxide
powder.
a t approxim ately
s i x pm,
w ith
t e n grams o f
The c h r o m i c o x i d e p o w d e r w a s c o n t a i n e d i n
28
gram (one o u n c e ) g e l a t i n c a p s u l e s and a d m i n i s t e r e d w i t h a b a l l i n g gun.
At t h e sam e t i m e ,
e a c h co w,
a f e c a l g ra b sa m p le was ta k e n fro m
placed i n a p l a s t i c
sam ples
w ere
through
a Imm s c r e e n
colorim etric
thaw ed,
dryed
bag
in
and f r o z e .
a forced
then analyzed
for
air
At a l a t t e r
dryer
chrom ic
p r o c e d u r e o u t l i n e d by B o l i n e t a l .
th e rectum of
at
ground
content.
A
( 1 9 5 2 ) a n d m o d i f i e d by
The p e r c e n t o f
c h ro m ic o x id e i n a f e c a l g ra b sam p le was e n te r e d i n t o
=
HOC,
oxide
Newman ( 1 9 8 3 ) w a s u s e d f o r c h r o m i c o x i d e a n a l y s i s .
Fecal output/day
date these
the equation:
Q u a n t i t y o f Cr^Cb f e d / d a y x I 00
-------------------------- -— ------------------------------% o f CrgOg i n g r a b s a m p l e
to o b t a i n an e s t i m a t e o f d a i l y f e c a l d ry m a t t e r p r o d u c ti o n f o r each
cow.
E s tim a te s w ere then c o n v e rted
to an o rg a n ic m a t t e r b a s i s f o r
com parison w ith f e c a l o u tp u t e s t i m a t e s from t o t a l f e c a l c o l l e c t i o n .
In
1982,
lacta tin g
technique.
fecal
o u tp u t e s t i m a t e s w ere a ls o
d eterm in ed fo r
six
cows of each b re ed ty p e u s in g th e ch ro m ic o x id e d i l u t i o n
These
cows w ere dosed w i t h
t h e sam e m anner a s th e d ry cow s.
p a s t u r e d and h a n d l e d
together.
chromic oxide
and
sampled i n
Both d ry and l a c t a t i n g cows w e re
22
DJLet. DJLgeatlbjLjlty
D ietary
m aterial
org an ic
m atter
using S a m e 's
technique
of both
(H arris,
breed
co llectio n s
were
m odification
19 7 0 ) ,
types,
d ig estib ility
Extrusa
equipped
ma de
of
the
sam ples
w ith
approxim ately
was d e t e r m i n e d on e x t r u s a
T illey
e x tru s a sam ples,
p rio r
to m orning e x t r u s a
The a n i m a l s g r a z e d
b e fo re bein g herded back i n t o
co llectio n s.
the c o r r a l
unattended
b e fo re b e in g released.
from
placed in
the c o l l e c ti o n
bag,
A p o rtio n of the
d ig estib ility
procedure
10
cows w ere
To o b t a i n
for
o n e - h a lf hour
a plastic
E x tr u s a was removed
bag and f r o z e
prom ptly.
t h e e x t r u s a s a m p l e s w e r e d r y e d a t HOC i n a f o r c e d a i r
m ixed and a p o r t i o n
screen.
the
where t h e i r bags w ere removed
and c a n u la s r e i n s t a l l e d
dryer,
E xtrusa
during
F istu lated
cows,
t h e i r c a n u l a s w ere rem o v ed and e x t r u s a c o l l e c t i o n
bags were atta c h e d .
At a l a t e r d a t e ,
from
fistu las.
tim es/m onth
day p e r io d o f ch ro m ic o x id e a d m i n i s t r a t i o n .
penned o v e rn ig h t
Terry jji v i t r o
were c o l l e c te d
esophageal
four
and
t h r o u g h a Imm
ground s am p le was th en used i n
an aly sis.
was o b t a i n e d
o f th e s a m p le was g ro u n d
The
from
rum en
a m ature,
flu id
used
stall-fed
in
the i n v itr o
the
cow t h a t
in
v itro
received
a
r a t i o n of good q u a l i t y g r a s s hay and had f r e e a c c e s s to w a te r and a
trace
m ineral
S tatistical
s a l t block.
A nalysis
One f a c t o r
a n a l y s i s o f v a r i a n c e w a s u s e d t o c o m p a r e m o n t h l y mean
f e c a l o u t p u t an d f o r a g e i n t a k e e s t i m a t e s b e t w e e n b r e e d t y p e s and f e c a l
output
estim ating
techniques.
explaining v a ria tio n in in tak e,
To e x a m i n e f o r
factors
significant
in
m u l t i p l e r e g r e s s i o n a n a l y s i s was u s e d .
The a l p h a l e v e l u s e d f o r d e t e r m i n i n g s i g n i f i c a n c e w a s 0 . 1 0 .
23
RESULTS
Comparison o f F e o a l O utput E s tim a te s
Fecal
output
estim ates,
from
the
two e s t i m a t i n g
b o t h b r e e d t y p e s , a r e p r e s e n t e d i n T a b l e I.
1981 s e a s o n s h o w e d n o s i g n i f i c a n t
o u tp u t means,
between th e
two
for
C o lle c tio n s d u ring the
d ifference
techniques.
techniques
in the o v e ra ll fe cal
Both
techniques
estim ated
f e c a l o u t p u t a t 0.7% o f b od y w e i g h t / d a y f o r H e r e f o r d s w h i l e
the t o t a l
c o l l e c t i o n and c h r o m i c o x i d e t e c h n i q u e s e s t i m a t e d
a n d 0.5% o f b o d y w e i g h t / d a y ,
T a b l e I.
1981
H e r e f o r d Cows
Total
Chromic
C ollection
Oxide
Technioue
Technioue
using
the
total
C r o s s b r e d Cows
Total
C h r om i c
C ollection
Oxide
Technioue
Technioue
0.5b
0.6b
0.5b
0.5b
0.7b
0.7b
0.6°
0.6°
0.8b
0 . 7 bc
0 . 7c
0.5d
1981 o v e r a l l mean
0.7b
0.7b
0 . 6 bc
June,
1982
0 . 5b
0.7°
0 . 6 bc
0 . 6 bc
July,
1982
0.7b
0.8°
0.6b
0 . 7 bc
0.7b
0.7b
0.7b
0.8b
0.7b
0.8°
0.6d
0 . 8 bc
0.7b
0.8°
0.6b
0.7°
August,
1981
September,
August,
1981
1982
September,
1982
1982 o v e r a l l mean
0.6
r e s p e c t i v e l y f o r t h e c r o s s b r e d c ow s.
D a i l y f e c a l o u t p u t o f d r y cows a s e s t i m a t e d
c o l l e c t i o n and chrom ic o x id e t e c h n i q u e s .
C o lle c tio n Period
July,
fecal o u tp u t.at
^ P e r c e n t a g e o f body w e i g h t on a n o r g a n i c m a t t e r b a s i s .
b >c »dMeans w i t h i n a r o w w i t h d i f f e r e n t s u p e r s c r i p t s d i f f e r
. 0.5°
( P < .10).
24
For
in d iv id u al
m onth
m eans,
only
c o l l e c t i o n had a s i g n i f i c a n t d i f f e r e n c e
In
co n trast,
the
sig n ifican tly
deriv ed
1982 o v e r a l l
d ifferen t.
estim ate
of
means
w eig h t/d ay .
crossbred
estim ate
o f 0 .7
the
was
betw een th e
for
the
two
two
Septem ber
techniques.
techniques
0. 8% o f body w e i g h t / d a y i s a p p r o x i m a t e l y
co llectio n
estim ate
crossbred
w ere
For th e H e re fo rd cow s, th e ch ro m ic o x id e
g re a te r than the t o t a l
For
the
deriv ed e stim a te
cow s,
17 % l a r g e r
nearly
the
o f 0.7% o f body
chrom ic
than
the
14%
oxide
to tal
derived
co llec tio n
0. 6.
of
Forage D i g e s t i b i l i t y
Mean f o r a g e d i g e s t i b i l i t y
a r e d i s p l a y e d i n T a b l e 2.
1982 v a l u e s
and v a l u e s
Cook a n d H a r r i s ( 1 9 6 8 ) .
p reparation of
the
e s t i m a t e s and t h e i r s t a n d a r d d e v i a t i o n s
The 1981 v a l u e s a r e s o m e w h a t l o w e r t h a n t h e
reported
by K a r t c h n e r a n d C a m p b e l l ( 19 7 9 )
D i g e s t i b i l i t y may h a v e b e e n r e d u c e d i n t h e
1981 e x t r u s a s a m p l e s f o r t h e i n v i t r o a n a l y s i s by
ex c e ssiv e h ea t d u ring drying or e x c e ssiv e
p ortions
of
the
and
forage
lo ss
(A c p sta aqd Kothm ann,
of soluble
1978)
.
o rg an ic
Because
the
d i g e s t i b i l i t y v a l u e s f o r 1981 w e r e u s e d o n l y t o e s t i m a t e t h e f o r a g e
i n t a k e o f d ry cows,
concern o f the
T able
2.
t h e i r lo w e r th a n e x p e c te d n a t u r e was n o t a s e r i o u s
study.
Forage d i g e s t i b i l i t y
f i s t u l a t e d cows. a
June
Year
Mean
1981
—
1982
59
of
Julv
d iets
selected
August
SD
Mean
by
esophageal
Seotember
SD
Mean
SD
—
39
10
34
4
35
13
6
45
11
41
16
55
4
SD
^Percentage o f in v i t r o
organic m atter d i g e s t i b i l i t y .
Mean
25
The
1982
and H a r r i s ,
forage
values
1968).
expected v alu es
Forage d i g e s t i b i l i t y
was young,
contents.
approxim ate
su ccu len t
and low
in
cell
w all
contents.
( Cook
was h i g h e s t i n J u n e when
in le s s
d ig estib le
cell
w all
With
p r e c i p i t a t i o n and resum ed p l a n t g ro w th ,
plant
closely
I t d e c re a s e d th ro u g h J u ly and A ugust as th e fo r a g e d r ie d
and i n c r e a s e d
m arkedly
quite
in
Septem ber as th e
c o n s i d e r a b l e I a iI e A u g u s t
i
forage d i g e s t i b i l i t y increased
cows w e r e a g a i n g r a z i n g young s u c c u l e n t
growth.
No s i g n i f i c a n t d i f f e r e n c e s i n d i g e s t i b i l i t y e x i s t b e t w e e n e x t r u s a
co llectio n s
for
d ig estib ility
the
H ereford
and
crossbred
cows.
C onsequently,
v a lu e s f o r e x t r u s a c o l l e c t i o n s from both breed ty p e s a r e
co m b in ed t o make one v a l u e f o r e a c h c o l l e c t i o n p e r i o d .
F o r a g e I n t a k e o f Dr v Cows
Because
determ in e
the
in tak e
d ifferen ces
in
re flectio n s
differences
same
estim ates
intake
of
forage
for
H ereford
betw een th ese
th eir
between
d ig estib ility
fecal
intake
outp u t
estim ates
two
from
the
estim ates.
both
c o lle c tio n periods,
Mean i n t a k e
showed
chrom ic
oxide
are presented in
estim ates,
significant
values
for
differences
technique,
but
for
used
cow s,
ty p es w ere
sim ply
S ig n ific an t
to tal
c o l l e c t i o n and
betw een f e c a l
breed
to
ty p es,
output
for
all
T a b l e 3.
the th re e
between
not
those
w ere
crossbred
d ifferen ces.
to
intake
and
breed
chrom ic oxide te c h n iq u e s were i d e n t i c a l
Mean
values
the
the
c o l l e c t i o n p e r i o d s o f 1 98 1,
two
to tal
breed
types
co llectio n
w ith
the
technique.
26
However,
were
m e a n e s t i m a t e s f o r t h e 1981 A u g u s t a n d S e p t e m b e r c o l l e c t i o n s
significantly
estim ating
Table
3.
d ifferent
using
H e r e f o r d Cows
T otal
Chromic
C ollection
Oxide
Techniaue
Techniaue
both f e c a l
organic m a tte r
c o l l e c t i o n and
C r o s s b r e d Cows
T otal
Chromic
C ollection
Oxide
Technioue
Technique
0.9b
0.8b
0.8b
1.1b
I . Ib
0.9°
0.9°
1.2b
l.lb c
I . QG
0.8d
. 1.1b
I . Ob
0 . 9 bc
0.8°
1.7°
1 . 4 bc
1 . 6 bc
1981
1981 o v e r a l l me an
June,
1982
1.3b
July,
1982
1. 2b
1982
Septem ber,
1 982
1982 o v e r a l l me an
1. 2 b
1. 5°
1 . 4 bc
1.2b
1.2b
I . Ib
1.3b
1.5b
I.SC
1.3d
1 . 7 bc
I . Bb
1.5°
1.3b
1.5°
^ P e r c e n t o f body w e i g h t o n an o r g a n i c m a t t e r b a s i s .
b , c , d Meang w i t h i n a row w i t h d i f f e r e n t s u p e r s c r i p t s d i f f e r
Except
for
the
S eptem ber
co llectio n
tech n iq u e,
co llectio n
p erio d s,
types
the
when
output
0.9b
1981 '
September,
August,
types
D a i l y f o r a g e i n t a k e o f d ry cows u s i n g f e c a l
ou tp u t e s tim a te s determ ined w ith the t o t a l
chromic oxide d i l u t i o n te c h n iq u e s .
1981
August,
breed
techniques.
C o lle c tio n Period
July,
for
the
showed
same, f e c a l
intake
1982
mean
estim ates
in take
( P < . 10).
using
estim ates,
the
to tal
for
all
no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n b r e e d
output
estim ating
technique
was
used.
27
F o r a g e I n t a k e o f L a c t a t l n g .Cows
F o r a g e i n t a k e v a l u e s f o r l a c t a t i n g c o w s a r e p r e s e n t e d i n T a b l e 4.
Mean c r o s s b r e d
co llectio n
v a lu e s were l a r g e r
p erio d s
t h a n mean H e r e f o r d v a l u e s f o r
e x c e p t A ugust,
all
but only the m ean .v alu es of the
S eptem ber c o l l e c t i o n w ere s i g n i f i c a n t l y
larger.
Whe n m e a n i n t a k e
v a lu e s f o r a l l 4 c o l l e c t i o n p e rio d s w ere av erag ed ,
t h e mean i n t a k e
v a l u e s f o r t h e H e r e f o r d and c r o s s b r e d cow s a r e
1.9. a n d 2.1% o f b o d y
w e ig h t/d ay ,
w ere
different.
the
July
resp ectiv ely .
The d e c l i n e
and
d ig estib ility
August
These
mean
values
sig n ifican tly
t h a t o c c u rs i n i n t a k e v a lu e s from
co llectio n s
was
due
not decreasing fe c a l outut.
to
th e June to
d ecreasin g
forage
The f e c a l o u t p u t f i g u r e s i n
T a b l e 4 s ho w t h a t t h e m e a n f e c a l o u t p u t w a s h i g h e s t i n A u g u s t a n a J u l y
for
t h e H e r e f o r d and c r o s s b r e d
cows,
respectively.
m o n th s when f o r a g e d i g e s t i b i l i t y
was l o w e s t .
T a b l e 4. D a i l y f e c a l o u t p u t a n d
and c r o s s b r e d cows.
forage
I
lactatin g
Hereford
forage. Intake
Hereford
Crossbred
%a - - h -----------2 . Ib
June
cr
I
of
t h e two
O
I
F eca l Outout _
Crossbred
Hereford
VO I
C o lle c tio n Period
intake
These a r e
1.0b
July
i . ob
I . Ib
August
I J b
0 . 9b
September
0.9b
I . Oc
O v e r a l l mean
0.9b
1.0°
1 . 9b
2.1°
2.4b
1.9b
2.2b
JD
CO
1.6b
1.9b
2.3°
^ P e r c e n t a g e o f b od y w e i g h t p e r d a y on a n o r g a n i c m a t t e r b a s i s .
b , c A s s o c i a t e d m e a n s w i t h i n a r ow w i t h a d i f f e r e n t s u p e r s c r i p t
(P<.10).
differ
28
&L f o r a g e J n t a k e sJL S jcx a n d L a c t a t i n g Cows
L a c t a t i n g cows had a s i g n i f i c a n t l y g r e a t e r i n t a k e
co u n terp arts.
L a c t a t i n g H e r e f o r d s had an a v e ra g e i n t a k e
ap p ro x im ately
26%
g reater
th an
c r o s s b r e d s had an a v e ra g e i n t a k e
crossbreds.
than
the
dry
H erefords.
t h a t w a s 40% g r e a t e r
t h e i r dry
th at
was
L actatin g
t h a t the dry
T able 5 p ro v id e s a c o m p ariso n of i n ta k e v a lu e s f o r dry
a n d l a c t a t i n g cows o f b o t h b r e e d t y p e s .
T a b l e 5.
D a ily f o r a g e i n t a k e of d ry and l a c t a t i n g cow s u s in g f e c a l
o rg a n ic m a tte r o u tp u t e s t i m a t e s d e te rm in e d w ith the
chromic oxide d i l u t i o n te c h n iq u e .
CO
3
O
O
Drv
Hereford
.
L a c t a t i n g Cows
Hereford
Crossbred
Crossbred
June
1.7b
1.6 b
2.1°
2.4°
July
1.5b
1.4b
1.9C
2.2°
August
1. 2 b
1.3b
1.80
1.6°
September
1.8b
1.7b
1.9°
2 . Ba
O v e r a l l mean
1.5b
. 1.5b
1.9°
2 . id
a P e r c e n t o f b od y w e i g h t p e r d a y on a n o r g a n i c m a t t e r b a s i s .
b , c , d ^ e a n s w i t h i n a row w i t h a d i f f e r e n t s u p e r s c r i p t d i f f e r
Z aslaca Z & a W a im
VarJalJoJi I n I n t a k e E s tim a te s
Forage i n t a k e v a lu e s f o r a l l
cows w ere r e g r e s s e d
type
facto rs.
w ith
Only
the
m onths and f o r a l l
t h e b od y w e i g h t ,
lacta tio n
ex p lain e d a p o rtio n of the v a r ia t io n
lactatin g
Hereford
( P < , 10).
and
crossbred
cows.
d ry and l a c t a t i n g
lactatio n
statu s
facto r
status
and b re ed
sig n ifican tly
i n i n t a k e b etw e en th e dry ana
The p a r t i a l - r
values for
the
29
body w e i g h t ,
0.004,
l a c t a t i o n s t a t u s and b re e d ty p e f a c t o r s w e re .02,
respectively.
lacta tin g
cows w ere r e g r e s s e d
facto rs.
In
sig n ifican t
for
the
Forage i n t a k e v a lu e s f o r a l l
in
body
respectively.
th is
w ith
reg ressio n
explaining
w eight
and
breed
m o nths and f o r
all
th e body w e ig h t ana b re e d ty p e
only
variatio n
. 65 a n d
in
type
the
breed
type
facto r
intake.
The p a r t i a l - r
facto rs
w ere
-.23
was
values
and
.34,
30
DISCUSSION
FeggQ O u t p u t E s t i m a t i n g T e c h n i q u e
A method which a c c u r a t e l y e s t i m a t e s th e f e c a l o u tp u t o f a g r a z in g
anim al,
w i t h o u t e n c u m b e r i n g i t i n s o m e m a n n e r , h a s y e t t o be d e s i g n e d .
C onsequently,
all
i n d i r e c t l y d e r i v e d e s t i m a t e s o f f e c a l o u t p u t m u s t be
compared w i t h m easurem ents d e r iv e d from a l e s s
Total fe c a l
anim al,
is
co llectio n
as
of a free-ro am in g anim al obviously a f f e c t s the
bu t th e d eg ree to which i t
n ot w e ll understood.
which an an im a l i s
the
d u ratio n
contents,
re la tiv e
Several
affected
of
fecal
en v iro n m en tal
to
the load
of
alters
fecal
co llec tio n ,
conditions
feces
its
b e h a v io r and p h y s io lo g y
f a c t o r s must in f l u e n c e th e degree to
by t o t a l
gear are im portant v ariab les.
fecal
than p e r f e c t technique.
and
co llectio n s.
w eight of
and
the
et al.,
1967).
size
T echniques
fecal
of
the incum berance of
bag ana
the
anim al
the c o lle c tio n
w hich i n d i r e c t l y
o u t p u t may n o t e n c u m b e r t h e a n i m a l a t a l l ,
have sh o rtc o m in g s which,
the
F a c to r s such
estim ate
but tn ese techniques
t o s om e d e g r e e , a f f e c t t h e i r a c c u r a c y ( H a r r i s
The c h r o m i c o x i d e d i l u t i o n t e c h n i q u e a p p e a r s t o h a v e
few er sh o rtc o m in g s than o th e r i n d i r e c t te c h n iq u e s (H avstad,
1982).
I t s p rim a ry problem s a r e v a r ia b le re c o v e ry of chrom ic o xide in th e
f e c e s and d i u r n a l v a r i a t i o n i n i t s
19 8 0 ).
output.
excretion ra te
( R aleigh
et al.,
Both o f t h e s e p r o b le m s l e a d t o i n a c c u r a t e e s t i m a t i o n s o f f e c a l
U nfortunately,
r e s e a r c h on t h e s e
problems
in
several
states
a n d by a n u m b e r o f d i f f e r e n t w o r k e r s h a s n o t d e m o n s t r a t e d r e l i a b l e
methods to avoid
these
shortcom ings (R aleigh e t a l.,
19 80 ) .
31
Comparisons o f m easured f e c a l
estim ates
have
produced
E stim ates rep o rted in
of
31%
to
an
When f e c a l
v ariab le
re su lts
(R aleigh
et
al.,
1980).
t h e l i t e r a t u r e have v a r i e d from an u n d e r e s t i m a t e
o v erestim ate
approxim ately
o u tp u t w ith chrom ic oxide d eriv e d
20% h i g h e r
of
then
output e s tim a te s
87%,
but
measured
the
estim ates
values
were averaged
(R aleigh
by s e a s o n ,
tend
et
the
to
al.
be
1980) .
differences
b etw e e n m eas u r e d f e c a l o u t p u t and e s t i m a t e d f e c a l o u t p u t w ere s m a l l e r .
As r e p o r t e d
by R a l e i g h e t a l . ( 1 9 8 0 ) ,
v a ria tio n in
by r e m o v i n g t h e l a r g e
anim al-day
chrom ic ox id e e s tim a te s a c lo s e r r e l a t i o n s h i p e x i s t s
b etw e e n th e m easu re d and e s t i m a t e d v a l u e s .
A l t h o u g h no o v e r e s t i m a t i o n
o f f e c a l o u t p u t e x i s t s i n t h e 1981 v a l u e s o f t h i s s t u d y ,
a 14% a n d 17%
o v erestim a tio n
occured
crossbred
respectively.
cows,
in
the
1982
values
for
the
H ereford
A frikander
and
Mashona
and
Jfesal D a l m t E stim a te s
In
stu d ies
of
forage
g r a z i n g Zim babw e v e l d ,
(1961) r e p o r t e d
cows.
fecal
intake
of
E l l i o t and Fokkema (1961) and E l l i o t e t a l .
output
estim ates
for
both dry ana l a c t a t i n g
The c h r o m i c o x i d e t e c h n i q u e w a s u s e d f o r
based e s tim a te s .
For
the
dry
cow s,
their
organic
0.8% or. b o d y w e i g h t / d a y ,
the
w eight/day,
Mashona cow s had a f e c a l
respectively.
(1961) and E l l i o t
fecal
respectively,
outputs
of
et
al.
1.5 a n d
for
the la r g e r
output of
For the l a c t a t i n g
(1961)
reported
th at
1.1 a n d
A f r i k a n d e r cows
1.1 a n d
cows,
1.2% o f b od y w e i g h t / d a y ,
th e M ashonas had f e c a l o u t p u t s o f
m atter
E l l i o t and Fokkem a (1961) ana
E l l i o t e t a l . (1961) r e p o r t e d f e c a l o u t p u t s o f a p p r o x i m a t e l y
w hile
cows
1.0% o f
body
E l l i o t a n d F o kk em a
the
A frikanders
respectively,
had
w hile
1 . 7 a n d 1.3% o f b o d y w e i g h t / d a y ,
32
resp ectiv ely .
These f e c a l
than th o se of th is
fecal
output
study.
o utput
Th e d r y H e r e f o r d a n d c r o s s b r e d
and
w eight/day,
c o w s had.
e s t i m a t e s o f 0. 7 a n d 0.5% o f body w e i g h t / d a y i n
0. 8 a n d 0.7% o f b o d y w e i g h t / d a y
H ereford
e s tim a te s are considerably la rg e r
crossbred
in
1982,
cows had f e c a l
respectively.
respectively.
The l a c t a t i n g
o u t p u t s o f 0.9 a n d
Total d a ily
fecal
1981 a n d
1.0% o f b od y
o u t p u t on a w e i g h t
basis
i s v e r y s i m i l a r b e tw e e n cow s o f t h i s s t u d y and t h e Zim babw e s tu d y .
A fr ik a n d e r and
Mashona cow s w e re a p p r o x i m a t e l y
H ereford
and
produced
a b o u t 40% m o r e f e c e s a s a p e r c e n t o f bod y w e i g h t .
Fecal
crossbred
output
cow s,
consequently,
40% l i g h t e r
rem ained r e l a t i v e l y
the
constant
for
sm aller
dry
than
the
Zim babw e
and l a c t a t i n g
cows t h r o u g h o u t t h i s s tu d y , a s i n th e s tu d y of E l l i o t e t a l . (1961).
R elatively
constant
fecal
m o d e ra te t o low q u a l i t y .
to gut f i l l
p ro d u ctio n
With d i e t s o f
is
expected
this
nature,
w ith
intake
d iets
of
continues
and d i g e s t a p a s s e s t h r o u g h t h e s y s te m a t a f a i r l y c o n s t a n t
rate.
Forage In ta k e
U sing
the
chrom ic
oxide
deriv ed
fecal
output
estim ates,
H e re fo r d and c r o s s b r e d cows consum ed a p p r o x im a te ly
body w e i g h t / d a y ,
both b reed s,
in
resp ectiv ely in
1982.
1.6 a n d
cow s,
A yrshire
1981 a n d 1.5% o f b o d y w e i g h t / d a y ,
cows
at
for
E l l i o t and Fokkema (1961) e s t i m a t e d i n t a k e
1.7% o f b o d y w e i g h t / d a y
resp ectiv ely .
1 . 0 a n d 0.8% o f
These e s t i m a t e s a r e so m ew hat s m a l l e r t h a t t h o s e
reported in other studies.
at
dry
Holm es e t
1.8% o f
body
al.
for
dry
A frik a n d e r and
(1961) e s t i m a t e d
w eig h t/d ay .
The
dry
intake
M ashona
of dry
H ereford
and
33
crossbred
cows o f
this
study
were g e n e r a l l y
o t h e r s t u d i e s and a p p a r e n t l y c o n s u m e d l e s s
heavier
t h a n cows o f
forage r e la tiv e
to
the
th eir
body siz e .
Mean i n t a k e
in
th is
study
estim ates
w ere
V alues r e p o r t e d i n
for
lactatin g
1. 9 a n d 2.1% o f
H ereford
body
w eig h t/d ay ,
Angus cow s g r a z i n g t a l l
f e s c u e - l e g u m e m ix p a s t u r e s , r e s p e c t i v e l y .
o f 2.3% o f
lactatin g
f e s c u e and t a l l
H o l m e s a n d Osman ( I 9 6 0 )
A yshire
K i r c h g e s s n e r (1976) r e p o r t e d an i n t a k e o f
cows.
1.6 t o
H o l l o w a y e t a I.. ( 1 9 7 9 ) r e p o r t e d v a l u e s o f
2 . 0 a n d 2.1% f o r l a c t a t i n g
on i n t a k e
cows
respectively.
t h e l i t e r a t u r e f o r l a c t a t i n g cows ra n g e from
3*2% o f b o d y w e i g h t / d a y .
reported
and c r o s s b r e d
cows w h i l e S t e h r and
1.6% f o r l a c t a t i n g
Sim m ental
E l l i o t a n d F o k k e m a ( 1 9 6 1 ) r e p o r t e d e s t i m a t e s o f 2 . 2 a n d 2.6%
for lacta tin g
A f r i k a n d e r and Mashona cow s,
(1961) r e p o r t e d
M a s ho n a c o w s ,
estim ates
o f 2. 6 a n d 3 . U
respectively.
S treeter
respectively.
for lacta tin g
et al
E llio t et
al
A f r i k a n d e r and
(1974) r e p o r t e d v a l u e s
of
2 . 8 , 3 . 1 a n d 3.2% f o r l a c t a t i n g H e r e f o r d , B r o w n S w i s s a n d C h a r o l a i s Angus c o w s ,
respectively.
D ifferences
am on g t h e s e
estim ates re fle c t
th e ac cu ra cy of te c h n iq u e s used as w e ll as d i f f e r e n c e s in in ta k e of
d i s s i m i l a r cows i n u n l i k e e n v ir o n m e n ts .
L actating
m ore
forage,
sim ilar
to
H ereford
and c r o s s b r e d
resp ectiv ely
than
c o w s c o n s u m e d a b o u t 29 a n d 40%
th eir
t h e 25 a n d 32% i n c r e a s e
dry
in in tak e of la c ta tin g
a n d M a s h o n a c o w s s t u d i e d by E l l i o t e t a l .
Jones et al.
the l a c t a t i n g
is
w ell
co u n terp arts.
(1961).
F ield
This
is
A frikander
(1966) and
( 1 9 6 5 ) f o u n d i n c r e a s e s o f 2 5 a n d 35%, r e s p e c t i v e l y , f o r
cows th e y
documented i n
studied.
the
Increased
literatu re
intake
(H utton,
1963;
of la c ta tin g
cows
C am pling,
1966).
Leaver
et
al.
(1969)
and
Sm ith
and
B aldw in
(1974)
h y p e rtro p h y of the a lim e n ta r y t r a c t in l a c t a t i n g
(1970) s u g g e s t e d
th at
th is
occurs w ith
observed
the
cows and C am pling
endocrine changes a s s o c ia te d
w ith the beginning of la c ta tio n .
factors
-V ariation In In ta k e
When b od y w e i g h t ,
b r e e d t y p e and l a c t a t i o n s t a t u s w e r e c o n s i d e r e d
as fa c to rs explaining v a ria tio n
in
in tak e
cow s,
the
only
lacta tio n
co n trad icts
the
co rrelatio n s
correlations
body
size
statu s
was
su g g estio n
b etw een
in tak e
between in ta k e
and
breed
of
and
type
w ere
sig n ifican t
B ines
and
(1976)
m ilk
b od y
y ield
w eight
considered
v a r i a t i o n i n i n t a k e o f l a c t a t i n g cows,
sig n ifican t.
betw een dry and l a c t a t i n g
only
factor.
who
stated
w ere
are
usually
as
facto rs
the breed
This
th at
lo w ,
w hile
high.
When
ex plaining
t y p e f a c t o r was
This a g a in s u g g e s ts t h a t tn e d i f f e r e n t m ilk y i e l d of
th e H e r e f o r d and c r o s s b r e d
cows was th e m ost i m p o r t a n t f a c t o r
explaining th e ir in tak e d iffe re n c e s.
consum ption r e q u ir e d
for
m ilk
in
C o n sid erin g th e la r g e energy
production,
it
is
not
surprising
that
l a c t a t i o n w ould be su ch a s i g n i f i c a n t f a c t o r a f f e c t i n g f o r a g e i n t a k e .
Energy Xntake
For
one
NRC,
the
Meal
th e energy c o s t of producing m ilk i s
of m etabolizable
1976).
C enter,
c ow ,
A related
estim ated
en e rg y /kg
study,
m ilk
of m ilk
produced
approxim ately
(B laxter,
1962;
a t th e N o rth ern A g r ic u ltu r e R esearch
output
of H ereford
and
75$
Sim m ental-25%
H e r e f o r d c o w s t h r o u g h t h e 1982 s u m m e r g r a z i n g s e a s o n ( C a s e b o l t e t a l . ,
1983).
T his
approxim ately
study
11,
co n clu d ed
th at
the
H ereford
cows
produced
8, 6 , a n d 5 k g / d a y d u r i n g t h e J u n e ,
July,
August and
35
Septem ber c o l l e c t i o n s ,
resp ectiv ely .
The c r o s s b r e d
cows p roduced
ap p ro x im ately
1 2 , 11., 10 a n d 9 k g / d a y d u r i n g t h e J u n e ,
and
co llectio n s,
S eptem ber
resp ectiv ely .
July,
August
The a d d i t i o n a l
energy
r e q u i r e m e n t s (M eal o f m e t a b o l i z a b l e e n e rg y ) f o r m ilk p r o d u c ti o n i s
approxim ated
by t h e s e
considerable
energy
p ro d u ctio n ,
the
m ilk
production values.
req u irem en t.
ad d itio n al
At
energy
the
Milk p ro d u c tio n h as a
higher
needed
to
lev els
produce
of
m ilk
m ilk
was
a p p r o x i m a t e l y 80% o f t h e m a i n t e n a n c e e n e r g y r e q u i r e m e n t s f o r t h e s e
l a c t a t i n g H e r e f o r d and c r o s s b r e d cows.
to tal
energy
exercise
is
demand f o r
the
prim ary
M cC l ym o nt ( 1 9 6 7 ) s u g g e s t s t h a t
m aintenance,
fa cilito ry
stim ulus
t h e c o w ’s t o t a l e n e r g y d e m a n d r i s e s ,
increase.
forage
However,
in tak e
may
lim ited
by
for
m ilk
secretio n
and
behavior.
As
phagic
her forage in tak e
w i t h f o r a g e o f low
be
grow th,
should a ls o
t o m ed i um q u a l i t y ,
the
physical
additional
capacity
of
the
Forage m e ta b o liz a b le energy c o n t e n t was a p p r o x i m a t e l y 2.4 ,
2.2,
r e t i c u l o / r u m e n and p a s s a g e r a t e of th e d i g e s t a .
1 .9 a n d 2 . 3 M c a l / k g (OMB) (NRC,
July,
A ugust and S ep tem b er o f
w eight
of
the
lactatin g
1976; C h u rch and Pond,
198 2,
H erefords
a v e r a g e d 2.1% o f b od y w e i g h t / d a y .
Meal
of
m etabolizable
lactatin g
2.4% o f
crossbred
th eir
b od y
respectively.
1974) i n Ju n e ,
In June the average
w a s 441 k g a n d t h e i r
Therefore,
energy/day.
t h e y c o n s u m e d a b o u t 22. 3
Average
June
w eight
of
the
c o w s w a s 563 k g a n d t h e y c o n s u m e d a n d
average
w eight
energy/day.
and
32.4
Meal o f m e t a b o l i z a b l e
The NRC ( 1 9 7 6 )
m etabolizable
energy re q u ire m e n ts f o r
lactatio n ,
for
cows o f
w e ig h t and m i l k p r o d u c t i o n ,
27.4
of
M eal
forage in tak e
this
m etab o lizab le
en erg y /d ay
for
the
m aintenance
of
and
a r e 23.8 a n d
H erefords
and
36
crossbreds,
respectively.
was e s t i m a t e d a t
cow s,
For
July
m etabolizable
energy
consum ption
19.1 a n d 26 . 8 M c a l / d a y f o r t h e H e r e f o r d a n d c r o s s b r e d
resp ectiv ely .
These
v alu es
com pare
w ith
NRC d e r i v e d
r e q u i r e m e n t s o f 21.1 a n d 26. 2 M e a l o f m e t a b o l i z a b l e e n e r g y / d a y f o r
H ereford
and c r o s s b r e d
energy in ta k e
estim ates
and c r o s s b r e d s ,
and
were
respectively.
crossbred
m etabolizable
cow s,
cow s,
in
energy/day,
energy in ta k e
estim ates
resp ectiv ely .
17.8 a n d
crossbred
respectively.
E stim ated
19.7 M c a l / d a y f o r
w ere
resp ectiv ely .
19.5
and
If
25.8
M eal
of
the
Hereford
w h i l e t h e NRC e s t i m a t e s t h a t t h e
cow s w ould r e q u i r e
energy
the Hereford
Septem ber m e ta b o liz a b le
intake
18 . 5 a n d 2 4 . 8 M c a l / d a y ,
values,
in
th is
t h e a v e r a g e 5% b e l o w a n d 5% a b o v e t h e NRC v a l u e s f o r
c r o s s b r e d cows.
the Herefords
w e r e 20.7 and 31.0 M c a l/ d a y f o r
and c r o s s b r e d cow s, r e s p e c t i v e l y ,
H e re fo rd and
August m e ta b o liz a b le
NRC b a s e d r e q u i r e m e n t s f o r
A ugust,
the
study,
are
on
t h e H e refo rd and
t h e NRC b a s e d r e q u i r e m e n t s a r e i n c r e a s e d by 25-30%
to account f o r a d d itio n a l
e n e r g y e x p e n d e d by t h e s e f r e e - r o a m i n g c o w s ,
t h e n t h e e n e r g y i n t a k e e s t i m a t e s , o f t h i s s t u d y , a r e a p p r o x i m a t e l y 20%
less
than e s tim a te d energy re q u ire m e n ts .
in tak e
In a re c e n t
of m a tu re H e re fo rd and c r o s s b r e d cow s,
study of energy
F errell
and J e n k i n s
(1982) fo u n d t h a t e n e rg y r e q u i r e m e n t s f o r m a i n t e n a n c e ,
d u rin g m ild
w eather,
requirem ents
were
su b stan tially
r e p o r t e d b y NRC ( 1 9 7 6 ) .
Jenkins
m etabolic
for
low er
than
the
m aintenance
U s i n g t h e e s t i m a t e p r o v i d e d by F e r r e l l a n d
m aintenance
energy
req u irem en t
body w e i g h t / d a y c o m p ared t o
(112
t h e NRC v a l u e
kcal
of
ME/kg
of
approxim ately
37
133 k c a l
ME/kg o f
m etabolic
body
w eig h t/d ay ),
the
energy
i.ntake
e s t i m a t e s o f t h i s s t u d y a r e a p p r o x i m a t e l y I 5% l o w e r t h a n e s t i m a t e d
energy re q u ire m e n ts .
The
d iscrep an cy
betw een
estim ated
r e q u i r e m e n t s may be d u e t o s e v e r a l
have been lo w e r ,
in
values
d eterm in in g
used
D ifferen t
in
cows
production.
this
t h e cows o f
w ere
Second,
occurred,
the
used
forage
facto rs.F irst,
this
intake
may h a v e
underestim ation
intake
values
and
estim ates
the
same
for
the
forage
for
lacta tio n .
intake
and
m ilk
been u n d e r e s t im a te d .
cows w e re
values
energy
m i l k p r o d u c t i o n may
to
d ig estib ility
d ig estib ility
and
than the m ilk production
may be d u e
dry
intake
req u irem en ts
estim ating
f o r a g e d i g e s t i b i l i t y i n t h e JLq v i t r o
forage
study,
energy
for
energy
u n d erestim ation
analysis.
sim ilar
w ere
to
used
If
of
However,
literatu re
for
dry
and
l a c t a t i n g cows.
L a c t a t i ng c o w s may h a v e s e l e c t e d f o r a g e s o m e w h a t m o r e
d ig estib le
than
the predom inantly, dry,
co llectio n
cows.
Third,
been u n d e r e s tim a te d ,
values higher
than
forage
though
those
esophageal f i s t u l a t e d ,
m etabolizable
th is
is
energy
u n lik ely ,
content
because
extrusa
may h a v e
lite ratu re
u s e d a r e v e r y uncommon f o r r a n g e f o r a g e .
F u r t h e r s t u d y on en e rg y e x p e n d i t u r e s w i l l im p r o v e t h e u n d e r s t a n d i n g o f
energy balance fo r
t h e s e l a c t a t i n g H e r e f o r d and c r o s s b r e d cows.
38
SUMMARY
D uring
lactatin g
fecal
the
H ereford
output
obtained
D uring
summer
seasons
of
1 981
a n d 75% S i m m e n t a l —25% H e r e f o r d
estim ation
w ith
these
grazing
the
to tal
trials
trials.
E stim ates
co llectio n
another
and
group
of
of
1982
dry
cows
were
used
fecal
chrom ic
dry,
and
output
and
in
w ere
oxide
techniques.
esophageal
fistu lated
H e r e f o r d a n d 75% S i m m e n t a l - 2 5 % H e r e f o r d c o w s w e r e u s e d t o c o l l e c t
forage
sam ples.
These
sam ples
w ere
then
used
for
jji
v itro
d i g e s t i b i l i t y a n a l y s i s to o b t a i n e s t i m a t e s of th e d i g e s t i b i l i t y
forage grazed
estim ation
by t h e H e r e f o r d
trials.
These
and c r o s s b r e d
fecal
output
cows i n
and
the fe c a l
forage
of
output
d ig estib ility
e s t i m a t e s were th en used to d e r iv e fo ra g e in t a k e e s t i m a t e s f o r the dry
s n d l a c t a t i n g H e r e f o r d and c r o s s b r e d cows.
rough fe s c u e ,
T h e s e c o w s w e r e g r a z e d on
I d a h o f e s c u e a n d b l u e b u n c h w h e a t g r a s s d o m i n a t e d r a n g e on
th e n o r t h w e s t e r n s l o p e s of th e Bearpaw m o u n ta in s i n n o r th
cen tral
M ontana.
The s t u d y a r e a w a s s i m i l a r t o f o o t h i l l r a n g e i n n o r t h e r n
M ontana.
The
m aintained
for
this
cows
part
of
the
H ereford
and
crossbred
herd
b y M o n t a n a ’ s N o r t h e r n A g r i c u l t u r a l R e s e a r c h C e n t e r (NARC)
p roductivity
study
w ere
studies.
With f o r a g e
and p r o d u c ti o n i n f o r m a t i o n
25% H e r e f o r d c o w s i n
t h e NARC h e r d
the
intake
estim ates
derived
from
on H e r e f o r d a n d 75% S i m m e n t a l productive e f fic ie n c y
of th ese
c o w s c a n be d e t e r m i n e d .
Fecal
output
estim ates
w ere
w e i g h t / d a y on an o r g a n i c m a t t e r
expressed
basis.
In
1981,
as
a
percent
mean f e c a l
of
body
output
of
d r y H e r e f o r d c o w s w a s 0.7 an d 0.7 w i t h b o t h f e c a l o u t p u t e s t i m a t i n g
39
tech n iq u es.
and
0.8
I n 1 9 82, m ean f e c a l o u t p u t o f d r y H e r e f o r d co w s w a s 0.7
w ith
the
resp ectiv ely .
to tal
co llectio n
and
chrom ic
oxide
tech n iq u es,
These m eans w ere s i g n i f i c a n t l y d i f f e r e n t .
In 1981,
m e a n f e c a l o u t p u t o f t h e d r y c r o s s b r e d c o w s w a s 0.6 a n d 0 .5 w i t h t h e
to tal
co llectio n
and ch ro m ic o x id e
techniques, resp ectiv ely .
means w ere n o t s i g n i f i c a n t l y d i f f e r e n t .
dry
crossbred
chrom ic
cows
oxide
was
0.6
and
techniques,
0.7
In
These
1982, m e a n f e c a l o u t p u t o f
w ith
the
resp ectiv ely .
to tal
These
co llectio n
means
w ere
ana
not
significantly different.
Forage d i g e s t i b i l i t y
July,
A ugust and
Septem ber
forage d i g e s t i b il i t y
July,
was e s t i m a t e d
co llec tio n
a t 3 9 , 3 4 , a n d 35% f o r
perio d s
of
intake
we i g h t / d a y .
a n d 0.9 f o r
estim ates
w ere
expressed
as-a
t h e H e r e f o r d and c r o s s b r e d
1.0 a n d 0 .8 f o r
cows,
respectively^
co llectio n
the
breed types.
d eriv ed
chrom ic
derived
whereas,
o u tp u t e s t i m a t e s were used,
the H ereford
co llectio n
w ere
p e r c e n t o f body
I n 1 9 8 1 , f o r a g e i n t a k e e s t i m a t e s f o r d r y c o w s w e r e 1.1
oxide d eriv ed fe c a l
cows,
1982,
w a s e s t i m a t e d a t 5 9,, 4 5 , 4 1 , 55% f o r t h e J u n e ,
to ta l c o lle c tio n deriv ed fe c a l ou tp u t e stim a te s.
nor
In
August and Septem ber c o l l e c t i o n p e r i o d s .
Forage
to tal
1981.
the
and c r o s s b r e d
Whe n t h e c h r o m i c
i n t a k e e s t i m a t e s were
cows,
respectively.
These
e s t i m a t e s were not s i g n i f i c a n t l y d i f f e r e n t
oxide
intake
using the
deriv ed
estim ates
estim ates.
were
the chrom ic oxide d e riv e d
1.3 f o r
both
The
1982
breed
e s t i m a t e s were
to tal
types of
1.5 f o r
both
There was a s i g n i f i c a n t d i f f e r e n c e b e tw e e n e s t i m a t e s
d e r i v e d w i t h t h e two t e c h n i q u e s .
The l a c t a t i n g H e r e f o r d c o w s h a d a
mean i n t a k e
in tak e
of
of
1.9 w h i l e
2.1.
These
the
mean
lacta tin g
intake
crossbred
estim ates
cow s had a mean
w ere
sig n ifican tly
different.
1981
When a c o m p a r i s o n
of
mean f e c a l
values,
output
fecal
e s tim a te s s i m i l a r to the t o t a l
th is
was
not
approxim ately
the t o t a l
the
case.
15% l a r g e r
The
output
the
estim ates
chrom ic
w a s m a d e among t h e
oxide
technique
c o l l e c ti o n derived e s tim a te s .
chrom ic
oxide
d eriv ed
I n 1982,
values
w ere
than th e f e c a l o u tp u t v a lu e s determ ined w ith
c o lle c tio n technique.
When i n t a k e
values fo r
all
d ry and l a c t a t i n g
cows w e re combined
and r e g r e s s e d w i t h s e v e r a l c h a r a c t e r i s t i c s o f th e s t u d y cows,
lacta tio n
variatio n
provided
statu s
in
facto r
intake.
was fo u n d to
Body w e i g h t a n d
only the
be s i g n i f i c a n t i n e x p l a i n i n g
breed
type
were
in sig n ifican t.
When t h e i n t a k e v a l u e s f o r l a c t a t i n g c o w s w e r e r e g r e s s e d w i t h b o d y
w eight
and
breed
significant.
type
facto rs,
These r e l a t i o n s h i p s
only
the
suggest
breed
type
that lacta tio n
facto r
was
ana q u a n t i t y
o f l a c t a t i o n h ad t h e m o s t i m p o r t a n t a f f e c t on f o r a g e i n t a k e .
T h e m e a n m e t a b o l i z a b l e e n e r g y (ME) c o n t e n t o f t h e r a n g e f o r a g e
was e s t i m a t e d
a t 2 . 2 M c a l / k g on a n
assum ption
correct
is
o rg an ic
then l a c t a t i n g
m atter
H ereford
If
th is
and c r o s s b r e d
cows
c o n s u m e d a p p r o x i m a t e l y 1 9 . 2 a n d 2 6 . 3 Mea l o f ME/ day.
basis.
LITERATURE CITED
42
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43
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C h lo ris gavana a t v a r io u s stages, o f growth.
24:821.
on t h e i n t a k e o f
siz e of grazing
r e on th e i n ta k e o f
structure, n u tritiv e
S e t a r i a an cen s and
A u s t s . J . A g r i c . Res .
S t r e e t e r , C . L . , C.B. R u m b e r g , T.H. H a l l a n d E.G. S i e m e r . 1 9 7 4 . M e a d o w
f o r a g e q u a l i t y , i n t a k e an d m i l k p r o d u c t i o n o f cow s. J . Range
Manage. 2 7 :1 3 3 .
T h o r l e y , C.M., E . S h a r p e a n d M.P. B r y a n t . 1 9 6 8 . M o d i f i c a t i o n o f t h e
r u m e n b a c t e r i a f l o r a by f e e d i n g c a t t l e g r o u n d a n d p e l l e t e d
ro ughage as d e te r m in e d w i t h c u l t u r e m edia w i t h and w i t h o u t rum en
f l u i d . J . D airy S c i . 51:1811.
T r i b e , D.E. I 9 5 0 . I n f l u e n c e o f p r e g n a n c y a n d s o c i a l f a c i l i t a t i o n o n
th e b e h a v io r o f g r a z i n g sh e e p . N a tu re 166:74.
U n i t e d S t a t e s D e p a r t m e n t o f A g r i c u l t u r e (USDA). 1974. O p p o r t u n i t i e s t o
i n c r e a s e re d m eat p ro d u c tio n from ra n g e s o f th e U n ited S ta te s .
USDA I n t e r - a g e n c y w o r k g r o u p o n r a n g e p r o d u c t i o n .
U n i t e d S t a t e s D e p a r t m e n t o f A g r i c u l t u r e (USDA) - S o i l C o n s e r v a t i o n
S e r v i c e (SCS). 1976 . C l i m a x v e g e t a t i o n o f M o n t a n a : b a s e d o n s o i l s
a n d c l i m a t e . USDA-SCS. B o ze ma n . MT. 6 4 p .
49
V a n D y n e , G.M., N.R. B r o c k i n g t o n , Z. S z o c s , J . D u e k a n d C.A. R i b i c .
1 9 8 0 . L a r g e h e r b i v o r e s u b s y s t e m , ( i n : B r e y m e y e r , A . J . a n d G.M.
Van Dyne ( e d s ) . G r a s s l a n d S y s t e m A n a l y s i s a n d Man. I n t e r n l . B i o l .
P r o g . 19. C a m b r i d g e U n i v . P r e s s ) p . 2 6 0 .
Van S o e s t , - p . J . 1965. S y m p o s i u m o n f a c t o r s i n f l u e n c i n g t h e v o l u n t a r y
i n t a k e o f h e r b a g e by r u m i n a n t s : v o l u n t a r y i n t a k e i n r e l a t i o n t o
c h e m i c a l c o m p o s i t i o n a n d d i g e s t i b i l i t y . J . Anim. S c i . 2 4 : 8 3 4 .
Va n S o e s t , P . J . 1982. N u t r i t i o n a l E c o l o g y o f t h e R u m i n a n t . 0 & B B o o k s
P u b l . C o r v a l i s . 374p.
W a l l a c e , L. R. I 9 5 6 . T h e i n t a k e a n d u t i l i z a t i o n o f p a s t u r e b y g r a z i n g
d a i r y co w s. P r o c . V I I I n t . G r a s s l d . C ongr. p .1 35..
W arner,
A.C.I.
1965. F a c t o r s i n f l u e n c i n g n u m b e rs and k i n d s o f
m i c r o o r g a n i s m s i n t h e r u m e n , ( i n : D o u g h e r t y , R.W. ( e d ) .
P h y s i o l o g y o f D i g e s t i o n i n t h e R u m i n a n t . B u t t e r w o r t h . Wash. D.C.
4 8 0 p .) p . 346.
Y o u n g , B.A. 1 9 7 0 . A p p l i c a t i o n o f t h e c a r b o n d i o x i d e e n t r y r a t e
t e c h n i q u e t o m e a s u r e m e n t o f e n e r g y e x p e n d i t u r e by g r a z i n g c a t t l e
( i n : S c h u r c h , A. a n d C. We nk ( e d s ) . E n e r g y M e t a b o l i s m o f F a r m
A n i m a l s . E . A . A . P . P u b . No. 1 3 . 2 5 9 p . ) p . 2 3 7 .
50
APPENDICES
vJ'
51
Appendix A
L i s t o f p la n t s p e c ie s o c c u rrin g i n the study p a s tu re .
S c i e n t i f i c Bionomial
G ram inoids
,
Forbs
C actus
Common Name
Agroovron dasvstachvuin
Agropvron s m i t h i i
Agroovron soicatum
Bromus i a p o n i c u s
Bromus t e c t o r u m
Carex e l e o c h a r i s
Carex f i l i f o l i a
Festuca idahoensis
Festuca s c a b re lla
K oelaria pvrim idata
P oa p r a t e n s i s
S t l o a comata
S t i o a Columbiana
S tloa v irid u la
th ick sp ik e w heatgrass
w estern w heatgrass
bluebunch w h e atg rass
J a p a n e s e b ro me
c h e a t g r a s s b ro me
n e e d le l e a f sedge
t h r e a d l e a f sedge
Idaho fe s c u e
rough fe sc u e
p r a ir ie junegrass
Kentucky b l u e g r a s s
needleandthread
Columbia n e e d l e g r a s s
green needlegrass
A chillea m illifo liu m
A goseris glauoa
A ntennaria o a r v if o lia
A rtem isia f r ig id a
A rtem isia ludoviciana
A stragalus b isu icatu a
B alsom orhlza s a g i t t a t e
Campanula r o t u n d i f o l i a
E rigeron g lab ellu s
G aillard ia a r is ta ta
Galium b o r e a l e
Geranium v is c o s is s im u m
Geum t r i f l o r u m
G rindelia sauarrosa
H eterotheca v i l lo s a
L ia tr is punctata
Lithosoerm a r u d e ra le
Lomatium f o e n i c u l a c e u m
Luoinus s p e c ie s
Monarda f i s t u l o s a
Phlox h o o d ii
P o ten tilia fru itico sa
P o te n tilla hiooiana
Psoralea lan ce o tata
R a tib id a colum nifera
Rosa a r k a n s a n a
S e l i g i n e l l a dense
w e s te r n yarrow
f a ls e dandelion
s m a ll-le a f pussytoes
frin g e d sagewort
c u d w e ed s a g e w o r t
twogrooved m i lk v e tc h
a rro w lea f balsam root
harebell
smooth f l e a b a n e
g aillard ia
n o r t h e r n b e d s t r aw
s t i c k y geranium
p rairiesm oke
c u r l y c u p gumweed
hairy goldenaster
dotted gayfeather
w e s t e r n gromwell
lomatium
lupine
horse m int
Hood’ s p h l o x
shrubby c in q u e f o il
horse cin q u efo il
lemon s c u r f p e a
p r a i r i e coneflow er
p ra irie rose
dense clubmoss
O ountia oolvacantha
pricklypear
52
S h r u b s Si T r e e s
Junioerus h o riz o n ta lis
Prunus V i r e in i a n a
SvmphorioarDos o c c i d e n t a l i s
Pinus nonderosa
creeping ju n ip e r
chokecherry
w e s te rn snowberry
' ponderosa pine
Appendix
B.
Table
6.
L a c t a t i o n s t a tu s ,
information
R e feren ce
Type o f
P a s tu re
E l l i o t & Fokkeoa
(1961)
v e ld
g ra s s la n d
for
m i l k production,
free-roaming
B reed
o f Cow
L a c ta t io n a l
S ta t u s
A frik a n d e r
Mashona
A frik a n d e r
Mashona
d ry
dry
la c ta tin g
la c ta tin g
cow s
body weight
compiled
M ilk P ro d u c tio n
(k g /d a y )
-
_
and forage
intake
f r o m the l i t e r a t u r e .
Body W eight
(kg)
F orage In ta k e
(> Body W eight)
(OMB)
(OMB)
(OMB)
(OMB)
B a s is of
M easurem ent'
533
318
408
295
1 .5
1.3
2 .5
2 .6
436439
1 .7 3 .3 (DMB)
LRZCr3O3
TC/LR
s e m id e s e r t
g ra s s la n d
H e re fo rd 4
S a n ta G e r tr u d is
Holloway e t a l .
(1979)
t a l l fe s c u e
Angus
la c ta tin g
8 .5
458
2 .0 (DMB)
Cr3O3ZADL
Holloway e t a l .
(1979)
t a l l fe s c u e legum e mix
Angus
la c ta tin g
8 .3
472
2 .1 (DMB)
Cr3O3ZADL
Holmes 4 Osman
(1960)
ry e g ra ssc lo v e r mix
A y rs h ire
la c ta tin g
14.4
513
2 .3 (OMB)
FNIZCr3O3
Holmes e t a l .
(1961)
ry e g ra ssc lo v e r mix
A y rs h ire
dry
537
1.8 (OMB)
FNIZCr3O3
K a rtc h n e r
(1975)
c r e s te d
w h e a tg ra s s
la c ta tin g
523615
I »6—
2 .9 (DMB)
TCZIVDMD
S tre e te r e t a l.
(1974)
n a tiv e
meadow
(C o lo rad o )
S te h r 4 K irc h g e s sn e r
(1976)
Brown S w iss
C h a ro la is x Angus
H ere fo rd
la c ta tin g
la c ta tin g
la c ta tin g
10.3
7 .5
6 .0
473
374
363
3.1 (DMB)
3 .2 (DMB)
2 .8 (DMB)
Cr3O3ZIVCWC
Slm m ental
la c ta tin g
17.5
675
1.6 (OMB)
Agronomic
1TC = t o t a l f e c a l c o l l e c t i o n ; LR = l i g n i n . r a t i o ; Cr3 O3 = chrom ic o x id e ; IVCWC = i n v i t r o c e l l w a ll c o n s t i t u e n t s ; IVDMD = in v i t r o
d ry m a tte r d i g e s t i b i l i t y ; FNI = f e c a l n it r o g e n In d e x ; ADL = a c id d e te r g e n t l i g n i n .
Appendix
H i l l s (1968)
A p p e n a i x B.
Table
Soecies
7.
Prom inent p l a n t s p e c i e s o c c u r r i n g i n th e stu d y p a s t u r e w ith e s t i m a t e s of
t h e i r canopy c o v e r a g e a n d i m p o r t a n c e i n t h e community.
____
Lowland A reas
Canopy
Cover
Com oosition
Soecies
Upland Areas
Canopy
Cover
— — — •■>
— — — — %( SB) — — — 31(6)
Poa o r a t e n s i s
71(33)
Festuca s c a b re lla
Comoositibn
( SD ) — —
10(13)
15(19)
10(13)
Aeroovron s m i t h i i
2(2)
3(2)
Festuca idahoensis
7(9)
Festuca id ahoensis
KD
KD
Aeroovron s o ic a tu m
I
2
S tioa v irid u la
KD
1 ( 1) .
Aeroovron dasvstachvum
5(6)
8(9)
Carex e l e o c h a r i s
1(1)
1(1)
S t i o a comata
I
5(4)
Svm ohoricarcos o c c i d e n t a l i s
5(7)
7(10)
Carex f i l i f o l i a
9(4)
Luoinus s o e c ie s
4(5)
5(7)
Psoralea lan ce o late
6(7)
9(11)
Geranium v i s c o s i s s i m u r n
3(4)
4(6)
Luoinus s o e c ie s
11(7)
16(11)
R o sa a r k a n s a n a
2(2)
3(2)
Geum t r i f l o r u m
4(1)
5(1)
Geum t r i f l o r u m
KD
2(1)
Phlox h o o d i i
4(1)
5(3)
H eterotheca v i l l o s a
T(I)
1(1)
Misc.
10(6)
11(4)
1R a c e d m i c r o p l o t s ,
•
■
a s d e s c r i b e d by M o r r i s
species
14(7)
( 1 9 7 3 ) , were u sed t o e s t i m a t e canopy c o v e r and c o m p o s itio n .
—
M ONTA NA S T A T E U N IV E R SIT Y L IB R A R IE S
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