ACTA THERIO LO G ICA
Vol. 22, 14: 225—230,1977
B IS O N IA N A . L X V I
Comparison of Forage Intake and D igestibility
by American Bison, Yak and Cattle
R. J. RICHMOND, R. J. H UDSO N & R. J. CHRISTOPHERSON
Richm ond R. J., H udson R. J. & C hristopherson R. J., 1977: Com parison
of forage in ta k e and digestibility by A m erican bison, y ak and cattle.
A cta theriol., 22, 14: 225—230 [With 2 Tables],
Feed intake, selectivity and ap p a ren t digestibility coefficients of dry
m atte r, protein and d etergent fib er fractions w ere d eterm in ed in groups
of four yearling bison, yak and cattle. Diets of co n trastin g q u ality for
th ese cam parisons w ere provided by native sedge m eadow hay, brom efescue grass hay and alfalfa hay. Feed intakes fo r bison and cattle w ere
sim ilar b u t considerably h igher on a p er u n it body w eight basis th a n
for yak. A p p aren t digestibility coefficients fo r dry m a tte r an d deterg en t
fiber fractions tended to be highest in bison follow ed by yak th en cattle,
a digestive su p e rio rity w hich was m ost m ark ed on th e grass h ay diet.
H ow ever, off-settin g the digestive advantage of bison in rela tio n to the
other tw o species w as an a p p a re n t higher digestible dry m a tte r re q u ire ­
m ent for m aintenance. G ains and feed conversion for cattle exceeded
those of yak and bison on sedge and grass hays b u t not on alfalfa.
[Dept. Anim. Sci., Univ. A lberta, E dm onton, C anada T6G 2E3].
1. INTRODUCTION
Several studies have compared the d igestive characteristics of European
bison (Bison bonasus) and cattle ( S z a n i a w s k i , 1959; G ę b c z y ri­
s k a et al., 1974: K o w a l c z y k et al., 1976). It is of interest to com pare
results of sim ilar studies on the Am erican bison (Bison bison).
In Northern Canada, such stu d ies are of pragm atic as w ell as academ ic
interest. Spiralling production costs have resulted in renew ed interes*
in meat production from pasture and range. Particularly in more
m arginal areas productivity of grazing system s based on conventional
agricultural anim als rem ains low and opportunities for range im prove­
m ent are lim ited by prohibitive input costs. Under such circum stances
it has been claim ed that indigenous or exotic herbivores m ay make
an im portant contribution to the harvesting of n ative vegetation.
T h is stu d y represents an initial phase in a program to evaluate
a num ber o f native and exotic herbivores as a basis for m eat production
[225]
R. J. R ichm ond et al.
226
from m arginal lands. P relim inary to more detailed physiological and
ecological investigations, the digestive capabilities of bison and yak were
com pared w ith those of cattle.
2. M ATERIALS AND METHOD
Bison, y ak and cattle used in this stu d y w ere provided and raised by a ran ch er
in W estern A lberta. F our fem ale yearlings com prised the cattle group w hereas
one m ale and th ree fem ale yearlings m ade up each of th e yak and bison groups.
The average in itial body w eights of th e calves w ere 136, 173 and 263 kg fo r the
yak, bison and cattle respectively. A nim als w ere penned indoors in d iv id u ally and
offered test forages in th re e tre a tm e n t periods of th ree w eeks duration. T he study
w as conducted from M arch 31 to Ju n e 2 during w hich tim e anim als w ere exposed
to tem p eratu re s ran g in g from —30 to +21°C.
T est forages w ere sedge m eadow hay (C orex sp.), brom e-fescue grass hay, and
alfalfa hay (Table 1). Follow ing a tw o-w eek a d ju stm e n t period d u rin g which
v o lu n ta ry feed in tak e w as m easured and fo rag e-o n -o ffer and refu sals w ere
T able 1
C h aracteristics of ex p e rim en tal forages offered to bison, yak and cattle.
Dry m a tte r °/o
P ro tein (nitrogen X 6.25)
N eutral deterg en t fib er (%>)
Acid d eterg en t fib er (%>)
A lfalfa
G rass hay
Sedge
88.54
18.74
42.47
30.53
90.38
6.59
63.24
40.32
89.48
8.30
70.20
39.15
sam pled, feed and fecal sam ples from a one w eek period for each an im al w ere
pooled for d eterm in atio n of ap p a ren t d ig estib ility coefficients fo r d ry m atter,
nitrogen, n e u tra l d eterg en t fiber, hem icellulose and acid d eterg en t fiber. A forage
selectivity coefficient was calculated by dividing the nitrogen co n ten t of the
feed actu ally consum ed w ith th a t on offer.
F orage and feces analyses included K jeh ld ah l nitrogen (AOAC), (1960) and
n e u tra l d eterg en t and acid detergent fib ers ( G o e r i n g & V a n S o e s t , 1970).
In order to avoid stress induced by harn essin g or confining anim als fo r to tal
collection, d igestib ility w as determ ined by use of 6N HC1 insoluble ash as an
indigestible in te rn a l m a rk e r ( M c C a r t h y et al., 1974).
3. RESULTS
The results of the trial are sum m arized in Table 2. Significant
contrasts in voluntary feed intake, forage selectiv ity , digestion and
perform ance as reflected in body w eight change w ere noted in the
three bovids.
V oluntary feed intakes for all species varied inversely w ith neutral
detergent fiber (cell wall) content. Feed intakes per unit body mass
Forage in tak e by A m erican bison, y ak and cattle
227
w ere sim ilar for bison and cattle but higher than those show n bv yak.
V oluntary intakes of alfalfa by all species were greater than intakes of
grass or sedge hays.
A ll bovids showed som e forage selectivity as show n by com parison
of feed -o n -o ffer and refusals. The greatest opportunity for selection
apparently existed w ith alfalfa and least w ith sedge. G enerally, cattle
w ere m ost selectiv e and bison most indiscrim inate.
T able 2
C om parative digestive capacites of cattle, y ak and bison o ffered forages of v ary in g
Quality.
CO
Species
T3
T3
> §
¿i
^ 05.2
lia
O
0)
.2 «
.S
• 3ÜÍ
TJ
s "So
A p p aren t digestibility coefficients
Q £
C attle
Y ak
Bison
281.4
149.9
176.7
.42
—.05
—.48
.013
.008
.009
Sedge
83.00
76.00
54.00
63.00
54.25
64.25
67.50
69.75
69.00
75.75
79.75
76.50
64.25
61.75
62.75
1.76
0.96
1.04
C attle
Yak
Bison
272.3
141.3
169.7
.45
.04
—.10
.011
.008
.011
G rass
61.75
58.25
57.50
70.75
70.00
74.00
56.75
70.00
71.50
68.00
81.00
79.25
50.50
63.75
67.25
1.15
1.10
1.09
C attle
Yak
Bison
281.4
151.0
186.8
.00
.46
.81
63.25
62.50
68.25
73.50
72.50
76.50
55.00
58.50
65.00
0.80
1.42
1.08
***
ns
**
**
ns
**
***
ns
**
*
***
***
Species
Forages
In teractio n s
ns
***
***
A lfalfa
57.50
46.50
72.00
79.50
77.50
83.75
Source of variation
***
***
***
***
***
***
♦
**
ns
.009
.010
.013
* P < .05,
** P C . 01 ,
*** P < .001
A pparent d igestib ility coefficients for nitrogen and for each of the
forage detergent fractions tended to parallel changes in dry m atter
digestibility. B ison digested all forages m ost efficien tly. Yak w ere more
efficient than cattle on grass and sedge hays but not on alfalfa. In spite
of this contrasting pattern of d igestive efficiencies, cattle surprisingly
tended to show superior rates o f gain or lesser w eigh t losses on sedge
and grass hay although not on alfalfa.
228
R. J. Richm ond et al.
4. DISCUSSION
B eth bison and yak are noted for their ability to survive in harsh
environm ents. Their apparent superior ability to digest low quality
forages often is cited as one reason for their success. This study con­
firm ed their alleged digestive superiority. H ow ever, w hen perform ance
was m easured in term s of voluntary feed intake, gain or feed conversion
efficien cy under the conditions of the study, cattle w ere best able to
utilize low quality forage whereas bison and yak fared som ew hat better
on higher quality forage.
Several studies have compared th e digestive capacities of bison and
cattle. S z a n i a w s k i (1959) compared a 6 m onth old European bison
calf (Bison bonasus) w ith a domestic bull calf. In that study d igestib ility
of protein, fiber and nitrogen-free extract was higher in the dom estic
anim al. In contrast G q b c z y ri s k a et al. (1974) noted higher apparent
d igestibility coefficients for crude protein, ether extract and ash but
not celluose or soluble carbohydrate in tw o adult European bison. In
com paring their results with those of S z a n i a w s k i (1959) the authors
pointed to the late w eaning and hence poorer d igestive tract developm ent
of free-ranging bison calves.
A lthough closely related to the Am erican bison, th e European bison
differs m arkedly in feeding behaviour in that it selects a high proportion
of browse ( B o r o w s k i et al., 1967). More relevant com parative data
for Am erican bison and cattle were provided by P e d e n (1971) and
P e d e n et al. (1974) who used the nylon-bag digestion technique w ith
rum inally fistu lated animals. These results show ed a definite d igestive
superiority of bison on lower quality forages (w inter grazing) w h ich
was lost on higher quality diets (spring grazing).
A lthough a standard of comparison for yak is not available, the
results of the present study with respect to bison are supported by
studies on th e feedlot performances of bison, cattalo and hereford
calves ( P e t e r s , 1958). The observed contrast was explained on the
basis of th e inferior voluntary intake of bison although a low er efficien cy
of utilization of ingested feed also was evident.
It is perhaps surprising that the high d igestive efficien cy of bison was
not accom panied by higher rates of gain. One explanation for the pattern
of results obtained could be the differential response of th e three species
to indoor confinem ent. Both bison and yak resisted handling and
appeared more stressed than cattle. This could explain low er feed intake
of yak and low m etabolic efficiency of bison. H ow ever, if this w ere
a significant factor then the apparent superiority of both species on
alalfa demands explanation.
Forage intake by A m erican bison, yak and cattle
229
Since w eight changes w ithin each trial period w ere sm all, it is pos­
sible that rumen fill or body w ater content could have contributed to the
observed differences. If this w ere the case, w eight change over th e three
trial periods would be more reliable criterion for evaluating the three
species. H owever, even on this basis cattle m aintained their productive
superiority under the conditions of confinem ent im posed during the
study.
Other explanations are speculative. Seasonal factors m ay have con­
tributed to the observed differences and it cannot be ruled out that
studies repeated at other tim es of the year would yield different results.
A num ber of w ild rum inants adapt to seasonal environm ents with
endogenous bioenergetic rhythm s in which voluntary feed intake, dige­
stiv e capacity and grow th is restricted during the w in ter m onths
(N o r d a n et al., 1968; M c E w a n , 1970).
F inally, it is possible that low forage quality is not the major lim iting
factor in the environm ents in which bison and yak evolved. Other
physiological, ecological and behavioral adaptations m ay account for
their w ell-know n ability to su rvive and reproduce in harsh environm ents.
REFERENCES
1. A ssociation of O fficial A g ricu ltu ral Chem ists, 1960: O fficial M ethods of A nalysis
of the A ssociation of Official A g ricu ltu ra l C hem ists. 9th Edition.
2. B o r o w s k i S., K r a s i ń s k i Z. & M i ł k o w s k i L., 1967: Food and role
of E uropean bison in forest ecosystem s. A cta theriol., 12: 367—376.
3. C om m onw ealth B ureau of A nim al B reeding and G enetics, undated: Y aks and
Yak H ybrids. A nnotated Bibliog, 182 (1937—1971). 7p.
4. G ę b c z y ń s k a Z., K o w a l c z y k J., K r a s i ń s k a M. & Z i o l e c k a A.,
1974: A com parison of the digestibility of n u trie n ts by E uropean bison and
cattle. A cta theriol., 19: 283—289.
5. G o e r i n g H. K. & Van S o e s t P. J., 1970: F orage fib er analysis (ap p aratu s,
reagents, procedures and some applications). ARS U.S. G overnm ent P rin tin g
Office, W ashington.
6. K o w a l c z y k J., G ę b c z y ń s k a Z. & K r a s i ń s k a M., 1976: The digesti­
b ility of n u trie n ts of n a tu ra l diet by E uropean bison in d ifferen t seasons.
A cta theriol., 21: 141— 146.
7. M c C a r t h y J. F., A h e r n e F. X. & O k a i D. B., 1974: Use of HC1 insoluble
ash as an index m a terial fo r determ ining ap p a ren t digestibility w ith pigs.
Can J. Anim. Sci., 54: 197—199.
8. M c E w a n E. H., 1970: E nergy m etabolism of b a rre n ground caribou. Can.
J. Zool., 48: 391—392.
9. N o r d a n H . C , C o w a n I . McT. & W o o d A. J., 1968: N u tritio n al req u irem en ts
and grow th of black tailed deer in captivity. [In: »C om parative N u tritio n of
W ild Animals« ed. M. A. C raw ford]. Symp. zool. Soc., Lond., 21: 89—96.
10. P e d e n D. G., 1971: A com parison on shortg rass p ra irie in w inter. P resen ted
to Am. Soc. M am m al. A nnual Meet., V ancouver.
R. J. R ichm ond et al.
230
11. P e d e n D. G., Van D y n e G. M., R i c e R. W. & H a n s e n R. M., 1974:
The trophic ecology of Bison bison on sho rtg rass p rairie. J. Appl. Ecol., 11:
489—498.
12. P e t e r s H. F., 1958: A feedlot stu d y of bison, cattalo and hereford calves.
Can. J. Anim. Sci., 38: 87—90.
13. S z a n i a w s k i A., 1958: C om parison of digestibility of feedingstuffs w ith
d ifferent protein ratios for calves of dom estic cattle and of bison, B ison
bonasus. A cta theriol., 3: 318—319.
A ccepted, Ju ly 29, 1976.
R. J. RICHMOND, R. J. HUDSON i R. J. CH RISTOPH ERSO N
PORÓW NANIE ZAPOTRZEBOW ANIA POKARM OW EGO I STRAW NOSCI
U BIZONA AM ERYKAŃSKIEGO, JA K A I BYDŁA
Streszczenie
Oznaczono zapotrzebow anie pokarm ow e, w ybiórczość i w spółczynniki s tra w ności suchej masy, białka oraz składników w ęglow odanow ych u rocznych bizo­
nów, jak ó w i bydła. Do dośw iadczeń w zięto po cztery zw ierzęta każdego g atu n k u
i karm iono je sianem turzycy, stokłosy kostrzew y lub lucerny, zróżnicow anym
pod względem zaw artości w łókna (Tabela 1).
Z apotrzebow anie pokarm ow e u bizona i bydła było podobne i w yraźnie wyższe
na jednostkę ciężaru ciała niż u jaka. W spółczynniki straw n o ści suchej m asy
i w łókna m alały w kolejności: bizon, jak, bydło (Tabela 2), przy czym różnice te
były najw yraźniej zaznaczone w przy p ad k u siana. Z apotrzebow anie bytow e bizona
było wyższe niż dwu pozostałych gatunków , choć zrów now ażone przez wyższy
w spółczynnik straw ności. W skaźnik p rzyrostu i p rzy sw ajan ia p o karm u u bydła był
wyższy niż u ja k a i bizona w przypadku suszonej turzycy i siana, n ato m iast
w przypadku lucerny różnic nie było.