to retain high nutrient levels to maturity and, 
even better, through dormancy, are preferred. 
Numerous other plant characteristics have a 
direct effect on the value of a range plant for 
forage production. Included would be features 
affecting establishment and growth, persist- 
ence, and production efficiency. Annuals are 
usually less desirable than perennials because 
of greater yearly fluctuations of forage produc- 
tion. Rhizomatous species are usually superior 
to nonrhizomatous species because of greater 
flexibility in methods for establishment and 
survival. Physiological and morphological at- 
tributes contributing to grazing, drought and 
freezing resistance are of major importance. 
Available moisture is the major limitation to 
forage production on many of our western 
ranges. A high water consumption to forage 
production ratio for a species is a decidedly ob- 
jectionable characteristic, particularly for a 
plant growing on arid rangeland. 
OTHER CONSIDERATIONS 
Most poisonous plants are eaten in harmful 
quantities only when livestock are forced to do 
so (U.S.D.A., A.D. & P.R.D. 1964; Durrell et 
al. 1950; Stoddart et al. 1949). Certain species 
of Prunus, Delphinium, Lupinus, Triglochin, 
and Astragalus may be exceptions (Stoddard 
et al. 1949). Livestock are forced to eat poison- 
ous plants because of poor management. Poor 
management has numerous forms, but the most 
obvious is extreme overgrazing where the live- 
stock are left little but poisonous species to eat. 
Placing livestock on a range before substantial 
growth of good forage has occurred and where 
early-growing poisonous plants are abundant is 
another form of poor management. It is defi- 
nitely poor management to rapidly drive hun- 
gry animals through areas containing poison- 
ous species. In all these cases, livestock are not 
given the opportunity to be selective. Conse- 
quently, they eat almost anything to satisfy 
their hunger. 
Many livestock die because they are trailed 
across ranges infested with poisonous plants. 
Such losses can generally be reduced substan- 
tially by feeding them supplements before 
placing them on such ranges. Repeated feeding 
of specific supplements has effectively alle- 
viated poisoning by certain species. Oxalate 
poisoning by Halogeton and Sarcobatus usually 
can be prevented if sheep are fed a daily grain 
or alfalfa pellet supplement containing 10-per- 
cent dicalcium phosphate (U.S.D.A., A.D. & 
P.R.D. 1964). The use of salt containing sulfur 
in a 12:1 ratio or the addition of about 1-per- 
cent maltose or glucose sugar to the daily ra- 
tion (Durrell et al. 1950) has been reported 
helpful in lessening prussic acid poisoning in 
animals of the cyanogenic species. Poisoning 
from the glycosides in Helenium hoopesw can 
68 
be reduced by daily feedings of a mineral-oil 
supplement containing seven parts trace-min- 
eralized salt and three parts dicalcium phos- 
phate (U.S.D.A., A.D. & P.R.D. 1964). Devel- 
opment of such alleviants is a promising ap- 
proach to the problem of learning how to 
safely use the forage produced on ranges 
where poisonous plants are found. 
Poisonous plants seldom grow in such abun- 
dance as to justify extensive eradication pro- 
grams. Judicious management will usually 
prevent livestock losses. For this reason, the 
potential problem caused by the presence of 
poisonous plants should be carefully considered 
in any proposed grazing system. Both choice of 
season and choice of animal come into play. 
For example, it would be foolhardy to inten- 
sively graze a lupine-infested range in late 
summer with sheep, even though this same 
range might be intensively grazed in early 
summer without danger. Similarly, use of lark- 
spur-infested ranges could be fatal to cattle, 
but these might be safely grazed by sheep. In 
all cases, grazing influences should be con- 
trolled so that they do not promote an increase 
in the toxic species. Such considerations must 
be carefully evaluated and incorporated into 
management systems designed for specific 
range areas. 
The problem of nutritious but unpalatable 
species is even more challenging. Just why do 
animals refuse to eat many of our abundant 
range plants? Some investigators maintain 
that the grazing animal instinctively selects 
the most nutritious species (Stapledon 1947; 
Ellison 1948). Others disagree with this hy- 
pothesis (Tribe and Gordon 1950). Smell, 
taste, and touch have been shown to markedly 
affect forage preference (Arnold 1966b) ; how- 
ever, sight apparently is insignificant (Arnold 
1966a). Plice (1952) found that cows have a 
definite ‘“‘sweet tooth’ and readily graze usu- 
ally unpalatable forage sprayed with sugar so- 
lutions or even with noncaloric artificial sweet- 
eners. Palatability and utilization of rank, dry 
forage can be greatly increased in some cases 
by spraying with molasses (Wagnon and Goss 
1961). Fertilizing with available phosphorus 
has been suggested as a means to increase the 
sugar content of forage and thus enhance pal- 
atability (Plice 1952). If we better understood 
the chemical constituents contributing to the 
unpalatability of certain species, we would be 
better able to develop techniques to nullify 
their objectionable effects. 
Our knowledge of the forage values of range 
species is still fairly superficial. Our judgments 
are largely based upon what the cow likes. 
This could be equated to feeding one’s children 
a diet of cookies, cake, and candy—that is 
what they like! A critical evaluation of a spe- 
cies’ value for producing range forage should 
