niques. In a mixed-species stand, nutritive 
values are not necessarily the same for all spe- 
cles at any given time, and are constantly 
changing with time. Mixtures of the same spe- 
cies in varying proportions often will show in- 
teracting values as reflected in the animal re- 
sponse. A _ single-species stand involves less 
complexities, but still presents many problems 
such as changes within and between growing 
seasons, differences due to locality, and genetic 
differences in individuals. 
In many livestock studies, changes in animal 
weights have been used to measure response 
to treatment. While the main source of 
error for output per animal is the between-ani- 
mal component, overall error could be reduced 
if more accurate estimates of true animal 
weights could be obtained. A scale that auto- 
matically weighs cattle as they go to and from 
a water supply has been developed by Martin 
et al. (1967). Thus, automatic weighing of 
livestock may reduce overall error both by 
providing many more weights during the 
growing season, and by eliminating the weight 
losses due to fasting the animals prior to 
weighing, the conventional system now in use. 
If we try to relate forage values to animal 
products, it seems that the real statistical 
problem is one of returning to specifics. In 
other words, we are talking about treatment 
populations of individual animals or very small 
groups of animals being grazed on small areas. 
For some studies it might even imply the clip- 
ping or mowing of the vegetation and subse- 
quent feeding to animals in pens or stalls. Di- 
gestibility could then be determined by total 
collection methods. From small sample tests, 
we could then devise sensible treatments that 
would change forage values. Then we could try 
them on larger areas. 
Experimental designs utilizing individual 
animals or small groups of animals that are 
confined or grazing small areas are availa- 
ble. Many of these designs have been reviewed 
by Federer (1955). Some recent papers include 
those by Stobbs and Joblin (1966a, 1966b), 
who discuss an “animal” Latin-square design 
and variable stocking-rate designs, and by 
Gardner and Centeno (1966), who discuss the 
removal of the effects of uneven grazing in 
pasture experiments. 
On native and seeded western ranges, it 
seems that the problem of forage quality evalu- 
ation can be resolved if the following questions 
are answered. 
1. How far can we go in using the methods 
and designs developed for pasture research in 
more humid regions? An answer to this ques- 
tion should be the first step. 
2. Can we develop new methods and tech- 
niques for use on western or forested ranges? 
For vegetation-oriented studies, an answer 
could be possible through further research and 
development of electronic or radioisotope, or 
even through laser instrumentation. For ani- 
mal-oriented studies, the picture seems clou- 
dier. However, we should intensify our efforts 
on such studies. 
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