370 THE FUTURE OF ARID LANDS 
lands where agricultural improvements cannot easily be made. 
However, I shall return to the question of increasing the amount 
of available feed in a somewhat different way, with stress on the 
word ‘‘available.” 
Colonel Draz, in his paper in this symposium, has pointed out 
the importance of raising the level of nutrition of the animals for 
increased production. It is obvious that when animals are fed 
just enough for maintenance, no production can take place. By 
cutting down on the number of animals, the same amount of feed 
will serve for production as well as maintenance for the rest of the 
animals. How production increases with increasing level of feed- 
ing, but only above a certain level, is shown in Figure 1. 
One desirable way to increase actual production on a limited 
feed supply would be to indoctrinate the animal owners in this 
very simple fact of production physiology. 
In Norway, as a young student, I tried to convince a country 
woman of the poor economy of keeping chickens too long. She was 
unwilling to kill any hen that was still producing some eggs and 
was angele to see that they consumed an ever increasing amount 
of feed as compared to her return in eggs. It must be equally 
difficult to teach principles of production economy to populations 
where wealth and social prestige is proportional to the number of 
livestock. 
It is well known that overstocking reduces productivity also 
in another way, which has more serious proportions because of 
its more far-reaching effects. I am referring to the effects of 
overgrazing on depletion of vegetation, and the consequential 
reduction of plant production, soil erosion, increased aridity, etc. 
It may prove less difficult to inform people of this chain of events 
than of the more subtle arguments of production economy. 
The Physiological Role of Water 
In arid lands feed is not the only limiting factor; water is a 
precarious commodity that in the hotter part of the year takes on 
the role of a limiting factor of all-encompassing importance. Here 
also there are two ways out: providing more water or being more 
economical with the available water. 
