Abstract
Ruminants comprise a large class of mammals
distributed over the greater part of the earth's
surface. The digestive system of these animals has
been adapted for the digestion of grass and other
cellulosic materials which form the natural diet of
the group as a whole. Since this diet is both bulky
and indigestible it is to be expected that the ratio
of the capacity of the digestive system to body
weight is higher in ruminants than it is for example
in carnivorous animals. For this purpose the lower
part of the oesophagus in the ruminant forms a large
sac or rumen. The ingested food passes into the
rumen and is mixed with the dense rumen microbial
population. It is in the rumen that the digestion
of cellulose by rumen bacteria takes place. The
relationship between the rumen microflora and the
host is thought to be symbiotic and since a large
percentage of the world's human population is
dependent directly or indirectly upon ruminants for
food the economic importance of this symbiotic
relationship cannot be over emphasised. Especially
asp but for these animals much of the yearly crop of grass and other cellulosic material would not be
converted into protein but broken down by soil
bacteria and so be lost to man.
In most parts of the world the continuous
growth of plants is not possible, due to the
sequence of the seasons or to the alternation of wet
and dry periods. Thus, at intervals, herbivores
must live on vegetation which has completed its
growth cycle and has become dry, woody and resistant
to digestion. The digestive system of the ruminant
can utilise such material and as a result these
animals are not seriously affected by drought and
other inclement weather conditions. This may account
for the success of the group in the modern world.
In addition it is this ability to utilise cellulose
efficiently that has led to the domestication and
breeding of the ruminant.
