Most of the future increase in livestock production is expected to occur
in the tropical and subtropical regions of the world. Cattle are the
most numerous of the ruminant species in the tropics and provide the
largest quantity of animal food products. More than one-third of the
world's cattle are found in the tropics. Disease is the major factor
which prohibits full utilization of these regions for cattle production.
Various infectious and transmissible viral, rick- ettsial, bacterial,
and particularly protozoan and helminthic diseases, are widespread in
the tropics and exert a heavy toll on the existing cattle industry
there. This uncontrolled disease situation also discourages investment
in cattle industries by private and government sectors. In Africa alone,
it is estimated that 125 million head of cattle could be accommodated in
the tropical rainbelt if the disease and other animal husbandry factors
could be resolved. The potential of efficient cattle production under
more favorable conditions prompted various international agencies to
establish a multi- million dollar International Laboratory for Research
in Animal Diseases (ILRAD) in Nairobi, Kenya, Africa. In South America,
principal sites for raising cattle are shifting to the savannah lands
because the more fertile soils are being used for crop produc- tion,
however, in the savannahs also, disease remains the most powerful
deterrent in implementing the cattle industry.