One option to safeguard a breed is to use it
as one of the components of a cross-breeding
programme. However, any use of pure-bred
females to produce cross-breeds will reduce the
population size unless there is a reproductive surplus
of females. In many cases, the environmental and
management conditions do not allow for much
reproductive surplus – especially in cattle, which
have low reproductive rates. As such, most of
the females that are raised must be retained as
breeding animals in order to maintain the size of
the population. In fact, the largest effect comes
from the requirement for a smaller number of
indigenous breeding males, brought about by
the smaller number of indigenous females that
are being used to produce pure-bred offspring