This trial has provided additional evidence for a
maternal nutritional deficiency in the aetiology of
CCUO. The association of CCUO with native pastures,
drought and hilly to steep terrain is in agreement with
other findings. The possibility of a primary deficiency
of Mn is unlikely, as pasture levels of Mn were suffi-
cient in the samples analysed and liver levels were
considered within normal limits. A deficiency of dietary
Zn is possible as pasture levels were found to be
low, and liver Zn levels were low in a number of cows.
A more extensive trial involving more cows, for the
entire gestation period, may assist in determining
whether a primary nutritional deficiency involving
trace minerals, especially Zn, exists and contributes to
the birth of CCUO calves.