1. Data are presented on the effect of KI in the feed of 40 merino
ewes for a period of 30 months.
2. The quantities of KI given per sheep daily were 0.002 grm.,
0.02 grm., 0.06 grm. in three groups respectively, while one group
received no KI and acted as controls.
3. Observations were made on the food consumption, weight
increase, wool production, reproduction and health of the animals
for the full period of the experiment. Further, observations were
made on the oestrus cycle of the ewes and no significant group
differences were observed.
4. The animals were fed in individual feeding boxes except the
hay, which was given ad lib.
5. It is concluded that neither the small dose nor the bigger
quantities of KI fed had any visible effect on the weights, wool
production and reproduction of the animals.
6. It is also pointed out that the ill effects ascribed to iodide
feeding in the earlier work were apparently aggravated by another
deficiency, the possibility of the existence of which was not considered in the earlier work, viz. vitamin A.
7. It is concluded that the addition of KI to sheep licks is unwarranted,
may even produce visibly detrimental effects under conditions
of drought, when a vitamin A shortage may exist, and is to be
discouraged in practical farming unless there is reason for believing
that an iodine deficiency exists.
8. Further work on the effects of iodine feeding under practical
conditions, as for instance during severe droughts when apparently
detrimental effects may be experienced, is being undertaken.
The writers wish to acknowledge gratefully the assistance of
Mr. A. P. Malan, Statistician, in dealing with the results given in
the lambing charts.