Ideally one should test 10 animals individually. T 4 tests are most unreliable in assessing I status. I tests are unreliable also. They are useful only if they are low but can mislead otherwise. However, clinical and subclinical signs of I-deficiency have been confirmed in herds and flocks throughout the state.
Similar problems occur in sheep.
Pro rata supplements are suggested for other ruminants. As long as the animals get this level of I-supplement during the critical times of the year, it does not matter whether the supplement is given in the feed , on the feed , or via the water supply . Differential diagnosis is important. For animal treatment only. Keep away from children.