Trace Element Supplementation of Livestock in New Zealand: Meeting the Challenges of Free-Range Grazing Systems

Figure 6

Effect of no treatment (◯) or intramuscular injection of 400 mg iodised oil (about 7 mg I/kg LW) (●) administered to ewes during early gestation on the concentrations of serum total I in ewes (◯, ●) and their lambs (∆, ▲). The percentage perinatal mortality and the thyroid-weight : birthweight ratio (g/kg) in lambs from the unsupplemented and I-supplemented ewes were 27% versus 16% and 0.70 versus 0.27, respectively. Ratios >0.4 g/kg indicate that a flock is at risk of deficiency and is likely to respond to I supplementation [10, 13].