Effect of dietary iodine on tissue iodine content in the bovine

Twelve yearling Holstein steers were blocked by weight and assigned to receive one of three dietary I levels (0, 50 or 400 mg ethylenediamine dihydriodide [EDDI]/head/day) for 4 weeks. Average daily gain, body temperature and respiration rate were measured before and during the I feeding period, and no significant differences among treatment groups were found. Serum total I showed a significant increase with each increment of I. When animals were slaughtered, five muscle samples and liver and thyroid samples were dissected for I analysis. Mean total muscle I levels for the 0-, 50- and 400-mg treatment groups were .092, .127 and .406 micrograms/g wet tissue, respectively, each being different (P less than .05) from the other two. I concentrations did not differ statistically between individual muscles within the 0- and 50-mg treatment groups, but in the 400-mg EDDI group, the trapezius (.469 micrograms/g) and biceps brachii (.569 micrograms/g) muscles had higher (P less than .05) I concentrations than the semimembranous (.316 micrograms/g), psoas major (.365 micrograms/g) and longissimus (.307 micrograms/g). Dietary I increased (P less than .05) liver and thyroid I concentrations in the 400-mg treatment group over those observed for the 0- and 50-mg treatment groups.