Iodine concentrations in milk from iodophor teat dips.

Forty Holstein and Jersey cattle were assigned to four groups by milk production of Dairy Herd Improvement Association records. Cattle were on pasture and free-choice roughage supplemented with a concentrate and mineral mixture that was mixed without iodine supplementation. Teats of cows in each group were dipped for 27 days with chlorhexidine (controls) or iodophor teat dips with 1, .25, or .1% concentrations of iodine. Individual milk samples were taken on days 0, 20, and 27 for determination of iodine in milk. Mean iodine remained fairly constant, although there was a transitory increase for 1 and .25% dips at day 20. Mean iodine in milk (microgram/liter) for days 0, 20, and 27 were control: 31.3, 19.8, 14.7; 1.0%: 21.8, 51.5, 23.7; .25%: 34.5, 46.9, 36.7; .1%: 13.6, 14.5, 14.9. Iodophor teat dips did not add appreciable amounts of iodine to the bulk milk.