The objective of this study was to determine potential iodine residues in milk after predipping with a teat disinfectant containing 0.27% polyvidone iodine. For a period of 12 days the teats of 8 lactating dairy cows were alternately predipped or conventionally cleaned. Identical treatments were applied during morning and afternoon milkings but changed from day to day. After dipping, teats were dried manually with disposable paper towels. Two aliquots of 50 ml were collected from bucket milk at each milking. The samples were frozen (-20 degreesC) until analysis. An iodine selective electrode (pH340 - Ion, WTW GmbH, Weilheim, Germany) was used to measure the iodine concentration in milk. The influence of cow, milk yield and treatment on iodine concentration in milk was analyzed using the UNIANOVA procedure of SPSS(C)10.0 (SPSS Inc. Munich, Germany). Iodine concentration of milk was 243+/-51 ppb on days with predipping and 213+/-38 ppb on control days, respectively (p<0.01). However, iodine concentrations remained within the physiological range of milk in all animals. Iodine concentration was influenced by the individual cows (p<0.01) and negatively correlated to milk yield. The difference between treatment and control days decreased with increasing milk production.
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