Cream removal, pasteurization, and spray-drying of milk did not affect concentration of either natural or iodophor-derived iodine, as measured by both chemical and electrode methods, although electrode results were significantly higher. The use of iodine-131 labeled iodophor showed that only .02% of iodine was lost from milk on boiling and that 3.4% of iodophor-iodine became associated with milk casein.

SUMMARYTwo groups of pregnant ewes were given either 1 (control) or 31 (treatment) mg fluoride/1 drinking water. Weekly blood samples were tested for serum fluoride, haematocrit, T3, T4, cortisol, calcium and magnesium. At parturition, serum fluoride was measured in both ewes and lambs. Later, parallel blood and milk samples were taken from ewes and measured for fluoride. Weekly blood samples from the lambs were measured for the same variables, as well as serum phosphate, body weight, bone fluoride and wool production. Serum fluoride in control ewes ranged from 0·6 to 1·9 μmol/1 and in treatment ewes from 8·7 to 35·4/ μmol/1. At birth, serum fluoride of control lambs averaged 0·50 ± 0·042 μmol/1 and of treatment lambs 1·72 ± 0·167 μmol/1. In milk from the control group mean fluoride concentration was 7·11 ± 0·403 μmol/1, and from the treatment group 22·0 ± 1·48 μmol/1. No differences in haematocrit T3, T4, cortisol, calcium or magnesium of ewes were apparent during pregnancy. At birth, body weight of the treatment group lambs was reduced, and T3, calcium and magnesium increased. At 3–4 weeks mean bone fluoride of lambs was higher in the treatment group (580 ± 117 mg/kg) than the control group (105 ± 26·9 mg/kg). After 7 weeks there was an upward trend in serum phosphate of treated lambs, and their wool production (clean fleece weight) at 17 weeks was reduced by 18%, primarily because of decreased staple length.

The retention and release of iodophor-derived iodine from milking machine materials was studied using 1311-labelled iodophor and small tubes of materials used in the construction of milking machines. After one hour's exposure to this iodophor, plastic retained 56% of the l31I label, followed by silicone rubber (31 %), rubber (IS%), steel (2 %,) and glass (0.5 %). Water rinsing after exposure to iodophor reduced these values to 49:/,, 26%, 14%, 0.5% and 0.3 % respectively. When the tubes were exposed to the iodophor and subsequently rinsed with milk, rubber released the largest amount of iodine into milk (0.099 pg I cm-2), followed by silicone (0.038 pg I cm-2), plastic (0.010 pg 1 cm-2), glass (0.009 pg I cm-2) and steel (0.002 pg I cm-"). The contact time of iodophor with a particular material influenced both the amount of iodine adsorbed, and the amount subsequently released into milk. The importance of iodine adsorption and desorption phenomena in contributing iodine to milk was compared to that iodine in milk arising from inadequate drainage of iodophor solution from a milking machine, and found to be comparable in magnitude.

Iodophor chemistry was studied by using a laboratory-prepared iodophor and varying the proportions of its components (elemental iodine, hydriodic acid, nonionic surfactand and phosphoric acid). In the control formulation, all of the iodine was recovered in the inorganic form with about 70% of this being present as the available (bactericidal) form, and the remaining 30% as iodide. In the absence of hydriodic acid, about 5-10 "/, of the added iodine became chemically bound to the surfactant. The surfactant was responsible for the solubilisation of 47% of the formula iodine, and decreasing surfactant concentration or increasing iodine concentration produced heterogeneous preparations. Alteration of phosphoric acid concentration did not affect the iodine equilibrium of the preparation.

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