Iodine Concentration in Milk of Sheep and Goats from Farms in South Bohemia

Abstract

Travniaek, J., J. Kursa: Iodine Concentration in Milk Sheep and Goats from Farms in South Bohemia. Acta Vet. Brno 2001, 70: 35-42. Iodine concentration was determined in milk samples collected from 60 sheep on 10 farms and from 94 goats of 64 farmers. The animals were grazed in the summer and fed hay of local harvests in the winter. Pregnant and lactating sheep received daily 0.2 to 0.4 kg of cereal meal. The iodine concentration in the hay fed to the sheep and goats ranged from 20.5 to 162.4 µg per 1 kg dry matter. The mean iodine concentration in sheep milk was 105.5 µg . l -1 . The corresponding value for the farms (n = 4) where the sheep had access to mineral licks (35 mg iodine per 1 kg) was 243.3 ± ± 87.2 µg . l -1 (ranged from 107.7 to 436.6) and for the rest of the farms (n = 6) 47.9 ± 27.8 µg . l -1 . Mean iodine concentrations in goat milk (31.6 µg . l-1 in 1998 and 63.0 µg . l-1 in 1999) were indicative of iodine deficiency. The corresponding value for the goats (n = 17) receiving iodised salt was 142.1 ± 102.6 µg . l-1 (ranged from 51.8 to 393.6) and for the remaining goats 19.3 ± ± 13.2 µg . l -1 . The mean iodine concentrations in goat milk on three farms on which neonatal goitre in kids was diagnosed ranged from 8.5 to 23.3 µg . l-1. Kids, lambs, goitre, iodine deficiency, iodine supplementation. Current methods for the assessment of the iodine status include the determination of concentrations of not only urinary, but also milk iodine (Grace 1995), because it has been found that iodine excretion in the milk varies significantly in dependence on its dietary intake. Miller et al. (1974) found that, under normal conditions and an adequate iodine supply, ruminants excrete 8% of ingested iodine in the milk. Determination of milk iodine for diagnostic and epidemiological purposes is often used in studies of the prevalence of juvenile goitre regarded as the most significant manifestation of iodine deficiency (Korber et al. 1985). Groppel (1991) pointed out that, at an equal dietary intake, the ovine and caprine colostrum and milk contain more iodine than milk of cows and that iodine concentrations of 79 µg . l -1 and 62 µg . l -1 in the sheep and goat milk, respectively, are indicative of iodine deficiency. Azuolas and Caple (1984) used milk iodine concentration as a marker of the metabolic and iodine status of sheep in Australia. Mean concentrations found within an extensive monitoring in 59 sheep flocks in the state Victoria ranged from 79 to 1 831 µg . l -1 . Two flocks in which goitre was diagnosed in lambs showed variations in the milk iodine concentration within the range of 45 to 98 µg . l -1 . Milk of ewes receiving 30 µg of iodine per animal per day contained 45 µg . l -1 and 80% of their lambs developed neonatal goitre. On the other hand, daily intake of 80 to 100 µg I resulted in milk concentrations 95 to 131 µg . l -1 and lambs were