Feeds, iodine content

Although trace amounts of supplemental iodine (50-100 rg/kg feed dry matter) effectively prevent goiter, they are currently difficult to detect and measure accurately. More sensitive methods to determine the iodine content of feed, including matrix disintegration, are required. Methods with the potential to reliably detect < 20 ig iodine/kg should be critically evaluated. The reliability of the reported feed iodine content should be questioned in animal studies if goiter or other symptoms of iodine deficiency are reported, despite the use of diets thought to contain more than 100 xg detected iodine/kg... 

The major catalytic uses involve the complex cis-[Rh(CO)2l2] in the Monsanto acetic acid and Termessee-Eastman acetic anhydride processes, discussed in detail in Section 26.4. Application of iodine as a stabilizer includes its incorporation into nylon used in carpet and t5re manufacture. Iodized animal feed supplements are responsible for reduced instances of goitre (enlarged thyroid gland) which are otherwise prevalent in regions where the iodine content... 

The analysis of iodine contents of several feeds and foodstuffs grown on German soils from the Triassic formation (distance from seaside 400 km) shows that vegetation on Bunter, Muschelkalk and Keuper weathering soils have, on average, a 28% lower iodine concentration (Table 9-4.2). This reflects the distance to the seaside and the lower iodine levels in sediments of the Triassic formation. 

In varying with species, the thyroids of iodine-deficient goats, sheep and cattle receiving less than 100 jg I kg feed DM retained significantly smaller amounts of iodine (Table 9.4-24). The thyroid iodine content in iodine-deficient kids and calves was < 5% of the amount stored in the thyroids of control kids and calves. Their mothers accumulated only < 10% of the normal... 

Table 9.4-25). The consumption of 200 jg I kg feed DM by growing animals and of 300 xg kg feed DM by milking and egg-laying species met the iodine requirement of farm animals (Anke 1982). The total iodine content of blood serum under these conditions reached the limits of a normal iodine status of farm ruminants (Table 9.4-25). 

Hemken RW, Fox JD and Hicks CL (1981) Miife iodine content as influenced by feed sources and sanitizer residues. J Food Protect 44 476-487. 

In 1985, to combat iodine deficiency in the former state of East Germany, salt for human consumption was iodized and iodine was added to animal feed (Anke et al., 1993). Eliminating iodine deficiency in farm animals improved the iodine content of milk and eggs. This further increased the dietary iodine intake of East Germans (see section The Effect of Iodine Intake on the Iodine Gontent of Eggs, Meat and Milk ). The program successfully reduced iodine deficiency in both humans and farm animals, and could be used as a model for iodine supplementation in other countries. 

This chapter discusses the importance of iodine supplementation of animal feed. The iodine content of animal feed and the impact on the health of animals and the food obtained from animals (e.g., milk, eggs and meat) are considered. 

Despite the low iodine content of plants, the development or severity of iodine deficiency is amefiorated by the trace amounts of iodine in some feeds, drinking water and even air. As a result of the iodine content of seawater and its vaporization and precipitation air, water, soil and plants in coastal regions contain more iodine (McDowell, 2003). Livestock kept on coastal farms are therefore less at risk of iodine deficiency than those reared on mountains. In addition, the types and amounts of iodine antagonists, the iodine reserves and salvaging mechanisms vary between farm animal species, categories, herds and individuals. 

The iodine content of eggs, milk, and to some extent meat, produced by farm animals reflect the feed iodine supplementation. The effects of increasing iodine intake... 

The higher iodine concentration of winter milk is explained by the use of cow fodder fortified with iodine (Dahl et at, 2003b), and these findings are in accordance with a number of studies from other countries (Varo et al., 1982 Pennington, 1990 Lee et al., 1994 Phillips, 1997 Ministry of Agriculture, Fisheries and Food, 1997, 1999, 2000 Larsen et al., 1999 Rasmussen et al., 2000). The iodine content of animal feed is controlled by legislation in Norway. The fortification of cow fodder with 2 mg-l/kg... 

Variances in iodine content of formula feeds, and the limited number of studies, emphasize the need for carefully-conducted research to investigate the infiuences of gestation, postnatal age, intercurrent illnesses, and so on, on iodine homeostasis in preterm infants. 

The aim of this chapter is to describe iodine intakes based on the calculated amounts for standard infant formulas available in the UK, and for all proprietary enteral preparations that can be used as standalone feeds for complete nutrition. The proprietary preparations highlighted in this review are those that are fisted in the British National Formulary, and the corresponding version for Children 2006 (British National Formulary for Children, 2006) mostly in the section Appendix A2 Borderline Substances excluding those which we know have been discontinued (from 2007). Enteral supplements which are not the sole source of nutrition have not been included, as potential iodine intake will be variable and dependent on the proportion of enteral supplement consumed, as well as the amount and iodine content of nonsupplemented food. 

The major natural food source of iodine is fish. The iodine content of fish reflects that of the water they inhabit thus, high levels of iodine are present in marine fish and shellfish compared to freshwater fish (Figure 45.1). Milk and dairy products contain relatively high amounts of iodine and are considered to be the most important sources of iodine in developed countries. The iodine content of milk is largely influenced by the use of iodophors as teat sterilants and equipment sanitizers in dairy husbandry, and the supplementation of animal feeds due to iodine deficiency in dairy cattle, exacerbated by the inclusion of goitrogenic feeds in the diet (COT, 2003). In addition, seasonal variations in the iodine content of foods are particularly evident in cows milk, with greater iodine... 

Iodine deficiency during the perinatal period and exposure to an iodine excess is quite conspicuos. The iodine intake of newborns is entirely dependent on the iodine content of breast milk and formula preparations used to feed them. The minimum recommended dietary allowance (RDA) for different age groups is summarized in Table 50.1. To meet such requirements, the iodine content of formulas for premature newborns should contain 20 j,g/dl, and that of first and follow-up preparations 10 j,g/dl. We refer here to these new... 

Generally, the iodine content of foods varies across regions and countries, according to the amounts of naturally occurring iodine and the levels and extent of iodine supplementation in table salt, animal feed and processed foods. This is illustrated in Tables 54.3-54.5, which also reflect differences in reference tables used in various countries to describe the nutritional content of common foods (Krajcovicova-Kudlackova et al., 2003 Lightowler etal., 1996). 

Large doses of iodate (1.4—15 mg iodine per kilogram) blocked thyroidal uptake of injected labeled iodide in rats, again suggesting that iodine from iodate is available to the thyroid (Pahuja et al., 1993 Wyngaarden et al., 1952). When added to animal feed, iodate increases the iodine content of eggs and milk (Anke et al., 1998). 

Iodine is a trace element whose only identified role is the synthesis of thyroid hormones. The most important source of dietary iodine in developed countries is dairy products, partly due to the high iodine content in some cattle feed. In... 

Despite the reduction in iodine content of dairy products, the contribution of these foods to the total iodine intake in the 2003-2004 NZTDS was still high, with 34% of the intake of a young male and 67% of that of a 1—3-year-old child (Vannoort and Thomson, 2005). A comparison of concentrations in corresponding foods analyzed for the 2003—2004 NZTDS (Vannoort and Thomson, 2005) with early values produced by Hercus and Roberts (1927), indicates that the only foods that show higher concentrations are cheese and milk as a result of iodophor contamination, and eggs as a result of trace mineral supplementation of poultry feed (Table 129.1). 

Dierick, N., Ovyn, A., and De Smet, S. (2009). Effect of feeding intact brown seaweed AscophyUum nodosum on some digestive parameters and on iodine content in edible tissues in pigs. /. Sci. Food Agric. 89,584r-594. 

---