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Groundwater as a Source of High Iodine Levels in Milk in Eastern and Southwestern Ontario Dairy Herds

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dc.contributor.advisor Kelton, David Rogerson, Courtney Marie 2018-03-15T12:54:53Z 2018-03-15T12:54:53Z 2018-02 2018-02-28 2018-03-15
dc.description.abstract The work described in this thesis was conducted to evaluate if groundwater containing naturally high levels of iodide, consumed by lactating cows, contributes to increased levels of iodine in bulk tank milk. The study included 80 dairy herds in eastern (n=58) and southwestern (n=22) Ontario with consistently low, elevated, or high bulk milk iodine (BMI) levels. The first study objective was to evaluate the variation in BMI levels, and identify potential explanatory variables that may contribute to increased milk iodine levels on farms. Results of this analysis indicate that higher iodide content in groundwater is significantly associated with BMI concentration. In addition, BMI content was associated with the coverage goal of post-milking disinfectants on teats, and iodine content of feed. The second objective was to evaluate the isotopic composition of iodine in bulk tank milk (BTM) produced and the water consumed by the lactating herds, and to compare the respective isotopic 129I/127I ratios to determine if groundwater is a major contributing source of iodine in BTM. The isotopic fingerprint of raw milk and groundwater consumed by lactating cattle contained similar radiogenic and geogenic identities, further indicating that BMI levels can be altered by iodine inputs from groundwater consumed by the milking herd. Overall, the current field-based study provides strong evidence that groundwater is a significant contributing source of iodine to BTM in dairy herds located in eastern and southwestern Ontario. en_US
dc.description.sponsorship Dairy Farmers of Ontario, Ontario Ministry of Agriculture, Food and Rural Affairs, Ontario Veterinary College, Ontario Geological Survey en_US
dc.language.iso en en_US
dc.subject Milk Iodine en_US
dc.subject Milk Quality en_US
dc.subject Dairy Cattle en_US
dc.title Groundwater as a Source of High Iodine Levels in Milk in Eastern and Southwestern Ontario Dairy Herds en_US
dc.type Thesis en_US Population Medicine en_US Master of Science en_US Department of Population Medicine en_US
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