ARS | Publication request: Assessing the Relationship Between Ruminal Perchlorate Infusion in Dairy Cows and Its Levels in Milk

Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract
Publication Acceptance Date: February 21, 2005
Publication Date: May 20, 2005
Citation: Capuco, A.V., Baldwin, R.L., Rice, C., Hare Jr, W.R., Paape, M.J., Bannerman, D.D., Kauf, A.C., Mccarty, G.W., Sadeghi, A.M., Starr, J.L., Mcconnell, L.L., Hapeman, C.J., Van Tassell, C.P. 2005. Assessing the relationship between ruminal perchlorate infusion in dairy cows and its levels in milk [abstract]. Journal of Dairy Science. 88(1):237.

Technical Abstract: Perchlorate is a goitrogenic anion that is a competitive inhibitor of the sodium-iodide symporter. At sufficient concentration, perchlorate can reduce thyroid uptake of iodine and ultimately reduce the secretion of thyroxine and triiodothyronine. Perchlorate has also been perceived as an environmental contaminant of concern in regions of the country where it has been released during its manufacture or distribution for use in rocket fuel and other oxidative products. Recent studies have shown the presence of perchlorate in dairy cow feed components, such as alfalfa, and in milk samples collected from cows throughout the U.S. A comprehensive study was performed to determine the relationship between dietary perchlorate and concentrations of perchlorate in milk, as well as its effect on thyroid hormone secretion and general animal health. Sixteen Holstein cows were randomly assigned to receive 0, 0.4, 4 or 40 mg of perchlorate daily as a 22-h continuous infusion. The total mixed ration contained an average of 21 ppb perchlorate and 1.6 ppm of iodine. Concentrations of perchlorate in milk averaged 5.4, 7.8, 16.7 and 97.3 ng/ml for the 0, 0.4, 4.0 and 40 mg/d doses, respectively. The Pearson correlation coefficient of milk perchlorate vs. perchlorate intake was 0.99. The daily total output of perchlorate in milk, urine and feces was significantly less than that infused, suggesting that a large portion of the infused perchlorate was metabolized. Concentrations of thyroid hormones in the circulation were not influenced by perchlorate treatment during the 5-wk infusion period. Upon termination of perchlorate infusion, concentrations in milk, blood and urine returned to control values within 72 h. Overall, our data indicate that milk perchlorate is highly correlated with perchlorate intake and, within the confines of a 5-wk treatment, no demonstrable health effects on the cow were observed.