Iodine concentration in forages from dairy farms in the IXth and Xth Regions of Chile

Abstract

Iodine (I) content of rations is a factor associated with the blood concentration of thyroxine (T₄) and triiodothyronine (T₃) in cattle. In herds from southern Chile, low blood concentrations of T₄ in grazing dairy cows have been reported. The objective was to obtain information about the I content in forage samples from dairy farms in the IXth and Xth Regions of Chile. During 1999 forage samples were taken from 25 dairy farms located in both Regions. The I concentration was analysed by a kinetic-colorimetric method. Mean, standard deviation and ranges and the frequency of samples with values below 0.4 ppm on a dry matter basis (normal value) were obtained. The average of I concentration in the forage samples was 0.20±0.08 ppm. Forage with normal concentrations were not found. These results suggest an I deficiency in forage from southern Chile, and may be associated with low blood concentrations of T₄ in grazing dairy cows.