Milking Management and Bulk Milk Iodine Concentrations in Ontario Dairy Herds

Abstract

The role of hygiene in the prevention of new intramammary infections has been well understood since the late 1950's. In 1965, Newbould reviewed the literature on disinfection in the prevention of udder infections.¹ Throughout the next decade, numerous disinfectant products were approved and marketed. Even though significant extension education efforts were mounted, in 1981 a formal observational study reported that the implementation of proper milking management methods on Ontario dairy farms had not kept pace with the current knowledge on mastitis control.² Barely 50% of herds were using post-milking teat dipping. Since that time, there has been relatively little published regarding implementation of recommended mastitis control practices.³ During the same time period, the iodine content of fluid milk has been questioned. The concentration of iodine has been reported for raw farm milk⁴ and for retail milk samples.⁵ Some evidence of samples with high milk iodine content was documented in these reports. Even though iodine is essential, it is a potentially harmful dietary element, and cause for public concern. The impact of pre-milking teat disinfection on the iodine content of milk has been studied.⁶ However, recent literature is lacking on the prevalence of elevated iodine in the farm-gate milk supply. The objective of this project was to determine the current status of the Ontario dairy industry for frequency of use of various milking management procedures, and to study the association between the use of these practices and bulk milk iodine concentrations.