Iodide Residues in Milk Vary between Iodine-Based Teat Disinfectants.

Majority of iodine found in dairy milk comes from the diet and teat disinfection products used during milking process. The objective of this study was to evaluate the effects of 4 iodine-based teat dips on milk iodide concentrations varying in iodine level (0.25% vs. 0.5%, w/w), normal low viscosity dip versus barrier dip, and application method (dip vs. spray) to ensure safe iodine levels in dairy milk when these products are used. The iodine exposure study was performed during a 2-wk period. The trial farm was purged of all iodine-based disinfection products for 21 d during a prestudy "washout period," which resulted in baseline milk iodide range of 145 to 182 ppb. During the experiment, iodine-based teat dips were used as post-milking teat disinfectants and compared to a non-iodine control disinfectant. Milk iodide residue levels for each treatment was evaluated from composited group samples. Introduction of different iodine-based teat disinfectants increased iodide residue content in milk relative to the control by between 8 and 29 µg/L when averaged across the full trial period. However, residues levels for any treatment remained well below the consumable limit of 500 µg/L. The 0.5% iodine disinfectant increased milk iodide levels by 20 µg/L more compared to the 0.25% iodine. Compared to dip-cup application, spray application significantly increased milk iodide residue by 21 µg/L and utilized approximately 23% more teat dip. This carefully controlled study demonstrated an increase in milk iodide concentrations from iodine disinfectants, but increases were small and within acceptable limits.

Declines in blood lead concentrations in clinically affected and unaffected cattle accidentally exposed to lead.

Lead (Pb) poisoning remains a common cause of morbidity in dairy and beef cattle. Although Pb toxicosis is typically diagnosed in cattle with clinical signs of acute or subacute Pb poisoning, it has been hypothesized that subclinical chronic exposure of cattle to Pb, which often goes undiagnosed, poses more of a risk to the human consumer. There is not adequate information on Pb kinetics to determine when or if Pb-exposed cattle can safely enter the food chain. The objectives of the current study were to determine whether subclinical elevations in blood Pb (bPb) were present in cattle from herds where 1 or more individuals had clinical Pb poisoning and to determine the half-life (t(1/2)) of bPb in Pb-exposed cattle. Samples of blood were collected and analyzed for Pb from 126 cattle from 9 farms. Blood lead concentrations ranged from below the detection limit (2.50 µg/dl) to 423.0 µg/dl. Only 11 of the 94 cattle with detectable bPb had clinical signs such as diarrhea, blindness, bruxism, or seizures. When possible, cattle with detectable bPb had serial samples taken. The mean t(1/2) calculated from 44 serially sampled cattle was 135 days (standard deviation: 125 days, range: 3-577 days). A source of Pb on the farm was determined for all but one herd.

The effects of formalin fixation and tissue embedding of bovine liver on copper, iron, and zinc analysis.

Veterinary analytical chemistry laboratories might be called upon to analyze formalin-fixed or paraffin-embedded tissue samples for trace minerals. The purpose of this study was to determine whether concentrations of copper (Cu), iron (Fe), and zinc (Zn) are comparable among fresh or frozen, formalin-fixed, and paraffin-embedded bovine liver samples on an as-received basis. Three liver sample subtypes (fresh or frozen, formalin-fixed, and paraffin-embedded) from 12 cows were collected and analyzed for Cu, Fe, and Zn concentrations. Concentrations were measured by using inductively coupled argon plasma atomic-emission spectroscopy. There was no significant difference in mineral measurements between fresh or frozen and formalin-fixed samples for Cu and Zn (both P > or = 0.052). The median concentration of Fe was lower in the fresh or frozen samples than in the formalin-fixed samples. However, for every pair of fresh or frozen and paraffin-embedded samples for all 3 minerals, the fresh or frozen sample had a lower measurement than the paraffin-embedded sample (all P = 0.005). Differences in mineral measurements associated with tissue processing did not result in differences in classification (within or outside the reference range) for Fe. However, the classification of Cu and Zn was different up to 25% of the time with fresh or frozen versus formalin-fixed or embedded liver. Although Cu, Fe, and Zn concentrations attained from processed tissue may be useful, they must be evaluated with caution.