This manual describes the use of the transfer model to estimate the concentration of dioxins in egg yolk fat and body fat of the laying hen based on oral exposure to feed contaminated with dioxins. The model has several input fields (left side) and output fields (right side). The input and results can be saved using the button “Report (*.docx)”. Source information and a citation suggestion are provided (top).
Step1: Contamination level of feed
The user can provide the contamination levels of the individual dioxin congeners (expressed in ng/kg feed) in two ways:
- the user can download a CSV template, fill in the contamination levels and upload the file;
- the user can directly enter the values in the input fields of the individual congeners.
Instead of providing concentrations for the individual dioxin congeners, the user can also enter the total TEQ concentration in the input field for 2,3,7,8-TCDD (input field 11) or in the CSV file.
The reset button at the lower left corner can be used to reset the contamination levels for all congeners at once.
Step 2: Feed intake
The user first has to select the type of feed that is contaminated with dioxins.
a) This can either be:
- Total compound feed (blend of various raw materials and additives)
- Compound feed ingredients
When compound feed ingredients are selected, a drop down menu will appear to select the contaminated compound feed ingredient.
b) After selecting the contaminated feed (ingredient), a default feed intake value is provided (in kg dry matter per day) for the laying hen1. The user can adjust this default value to the value corresponding to the actual feeding regime.
Step 3: Exposure period of laying hen to contaminated feed
To estimate the concentration in egg yolk fat, the user has to enter the duration of the exposure of the animals to the contaminated feed (expressed in days).
Step 4: Regulatory limit (optional)
A regulatory limit (for instance maximum level) (expressed in pg total TEQ/g egg fat) can be inserted. This limit will be displayed in the output graph on the screen, but not yet in the report.
Step 5: Results
The top graph shows either the total TEQ concentration in egg yolk fat (in pg TEQ/g egg yolk fat) or the central compartment (in pg TEQ/g central compartment) versus time. In addition to the calculation based on the total TEQ concentration in the contaminated feed (ingredient), the model also calculates the dioxin concentration in egg yolk fat based on the concentrations provided for the individual congeners. The solid line shows the model calculation based on total TEQ concentration in the contaminated feed (ingredient). The dashed line shows the model calculation based on the concentrations provided for the individual congeners.
All concentrations are valid for the average laying hen. The user can switch between the different graphs using the button below the graph.
In the bottom graph, the user can select a specific day after the beginning of the exposure period using the scroll bar up to a maximum of 250 days. The graph shows the percentages of specific congeners of the total TEQ present/estimated in the contaminated feed (ingredient) and in the egg yolk fat.
Step 6: Saving input and output
Using the “Report (*.docx)” button, present in the left corner, input data and the results of the model run can be stored locally as a report file in word. The optional regulatory limit is not yet visible in the report. Input data and results are not stored at the website.
Step 7: Citation suggestion
At the top of the model page the references that describe the model are listed, as well as a citation suggestion. Please use the suggested citation at the bottom of the webpage, when referring to the model.
1 Van Raamsdonk LWD, Kan CA, Meijer GAL, Kemme PA (2007) Key figures for some farm animals and their consumption patterns [in Dutch]; https://research.wur.nl/en/publications/kengetallen-van-enkele-landbouwhuisdieren-en-hun-consumptiepatron.