The VWC for feed was calculated based on the amount of feed consumed by an animal, water consumption in feed production, and slaughtering age (Chapagain and Hoekstra 2003).
The conversion for any given feed was calculated as (feed converted)/(feed fed), while the yield was based on a carbon equivalency, so for all feeds the yield = (carbon in product molecule)/(carbon fed).
The detection limit in swine feed was calculated to be 0.008 mg/g and the recoveries were in the range of 97%–102%.
Use of feeding substitutes (tube feeding) was calculated per disease severity stage from the two databases.
Antimicrobial use in feed was calculated separately for each growth stage.
Silicon concentration of the drinking water was obtained directly from the ICP-OES measurement, whilst the Si content of the feed was calculated using the method described below.
The feed was calculated to contain 23% protein and 3200 kcal of metabolized energy/kg of diet, and all other nutrient rations met or exceeded the standards established by the National Research Council (1994).
The time of the first mixed feed was calculated based on data from multiple sources: the current breastfeeding question in the clinic visit form, the current breastfeeding question and evidence of current mixed feeding (e.g., baby seen eating other foods, food on baby's clothes) in the home visit form, the breastfeeding cessation date form, and a mixed feeding form.
Ratios of NOAEL (and LOAEL), expressed as pesticide concentrations in feed, were calculated from subacute to subchronic, subchronic to chronic and subacute to chronic studies.
