Table 1.

Methods used to calculate antimicrobial use for surveillance data collected from sentinel broiler chicken and turkey farms, 2013–2019.

Measurements	Numerator	Denominator
1. Frequency	No. of flocks using antimicrobials	Total no. of flocks surveyed
2. Days exposed per AAI	No. of days exposed	N/A
3. mg AAI	Feed: Ton fed × level of drug in the feed in grams × 1,000 Water: g AAI per liter of water × 1,000 Injections: mg AAI injected per bird or hatching egg
Routine CIPARS AMU estimation methodology
4. ${\text{mg/PCU}}_{\text{Br}}^{\text{a}}$ and ${\text{mg/PCU}}_{\text{Tk}}^{\text{a}}$	By class: mg of all AAIs (#3) Total flock: mg of all classes	Broilers: Birds at risk × 1 kg ESVAC average weight at treatment Turkeys: Birds at risk × 6.5 kg ESVAC average weight at treatment
5. nDDDvetCA/1,000 broiler chicken-days at riska and nDDDvetCA/1,000 turkey-days at riska	mg adjusted by the DDDvetCA standard By class: nDDDvetCAc's of all AAIs Total flock: nDDDvetCA's of all classes	Broilers: Birds at risk × 1 kg ESVAC average weight at treatment × days at risk Turkeys: Birds at risk × 6.5 kg ESVAC average weight at treatment × days at risk
6. ${\text{nDDDvetCA/PCU}}_{\text{Br}}^{\text{a}}$ and ${\text{nDDDvetCA/PCU}}_{\text{Tk}}^{\text{a}}$	As above in #5	As above in #4
Alternate AMU estimation methodology
7. ${\text{mg/kg}}_{\text{Br}}^{\text{b}}$ and ${\text{mg/kg}}_{\text{Tk}}^{\text{b}}$	By class: mg of all AAIs, all routes (as in #4) Total flock: mg of all classes, as in #4	Broilers: Birds at risk × kg broiler biomass1 Turkeys: Birds at risk × kg turkey biomass1
8. nDDDvetCA/1,000 broiler chicken days at riskb and nDDDvetCA/1,000 turkey-days at riskb	By class: nDDDvetCAs of all AAIs (as in #5) Total flock: nDDDvetCA's of all classes (as in #5)	Broilers: Birds at risk × kg broiler biomass × days at risk Turkeys: Birds at risk × kg turkey biomass × days at risk
9. ${\text{nDDDvetCA/kg}}_{\text{Br}}^{\text{b}}$ and ${\text{nDDDveCA/kg}}_{\text{Tk}}^{\text{b}}$	As above in #8	(As in #7)

¹Broiler chicken and turkey average pre-slaughter live weights in kg (the animal biomass).

^aBased on routine CIPARS formula (7, 19).

^bkg broiler chicken and turkey live pre-slaughter weights.

^cDDDvetCA—defined daily doses for animals using Canadian standards. DDDvetCA standards described elsewhere (20).

AAI, antimicrobial active ingredient.

nDDDvetCA, number of defined daily doses for animals using Canadian standards.

ESVAC, European Surveillance for Veterinary Antimicrobial Consumption.

PCU, population correction unit.

N/A, not applicable.

Br, broilers.

Tk, turkeys.